U.S. patent application number 13/799549 was filed with the patent office on 2014-09-18 for systems and methods for stimulating swallowing.
This patent application is currently assigned to PASSY-MUIR, INC.. The applicant listed for this patent is PASSY-MUIR, INC.. Invention is credited to Larry Lee Hood, Christy Leslie Ludlow.
Application Number | 20140276270 13/799549 |
Document ID | / |
Family ID | 51530611 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140276270 |
Kind Code |
A1 |
Ludlow; Christy Leslie ; et
al. |
September 18, 2014 |
SYSTEMS AND METHODS FOR STIMULATING SWALLOWING
Abstract
A device includes a first vibrational transducer and a second
vibrational transducer. The first vibrational transducer has a
first vibrating property. The second vibrotactile stimulator has a
second vibrating property different than the first vibrating
property. A collar may be configured to position the first
vibrational transducer and the second vibrational transducer over a
neck of a subject. A method for stimulating swallowing in a subject
includes applying a first vibrotactile stimulation and applying a
second vibrotactile stimulation to a throat area of the subject.
The first vibrotactile stimulation has a first vibrating property
and the second vibrotactile stimulation has a second vibrating
property different than the first vibrating property. Example
vibrating properties include vibrating frequency, vibrating
frequency range, wave shape, continuousness, frequency phase, and
direction of mechanical force.
Inventors: |
Ludlow; Christy Leslie;
(Castleton, VA) ; Hood; Larry Lee; (Irvine,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PASSY-MUIR, INC. |
Irvine |
CA |
US |
|
|
Assignee: |
PASSY-MUIR, INC.
Irvine
CA
|
Family ID: |
51530611 |
Appl. No.: |
13/799549 |
Filed: |
March 13, 2013 |
Current U.S.
Class: |
601/46 |
Current CPC
Class: |
A61N 2005/067 20130101;
A61H 2201/10 20130101; A61H 2230/201 20130101; A61H 2201/5002
20130101; A61B 5/0205 20130101; A61H 2201/5035 20130101; A61N
2007/0026 20130101; A61H 2201/165 20130101; A61H 2230/208 20130101;
A61H 2201/5084 20130101; A61H 2201/0214 20130101; A61H 2201/1609
20130101; A61H 2230/065 20130101; A61H 2201/5097 20130101; A61N
5/0622 20130101; A61H 2201/5005 20130101; A61H 2201/0207 20130101;
A61H 23/00 20130101; A61H 2201/5038 20130101; A61H 2205/04
20130101; A61H 2230/305 20130101; A61H 2230/405 20130101; A61H
2201/102 20130101; A61H 2201/5041 20130101; A61H 2201/5043
20130101; A61H 9/0078 20130101 |
Class at
Publication: |
601/46 |
International
Class: |
A61H 23/00 20060101
A61H023/00 |
Claims
1. A device comprising: a first vibrotactile stimulator configured
to operate at a first vibrating rate; a second vibrotactile
stimulator configured to operate at a second vibrating rate
different than the first vibrating rate; and a collar configured to
position the first vibrotactile stimulator and the second
vibrotactile stimulator over a neck of a subject.
2. The device of claim 1, further comprising a switch configured to
activate the first vibrotactile stimulator and the second
vibrotactile stimulator, the switch configured to be volitionally
operated by the subject.
3. The device of claim 1, further comprising an automatic clock
configured to activate the first vibrotactile stimulator and the
second vibrotactile stimulator.
4. The device of claim 1, wherein the first vibrotactile stimulator
and the second vibrotactile stimulator are configured to operate at
partially simultaneously.
5. The device of claim 1, wherein the first vibrating rate is
between about 30 Hz and about 60 Hz and the second vibrating rate
is between about 60 Hz and about 80 Hz.
6. The device of claim 1, wherein the first vibrating rate is
between about 50 Hz and about 90 Hz and the second vibrating rate
is between about 90 Hz and about 130 Hz.
7. A method for stimulating swallowing in a subject, the method
comprising: applying a first vibrotactile stimulation to a throat
area of the subject, the first vibrotactile stimulation having a
first vibrating property; and applying a second vibrotactile
stimulation to the throat area of the subject, the second
vibrotactile stimulation having a second vibrating property
different than the first vibrating property.
8. The method of claim 7, wherein applying the first vibrotactile
stimulation and applying the second vibrotactile stimulation
includes the subject voluntary activating a first vibrational
transducer and a second vibrational transducer.
9. The method of claim 7, wherein applying the first vibrotactile
stimulation and applying the second vibrotactile stimulation
includes automatically activating a first vibrational transducer
and a second vibrational transducer.
10. The method of claim 9, wherein automatically activating the
first vibrational transducer and the second vibrational transducer
includes coordinating automatically activating the first
vibrational transducer and the second vibrational transducer with a
monitored bodily parameter.
11. The method of claim 7, wherein applying the first vibrotactile
stimulation is at least partially simultaneous with applying the
second vibrotactile stimulation.
12. The method of claim 7, wherein the first vibrating property
comprises a first vibrating frequency and the second vibrating
property comprises a second vibrating frequency different than the
first vibrating frequency.
13. The method of claim 7, wherein the first vibrating property
comprises a first vibrating frequency range and the second
vibrating property comprises a second vibrating frequency range
different than the first vibrating frequency range.
14. The method of claim 7, wherein the first vibrating property
comprises a first wave shape and the second vibrating property
comprises a second wave shape different than the first wave
shape.
15. The method of claim 7, wherein the first vibrating property
comprises a first vibrating frequency and the second vibrating
property comprises a second vibrating frequency out of phase with
the first vibrating frequency.
16. The method of claim 7, wherein the first vibrating property
comprises a continuous vibrating frequency and the second vibrating
property comprises a pulsed vibrating frequency.
17. The method of claim 7, wherein the first vibrating property
comprises a first direction of mechanical force and the second
vibrating property comprises a second direction of mechanical force
different than the first direction of mechanical force.
18. A device comprising: a first vibrational transducer having a
first vibrating property; a second vibrational transducer having a
second vibrating property different than the first vibrating
property; and a collar configured to position the first vibrational
transducer and the second vibrational transducer over a neck of a
subject.
19. The device of claim 18, further comprising a switch configured
to activate the first vibrational transducer and the second
vibrational transducer, the switch configured to be volitionally
operated by the subject.
20. The device of claim 18, further comprising an automatic clock
configured to activate the first vibrational transducer and the
second vibrational transducer.
21. The device of claim 18, wherein the first vibrational
transducer and the second vibrational transducer are configured to
operate at partially simultaneously.
22. The device of claim 18, wherein the first vibrating property
comprises a first vibrating frequency and the second vibrating
property comprises a second vibrating frequency different than the
first vibrating frequency.
Description
INCORPORATION DATA
[0001] U.S. patent application Ser. No. 12/211,633, filed Sep. 16,
2008, U.S. patent application Ser. No. 12/240,398, filed Sep. 29,
2008, U.S. patent application Ser. No. 11/993,094, filed Dec. 19,
2007, PCT Patent App. No. PCT/US2006/025535, filed Jun. 30, 2006,
PCT Patent App. No. PCT/US2007/007993, filed Mar. 30, 2007, U.S.
Prov. Patent App. Ser. No. 60/695,424, filed Jul. 1, 2005, and U.S.
Prov. Patent App. Ser. No. 60/787,215, filed Mar. 30, 2006, are
each hereby incorporated by reference in its entirety.
FIELD
[0002] The present disclosure relates generally to systems and
methods for stimulating swallowing. More specifically, the present
disclosure relates generally to systems and methods for
vibrotactilely stimulating the throat area of a subject to treat
and manage diseases and disorders affecting the muscles of the neck
and/or pharynx.
BACKGROUND
[0003] A wide range of neurological diseases and disorders exist
that are not well addressed by present medical technology. Among
these, dysphagia (a swallowing disorder that affects the central
nervous system thereby weakening neuromuscular control and
effectively reducing the ability to properly swallow) is a
particularly life threatening disorder placing persons at risk of
aspiration pneumonia. Patients at risk of aspiration pneumonia have
a 17% survival rate over three years. Estimates are that over 7
million persons in the United States have dysphagia as a result of
neurological diseases or disorders such as stroke, traumatic brain
injury, brain tumors, Parkinson's disease, multiple sclerosis, and
other neurological diseases, and over 300,000 persons in the United
States develop a swallowing disorder as a result of a neurological
disease or disorder each year. Over 50% of patients with
neurological diseases or disorders are at risk of aspiration
pneumonia because of loss of central nervous system control of
their swallowing resulting in either delayed or reduced elevation
of the hyolaryngeal complex, which does not allow them to prevent
food or liquid from entering the airway. Normally the hyoid and
larynx are raised by about 20 millimeters (mm) during swallowing,
producing an inversion of the epiglottis and assisting with opening
of the upper esophageal sphincter.
[0004] Patients having dysphagia often need 24-hour attention to
inhibit aspiration and ensure that the passage of food and/or
fluids, particularly saliva, into the respiratory system is
minimized. Glass rod pressure stimulation to the faucial pillars in
the mouth can trigger swallowing, while chemical blocks of
laryngeal sensation can severely impair volitional swallowing in
normal adults. Pharyngeal stimulation can initiate laryngeal
closure and elevation for swallowing in animals, while laryngeal
stimulation will trigger a swallow. In humans, sensory stimulation
of the oropharynx presented during a period separate from
swallowing can enhance cortical activity in the swallowing regions,
but does not benefit subsequent swallowing in dysphagic patients.
Such approaches to stimulation generally involve the placement of a
device or probe into the oral cavity, which interferes with eating
food and liquids and can alter oral sensory function in patients
already having oral sensory deficits.
SUMMARY
[0005] Various stimulations methods have been successful at
inducing swallowing and/or speech in subjects, for example,
vibrotactile stimulation using one or more vibrational transducers
each operating between about 30 Hz and about 60 Hz. The use of
multiple vibrational transducers at the same frequency may provide
one or more benefits such vibrating each side of the thyroid
cartilage to support penetration of the vibration into the vocal
folds on each of the right and left sides of the larynx. The use of
multiple vibrational transducers at different vibrating properties
may provide increased subject response. Different vibrating
properties may include vibrating frequency, vibrating frequency
range, wave shape, vibrating continuousness, frequency phase, and
direction of mechanical force. For example, a subject wearing a
device including a first vibrotactile stimulator having a first
frequency and a second vibrotactile stimulator having a second
frequency different than the first frequency may experience greater
increase in induced swallowing compared to one or more vibrotactile
stimulators having a single frequency. A higher success rate can
reduce learning duration, increase use desirability, and produce
more favorable outcomes. Different vibrating properties can also
reduce a subject's ability to adapt to a single frequency.
[0006] In some embodiments, a method for stimulating swallowing in
a subject comprises applying a first vibrotactile stimulation to a
throat area of the subject and applying a second vibrotactile
stimulation to the throat area of the subject. The first
vibrotactile stimulation is at a first vibrating rate. The second
vibrotactile stimulation is at a second vibrating rate different
than the first vibrating rate. Applying the first vibrotactile
stimulation and applying the second vibrotactile stimulation may
include the subject voluntary activating vibrotactile stimulators.
Applying the first vibrotactile stimulation and applying the second
vibrotactile stimulation may include automatically activating the
vibrotactile stimulators. Applying the first vibrotactile
stimulation may be at least partially simultaneous with applying
the second vibrotactile stimulation. The first vibrating rate may
be between about 50 Hz and about 90 Hz and the second vibrating
rate may be between about 90 Hz and about 130 Hz. The first
vibrating rate may be between about 30 Hz and about 60 Hz and the
second vibrating rate may be between about 60 Hz and about 90 Hz.
The first vibrating rate may be between about 20 Hz and about 40 Hz
and the second vibrating rate may be between about 60 Hz and about
80 Hz. The first vibrating rate may be about 30 Hz and the second
vibrating rate may be about 70 Hz. The first vibrating rate may be
about 70 Hz and the second vibrating rate may be about 110 Hz. The
first vibrating rate may be between about 20 Hz and about 60 Hz
different than the second vibrating rate. The first vibrating rate
may be about 40 Hz different than the second vibrating rate.
[0007] In some embodiments, a device comprises a first vibrotactile
stimulator, a second vibrotactile stimulator, and a collar. The
first vibrotactile stimulator is configured to operate at a first
vibrating rate. The second vibrotactile stimulator is configured to
operate at a second vibrating rate different than the first
vibrating rate. The collar is configured to position the first
vibrotactile stimulator and the second vibrotactile stimulator over
a neck of a subject. The device may further comprise a switch
configured to activate the first vibrotactile stimulator and the
second vibrotactile stimulator. The switch may be configured to be
volitionally operated by the subject. The device may further
comprise an automatic clock configured to activate the first
vibrotactile stimulator and the second vibrotactile stimulator. The
first vibrotactile stimulator and the second vibrotactile
stimulator may be configured to operate at partially
simultaneously. The first vibrating rate may be between about 50 Hz
and about 90 Hz and the second vibrating rate may be between about
90 Hz and about 130 Hz. The first vibrating rate may be between
about 30 Hz and about 60 Hz and the second vibrating rate may be
between about 60 Hz and about 90 Hz. The first vibrating rate may
be about 30 Hz and the second vibrating rate may be about 70 Hz.
The first vibrating rate may be about 70 Hz and the second
vibrating rate may be about 110 Hz. The first vibrating rate may be
between about 20 Hz and about 60 Hz different than the second
vibrating rate. The first vibrating rate may be about 40 Hz
different than the second vibrating rate.
[0008] In some embodiments, a method for stimulating swallowing in
a subject comprises applying a first vibrotactile stimulation to a
throat area of the subject, applying a second vibrotactile
stimulation to the throat area of the subject. The first
vibrotactile stimulation has a first vibrating property. The second
vibrotactile stimulation has a second vibrating property different
than the first vibrating property.
[0009] Applying the first vibrotactile stimulation and applying the
second vibrotactile stimulation may include the subject voluntary
activating a first vibrational transducer and a second vibrational
transducer. Applying the first vibrotactile stimulation and
applying the second vibrotactile stimulation may include
automatically activating a first vibrational transducer and a
second vibrational transducer. Automatically activating the first
vibrational transducer and the second vibrational transducer may
include coordinating automatically activating the first vibrational
transducer and the second vibrational transducer with a monitored
bodily parameter. Applying the first vibrotactile stimulation may
be at least partially simultaneous with applying the second
vibrotactile stimulation. The first vibrating property may comprise
a first vibrating frequency and the second vibrating property may
comprise a second vibrating frequency different than the first
vibrating frequency. The first vibrating rate may be between about
30 Hz and about 60 Hz and the second vibrating rate may be between
about 60 Hz and about 80 Hz. The first vibrating rate may be
between about 50 Hz and about 90 Hz and the second vibrating rate
may be between about 90 Hz and about 130 Hz. The first vibrating
rate may be about 30 Hz and the second vibrating rate may be about
70 Hz. The first vibrating rate may be about 70 Hz and the second
vibrating rate may be about 110 Hz. The first vibrating property
may comprise a first vibrating frequency range and the second
vibrating property may comprise a second vibrating frequency range
different than the first vibrating frequency range. The first
vibrating rate range may be between about 30 Hz and about 60 Hz and
the second vibrating rate range may be between about 60 Hz and
about 80 Hz. The first vibrating rate range may be between about 50
Hz and about 90 Hz and the second vibrating rate range may be
between about 90 Hz and about 130 Hz. The first vibrating property
may comprise a first wave shape and the second vibrating property
may comprise a second wave shape different than the first wave
shape. The first wave shape may comprise sinusoidal and the second
wave shape may comprise saw-tooth. The first wave shape may
comprise sinusoidal and the second wave shape may comprise
triangular. The first wave shape may comprise sinusoidal and the
second wave shape may comprise square. The first wave shape may
comprise saw-tooth and the second wave shape may comprise
triangular. The first wave shape may comprise saw-tooth and the
second wave shape may comprise square. The first wave shape may
comprise triangular and the second wave shape may comprise square.
The first vibrating property may comprise a first vibrating
frequency and the second vibrating property may comprise a second
vibrating frequency out of phase with the first vibrating
frequency. The first vibrating frequency and the second vibrating
frequency may be between about 150.degree. and about 210.degree.
out of phase. The first vibrating frequency and the second
vibrating frequency may be about 180.degree. out of phase. The
first vibrating property may comprise a continuous vibrating
frequency and the second vibrating property may comprise a pulsed
vibrating frequency. The first vibrating property may comprise a
first direction of mechanical force and the second vibrating
property may comprise a second direction of mechanical force
different than the first direction of mechanical force. One of the
first direction of mechanical force and the second direction of
mechanical force may be substantially perpendicular. One of the
first direction of mechanical force and the second direction of
mechanical force may be non-perpendicular and non-parallel.
[0010] In some embodiments, a device comprises a first vibrational
transducer and a second vibrational transducer. The first
vibrational transducer has a first vibrating property. The second
vibrational transducer has a second vibrating property different
than the first vibrating property.
[0011] In some embodiments, a device comprises a first vibrational
transducer, a second vibrational transducer, and a collar. The
first vibrational transducer has a first vibrating property. The
second vibrational transducer has a second vibrating property
different than the first vibrating property. The collar is
configured to position the first vibrational transducer and the
second vibrational transducer over a neck of a subject.
[0012] The device may further comprise a switch configured to
activate the first vibrational transducer and the second
vibrational transducer, the switch configured to be volitionally
operated by the subject. The device may further comprise an
automatic clock configured to activate the first vibrational
transducer and the second vibrational transducer. The first
vibrational transducer and the second vibrational transducer are
configured to operate at partially simultaneously. The first
vibrating property may comprise a first vibrating frequency and the
second vibrating property may comprise a second vibrating frequency
different than the first vibrating frequency. The first vibrating
rate may be between about 30 Hz and about 60 Hz and the second
vibrating rate may be between about 60 Hz and about 80 Hz. The
first vibrating rate may be between about 50 Hz and about 90 Hz and
the second vibrating rate may be between about 90 Hz and about 130
Hz. The first vibrating rate may be about 30 Hz and the second
vibrating rate may be about 70 Hz. The first vibrating rate may be
about 70 Hz and the second vibrating rate may be about 110 Hz. The
first vibrating property may comprise a first vibrating frequency
range and the second vibrating property may comprise a second
vibrating frequency range different than the first vibrating
frequency range. The first vibrating rate range may be between
about 30 Hz and about 60 Hz and the second vibrating rate range may
be between about 60 Hz and about 80 Hz. The first vibrating rate
range may be between about 50 Hz and about 90 Hz and the second
vibrating rate range may be between about 90 Hz and about 130 Hz.
The first vibrating property may comprise a first wave shape and
the second vibrating property may comprise a second wave shape
different than the first wave shape. The first wave shape may
comprise sinusoidal and the second wave shape may comprise
saw-tooth. The first wave shape may comprise sinusoidal and the
second wave shape may comprise triangular. The first wave shape may
comprise sinusoidal and the second wave shape may comprise square.
The first wave shape may comprise saw-tooth and the second wave
shape may comprise triangular. The first wave shape may comprise
saw-tooth and the second wave shape may comprise square. The first
wave shape may comprise triangular and the second wave shape may
comprise square. The first vibrating property may comprise a first
vibrating frequency and the second vibrating property may comprise
a second vibrating frequency out of phase with the first vibrating
frequency. The first vibrating frequency and the second vibrating
frequency may be between about 150.degree. and about 210.degree.
out of phase. The device of Embodiment 55, wherein the first
vibrating frequency and the second vibrating frequency may be about
180.degree. out of phase. The first vibrating property may comprise
a continuous vibrating frequency and the second vibrating property
may comprise a pulsed vibrating frequency. The first vibrating
property may comprise a first direction of mechanical force and the
second vibrating property may comprise a second direction of
mechanical force different than the first direction of mechanical
force. One of the first direction of mechanical force and the
second direction of mechanical force may be substantially
perpendicular. One of the first direction of mechanical force and
the second direction of mechanical force may be non-perpendicular
and non-parallel.
[0013] Certain devices and methods disclosed herein can treat a
subject with dysphagia or other neurological disease, neurological
disorder, neurological injury, neurological impairment, or
neurodegenerative disease that affects voluntary motor control of
the hyoid, pharynx, larynx, and/or oropharyngeal area. Certain
devices and methods disclosed herein can be used to treat a subject
with a speech disorder.
[0014] In some embodiments, a device comprises a stimulator for
applying at least one stimulus to an outside surface of the neck of
a subject. The at least one stimulus can comprise a vibrational
stimulus, a pressure stimulus, an optical stimulus, an ultrasound
stimulus, an auditory stimulus, a temperature stimulus, a visual
stimulus, an olfactory stimulus, a gustatory stimulus, and/or
combinations thereof. The stimulator may comprise a vibrational
transducer. A manual stimulation module may be configured to
manually engage the vibrational transducer. An automatic
stimulation module may be configured to automatically engage the
vibrational transducer. A manual counter and/or an automatic
counter may determine the number of times the manual stimulation
module and/or the automatic stimulation module are engaged.
[0015] In some embodiments, the vibrational transducer produces a
wave having a frequency between about 50 Hz and about 70 Hz. In
some embodiments, the vibrational transducer produces a wave having
a frequency of about 59 Hz. In some embodiments, the automatic
stimulation module comprises an automatic timer. The automatic
timer can include an automatic clock configured to initiate onset
of the automatic stimulation module. An adjustable clock may be
configured to initiate the automatic stimulation module at an
adjustable interval of about 0.5 seconds (s) to about 30 minutes
(min). An adjustable timer may be configured to set a duration of
stimulation between about 100 milliseconds (ms) and about 10 s.
[0016] In some embodiments, a device comprises a connector for
attaching the stimulator to an outside surface of the neck of the
subject. The connector can be adjusted by an adjustment mechanism
for positioning a contact section of the stimulator substantially
over the larynx of the subject. In some embodiments, a device
comprises a switch control communicatively connected to the
stimulator to selectively engage the manual stimulation module and
the automatic stimulation module.
[0017] In some embodiments, a device comprises a physiological
sensor electrically coupled to the stimulator. The physiological
sensor can include breathing sensor, a movement sensor, a
temperature sensor, a skin color sensor, a hematocrit sensor, an
oxygenation sensor, a blood pressure sensor, a heart rate sensor,
combinations thereof, and the like. In some embodiments, the device
comprises a swallowing receptor comprising a piezoelectric stretch
receptor. For example, the swallowing receptor may comprise an
accelerometric movement sensor (e.g., MEMS, piezoelectric). In some
embodiments, the device comprises a battery configured to supply
power to components of the device. In some embodiments, the device
comprises a control box configured to select one or more of the
stimulus modes, stimulus types, stimulus shapes, stimulus rates,
stimulus continuousness, and stimulus amplitudes.
[0018] In some embodiments, a device comprises a digital clock
generator, a digital decade counter, and a vibrational transducer
(e.g., a motor, a hydraulic system, a pneumatic system,
piezoelectric, rainbow (reduced and internally biased oxide wafer),
combinations thereof, and the like). The digital clock generator is
configured to produce an initial clock signal having a first
frequency range. The digital decade counter is configured to
receive the initial clock signal and to produce sequential pulses
having a second frequency range. The vibrational transducer is
responsive to the sequential pulses by producing vibrations on the
larynx of the subject. The vibrations are at a third frequency
range. In some embodiments, the initial clock signal is adjustable
and comprises a frequency. In some embodiments, the frequency of
the clock signal comprises about one signal every 3 minutes to
about one signal every 30 minutes. In some embodiments, the second
frequency range is between about 1 Hertz (Hz) and about 10 Hz,
between about 20 Hz and about 75 Hz, or between about 30 Hz and
about 60 Hz, with durations between about 10 ms and 500 ms. In some
embodiments, the third frequency range is between about 15 and
about 200 Hz, or between about 20 and about 100 Hz. The motor can
include a gearbox (e.g., planetary, spur). In some embodiments, the
vibrational transducer is configured to produce a vibrational
frequency between about 50 Hz and about 70 Hz.
[0019] In some embodiments, a method comprises treating a subject
with dysphagia or another neurological disease, neurological
disorder, neurological injury, neurological impairment, or
neurodegenerative disease that affects voluntary motor control of
the hyoid, pharynx, larynx, oropharyngeal area, or hyolaryngeal
complex disorder comprise with a device. The method can be used to
treat a subject with a speech disorder.
[0020] In some embodiments, a method for inducing a swallowing
reflex in a subject can reduce drooling and/or aspiration of
secretions of the subject. The secretions can be saliva and/or
mucus. The method generally comprises applying a device to an
outside surface of the neck of the subject substantially over the
larynx of the subject and configuring an automatic timer to
activate a vibrotactile stimulator to induce a swallowing reflex.
In some embodiments, the automatic timer is configured to activate
the vibrotactile stimulator at an interval of about once every 3
minutes to about once every 30 minutes. In some embodiments,
activation of the vibrotactile stimulator produces vibrations at a
frequency between about 40 Hz and about 70 Hz and applies pressure
between about 1 psi and about 14 psi to the neck of the subject
during an onset period. In some embodiments, the onset period
comprises about 10 ms to about 1.5 s, about 50 ms to about 750 ms,
or about 100 ms to about 500 ms.
[0021] In some embodiments, a method for identifying a subject at
risk of aspiration from their own secretions comprises applying a
device to the neck of the subject substantially over the larynx of
the subject, downloading data from the device after a period of
use, and analyzing the data to determine if the subject is at risk
of aspiration from their own secretions. The subject may activate
the device to induce volitional swallowing, and the device records
the data to allow a health professional to determine if the subject
is at risk.
[0022] In some embodiments, a method for monitoring subject
compliance with a training or therapy regime comprises applying a
device to a neck of the subject substantially over the larynx of
the subject, downloading data from the device after a period of
use, and analyzing the data to determine the subject's compliance
with the training or therapy regime. The subject may activate the
device to induce volitional swallowing.
[0023] For purposes of summarizing the invention and the advantages
achieved over the prior art, certain objects and advantages are
described herein. Of course, it is to be understood that not
necessarily all such objects or advantages need to be achieved in
accordance with any particular embodiment. Thus, for example, the
invention may be embodied or carried out in a manner that can
achieve or optimize one advantage or a group of advantages without
necessarily achieving other objects or advantages.
[0024] All of these embodiments are intended to be within the scope
of the invention herein disclosed. These and other embodiments will
become readily apparent from the following detailed description
having reference to the attached figures, the invention not being
limited to any particular disclosed embodiment(s).
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] These and other features, aspects, and advantages of the
present disclosure are described with reference to the drawings of
certain embodiments, which are intended to illustrate certain
embodiments and not to limit the invention.
[0026] FIG. 1A schematically illustrates an example embodiment of a
system incorporating a device for use in volitional swallowing
retraining.
[0027] FIG. 1B schematically illustrates an example embodiment of a
system for treating neurological disorders.
[0028] FIG. 2 is an example diagram illustrating the neural
circuitry involved in the concurrent use of hand control and
substitute sensory stimulation to enhance volitional
swallowing.
[0029] FIG. 3 is a block diagram of an example embodiment of a
vibrotactile stimulator.
[0030] FIGS. 4A-4F are block diagrams of example embodiments of a
vibrotactile stimulator.
[0031] FIGS. 5A-5D are example circuit diagrams for a vibrotactile
stimulator.
[0032] FIG. 6 is a block diagram of an example embodiment of an
automatic timer circuit.
[0033] FIG. 7A is an example circuit diagram for an automatic
timer.
[0034] FIG. 7B is another example circuit diagram for an automatic
timer.
[0035] FIG. 8 is a block diagram of another example embodiment of a
vibrotactile stimulator.
[0036] FIG. 9 is an example circuit diagram for a vibrotactile
stimulator.
[0037] FIG. 10 is a diagram depicting a clock-based sequential
vibrator control.
[0038] FIG. 11 is a diagram of an example embodiment of a
controller box for a vibrotactile stimulator.
[0039] FIG. 12 is a bar chart illustrating efficacy of various
vibrotactile frequencies in inducing an urge to swallow.
[0040] FIG. 13 is graphically depicts conceptualization of events
after brain injury.
[0041] FIG. 14 is a graph showing the change in the degree of risk
of aspiration during swallowing for multiple subjects before and
after being trained to press a button for coordinating swallowing
with intramuscular electrical stimulation. A higher score
represents a greater risk of aspiration during swallowing.
[0042] FIG. 15 is a graph showing the change in the NIH safety
score for multiple subjects before and after being trained to press
a button for coordinating swallowing with intramuscular electrical
stimulation.
[0043] FIG. 16 is a graph showing mean values for hyoid position
for each subject during OFF and ON electrical surface stimulation
conditions after training.
[0044] FIG. 17 depicts traces of hyoid position during electrical
surface stimulation ON, then stimulation OFF, followed by
stimulation ON for each subject.
[0045] FIG. 18 is a graph showing the change in the NIH swallowing
safety score for multiple subjects showing the difference in
aspiration during swallowing without stimulation versus swallowing
with electrical surface stimulation.
[0046] FIG. 19 is another graph showing the change in the NIH
swallowing safety score for multiple subjects showing the
difference in aspiration during swallowing without stimulation
versus swallowing with electrical surface stimulation.
[0047] FIG. 20 is a line graph showing the change in the Rosenbek
Penetration-Aspiration Scale (Pen-Asp) scale for multiple subjects
showing the difference during swallowing with stimulation versus
swallowing without electrical surface stimulation.
[0048] FIG. 21 is a plot of measured peak elevation of the larynx
(LYPEAKCHNG) and the peak elevation of the hyoid bone during
swallowing (HYPEAKCHNG) in normal subjects with electrical surface
stimulation.
[0049] FIG. 22 is a side-by-side comparison of plots of
vibrotactile stimulation under various conditions compared to
control conditions.
[0050] FIG. 23 is a plot of measured continuous vibrotactile
stimulation and pulsed hybrid vibrotactile stimulation in normal
volunteers.
[0051] FIG. 24 shows a percent change in rate of swallowing for
healthy subjects between control and when hybrid stimulation is
applied.
DETAILED DESCRIPTION
[0052] Although certain embodiments and examples are described
below, those of skill in the art will appreciate that the invention
extends beyond the specifically disclosed embodiments and/or uses
and obvious modifications and equivalents thereof. Thus, it is
intended that the scope of the invention herein disclosed should
not be limited by any particular embodiments described below.
[0053] The present disclosure relates generally to systems and
methods for treating and managing neurological disease
co-morbidities and disorders affecting the volitional control of
muscles that are involved in raising and lowering the hyoid/larynx
and/or pharynx in the neck. Systems and methods that can produce
deglutition stimulation and vocalization stimulation and/or
combinations thereof are disclosed. The stimulation may be
volitionally controlled, automatically controlled, and controlled
electrically, mechanically, chemically, or biologically. For
example, vibrotactile and/or pressure stimulation on the neck
region of the larynx may elicit swallowing. Vibrotactile
stimulation at two different vibrating rates may be particularly
effective at eliciting a swallowing reflex. Certain such methods
and systems may be particularly useful for treating and managing
subjects having dysphagia and/or dysphonia.
[0054] Others have attempted providing stimulation to areas that
are reduced in sensory function to enhance swallowing in subjects
with dysphagia. For example, a dental plate may be constructed and
placed over the lower teeth, but this device interferes with mouth
closing and makes it difficult for subjects to control liquid in
their mouth. For another example, electrical stimulation of the
faucial pillars in the mouth via a probe placed in the mouth
interferes with mouth closing and makes it difficult for subjects
to swallow such that this technique can only be used at a time
separate from asking the subject to swallow. Placement of devices
into the oral cavity is not optimal, as such devices can interfere
with eating food and liquids and alter the oral sensory function in
subjects who already have oropharyngeal sensory deficits. In some
embodiments, the devices described herein may be applied to an
exterior surface of the throat area, and not inside the mouth or
the pharynx.
[0055] Many subjects with dysphagia already have oral sensory
deficits. Providing stimulation to regions that are already
impaired in sensation can be expected to provide less sensory
facilitation of volitional and reflexive swallowing than sensory
stimulation to unaffected areas. Therefore, certain systems and
methods described herein can facilitate sensory stimulation to
areas unaffected by sensory deficits such as the skin overlying the
throat area and the vibratory sensors in the musculature and
cartilages in the throat area and the thyroid cartilage. Vibratory
stimulation of the thyroid cartilage and the stemothyroid muscle
can also affect voice. Some methods and systems described herein
differ from some previous approaches in that the subject can
initiate the stimulation immediately prior to attempting to
swallow, and such stimulation is applied to an area that does not
interfere with oral and pharyngeal movement and sensation during
swallowing.
A. Stimulator Systems and Devices
[0056] FIG. 1A schematically illustrates an example embodiment of a
system 100 incorporating a device for use in volitional retraining,
for example for treating dysphagia or a speech disorder. The system
100 comprises a band 101 and a stimulator 102 coupled to the band
101. The band 101 may be wrapped around the neck of the subject 105
during treatment. The band 101 may comprise a stretchable fabric
such as a wrap including hook-and-loop fastener material, and may
be adjustable for individual subjects' bodies. The stimulator 102
may include a vibrotactile stimulator 102 configured to be
positioned over the larynx of the subject 105 to provide sensory
stimulation. In certain embodiments, a designated contact section
120 of the vibrotactile stimulator 102 is positioned to be in
contact with the outside of the throat over the larynx. The band
101 can include an adjustment mechanism 125 for tailorable
positioning of the contact section 120 over the larynx of the
subject 105. Vibrotactile and electrical stimulators are preferably
positioned close to the skin.
[0057] The system 100 further comprises an actuator 103 in
communication with the stimulator 102. The actuator 103 may be
physically wired to the stimulator 102 or in wireless communication
with the stimulator 102. The actuator 103 may be a button, switch,
or the like. The actuator 103 can be covered when not in use. In
some embodiments, the actuator 103 comprises a button in a small
cover that may be reversibly slid over the top of the handle of a
utensil 104 (e.g., a spoon, fork, or knife held by the subject 105)
or utensil handle-shaped mount. In some embodiments, the actuator
103 is independent of any utensil. Upon activation of the actuator
103, the stimulator 102 transmits vibrational energy to the throat
and the larynx of the subject 105.
[0058] In certain embodiments, the system 100 includes a device
configured to control operation of one or more stimulators 102. For
example, such a can comprise a control box (not shown) having
appropriate switches, knobs, dials, etc. that can be adjusted to
set a stimulus type, a stimulus shape (e.g., a wave shape (e.g.,
sinusoidal, sawtooth, square wave)), a stimulus continuousness
(e.g., continuous, pulsed) a stimulus rate (constant or changing
over time), a stimulation continuousness (e.g., continuous,
pulsed), and/or a stimulus amplitude (constant or changing over
time). The control box can include features to determine stimulus
duration. For example, the control box can be configured to allow
for stimulation for a specific duration upon activation of the
actuator 103 or as long as actuator 103 is activated (e.g., as long
as a button is pushed). In some embodiments, the duration of
stimulation is between about 6 seconds and about 25 seconds.
[0059] Still referring to FIG. 1A, instructions can be provided to
the subject 105 for practicing initiating the sensory stimulation
(e.g., by activating the actuator 103) immediately prior to an
attempted initiation of a motor act such as swallowing or speaking.
In some embodiments, the band 101 comprises, or the device 100 is
in communication with, a sensor 108 such as an accelerometric
movement sensor (e.g., MEMS, piezoelectric) and/or pressure sensor
that can provide a movement feedback signal 107 that can be
displayed on a screen 106 to help coordinate the initiation. The
movement feedback signal 107 can be displayed on the display screen
106 constantly or when movement. The signal 109 from the button
103, initiating sensory stimulation, can be presented on the same
display screen 106 for the subject 105 and/or a trainer to observe
when the actuator 103 was activated for sensory stimulation in
relation to the onset of the motor act. In this manner, the subject
105 can learn to optimize the timing of activating the stimulator
102 about 200 ms to about 600 ms prior to the onset of their motor
act. Communication between the sensor 108 and the display 106
and/or between the button 103 and the display 106 may be wired or
wireless. A vibrational transducer vibrating frequency of about 30
Hz to about 60 Hz may be particularly effective in eliciting the
swallowing reflex.
[0060] The stimulator 102 may comprise, for example, a low voltage
DC motor with a gearbox (e.g., planetary, spur) utilized to
generate a particular frequency. Other types of vibrational
transducers are also possible. In operation, the gearbox can reduce
the output rotation per minute (RPM) to the desired range and
increase the available torque. An eccentrically loaded mass may be
attached to the output shaft to generate the vibration. The mass
weight can be changed to increase or decrease the vibration
amplitude. In some embodiments, a lightweight, sealed aluminum tube
encapsulates the motor assembly. In certain embodiments, the
vibrator motor utilizes a sleeve shaft for the output shaft. In
certain embodiments, the vibrator motor utilizes a sleeve bearing
for the output shaft. In certain embodiments, the vibrator motor
utilizes a ball bearing for the output shaft.
[0061] FIG. 1B schematically illustrates an example embodiment of a
system 150 for treating neurological disorders such as dysphagia
and dysphonia. Certain features that may be similar to the features
of the system 100 utilize the same reference number and may share
at least some of the same characteristics as the features thereof
(e.g., the collar 101, the actuator 103, etc.).
[0062] The system 150 includes a stimulator device 152 comprising a
first vibrational transducer 154a, a second vibrational transducer
154b, and a collar 101. The vibrational transducers 154a, 154b may
include, for example, a vibrotactile stimulator, a motor, a
hydraulic system, a pneumatic system, piezoelectric, rainbow,
combinations thereof, and the like. The first vibrational
transducer 154a has a first vibrating property. The second
vibrational transducer has a second vibrating property different
than the first vibrating property. For clarity, a vibrating
property is not necessarily different merely because a different
vibrational transducer is used (e.g., slight differences in
frequency due to a range of mechanical error, slight differences in
direction of mechanical force due to a range of installation error,
etc. would not be considered to be different vibrating
properties).
[0063] In some embodiments, the vibrating property includes
vibrating rate or frequency phase. For example, the first
vibrational transducer 154a is configured to operate at a first
vibrating rate and the second vibrational transducer 154b is
configured to operate at a second vibrating rate similar to or the
same as the first vibrating rate, but the phase of vibration is
offset. For example, the first vibrating rate and the second
vibrating rate may be between about 150.degree. and about
210.degree. out of phase (e.g., about 180.degree. out of phase or
polarity shifted). In certain such embodiments, the first
vibrational transducer 154a may be pulling while the second
vibrational transducer 154b is pushing, and vice versa. Other phase
differences are also possible. For example, phase differences
between 0.degree. and 180.degree. or between 180.degree. and
360.degree. may create a chasing-type effect.
[0064] In some embodiments, the vibrating property includes
vibrating rate or frequency. The first vibrational transducer 154a
is configured to operate at a first vibrating rate and the second
vibrational transducer 154b is configured to operate at a second
vibrating rate different than the first vibrating rate. In some
embodiments, the first vibrating rate is between about 50 Hz and
about 90 Hz (e.g., about 70 Hz) and the second vibrating rate is
between about 90 Hz and about 130 Hz (e.g., about 110 Hz). In some
embodiments, the first vibrating rate is between about 30 Hz and
about 60 Hz (e.g., about 30 Hz) and the second vibrating rate is
between about 60 Hz and about 90 Hz (e.g., about 70 Hz). In some
embodiments, the first vibrating rate is between about 20 Hz and
about 60 Hz (e.g., about 40 Hz) different than the second vibrating
rate. Other example vibrating rates and differences are described
further herein.
[0065] In some embodiments, the first vibrating rate is between
about 10 Hz and about 40 Hz (e.g., about 25 Hz) different than the
second vibrating rate. In some embodiments, the first vibrating
rate is between about 10 Hz and about 200 Hz, between about 20 Hz
and about 150 Hz, or between about 30 Hz and about 100 Hz different
than the second vibrating rate. Larger differences between
vibrating rates may provide a broader range of stimulus. Smaller
differences between vibrating rates may provide more concentrated
stimulus at known useful frequencies and/or provide more overlap,
as described herein.
[0066] In some embodiments, the first vibrating rate and the second
vibrating rate are harmonic. For example, the first vibrating rate
may be about 30 Hz and the second vibrating rate may be about 60
Hz, about 90 Hz, about 120 Hz, about 150 Hz, etc. For example, the
first vibrating rate may be about 50 Hz and the second vibrating
rate may be about 100 Hz, about 150 Hz, etc. For example, the first
vibrating rate may be about 50 Hz and the second vibrating rate may
be about 75 Hz, about 100 Hz, about 125 Hz, about 150 Hz etc.
(e.g., when the first vibrating rate is not the fundamental
frequency). In some embodiments, the first vibrating rate and the
second vibrating rate are non-harmonic.
[0067] The differences in the vibrating rates may mimic and/or
enhance the effects of two vibrating rates that are the same but
with offset phases. For example, during some periods, the first
vibrational transducer 154a may be pulling while the second
vibrational transducer 154b is also pulling, increasing the pulling
effect of either vibrational transducer 154a, 154b alone, and the
first vibrational transducer 154a may be pulling while the second
vibrational transducer 154b is pushing, and vice versa.
[0068] A frequency between the first vibrating rate and the second
vibrating rate may produce a third or beat frequency. For example,
if the first vibrating rate is about 30 Hz and the second vibrating
rate is about 70 Hz, a beat frequency would be about 50 Hz. For
example, if the first vibrating rate is about 70 Hz and the second
vibrating rate is about 110 Hz, a beat frequency would be about 90
Hz. In some embodiments, the beat frequency is between about 30 Hz
and about 120 Hz, between about 40 Hz and about 60 Hz, or between
about 80 Hz and about 100 Hz different than the second vibrating
rate. Other beat frequencies are also possible, for example by
modifying at least one of the first vibrating rate and the second
vibrating rate.
[0069] In some embodiments, the vibrating property includes
vibrating rate or frequency range. At least one of the first
vibrational transducer 154a and the second vibrational transducer
154b is configured to operate within a vibrating rate range, for
example oscillating between the extremes of the vibrating rate
range. For example, in some embodiments, the first vibrational
transducer 154a is configured to operate at a first vibrating rate
range between about 30 Hz and about 90 Hz (e.g., centered around
about 60 Hz) and the second vibrational transducer 154b is
configured to operate at a single second vibrating rate between
about 90 Hz and about 130 Hz (e.g., about 110 Hz). In some
embodiments in which one of the vibrational transducers 154a, 154b
is configured to operate at a vibrating rate range and the other of
the vibrational transducers 154a, 154b is configured to operate at
a single vibrating rate, the vibrating rate range may overlap the
single vibrating rate. In some embodiments in which one of the
vibrational transducers 154a, 154b is configured to operate at a
vibrating rate range and the other of the vibrational transducers
154a, 154b is configured to operate at a single vibrating rate, the
vibrating rate range may not overlap the single vibrating rate.
[0070] For another example, in some embodiments, the first
vibrational transducer 154a is configured to operate at a first
vibrating rate range between about 30 Hz and about 90 Hz (e.g.,
centered around about 60 Hz) and the second vibrational transducer
154b is configured to operate at a second vibrating rate range
between about 70 Hz and about 130 Hz (e.g., centered around about
100 Hz). In some embodiments in which both vibrational transducers
154a, 154b are configured to operate at a vibrating rate range, the
ranges may at least partially overlap. In some embodiments in which
both vibrational transducers 154a, 154b are configured to operate
at a vibrating rate range, the ranges may not overlap.
[0071] In some embodiments in which at least one of the vibrational
transducers 154a, 154b is configured to operate at a vibrating rate
range, the beat frequency may vary over time. For example, if the
first vibrational transducer 154a is configured to operate at a
first vibrating rate range between about 30 Hz and about 90 Hz and
the second vibrational transducer 154b is configured to operate at
a single second vibrating rate of about 110 Hz, the beat frequency
may shift between about 70 Hz and about 100 Hz. In some embodiments
in which both of the vibrational transducers 154a, 154b are
configured to operate at a vibrating rate range, the beat frequency
may vary over time. For example, if the first vibrational
transducer 154a is configured to operate at a first vibrating rate
range between about 30 Hz and about 90 Hz and the second
vibrational transducer 154b is configured to operate at a second
vibrating rate range between about 90 Hz and about 130 Hz, the beat
frequency may shift between about 0 Hz and about 100 Hz. In some
embodiments in which both of the vibrational transducers 154a, 154b
are configured to operate at a vibrating rate range, the beat
frequency may not vary over time. For example, if the first
vibrational transducer 154a is configured to operate at a first
vibrating rate range between about 30 Hz and about 60 Hz and the
second vibrational transducer 154b is configured to operate at a
second vibrating rate range between about 60 Hz and about 90 Hz,
and the rate of change of frequency is the same, the beat frequency
remain at about 30 Hz (e.g., about 30 Hz when the first vibrating
rate is about 30 Hz and the second vibrating rate is about 60 Hz,
about 30 Hz when the first vibrating rate is about 45 Hz and the
second vibrating rate is about 75 Hz, about 30 Hz when the first
vibrating rate is about 60 Hz and the second vibrating rate is
about 90 Hz).
[0072] In some embodiments in which both of the vibrational
transducers 154a, 154b are configured to operate at a vibrating
rate range, the width of the range may be the same. For example, if
the first vibrational transducer 154a may be configured to operate
at a first vibrating rate range between about 30 Hz and about 60
Hz, having a width of about 30 Hz, and the second vibrational
transducer 154b may configured to operate at a second vibrating
rate range between about 70 Hz and about 100 Hz, also having a
width of about 30 Hz. In some embodiments in which both of the
vibrational transducers 154a, 154b are configured to operate at a
vibrating rate range, the width of the range may be the different.
For example, if the first vibrational transducer 154a may be
configured to operate at a first vibrating rate range between about
30 Hz and about 60 Hz, having a width of about 30 Hz, and the
second vibrational transducer 154b may configured to operate at a
second vibrating rate range between about 70 Hz and about 110 Hz,
having a width of about 40 Hz.
[0073] In some embodiments, the vibrating property includes
vibrating wave shape. Example wave shapes include sinusoidal,
triangular, saw-tooth, square, combinations thereof, and the like.
The first vibrational transducer 154a may have a first wave shape
and the second vibrational transducer 154b may have a second wave
shape different than the first wave shape. For example, the first
wave shape can be sinusoidal and the second wave shape can be
triangular, the first wave shape can be sinusoidal and the second
wave shape can be saw-tooth, the first wave shape can be sinusoidal
and the second wave shape can be square, the first wave shape can
be triangular and the second wave shape can be saw-tooth, the first
wave shape can be triangular and the second wave shape can be
square, or the first wave shape can be saw-tooth and the second
wave shape can be square.
[0074] In some embodiments, the vibrating property includes
vibrating continuousness. For example, the first vibrational
transducer 154a may be continuous and the second vibrational
transducer 154b may be pulsed, or vice versa. Pulsed vibration can
produce a ramped or building response and continuous vibration can
produce a steady response.
[0075] The collar 101 is configured to position the first
vibrotactile stimulator 154a and the second vibrotactile stimulator
154b over a neck 158 of a subject 105. The first vibrotactile
stimulator 154a and the second vibrotactile stimulator 154b are
configured to operate at partially simultaneously. A beat frequency
between the vibrating rates may be produced during any duration in
which both vibrotactile stimulators 154a, 154b operate. In some
embodiments, the first vibrotactile stimulator 154a and the second
vibrotactile stimulator 154b are configured to operate
substantially the same or the same duration. The durations may be
entirely cotemporal, or the durations may at least partially
overlap. In some embodiments, the first vibrotactile stimulator
154a is configured to operate for a duration and the second
vibrotactile stimulator 154b are configured to operate for a
shorter duration, or vice versa. The shorter duration may be
entirely during the longer duration, or the shorter duration may at
least partially overlap the longer duration. During periods of
operation of both vibrotactile stimulators 154a, 154b, the input to
the mechanoreceptors continually varies.
[0076] In some embodiments, the vibrating property includes
direction of mechanical force. In some embodiments, the collar 101
and/or the design of the vibrotactile stimulators 154a, 154b can
enable the direction of mechanical force produced by the
vibrotactile stimulators 154a, 154b to be different. For example,
the direction of mechanical force produced by the first
vibrotactile stimulator 154a may be substantially perpendicular or
perpendicular to the subject's skin under the first vibrotactile
stimulator 154a and the direction of mechanical force produced by
the second vibrotactile stimulator 154b may at a non-perpendicular
and non-parallel angle (e.g., greater than 0.degree. and less than
90.degree.) to the subject's skin under the second vibrotactile
stimulator 154b. For example, the direction of mechanical force
produced by the first vibrotactile stimulators 154a may be at a
first non-perpendicular and non-parallel angle (e.g., greater than
0.degree. and less than 90.degree.) to the subject's skin under the
first vibrotactile stimulator 154a and the direction of mechanical
force produced by the second vibrotactile stimulator 154b may at a
second non-perpendicular and non-parallel angle (e.g., greater than
0.degree. and less than 90.degree.) to the subject's skin under the
second vibrotactile stimulator 154b different than the first
non-perpendicular and non-parallel angle.
[0077] The illustrated system 150 includes a control box 160
including a schematic depiction of a number of optional features.
It will be appreciated that some features from the control box 160
may be integrated with the stimulator device 152 and/or the
actuator 103. The control box 160 may be in wired communication
(e.g., as shown by the heavy curved lines) or wireless
communication (e.g., as shown by the dashed cornered line) with the
stimulator device 152 and/or the actuator 103. The actuator 103 may
thereby be in wired and/or wireless communication with the
stimulator device 152. In some embodiments, some or all of the
components of the control box 160 may be integrated with the
stimulator device 152, although size and weight considerations may
be considered. In some embodiments, some or all of the components
of the control box 160 may be integrated with the actuator 103,
although considerations may include water resistance and
durability.
[0078] Although certain embodiments and examples of vibrating
properties are described herein in detail, various combinations,
sub-combinations, modifications, variations, substitutions, and
omissions of vibrating properties are possible, some of which will
now be described for example purposes only. The first vibrotactile
stimulator 154a may be configured to operate at a first vibrating
rate and to have a first direction of mechanical force and the
second vibrotactile stimulator 154b may be configured to operate at
a second vibrating rate different than the first vibrating rate and
to have a second direction of mechanical force different than the
first direction of mechanical force. The first vibrotactile
stimulator 154a may be configured to operate at a first vibrating
rate and a first wave shape and the second vibrotactile stimulator
154b may be configured to operate at a second vibrating rate
different than the first vibrating rate and a second wave shape
different than the first wave shape. These are two such examples of
combinations of at least two different vibrating properties, but
any two or more of the different vibrating properties described
herein or other vibrating properties may be combined.
[0079] The control box 160 may include a power supply 162 such as a
battery, a cord that plugs into a wall or an adapter (e.g., a
universal serial bus (USB) adapter). In embodiments in which the
control box 160 is in wired communication with the stimulator
device 152 and/or the actuator 103, the power supply 162 may
provide power to such stimulator device 152 and/or actuator 103.
Although not illustrated in FIG. 1B, the stimulator device 152
and/or the actuator 103 may also include a power supply. The
control box 160, the stimulator device 152, and/or the actuator 103
may be coupleable (e.g., via induction or wired connection), for
example to share a recharging power source.
[0080] In some embodiments, the system 150 comprises a switch 103
configured to activate the first vibrotactile stimulator 154a and
the second vibrotactile stimulator 154b. The switch 103 is
configured to be volitionally operated by the subject 105, for
example immediately prior to a volitional attempt to swallow. In
some embodiments, the control box 160 includes an automatic clock
164 configured to activate the first vibrotactile stimulator 154a
and the second vibrotactile stimulator 154b, for example as
described in further detail herein. During automatic mode, the
actuator 103 may be omitted from the system 150. In some
embodiments, the control box 160 includes a mode selector switch
166 for toggling between manual mode and automatic mode, and
optionally a system off, although the system may be substantially
or intermittently idle during manual mode, for example during
periods with no activation of the actuator 103.
[0081] The control box 160 includes electrical components 168
described in further detail herein, for example with respect to
FIGS. 3-11. The electrical components may include a processor, a
voltage regulator, a potentiometer, a transmitter, a receiver, or
any appropriate analog and/or digital circuitry. FIG. 1B
illustrates the electrical components 168 as being a processor, for
example because some processors may replace a wide variety of
electrical components. In some embodiments, a processor can perform
the functions of the automatic clock 164. In some embodiments, a
smart phone or the like may include an application configured to
control the stimulator.
[0082] The control box 160 may comprise adjustment controls 170.
The adjustment controls 164 may allow a user and/or the subject 105
to adjust parameters of the system 150, for example the first
vibrating rate of the first vibrotactile stimulator 154a, the
second vibrating rate of the second vibrotactile stimulator 154b,
amplitude, duration, delay after activation of the actuator 103,
etc. For example, the adjustment controls may be in communication
with the electrical components 168 (e.g., a potentiometer) to
adjust the vibrating frequency of the vibrotactile stimulators.
Parameters and other information may be stored in a system memory
174, which may comprise storage such as flash memory and/or a
magnetic drive and/or temporary storage such as random access
memory.
[0083] In some embodiments, the control box 160 comprises a counter
172, for example to track compliance with a treatment protocol or
to identifying a subject at risk of aspiration. A processor 168
and/or memory 174 may take the place of individual counters 172.
The adjustment controls 170 may be operated to reset a counter.
[0084] In some embodiments, the device 150 comprises a
physiological sensor. The physiological sensor can include, for
example, a breathing sensor, a movement sensor, a temperature
sensor, a skin color sensor, a hematocrit sensor, an oxygenation
sensor, a blood pressure sensor, a heart rate sensor, combinations
thereof, and the like. In some embodiments, the device can utilize
the input from one or more sensors to coordinate (e.g., initiate
and/or to delay) stimulation. For example, if a breathing sensor
senses that a subject is breathing in, stimulation may be delayed
(e.g., until the subject stops breathing in or is breathing out) to
reduce the risk of aspiration from swallowing and breathing in at
the same time. For example, if a heart rate sensor senses that a
subject diastole, stimulation may be delayed until the subject is
systole, or vice versa. Stimulation coordination may be useful, for
example when the device 150 is in automatic mode, for example when
the subject has little or no control over when the elicitation of
swallowing may occur.
[0085] Without wishing to be bound by any one theory, it is
believed that such motor training can produce concurrent brain
activation due to sensory input that induces a central pattern
generator in the subject's brain stem that produces the related
effect of swallowing. This principle may be applicable to many
other neurological impairments, their associated motor act
habituations, and related sensory stimulations. Accordingly, the
scope of the methods and systems disclosed herein may be applicable
to a large variety of subjects having various diseases and
disorders.
[0086] FIG. 2 is an example diagram 200 illustrating the neural
circuitry involved in the concurrent use of hand control and
substitute sensory stimulation to enhance volitional swallowing.
More specifically, FIG. 2 illustrates the neural circuitry in using
a hand control 203 to trigger volitional swallowing 204 along with
simultaneous sensory stimulation 201, which goes to the cortex 202.
This sequence occurs after button press training described herein.
Elicitation of the swallowing reflex and safety in swallowing may
be dependent upon sensory feedback 201 to the brain from sensory
mechanoreceptors in the upper airway. If sensory input is
withdrawn, subjects may feel that they can no longer swallow and
are at significant increase of aspiration during swallowing. The
neural circuitry enhances cortical motor control 202 of swallowing
coincident with substitution of sensory input 203 from stimulation
of the throat area to trigger brain stem circuitry to trigger
reflexive swallowing 204 simultaneous with volitional
swallowing.
[0087] FIG. 3 is a block diagram of an example embodiment of a
vibrotactile stimulator 300. The vibrotactile stimulator 300 can be
used in the example system 100. In certain embodiments, the
vibrotactile stimulator 300 is pressed against the outside surface
of subject's throat to stimulate the larynx such that, with
coordination, the vibrotactile stimulator 300 can enhance
volitional control of swallowing.
[0088] As described herein, the vibrotactile stimulator 300 may be
secured or connected to a connector or a band (e.g., the band 101)
that can be wrapped around the subject's neck. In this manner, a
designated contact section of the vibrotactile stimulator 300 can
be positioned on the subject's neck to vibrotactilely stimulate the
throat and larynx. The connector can include an adjustment
mechanism for a fine adjustment of the contact section over the
subject's larynx. In certain embodiments, the adjustment mechanism
is configured to shift the position of the vibrotactile stimulator
300 within a circle having an area of about 0.01 cm.sup.2 to about
10 cm.sup.2, about 0.25 cm.sup.2 to about 5 cm.sup.2, or about 0.5
cm.sup.2 to about 2.5 cm.sup.2. In certain embodiments, the
adjustment mechanism is configured to vertically shift the position
of the vibrotactile stimulator 300 by a distance of about 0.01 cm
to about 5 cm, about 0.25 cm to about 2.5 cm, or about 0.5 cm to
about 1.5 cm.
[0089] In general, the vibrotactile stimulator 300 includes a
manual stimulation module 310 operatively configured to allow a
user to manually operate the vibrotactile stimulator 300 by
activating an external actuator in communication with the
vibrotactile stimulator 300. Described at a high level, activating
the actuator can transmit energy from engage a vibrational
transducer to a subject's larynx. In some embodiments, the actuator
is a switch that, when activated, energizes a vibrational
transducer 305 that vibrates at a desired frequency a periodic
pressure wave that can transmit vibrational energy to the subject's
larynx. The vibrational transducer 305 may include, for example, a
motor, a hydraulic system, a pneumatic system, piezoelectric,
rainbow, combinations thereof, and the like. In some embodiments,
the actuator is a switch that, when activated, energizes a first
vibrational transducer 305 that vibrates at a first frequency that
can transmit vibrational energy to the subject's larynx and
energizes a second vibrational transducer 305 that vibrates at a
second frequency different than the first vibrating frequency that
can transmit vibrational energy to the subject's larynx. In some
embodiments, when the ON switch is released, the vibration produced
by the vibrational transducer(s) 305 is terminated. In some
embodiments, regardless of when the ON switch is released, the
vibration produced by the vibrational transducer(s) 305 is
terminated after a certain duration. There is substantially no
delay between pressing the ON switch and the vibration of the
throat area. In use, the manual stimulation module 310 may be
engaged during activities such as eating, drinking, and swallowing
to inhibit or prevent aspiration with subjects having
dysphagia.
[0090] The stimulator 300 further comprises an automatic
stimulation module 315 operatively configured to automatically
energize the vibrational transducer 305. In certain embodiments,
the automatic stimulation module 310 enables the subject or
caregiver to programmably define vibrational transducer 305
operating parameters such as duration, vibrational frequency, and
amplitude. For example, the automatic stimulation module 315 can
function to periodically energize the vibrational transducer 305 to
induce swallowing throughout the course of a day, thereby reducing
saliva aspiration (and in general for saliva control). For another
example, the automatic stimulation module 315 can function to
periodically energize a first vibrational transducer 305 having a
first vibrating frequency and a second vibrational transducer 305
having a second vibrating frequency different than the first
vibrating frequency to induce swallowing throughout the course of a
day, thereby reducing saliva aspiration (and in general for saliva
control). The automatic stimulation mode 315 may be useful for
subjects afflicted with dysphagia, for subjects with neurological
disorders who have uncontrolled drooling, and for subjects with
cerebral palsy who have uncontrolled drooling. In some embodiments,
the automatic stimulation module 315 includes an automatic timer
circuit configured to facilitate the periodic energizing of the
vibrational transducer(s) 305, as described in further detail
herein. In some embodiments, the automatic timer can provide
continuous practice throughout the day, which may be useful for
rehabilitation of speech and/or swallowing disorders. Automatic
stimulation occurring at regular intervals of one every 3 minutes
to one every 30 minutes can induce regular swallowing to reduce or
eliminate drooling.
[0091] Components of the vibrotactile stimulator 300 as described
in the present disclosure may be implemented via hardware and/or
software techniques. For example, the vibrotactile stimulator 300
may include a printed circuit board (PCB). The PCB may comprise a
plurality of discrete electrical components such as transistors,
capacitors, inductors, resistors, and functional integrated
circuitry such as a processor, a memory element, such as read-only
memory (ROM) and/or random access memory (RAM), a field
programmable logic array (FPGA), and/or input/output circuitry.
[0092] FIG. 4A is another block diagram of an example embodiment of
a vibrotactile stimulator 400. The vibrotactile stimulator 400 is a
possible implementation of the vibrotactile stimulator 300 of FIG.
3. In general, upon engagement of a power switch 460, a battery 405
supplies power to a three-terminal voltage regulator 410. In the
embodiment illustrated in FIG. 4A, the voltage regulator 410 is
used as an adjustable current source to control the vibrational
frequency of the vibrational transducer 415. This may be
accomplished, for example, by utilizing an external adjustable
potentiometer 420.
[0093] A switch control 425 enables the subject to voluntarily
engage the manual stimulation module 440. In certain embodiments,
the switch control 425 is in communication with an external
actuator such as a control box or a utensil. In the embodiment
illustrated in FIG. 4A, activation of the switch control 425
electrically loads a switch interface 430 such that a count select
mechanism 435 is actuated. A manual counter 440 is enabled when the
user operates the vibrotactile stimulator 400 in the manual mode,
and an automatic counter 445 is engaged when automatic stimulation
is employed, as described further below. Engagement of a counter
440, 445 may comprise incrementing the counter. In some
embodiments, the automatic stimulation module 315 may be
implemented with an automatic timer circuit such that the switch
control 425 can be controlled by the automatic timer circuit to
actuate the count select mechanism 435, thereby engaging the
automatic counter 445 and energizing the vibrational transducer
415.
[0094] In the embodiment illustrated in FIG. 4A, the counters 440,
445 are internally mounted to the vibrotactile stimulator 400. The
manual counter 440 records the number of times a subject engages
the manual stimulation module 310. The automatic counter records
the number of times the automatic stimulation module 315 is engaged
by the automatic timer circuit. After a period of use by a subject,
the counters 440, 445 may be visually and/or electronically
interrogated or read (e.g., the value of the counter may be
determined by a human or computing device), and manually and/or
electronically reset after the total number of counts are recorded.
In some embodiments, a wireless data interrogation using one of
many technologies (e.g., Bluetooth) may transfer the information to
an external application. The quantitative information provided by
the counters 440, 445 may provide, for example, an investigator or
caregiver quantitative information regarding subject compliance and
information regarding the effectiveness of the vibrotactile
stimulator 400. As subject compliance is generally low, around 50%,
it can be important to the rehabilitation process to identify poor
compliance, particularly in the management of dysphagia, a life
threatening disorder. Identification of poor compliance allows the
therapist to intervene to assure proper use of the device by the
subject and their caregivers.
[0095] The vibrational transducer 415 may include two different
vibrational transducers, for example configured to respond to the
same voltage by producing different vibrating frequencies. In
certain such embodiments, adjustment of the potentiometer would
adjust the voltage, and the frequency, of both vibrational
transducers 415 dependently. Lack of independent control of the
vibrating frequencies may be an acceptable alternative to some of
the more complicated systems described herein, although those
complicated systems may advantageously provide independent control
of vibrating frequencies.
[0096] In certain embodiments, the manual counter 440 and the
automatic counter 445 can be coupled to their own power supplies so
that cumulative counts are not lost when the power switch 460 is
disengaged.
[0097] The vibrotactile stimulator 400 optionally includes a low
battery indicator 450 such that if the battery 405 voltage drops
below a specified voltage level, a "Low Battery" indicator (e.g.,
light emitting diode (LED)) specifying that event is generated.
[0098] FIG. 4B is yet another block diagram of an example
embodiment of a vibrotactile stimulator 470. The vibrotactile
stimulator 470 is another possible implementation of the
vibrotactile stimulator 300 of FIG. 3. In general, the vibrotactile
stimulator 470 may operate similarly to the vibrotactile stimulator
400 in many aspects, although upon engagement of a power switch
460, a battery 405 supplies power to two three-terminal voltage
regulators 410a, 410b. In the embodiment illustrated in FIG. 4B,
the voltage regulators 410a, 410b are used as adjustable current
sources to independently control the vibrational frequency of the
vibrational transducers 415a, 415b. This may be accomplished, for
example, by utilizing two external adjustable potentiometers 420a,
410b. Other solutions are also possible (e.g., a switch to use one
potentiometer 420 to adjust both voltage regulators 410a, 410b, or
more advanced circuitry). In the embodiment illustrated in FIG. 4B,
the counters 440, 445 are configured to increment only upon
activation of the vibrational transducer 415a, although it will be
appreciated that other counting methods are also possible.
[0099] FIG. 4C is yet another block diagram of an example
embodiment of a vibrotactile stimulator 480. Rather than including
two voltage regulators 410a, 410b and two potentiometers 420a, 420b
as in the voltage regulator 470, the voltage regulator 480 includes
one voltage regulator 410, one potentiometer 420, and a voltage
divider 482. The voltage divider 482 splits a voltage from the
voltage regulator 410 into a first voltage V.sub.1, which is sent
to the first vibrational transducer 415a, and a second voltage
V.sub.2, which is sent to the second vibrational transducer 415b.
The voltage divider 482 may comprise, for example, a network of
resistors configured to proportionally split whatever voltage is
input. A voltage divider 482 may be useful, for example, in
embodiments in which the difference between the vibrating
frequencies of the vibrational transducers 415a, 415b is desirably
a certain delta (e.g., between about 20 Hz and about 60 Hz
different, about 40 Hz different). Some commercially available
voltage regulators 410 are able to output two different voltages
such that the voltage divider 482 may be omitted. In some
embodiments, the illustrated potentiometer 420 may be replaced by a
first potentiometer 420a between the voltage divider 482 and the
first vibrational transducer 415a and a second potentiometer 420b
between the voltage divider 482 and the second vibrational
transducer 415b, which can allow independent control over the
vibrating frequencies of the vibrational transducers 415a,
415b.
[0100] Although duplicating the voltage regulators 410a, 410b and
the potentiometers 420a, 420b may be more expensive than other
examples described herein, such embodiments may have better (e.g.,
more consistent) power characteristics, resulting in more uniform
and/or precise control over vibrating frequency.
[0101] The vibrotactile stimulator 480 does not include the
counters 440, 445, which may be appropriate, for example for
devices after it has been determined that the subject is known or
believed to be likely to have high compliance. The vibrotactile
stimulator 480 could include counters 440, 445, and any of the
vibrotactile stimulators described herein may omit the counters
440, 445. For simplification, the vibrotactile stimulator 480 does
not a low battery indicator 450 or a low battery LED, but the
vibrotactile stimulator 480 could include a low battery indicator
450 or a low battery LED, and any of the vibrotactile stimulators
described herein may omit the low battery indicator 450 and/or the
low battery LED.
[0102] FIG. 4D is still another block diagram of an example
embodiment of a vibrotactile stimulator 484. The vibrotactile
stimulator 484 includes a voltage regulator 410, a first
potentiometer 420a, and a second potentiometer 420b. Adjustment of
the first potentiometer 420a adjusts the voltage to the first
vibrational transducer 415a, and thus the vibrating frequency of
the first vibrational transducer 415a. Adjustment of the first
potentiometer 420a also adjusts the voltage to the second
potentiometer 420b, and then the voltage to the second vibrational
transducer 415b, and thus the vibrating frequency of the second
vibrational transducer 415b. Adjustment of the second potentiometer
420b adjusts the voltage to the second vibrational transducer 415b,
and thus the vibrating frequency of the second vibrational
transducer 415b. The vibrotactile stimulator 484 allows adjustment
of the vibrating frequency of the vibrational transducers 415a,
415b together and independently. For simplification, FIGS. 4D-4F do
not show components such as the counters 440, 445, the battery 405,
the switch 460, the low battery indicator 450, or the low battery
LED.
[0103] FIG. 4E is still yet another block diagram of an example
embodiment of a vibrotactile stimulator 486. The vibrotactile
stimulator 486 does not include a potentiometer 420 or redundant
components such as two voltage regulators 410a, 410b. The
vibrotactile stimulator 486 includes a voltage regulator 410 and a
metal oxide semiconductor field effect transistor (MOSFET) 488 such
as a bipolar junction transistor (BJT). The MOSFET 488 can adjust
the voltage to the second vibrational transducer 415b, for example
by modulating the pulse width of the signal. The MOSFET 488 may be
adjustable such that the on and/or off time of the signal
modulation may be adjusted to provide appropriate voltage to the
second vibrational transducer 420b to effect the desired vibrating
frequency.
[0104] FIG. 4F is another block diagram of an example embodiment of
a vibrotactile stimulator 490. The vibrotactile stimulator 490 does
not include a potentiometer 420 or redundant components such as two
voltage regulators 410a, 410b. The vibrotactile stimulator 490
includes a processor 495. The processor 495 is configured to adjust
one or more parameters of the signals sent to the vibrational
transducers 415a, 415b such as voltage, pulse width, frequency,
amplitude, duty cycle, combinations thereof, and the like. While a
processor 495 may be an expensive component compared, for example,
to a potentiometer, the processor 495 may be able to replace
multiple components of the vibrotactile stimulator 490 and/or as
system comprising the vibrotactile stimulator 490. The processor
495 may allow much more flexibility in adjustment of various
parameters and/or stability in achieving parameters once set.
[0105] FIGS. 4A-4F include many examples of components that can be
used to achieve different vibrating rates between two vibrational
transducers 415a, 415b. Any combination of analog and/or digital
electronic components, including those described herein, switches,
resistors, capacitors, amplifiers (e.g., operational amplifiers),
diodes, inductors, comparators, transistors, gates, and the like
may be designed affect voltage signals, which can result in the
first vibrational transducer 415a having a first vibrating
frequency and the second vibrational transducer 415b having a
second vibrating frequency different than the first vibrating
frequency, or to modify other vibrating parameters as discussed
herein. In some embodiments, a portable computing device such as a
smart phone or the like may include a processor that can be
programmed (e.g., include an application) to provide the
stimulation described herein, including providing different
vibrating properties. Such a device can include inputs (e.g.,
through serial bus, lighting connector, wireless, etc.) such as the
button 103, sensors, parameter setting, etc.
[0106] FIG. 5A is an example circuit diagram 500 for a vibrotactile
stimulator (e.g., the vibrotactile stimulator 400). FIG. 5B is
another example circuit diagram 505 for a vibrotactile stimulator
(e.g., the vibrotactile stimulator 400). FIG. 5A is an example
circuit diagram 500 for a vibrotactile stimulator (e.g., the
vibrotactile stimulator 470). FIG. 5B is another example circuit
diagram 505 for a vibrotactile stimulator (e.g., the vibrotactile
stimulator 470). Example circuit diagrams 500, 505, 510, 515 are
only example circuit architectures, and that the vibrotactile
stimulators 400, 470 may be implemented via any suitable
architecture. For example, the circuit diagrams 505, 515 do not
include counters. For another example, the vibrational transducers
in the circuit diagrams 510, 515 of FIGS. 5C and 5D, respectively,
are shown in parallel, which may cause the vibrational transducers
to have different vibrating frequencies if the vibrational
transducers respond differently to the same input, other components
may be added in the signal path ahead of one or both of the
vibrational transducers (e.g., the resistor ahead of the right
vibrational transducer, as shown in FIGS. 5C and 5D), portions of
the architecture may be replicated, a new component may be added
(e.g., processor, voltage divider, etc.), combinations thereof, and
the like. Modifications similar to those described with respect to
FIGS. 4A-4F and other modifications are also possible. In the
embodiments illustrated in FIGS. 5A and 5C, both passive and
discrete electrical components are shown, which can allow component
attributes and tolerances to fit a known specification.
[0107] FIG. 6 is a block diagram of an example embodiment of an
automatic timer circuit 700. In general, the automatic timer module
is communicatively connected to the vibrotactile stimulator 300
shown in FIG. 3. As described herein, the automatic timer circuit
600 may actuate the count select mechanism 435, thereby engaging
the automatic counter 445 and energizing the vibrational
transducer(s) 405 for a predetermined period of time. In the
embodiment illustrated in FIG. 6, the automatic timer circuit 600
comprises a digital oscillator 605 having an adjustable oscillating
frequency of about 2.2 Hz to about 28 Hz. The output signal of the
digital oscillator 605 is routed to a programmable timer 610 set to
divide the periodic digital input signal by the value 4096. The
input clock frequency from the digital oscillator 605 to the
programmable timer 610 at least partially determines when an output
pulse is generated. In the embodiment illustrated in FIG. 6, the
output pulse period may be generated in a range from about 3 to
about 30 minutes. Subsequently, the programmable timer 610 output
pulse triggers an adjustable monostable vibrator 615. An output
pulse width of the adjustable monostable vibrator 615 sets the "on"
time for the vibrational transducer(s) 415 by energizing a relay
through a transistor switch. In the embodiment illustrated in FIG.
6, the transistor switch and relay control is integral to relay
module 620. An LED 625 indicates that the relay has been activated,
which energizes the vibrational transducer(s) 415 in the automatic
mode. In some embodiments, the duration that the vibrational
transducer(s) are energized is between about 5 seconds and about 15
seconds.
[0108] The automatic timer circuit 600 is powered by a battery 630
or other power source when a power switch 635 is in the "on"
position. The automatic timer circuit 600 may optionally include a
low battery indicator 640 such that if the battery 630 voltage
drops below a specified voltage level, an indicator specifying that
event is generated. In the embodiment illustrated in FIG. 6, an LED
"Low Battery" indicator 645 comes on. It will be appreciated that
the battery 630, the power switch 635, the low battery indicator
640 and the LED 645 may be used to power the vibrotactile
stimulator 300 as shown in FIG. 3.
[0109] FIG. 7A is an example circuit diagram 700 for an automatic
timer (e.g., the automatic timer 600 of FIG. 6). Example circuit
diagram 700 is only an example circuit architecture, and that the
automatic timer circuit 600 may be implemented via any suitable
electrical architecture. In the embodiment illustrated in FIG. 8A,
both passive and discrete electrical components are shown, such
that component attributes and tolerances can fit a known
specification. FIG. 7B is another example circuit diagram 705 for
an automatic timer (e.g., the automatic timer 600 of FIG. 6). In
certain embodiments, the manual counter 440, the automatic counter
445, and the automatic timer circuit 600 can be incorporated into a
single functional counter, and timer module that is mounted
internally and communicatively connected to the vibrotactile
stimulator 300.
[0110] FIG. 8 is a block diagram of another example embodiment of a
vibrotactile stimulator 800. In general, the vibrotactile
stimulator 800 is a battery-powered device that sequentially
activates one or more small DC vibrational transducers as described
herein. An adjustable digital clock can set the timing for separate
events. The clock frequency can be adjusted between about 1 Hz and
about 10 Hz. This clock, in conjunction with a digital decade
counter, can generate sequential pulses that can control the "on"
and "off" durations of individual vibrators. At the end of the
pulse cycle, a short reset pulse can be generated to reset the
decade counter and begin the next cycle of pulses.
[0111] A subject can control the vibrotactile stimulator 800 by
activating an "ON" switch. The switch may activate an LED
indicator. The switch generates a digital pulse that can be used
for coordinating various recording devices. When the switch is
released, the vibration pulses will stop. In some embodiments, the
subject does not perceive any delay between activating the "ON"
switch and the first vibration to the throat.
[0112] FIG. 9 is an example circuit diagram 900 for a vibrotactile
stimulator (e.g., the vibrotactile stimulator 800). FIG. 10 is a
diagram 1000 depicting a clock-based sequential vibrator control
(e.g., implementable with the vibrotactile stimulator 800). FIG. 11
is a diagram of an example embodiment of a controller box 1100 for
a vibrotactile stimulator (e.g., the vibrotactile stimulator 800).
The controller box 1100 may set one or more vibrotactile stimulator
800 operating parameters. For example, an operating parameter may
include a stimulus type, a stimulus shape (e.g., a wave shape
(e.g., sinusoidal, sawtooth, square wave)), a stimulus
continuousness (e.g., continuous, pulsed), a stimulus rate
(constant or changing over time), a stimulation continuousness
(e.g., continuous, pulsed), a stimulus amplitude (constant or
changing over time), combinations thereof, and the like. The
control box 100 may be configured to allow for stimulation for a
specific duration upon activation of the button or as long as the
button is depressed. In some embodiments, the duration of
stimulation is about 2 seconds to about 6 seconds.
B. Methods and Uses
[0113] The systems and methods described herein can be used to
treat a number of conditions and disorders including, but not
limited to, stroke, cerebral hemorrhage, traumatic brain injury,
dysphagia, post brain surgery, Parkinson's disease, multiple
sclerosis, birth defects, ALS, cerebral palsy, CNS injury,
supranuclear palsy, and any other neurological disease,
neurological disorder, neurological injury, neurological impairment
or neurodegenerative disease that affects voluntary motor control
of the hyoid, pharynx, larynx, oropharyngeal area, and/or
hyolaryngeal complex. Neurological impairments that are
contemplated include reflex actions that involve interactions
between afferent and efferent paths, at the spinal cord or in the
brain stem, as well as higher order interactions in the primary
motor cortex of the hemispheres. The systems and methods may apply
to subjects who have lost or partially lost the ability to
voluntarily control motor functions and/or to subjects who were
born with birth defects that have prevented them from having
voluntary motor control, such as cerebral palsy. The systems and
methods may be applicable to treating various speech motor control
disorders such as stuttering and laryngeal dystonia.
[0114] The term "motor control" as used herein refers to the
ability of a subject to control activity of their muscle at will,
and should not be confused with a motor such as a vibrator motor of
a vibrational transducer. For instance, in some embodiments, motor
control refers to the ability of a subject to swallow at will.
Subjects with dysphagia, which is the complete or partial loss of
the ability to swallow, can be treated with the systems and methods
described herein. In some embodiments, the disease or disorder
reduces or delays motor control of swallowing and/or results in
delayed or reduced elevation of the hyolaryngeal complex, which
does not allow the subject to prevent food or liquid from entering
the airway.
[0115] In some embodiments, a method comprises stimulating a
substitute site for an affected area with a system or device to
trigger motor control of the affected area. The term "recovering"
as used herein includes within its meaning obtaining the ability to
volitionally control motor functions. "Volitionally" as used herein
means at the will of the subject. A "substitute site" as used
herein means an area of the body that is capable of eliciting a
desired reflex, but is not a sensory region that is able to elicit
reflex in impaired subjects.
[0116] Subjects are often not responsive to stimulation in the oral
and pharyngeal cavities, but remain sensate to vibratory
stimulation to the areas of the human head which include anatomical
structures (e.g., muscles, nerves, and/or connective tissue) that
work in concert to affect deglutition. By providing sensory
stimulation to sensate areas on the throat, substitute stimulation
can be used to enhance the volitional elicitation of swallowing.
For example, subjects with dysphagia following neurological disease
usually have sensory loss in the oropharyngeal area, which is
normally required to be sensate in order to elicit safe swallowing
without aspiration. Sensory triggering in "substitute sites" can
enhance the elicitation of reflex and volitional swallowing, such
as stimulation of afferents from the laryngeal area contained in
the superior laryngeal area.
[0117] Basic studies suggest that the second order neurons excited
by afferents in the superior laryngeal nerve are selectively
excitable at particular vibrational frequencies, and that
stimulation between about 30 Hz and about 70 Hz may be most useful
for exciting the swallowing system in the brainstem. Subjects are
often not responsive to stimulation in the oral and pharyngeal
cavities, but remain sensate to vibratory stimulation to the throat
area including the skin and laryngeal cartilages underlying the
skin. In certain such embodiments, the throat is the substitute
site and providing sensory stimulation to the throat can elicit
volitional swallowing.
[0118] Vibrational frequencies outside the range of about 30 Hz to
about 70 Hz may also be useful to elicit volitional swallowing. In
some embodiments, two different vibrating frequencies can elicit
more volitional swallowing than one vibrating frequency. For
example, a first vibrating frequency between about 30 Hz and about
60 Hz (e.g., about 30 Hz) and a second vibrating frequency between
about 60 Hz and about 90 Hz (e.g., about 70 Hz) may incorporate the
about 30 Hz vibrating frequency. For another example, as described
in further detail herein, a first vibrating frequency between about
50 Hz and about 90 Hz (e.g., about 70 Hz) and a second vibrating
frequency between about 90 Hz and about 130 Hz (e.g., about 110 Hz)
can provide at least a 65% or 85% increase in the urge to swallow
over control.
[0119] In some embodiments, a method for stimulating swallowing in
a subject comprises applying a first vibrotactile stimulation to a
throat area of the subject and applying a second vibrotactile
stimulation to the throat area of the subject. The first
vibrotactile stimulation is at a first vibrating rate. The second
vibrotactile stimulation is at a second vibrating rate different
than the first vibrating rate. Applying the first vibrotactile
stimulation and applying the second vibrotactile stimulation may
include the subject voluntary activating vibrotactile stimulators.
Applying the first vibrotactile stimulation and applying the second
vibrotactile stimulation may include automatically activating the
vibrotactile stimulators. Applying the first vibrotactile
stimulation may be at least partially simultaneous with applying
the second vibrotactile stimulation. The first vibrating rate may
be between about 50 Hz and about 90 Hz and the second vibrating
rate may be between about 90 Hz and about 130 Hz. The first
vibrating rate may be between about 30 Hz and about 60 Hz and the
second vibrating rate may be between about 60 Hz and about 90 Hz.
The first vibrating rate may be about 70 Hz and the second
vibrating rate may be about 110 Hz. The first vibrating rate may be
about 30 Hz and the second vibrating rate may be about 70 Hz. The
first vibrating rate may be between about 20 Hz and about 60 Hz
different than the second vibrating rate. The first vibrating rate
may be between about 10 Hz and about 40 Hz different than the
second vibrating rate. The first vibrating rate may be about 40 Hz
different than the second vibrating rate. The first vibrating rate
may be about 25 Hz different than the second vibrating rate.
[0120] The site for stimulation can be adjusted depending upon the
desired motor control. Those of skill in the art will readily
understand where to locate the stimulation based on the disorder.
In some embodiments, the affected area is the area of the body
responsible for swallowing, speech, or voice. In some embodiments,
the affected area is the oropharyngeal area. In some embodiments,
the substitute site is the area of the throat over the larynx. In
some embodiments, the recovered motor control is volitional
swallowing.
[0121] By providing a vibratory stimulus to the neck of a subject,
mechanoreceptors in the skin will be activated, providing feedback
to the brain stem and brain to assist with triggering voluntary
initiation of swallowing, speech, or voice. At greater vibration
amplitudes, mechanical stimulation induces movement of the thyroid
cartilage and of the extrinsic and intrinsic laryngeal muscles in
the region including: the platysma, the stemohyoid, the
sternothyroid, the thyrohyoid, the cricothyroid, and the
thyroarytenoid muscles. Some of these muscles contain muscle
spindles. The muscle spindle afferents can provide sensory feedback
to the central nervous system to assist with triggering voluntary
initiation of the muscles for swallowing, speech, and voice
initiation.
[0122] In some embodiments, the stimulation is asserted immediately
before a volitional attempt to move or carry out the physiological
impaired function, such as swallowing or speaking. In some
embodiments, the stimulation comprises an onset period in which the
stimulation is asserted about 1 second to about 10 seconds before,
about 0.1 seconds to about 1 second before, about 0.2 seconds to
about 0.5 seconds before, or about 0.2 seconds to about 0.4 seconds
before the volitional attempt. The stimulation may be asserted at
the same time as the volitional attempt. It will be appreciated
that constant or periodic stimuli that happen to coincide with a
volitional attempt would not necessarily be considered to be
asserted immediately before the volitional attempt, for example
because an aspect of the volitional attempt is the ability to
volitionally coincide the attempt with the stimulus.
[0123] The sensory modality for stimulation may include, but is not
limited to, vibratory stimulation, pressure stimulation, auditory
stimulation, optical stimulation, ultrasound stimulation,
temperature stimulation, visual stimulation, electrical
stimulation, olfactory stimulation, taste stimulation, combinations
thereof, and the like. The stimulation may be controlled
electrically, mechanically, chemically, biologically, or by any
other appropriate method. In some embodiments, the stimulation is
vibratory, tactile, pressure, or a combination thereof. In some
embodiments, the stimulation is vibrotactile. In some embodiments,
vibratory stimulation is combined with another type of stimulation,
such as electrical skin surface stimulation (e.g., having the same
or different timing). Combination of two types of stimulation, like
stimulation with two different vibrating properties but for other
reasons, may produce a synergistic effect versus either stimulation
type alone. For example, when vibrotactile stimulation is combined
with ultrasound stimulation, the ultrasound stimulation may be able
to relax muscles before or after the vibrotactile stimulation,
which can increase the effectiveness versus vibrotactile
stimulation alone because the muscles are relaxed rather than
tensed between vibrotactile stimulations. For example, when
vibrotactile stimulation is combined with optical stimulation
(e.g., a tissue-penetrating red laser), the optical stimulation may
be able to reach portions of the body that the vibrotactile
stimulation cannot, which can increase the effectiveness versus
vibrotactile stimulation alone because additional tissues are
stimulated and/or some same tissues may be stimulated in a
different way to produce a different response.
[0124] In some embodiments, vibratory stimulation may be applied at
a vibrating frequency of about 1 Hz to about 100 Hz, about 5 Hz to
about 70 Hz, about 30 Hz to about 60 Hz, about 50 Hz to about 60
Hz, about 55 Hz to about 60 Hz, or about 58 Hz to about 60 Hz.
Certain such frequencies may be useful, for example, for single
vibrator applications. FIG. 12 is a bar chart illustrating efficacy
of various vibrotactile frequencies in inducing an urge to swallow.
In some embodiments, the vibrator produces a sequential wave of
pressure across bars (such as 1 to 5 oblong bars) at about 0.5 Hz
to about 30 Hz, or about 2 Hz to about 25 Hz, or about 5 Hz to
about 10 Hz. In some embodiments, vibratory stimulation may be
applied at a first vibrating frequency of about 10 Hz to about 150
Hz, about 25 Hz to about 125 Hz, about 50 Hz to about 90 Hz, about
65 Hz to about 75 Hz, or about 68 Hz to about 72 Hz (e.g., about 70
Hz), and, at least partially simultaneously, at a second vibrating
frequency of about 50 Hz to about 200 Hz, about 75 Hz to about 175
Hz, about 90 Hz to about 130 Hz, about 105 Hz to about 115 Hz, or
about 108 Hz to about 112 Hz (e.g., about 110 Hz). In some
embodiments, vibratory stimulation may be applied at a first
vibrating frequency of about 10 Hz to about 100 Hz, about 15 Hz to
about 75 Hz, about 20 Hz to about 40 Hz, about 25 Hz to about 35
Hz, or about 28 Hz to about 32 Hz (e.g., about 30 Hz), and, at
least partially simultaneously, at a second vibrating frequency of
about 30 Hz to about 200 Hz, about 40 Hz to about 110 Hz, about 50
Hz to about 90 Hz, about 65 Hz to about 75 Hz, or about 68 Hz to
about 72 Hz (e.g., about 70 Hz). Such frequencies may be useful,
for example, for multiple vibrator applications. In some
embodiments, the vibrators produce sequential waves of pressure
across the same or different bars. In some embodiments, the
difference between the vibrating frequencies of multiple
stimulators is between about 10 Hz and about 100 Hz, between about
20 Hz and about 60 Hz, between about 30 Hz and about 50 Hz, between
about 20 Hz and about 30 Hz, between about 35 Hz and about 45 Hz,
between about 38 Hz and about 42 Hz (e.g., about 40 Hz), or between
about 23 Hz and about 27 Hz (e.g., about 25 Hz). The amplitude of
vibration may be, for example, about 1 micron (.mu.m) to about 2
mm, or about 100 .mu.m to about 1 mm.
[0125] In some embodiments, the pressure and/or electrical
stimulation is applied at a frequency of about 50 Hz, about 51 Hz,
about 52 Hz, about 53 Hz, about 54 Hz, about 55 Hz, about 56 Hz,
about 57 Hz, about 58 Hz, about 59 Hz, or about 60 Hz. The pressure
may be about 1 pound per square inch (psi) to about 14 psi with
rise times of about 2 ms to about 500 ms or rise times between
about 4 and about 150 ms. The pressure may be about 0.5 kiloPascals
(kPa) to about 8 kPa, about 2 kPa to about 6 kPa, or about 3 kPa to
about 5 kPa (e.g., about 4 kPa). Other pressures are also possible.
Greater pressure can increase the elicitation of swallowing, but
can also lead to increased discomfort. Healthy subjects generally
tolerate a pressure of less than about 4 kPa (e.g., about 3 kPa),
although a recent subject tolerated about 6 kPa. The pressure may
be an adjustable parameter that can be varied or tuned for each
subject.
[0126] Electrical stimulation, if used, may applied at a rate of 30
Hz at low levels of less than about 2 mA over a small area of 1
cm.sup.2 or 25 mA over a large area (about 10 cm.sup.2) or greater,
or less if the area is smaller (less than about 10 cm.sup.2), such
as about 0.01 mA to about 10 mA, about 0.1 mA to about 7 mA, about
0.5 mA to about 5 mA, or about 1 mA to about 3 mA to assure that
only sensory stimulation is occurring, and that the electrical
stimulation does not result in muscle contraction. Levels that do
not exceed about 10 mA (e.g., about 7 mA, about 5 mA, about 4 mA,
about 3 mA, about 2 mA, and about 1 mA) may be useful in this
regard. In some embodiments, electrical stimulation comprises
biphasic pulses (e.g., pulses at about 50 microsecond (.mu.s) to
about 300 .mu.s) of about 1 mA to about 5 mA current at about 15 Hz
to about 60 Hz. When a system or method comprises electrical
stimulation, care should be taken to assure that muscle contraction
is not occurring, as stimulation of muscles in the throat area pull
the hyoid downward and interfere with swallowing.
[0127] In some embodiments, the amplitude of the stimulation
(measured as energy output or more directly as, e.g., vibration
displacement) and/or the rate of the stimulation pulse increases
during the swallowing activity. In some embodiments, the duration
of stimulation is set to the average measured or expected duration
of the subject's swallow (e.g., between about 1 s and about 3 s,
between about 1 s and about 2 s, between about 1 s and about 1.5
s). In some embodiments, the stimulation lasts as long as the
swallow is perceived to occur (e.g., by a sensor or by the
subject). In some embodiments, the stimulation lasts as long as a
switch is activated. To inhibit or prevent central adaptation or
desensitization to the stimulation, the stimulation should only be
turned on by the subject when attempting to swallow and should
remain off when the subject is not attempting to swallowing. An
exception is the automatic mode described herein, which is not
necessarily considered a training mode.
[0128] The subject can activate a system stimulates their own
throat over the larynx to elicit the reflex swallowing. In some
embodiments, the stimulation is vibratory, tactile, pressure, or a
combination thereof. In some embodiments, the stimulation is
vibrotactile. In some embodiments, the subject controls the
stimulation via an actuator in communication with the stimulator.
The vibrotactile stimulator can provide substitute sensation to
assist with eliciting swallowing while training the subject to
volitionally control swallowing to substitute for their loss of
reflexive swallowing. Certain systems described herein can train
the subject to activate the actuation (e.g., press a button)
immediately before wanting to swallow to provide an alternate
sensory input via vibrotactile stimulation (or other sensory
modalities) to the throat area to enhance volitional control of
swallowing.
[0129] Swallowing retraining can provide subjects and their
caregivers the opportunity to practice volitional swallowing early
in the postextubation period. FIG. 12 is graphically depicts
conceptualization of events after brain injury. Referring again to
FIG. 2, certain neural circuitry is involved when using a hand
control 203 to trigger volitional swallowing 204 along with
simultaneous sensory stimulation 201 that goes to the cortex 202.
This may occur after button press training described herein.
Elicitation of the swallowing reflex and safety in swallowing is
dependent upon sensory feedback 201 to the brain from sensory
mechanoreceptors in the upper airway. If sensory input is
withdrawn, subjects feel that they can no longer swallow and are at
significant risk of aspiration during swallowing. The neural
circuitry enhances cortical motor control 202 of swallowing
coincident with substitution of sensory input 203 from stimulation
of the throat area to trigger brain stem circuitry to trigger
reflexive swallowing 204 simultaneous with volitional swallowing.
By practicing motor onset with a device that provides an
alternative sensory input to the brain, such as vibrotactile
stimulation, the subject can regain volitional swallowing control,
readying them to swallow safely first with their own saliva and
later to ingest small amounts of food in a controlled volitional
fashion. By providing volitional control over swallowing, the
subject can substitute voluntary swallowing for their loss of
reflexive swallowing.
[0130] An automatic timer can be used to stimulate the initiation
of swallowing on a periodic basis to inhibit or prevent drooling
and/or aspiration of the subject's own secretions. In some
embodiments, activation of the stimulator is not dependent upon
manual volitional activation by the subject, and can be set to
initiate swallowing without a user input at a predetermined or
variable interval. For example, the automatic timer can be
configured to initiate swallowing of saliva to inhibit or prevent
aspiration of secretions from drooling during sleeping. Methods for
automatically stimulating swallowing on a regular basis or set
interval may comprise applying a vibrotactile stimulator (e.g.,
comprising one vibrational transducer, two vibrational transducers,
or two vibrational transducers with different vibrating
frequencies) to an outside surface of the subject's neck
substantially over the subject's larynx and configuring an
automatic timer to activate the vibrotactile stimulator to induce
the swallowing reflex, for example at vibrating frequencies,
durations, pressures, etc. described herein. In some embodiments,
an onset period of the stimulation comprises about 10 ms to about
1.5 s, about 50 ms to about 750 ms, or about 100 ms to about 500
ms.
[0131] In some embodiments, the automatic timer is configured to
activate the vibrotactile stimulator once every 3 min to about once
every 30 min, once every 2 min to once every 10 min, or once every
1 min to once every 5 min. In some embodiments, the automatic timer
is configured to activate the vibrotactile stimulator for a
duration of about 10 ms to about 20 s, during which pulsed
stimulation is produced for about 200 ms to about 10 s to induce
the swallowing reflex. Activation of the vibrotactile stimulator
may be pulsed at a particular rate and last for a particular
interval to produce vibrations at desired a frequency or
frequencies and/or pressure.
[0132] The device may comprise a counter and timer system to aid in
monitoring a subject's use of the device. For example, the counter
and timer system can be used to determine or measure frequency of
stimulator activation, including how often the subject uses the
device, which mode the subject uses, how long and when the device
is stimulated, and the like. The data generated by the counter and
timer system can be used, for example, to determine compliance with
a training or therapy regime. Such data can be used to modify a
treatment or training program and/or can alert caretakers to a risk
of drooling or aspiration of secretions due to limited use of the
system.
[0133] Methods for identifying a subject at risk of aspiration from
their own secretions may comprise applying a device to an outside
surface of the subject's neck substantially over the subject's
larynx, downloading data from the device after a period of use of
the device by the subject, and analyzing to data to determine if
the subject is at risk of aspiration from their own secretions due
to limited use. The subject activates the device to induce
volitional swallowing and/or allows the device to function in
automatic mode, and the device records the data to allow a health
professional to determine if the subject is at risk due to limited
use.
[0134] Methods for monitoring subject compliance with a training or
therapy regime may comprise applying a device to an outside surface
of the subject's neck substantially over the subject's larynx,
downloading data from the device after a period of use of the
device by the subject, and analyzing to data to determine if the
subject is in compliance with the training or therapy regime. The
subject activates the device to induce volitional swallowing and/or
allows the device to function in automatic mode, and the device
records the data to allow a health professional to determine if the
subject is at risk due to limited use.
[0135] For dysphagia treatment, a band may be wrapped around the
neck, with an inflatable balloon positioned over the larynx. Upon
activation (e.g., pressing a button) by the subject or under orders
from the subject, the balloon inflates and puts pressure on the
larynx. A control box may set parameters such as the stimulus type,
stimulus shape (e.g., wave shape (e.g., sinusoidal, sawtooth,
square wave)), stimulus rate (constant or changing over time),
stimulation continuousness (e.g., continuous, pulsed), and/or
stimulus amplitude (constant or changing over time), and whether
the duration would be set or stay for 2 s to 6 s or as long as the
button is pressed. In some embodiments, the device that stimulates
the substitute site comprises a pressure-applying device that
attaches to the body by, for example, a hook-and-loop fastener,
strap, rubber band, belt, bandage, garment, ace bandage, wire,
string, piezoelectric band or film, and/or combination of these, or
by any other method known in the art.
[0136] In some embodiments, the stimulating device may include a
pressure applying device such as an inflatable tube that inflates
to a desired pressure or volume, for example adapted from a blood
pressure monitor. A neck wrap may position the pressure applying
device to the throat area above the larynx and is adjustable (e.g.,
via hook-and-loop fastener material or any other adjustable
fastener). A small point (e.g., as small as about 0.02 cm.sup.2) on
the throat over the larynx may be pressed, although larger areas
(e.g., about 0.1 cm.sup.2 to about 10 cm.sup.2, about 0.25 cm.sup.2
to about 5 cm.sup.2, about 0.5 cm.sup.2 to about 2.5 cm.sup.2) of
any shape may be used. For example, an area may be about a 2
cm.sup.2 circle. In some embodiments, at least about 25%, at least
about 35%, at least about 50%, at least about 75%, at least about
85%, at least about 90%, at least about 98%, or more of the total
pressure (calculated as an integrated sum measurement of pressure
times surface area) is placed on the throat over the larynx
cartilage, and not over surrounding muscle. In some embodiments,
vibratory energy is selectively confined on the throat over the
larynx versus the surrounding muscle. In some embodiments, less
than about 50%, less than about 25%, less than about 10%, less than
about 5%, or even less of the total pressure is applied to neck
muscles. In some embodiments, the stimulation may comprise
vibration, pressure, thermal (e.g., application of cold and/or
heat), and/or low levels of electrical stimulation capable of
inducing a sensory stimulus but not high enough to induce muscle
contraction, or a combination thereof.
[0137] Many subjects are intubated to maintain the airway for
ventilation, including following loss of consciousness due to brain
injury or stroke or following coronary artery bypass graft. An
endotracheal tube is extubated as the subject recovers cognitive
function, at which point the swallowing reflex may be reduced. FIG.
13 shows a conceptualization of events post brain injury, placing
subjects at high risk of aspiration post extubation with
tracheotomy due to reduced afferent stimulation in the upper airway
and restricted oral intake, limiting return of reflexive
swallowing.
[0138] There may be several factors that contribute to reduced
swallowing reflex associated with intubation. For example, sensory
feedback from the upper airway to the brain may be reduced due to
changes in the sensory function of the mucosa in the upper airway,
possibly as a result of injury to the mucosa by the endotracheal
tube, and sensory organs of nerve endings supplying those organs
due to the pressure of the endotracheal tube on the mucosa or
resultant edema in the upper airway. In some subjects, tissue
granulation/ulceration occurs when the endotracheal tube has been
in place for prolonged periods (greater than one week). Upon
extubation, such subjects often receive a tracheostomy to provide
an adequate airway. During the period following extubation, the
normal swallowing reflex is reduced, increasing the risk of
aspiration.
[0139] In addition to loss of the swallowing reflex, when such
subjects have a tracheotomy, sensory input to the upper airway may
be further reduced because of a lack of air flow through the
hypopharynx. In addition, such subjects are often placed on a
restricted oral intake to prevent aspiration. As a result of their
"nothing per oral" (NPO) status, such subjects are not swallowing
and may be fed through a nasogastric tube or long-term by enteric
means for several days or weeks. Some or all of these factors can
reduce reflexive swallowing. During this period, the methods
disclosed herein can enhance volitional swallowing.
[0140] Certain devices and methods described herein can provide
volitional control for subjects with motor control disorders
affecting speech and voice. Persons who stutter usually have
difficulty with speech initiation and have speech "blocks" when the
subject undergoes a loss of volitional control over the laryngeal
muscles in particular. This loss of volitional control is
manifested as delay in voluntary initiation of muscle contraction
or vocal fold movement or an interference due to chronic laryngeal
muscle contractions or sustained vocal fold closure. Several
studies have suggested that adults who stutter may have increased
thresholds to kinesthetic or vibratory stimulation during speech.
The devices and methods disclosed herein can enhance vibratory
sensory input to persons who stutter. Recent research has shown
that persons who stutter have delays in their onset of vocal fold
vibration during speech. Increasing vibrotactile input to the
central nervous system in persons who stutter can enhance their
volitional control for speech. When a mechanical displacement is
applied to the larynx, for example as described herein, it can
stimulate proprioceptors in the strap muscles, producing a
reflexive stemothyroid muscle contraction. Because extrinsic
laryngeal muscles have a high muscle spindle density, stretch or
vibratory stimuli applied to the larynx will serve to enhance
muscle activity in this region.
[0141] Certain devices and methods described herein can provide
enhanced volitional control for subjects with spasmodic dysphonia
and/or laryngeal dystonia. Spasmodic dysphonia is a laryngeal focal
dystonia, which produces voice abnormalities during speech similar
to stuttering. These subjects have particular difficulties
initiating voicing during speech and are often slow to initiate
laryngeal muscle activity and have problems maintaining vocal fold
vibration during speech. Many focal dystonias have associated
sensory abnormalities, with reduced cortical responses in the
somatosensory area including spasmodic dysphonia. By providing
increased vibratory stimulation to the laryngeal area, input to the
cortical somatosensory region will enhance volitional voice control
for speech in persons with spasmodic dysphonia.
[0142] In prior methods for treating stuttering, many devices
provide altered auditory input, auditory masking, or delayed or
frequency-altered feedback of the speaker's speech to them.
Examples include the Edinburgh Masker, Delayed Auditory Feedback by
Phonic Ear, Pacemaster, the Casa Futura System, Vocaltech, Fluency
Master.RTM., and SpeechEasy.RTM.. The VocalTech.RTM. device
includes a vibrator applied to the throat of the user. A microphone
picks up the user's voice and then provides both an auditory
feedback signal and a vibration to the throat to alter feedback
during speech. Certain embodiments described herein differ both in
concept and in function from these systems in that the subject
presses a button to initiate vibrotactile stimulation to aid their
ability to initiate speech/voice onset. In such embodiments, the
vibratory signal is initiated before the subject attempts to
initiate speech and can aid in their volitional control of speech
initiation. The VocalTech.RTM. device, by contrast, only detects
speech after speech has started and can only be triggered by the
subject's own speech. The VocalTech.RTM. device utilizes a feedback
of the subject's speech and no other inputs such that if the
subject is unable to initiate speech and/or voice, the vibratory
signal cannot be initiated. The lack of initiation of the vibratory
signal is further exacerbated as there is a delay between the onset
of the subject's speech and the onset of the vibratory and auditory
feedback. The VocalTech.RTM. device is therefore unable to enhance
the subject's ability to onset speech since the device is dependent
upon the speaker being able to initiate speech. Other auditory
masking or delayed or frequency altered feedback devices such as
SpeechEasy.RTM. also alter or delay the speaker's acoustic speech
signal and also require that the speaker is able to initiate speech
before the feedback can occur. In contrast, certain devices
disclosed herein can assist subjects with speech initiation because
the vibratory stimulus precedes the subject's speech initiation by
enhancing mechanical sensory input to cortical control centers for
speech.
[0143] In some embodiments, the devices described herein are
portable and can be supplied to adults who stutter and persons with
dysphonia to provide stimulation before speech to enhance
triggering and controlling voice onset and maintenance for speech.
The devices can be used in everyday speaking situations. Subjects
could purchase the device to use in everyday life to enhance
volitional control while speaking.
C. Kits
[0144] The present disclosure includes kits that include at least
two of: a stimulator adapted to be placed in contact with an
affected body part such as the larynx, a control box, an actuator,
a power supply, a disposable cover, a container, and instructions
for use. The instructions may include at least one instruction
corresponding to one or more of the methods disclosed herein. In
some embodiments, the stimulator includes at least one pump
configured to increase pressure within a chamber. The stimulator
may include a pressure, stretch, volume, power, or other sensor to
monitor exerted pressure. In some embodiments, the stimulator
and/or the control box may include controls, for example, for
setting frequency, amplitude, pressure, etc.
EXAMPLES
[0145] The present disclosure may be better understood with
reference to the following examples. Example 1 demonstrates that
low levels of sensory stimulation to the throat area in subjects
with severe chronic pharyngeal dysphagia enhances their ability to
swallowing safely while high levels of electrical stimulation that
activate throat muscles do not enhance swallowing in these
subjects. Example 2 demonstrates that two different vibrating
properties, such as two different vibrating frequencies, may better
elicit swallowing than a single vibrating property.
Example 1
[0146] Although surface electrical stimulation has received some
attention as an adjunct to swallowing therapy in dysphagia, little
is known about the effects of transcutaneous stimulation on
swallowing physiology. It has been hypothesized that electrical
stimulation may assist swallowing either by augmenting hyolaryngeal
elevation or by increasing sensory input to the central nervous
system to enhance the elicitation of swallowing.
[0147] When electrical stimulation is applied to the skin or oral
mucosa at low current levels, it activates the sensory nerve
endings in the surface layers, providing sensory feedback to the
central nervous system. With increased current amplitude, the
electric field may depolarize nerve endings in muscles lying
beneath the skin surface and may spread with diminishing density to
produce muscle contraction.
[0148] When electrodes are placed in the submental region, the
current density is greatest at the skin surface and diminishes with
depth through the platysma underlying the skin and subcutaneous
fat. As the current increases in amplitude, increasingly deeper
muscles may be recruited, albeit with less efficiency. Such muscles
include the anterior belly of the digastric, which can either lower
the mandible or pull the hyoid upward, depending on whether the
mouth is held closed. Deeper still are the mylohyoid and geniohyoid
muscles, which pull the hyoid bone upward and toward the mandible,
respectively. These muscles are much less likely to be activated by
surface electrical stimulation because of their greater depth.
[0149] When electrodes are placed on the skin overlying the thyroid
cartilage in the neck, the current will be greater at the skin,
with less intensity to the underlying platysma muscle, with further
reduction to the underlying sternohyoid and omohyoid muscles, which
pull the hyoid downward and backward towards the sternum. The
electrical field strength would be even further diminished if it
reaches the deeper thyrohyoid muscle, which brings the larynx and
hyoid together and the stemothyroid muscle, which lowers the larynx
towards the sternum. Given that the stemohyoid muscle is larger and
overlies the thyrohyoid and stemothyroid, high levels of surface
electrical stimulation on the neck could pull the hyoid downward,
interfering with the ability of certain subjects to raise the
larynx toward the hyoid bone as occurs in normal swallowing. In
fact, in some healthy volunteers, high intensity surface electrical
stimulation reduced swallowing safety as it allowed liquid to enter
the vestibule.
[0150] In VitalStim.RTM. Therapy, electrodes are simultaneously
activated over the submental and laryngeal regions on the throat,
with the aim of producing a simultaneous contraction of the
mylohyoid in the submental region (to elevate the hyoid bone) and
the thyrohyoid in the neck (to elevate the larynx to the hyoid
bone). However, because these muscles lie deep beneath the anterior
belly of the digastric, sternohyoid and omohyoid muscles,
simultaneous transcutaneous stimulation with two pairs of
electrodes at rest might cause: 1) the hyoid bone to descend in the
neck (due to sternohyoid muscle action); 2) the hyoid bone to move
posteriorly (due to the omohyoid muscle activity); and 3) the
larynx to descend (if current activates either the sternohyoid or
stenothyroid muscles), and, in severe chronic dysphagia: 4) when
the same array is used at low levels of stimulation just above the
sensory threshold, sufficient for sensation but without muscle
activation, subjects' swallowing might improve due to sensory
facilitation; while 5) at higher levels required for motor
stimulation, the descent of the hyoid might interfere with
swallowing causing increased penetration and aspiration.
[0151] Methods
[0152] Participant selection criteria included: chronic stable
pharyngeal dysphagia, at risk for aspiration for 6 months or more,
a score of 21 or greater on the Mini-Mental State Examination, a
severely restricted diet and/or receiving nutrition through enteric
feeding, and medically stable at the time of the study. To be
included for study, all participants had to demonstrate a risk of
aspiration for liquids on videofluoroscopy during the screening
portion of the study.
[0153] Procedures
[0154] Participants were administered informed consent, and had to
correctly answer 10 questions to demonstrate that they understood
the content of the consent before participating. VitalStim.RTM.
electrodes and the VitalStim.RTM. Dual Channel Unit were used for
the study. Two sets of electrodes were used; the top set was placed
horizontally in the submental region over the region of the
mylohyoid muscle above the hyoid bone. The bottom set was placed on
the skin over the thyroid cartilage on either side of the midline
over the region of the thyrohyoid muscle medial to the
sternocleidomastoid muscle. This electrode array was recommended as
effective during certification training. A ball bearing with a
diameter of 19 mm was taped to the side of the neck for measurement
calibration.
[0155] After familiarizing the participant with the device, the
sensory threshold, which was the lowest current level at which the
participant reported a "tingling" sensation on the skin, was
identified. Electrical surface stimulation at the sensory threshold
level did not produce movement on videofluoroscopic recordings, and
was the lowest level at which participants sensed the electrical
stimulation on the skin. Movement was first observed when
participants first reported a "tugging" sensation, usually around 7
milliamperes (mA) or 8 mA. The maximum vibrator motor level was the
highest current level a participant could tolerate without
discomfort during surface electrical stimulation on the neck. The
sensory and motor levels were determined independently for each set
of electrodes. The VitalStim.RTM. device cycles automatically from
"on" to "off" to "on" again for 1 second every minute. Because the
change in surface electrical stimulation is ramped, this cycling
process takes up to 4 s. For the stimulation at rest trials, the
participant was told to keep their teeth clenched to prevent jaw
opening and the stimulation was simultaneously set at the maximum
tolerated levels for both sets of electrodes. When the stimulation
duration reached 55 s, videofluoroscopy was turned on and the
fluoroscopic image was recorded on S-VHS videotape while the
participant was in the resting position, and the device
automatically cycled from "on" to "off" and then "on" again. The
examiner pressed a button at the time of stimulation offset to
place a visible marker on the videotape.
[0156] During the videofluoroscopic screening examination, a
volume, either a 5 mL or 10 mL of liquid barium bolus, was
determined to be more challenging and put a participant at risk of
aspiration for use during testing. During testing, between one and
three swallows were recorded in each of the following conditions in
random order: 1) with no stimulation, 2) with both electrode sets
on at the sensory threshold level, and 3) with both sets at the
maximum tolerated stimulation level. The surface electrical
stimulation remained on before, during, and after the stimulated
swallows. The videotaped recordings included an auditory channel
for documentation and a frame counter display for identifying when
stimulation changed.
[0157] Because radiation exposure during this study was
administered for research purposes only and was not for necessary
medical care, the Radiation Safety Committee limited exposure time
per participant for the total study. Therefore, depending on
radiation exposure time in each part of the study, only one to
three trials per condition were able to be performed in addition to
stimulation at rest for each of the participants.
[0158] Movement Analysis
[0159] The video of each trial was captured off-line using Peak
Motus 8, a 2D motion measurement system. The system was equipped
with a video capture board at -60 fields/s (-30 frames/s) and a
frame size of 608.times.456 pixels. The radius of the ball bearing
(9.5 mm) was used for all measurement calibrations in the
horizontal and vertical directions. An investigator used a cursor
to identify the points on the most anterior-inferior corner of the
second and fourth vertebra on each video frame and a straight line
was drawn between these two points to define the y axis. When
either the second or fourth vertebra was not visible, the bottom
anterior-inferior corner of the first and third vertebrae were used
in the same fashion. A line perpendicular to the y axis at the
anterior-inferior corner of the lower vertebra served as the x
axis. The x and y coordinates for all points were determined in mm
relative to the anterior-inferior corner of the second vertebra
serving as the origin with anterior and superior points being
positive and posterior and inferior points being negative for
direction of movement of the hyoid. Four points were marked for
each frame, the anterior-inferior points of the two interspersed
vertebrae, the anterior inferior point of the hyoid bone and the
most posterior and superior point in the subglottal air column (to
track the position of the larynx).
[0160] The time series plots of the x and y points of the hyoid
bone and the y coordinate of the larynx were exported from Peak
Modus into Microsoft Excel and then into Systat 11 (available from
Systat Software, Inc. of Richmond, Calif.) for analysis. The frame
when the stimulation cycled from "on" to "off" was added to the
file and used to sort measures into stimulation "on" and
stimulation "off." All of the position data were then corrected to
place the starting position at zero on both the x and y axes for
each subject and then the mean hyoid (x,y) and larynx (y) positions
were computed for the stimulation "on" and stimulation "off"
conditions for each subject.
[0161] Dysphagia Ratings
[0162] Four experienced certified speech pathologists initially
examined the screening videotapes of randomly selected subjects to
decide on a rating system. After assessing several swallows with
the Pen-Asp, it was noted that many of the participants who were on
enteric feeding because of their risk of aspiration could score
within the normal range, a score of 1 on this scale. This occurred
when no penetration or aspiration occurred, even though there was
severe residual pooling in the pyriform sinuses and none of the
bolus entered the esophagus. These participants regurgitated any
residual material back into the mouth after a trial, not swallowing
any of the liquid but scoring as normal because no material entered
the airway. Because scores of 1 on the Pen-Asp scale were at
ceiling (normal) and would not allow measurement of improvement,
this scale could only measure a worsening in swallowing in these
subjects. Therefore, another scale was developed that did not have
a ceiling effect.
[0163] The NIH Swallowing Safety Scale (SSS) captured the
abnormalities seen in this subject group, which involved pooling
and a lack of esophageal entry with and without penetration and
aspiration. When scoring a swallow, a score of 1 was assigned for
the occurrence of each the following abnormalities: pooling in the
vallecula, penetration into the vestibule from the hypopharynx,
pooling in the pyriform, and back up penetration from the pyriform
into the laryngeal vestibule. The amount of the bolus material
entering and clearing from the upper esophagus was rated as 3 if
none entered, 2 if a minimal amount entered, 1 if a moderate amount
entered and 0 if all of the bolus was cleared through the upper
esophagus. In addition, the total number of aspirations in each
swallowing sample were counted. Only normal swallows received a
total of 0 on this scale and the maximum score could reach as high
as 15 depending upon the number of aspirations or other
abnormalities in bolus flow that occurred in a single swallow.
[0164] All four speech pathologists viewed each videofluoroscopic
recording without knowledge of condition and came to a consensus on
all noted behaviors and the Pen-Asp rating before assigning the
scores. After repeating ratings on 21 trials to establish
reliability, differences in ratings of the same swallow were noted
and a set of uniform rules were developed to be followed in
assigning scores. These rules were subsequently used to assign
ratings to each of the trials in this study. Another set of 18
trials was then repeated to determine the measurement
reliability.
[0165] Statistical Analyses
[0166] To determine the reliability of the position measures, two
examiners measured the position for the hyoid on the x and y axes
and larynx on the y axis on each frame and then computed means for
each during both the stimulated and non-stimulated conditions on 4
of the 10 subjects. The output of the General Linear Model Systat
11 was used to calculate the mean square differences for the within
and between subject factors. The Intraclass Correlation Coefficient
(ICC) was computed by taking the mean square difference between
subjects and subtracting the mean square difference within subjects
and then dividing the result by the sum of the mean square
difference between subjects and the mean square difference within
subjects.
[0167] To determine the reliability of the ratings made using the
Pen-Asp scale and the NIH-SSS, ICCs were computed between the two
sets of ratings on each scale from the first 21 trials that were
reanalyzed. To identify the items that were unreliable, Cohen's
Kappa was computed for the two sets of ratings of each component
item of the NIH-SSS using Systat 11. After developing rules for
scoring those items that had low reliability, ICCs were computed on
the second set of repeated ratings for both the Pen-Asp Scale and
the NIH-SSS.
[0168] To address the first hypothesis that the hyoid bone would
descend in the neck with maximal levels of stimulation at rest, a
one-sample directional t-test was used to test for a lowering of
the hyoid bone on the y axis between "off" and "on" stimulation. To
address the second hypothesis that the hyoid bone would move
posteriorly, a one-sample directional t-test was used to test for a
retraction of the hyoid bone on the x axis in the "off" and "on"
stimulation conditions within subjects. To determine if the larynx
descended during stimulation, a one-sample directional t-test was
used to test for a lowering of the subglottal air column between
the two conditions.
[0169] To determine if swallowing improved due to sensory levels of
stimulation, one-sample directional t-tests were used to test
participants' mean changes in ratings between non-stimulated
swallows and stimulated swallows within participants on the Pen-Asp
scale and the NIH-SSS with a Bonferroni corrected p value of
0.05/2=0.025. To determine if swallowing worsened during maximum
levels of motor stimulation, one-sample directional t-tests were
used to test participants' mean changes in ratings between
non-stimulated swallows and stimulated swallows within participants
on the Pen-Asp Scale and the NIH-SSS with a Bonferroni corrected p
value of 0.05/2=0.025. Pearson correlation coefficients using a
Bonferroni corrected p value of 0.025 for statistical significance
were computed between both the participant's mean initial severity
on the Pen-Asp scale and the NIH-SSS and changes in mean ratings
during the sensory stimulation to determine if participant
characteristics predicted the degree of benefit. Similarly, Pearson
correlation coefficients were computed between the extent to which
the hyoid was pulled down in the neck during stimulation at rest
and the change in participants' mean ratings for swallowing on the
Pen-Asp scale and the NIH-SSS using a Bonferroni corrected p value
of 0.025 for statistical significance.
[0170] Results
[0171] 1. Participants
[0172] All 11 participants had chronic long-standing dysphagia
(Table 1). Their disorder was either subsequent to a CVA in six
(>6 months post), post craniotomy for a benign tumor in two (2
and 4 years post), or post traumatic brain injury in two (2 and 3
years post). Only one subject had a chronic progressive
neurological disease, Parkinson disease, of >20 years with
dysphagia for more than 2 years duration.
[0173] Ten of the 11 participants participated in the stimulation
at rest trials; one did not because of time constraints. During
swallow stimulation trials, one of the participants had severe
aspiration on an initial swallowing trial and for safety reasons
the study was discontinued for that participant. Therefore, ten
participants were included in the motor stimulation swallow trials.
Because of time constraints, two of the participants did not
participate in the low sensory levels of stimulation, leaving 8
participants in the study.
[0174] 2. Measurement Reliability
[0175] The ICC for the movement of the hyoid bone on the y axis in
the on and off stimulation conditions were 0.99 and 0.94,
respectively, and for hyoid movement on the x axis in the on and
off stimulation conditions were 0.94 and 0.87, respectively. The
ICCs for the larynx on the y axis in the stimulation "on" and "off"
positions were 0.58 and 0.66, respectively, indicating much less
reliability on these measures. Because the movement of the larynx
was extremely small, ranging from a mean position of 0.4 mm in the
stimulation "on" to 0.18 mm in the "off" condition, measurement
variability contributed to the variance on this measure.
[0176] 3. Movement Induced by Stimulation at Rest
[0177] To address the first hypotheses, a one-tailed directional
t-test comparing the mean position between "off" and "on"
stimulation conditions demonstrated a significant lowering of the
hyoid position on the y axis (f=-2.523, o7=9, p=0.016) (see FIG.
16). In FIG. 17, the individual tracings of hyoid movement in each
of the subjects is shown when the stimulator is turned "ON" and
then "OFF" and then "ON" again, showing elevation of the hyoid bone
when the stimulator is turned "OFF." High levels of electrical
stimulation on the throat area lower the hyoid bone when
stimulation is "ON." The hyoid is only able to return to a normal
position in the neck when stimulation is "OFF." Because of this
action, high motor levels of electrical stimulation interfere with
the usual elevation of the hyoid bone, which is required for
swallowing.
[0178] To address the second hypothesis that the hyoid bone would
move posteriorly with stimulation at rest, a directional t-test
comparing the mean positions in the "OFF" and "ON" stimulation
conditions within subjects was not significant (P=-0.102,
.alpha.f/=9, p=0.460). Similarly, a directional t-test found no
descent in laryngeal position on the y axis during stimulation
(.English Pound.=0.696, d/=9, p=0.748).
[0179] FIG. 21 shows that motor levels of surface electrical
stimulation (e.g., neuromuscular 8 mA or greater) can reduce
hyolaryngeal elevation during swallowing in healthy adults.
[0180] 4. Reliability of Ratings on the Pen-Asp and NIH SSS
[0181] After the first set of 21 repeated ratings, the ICC was
0.965 on the PenAsp scale and 0.764 on the NIH-SSS. Because of
concerns about the reliability of the NIH-SSS, more detailed
judging rules were implemented for each item where disagreement
occurred. A second set of 18 reliability measures using the new
judging rules resulted in an ICC for the NIH-SSS that was 0.925,
demonstrating adequate reliability when using the scale once the
judging rules were developed and implemented.
[0182] 5. Effects of Low Sensory Stimulation Levels During
Swallowing
[0183] Due to time constraints, only eight of the ten participants
completed the sensory condition. To address the fourth hypothesis
that swallowing improved with sensory levels of stimulation,
one-sample directional t-tests were computed to compare mean change
in ratings between non-stimulated swallows and stimulated swallows
within participants. The results were not significant on the
Pen-Asp Scale (.English Pound.=0.336, cf/=7, p=0.373), but were
significant on the NIH-SSS (.=.2.355, df=7, p=0.025) using a
Bonferroni corrected p value of 0.05/2=0.025. FIG. 18 is a graph
showing the change in the NIH-SSS for multiple subjects showing the
difference in aspiration during swallowing without stimulation
versus swallowing with low level electrical stimulation at
approximately 2 milliamps (mA) applied on the throat. Sensory
levels of stimulation can enhance swallowing safety. Six of the
eight of the participants showed a reduction on the NIH-SSS with
sensory stimulation during swallowing while five of the eight
participants showed a reduction on the Pen-Asp scale.
[0184] 6. Effects of Motor Stimulation Levels During Swallowing
[0185] To address the fifth hypothesis that the risk for aspiration
and swallowing safety worsened during stimulation, one-sample
directional t-tests were computed to examine mean change in ratings
between non-stimulated swallows and stimulated swallows within
participants. The result was not significant on either the Pen-Asp
scale (/=0.363, d/=9, p=0.637) or on the NIH-SSS (/=-0.881, d/=9,
p=0.201) at a Bonferroni corrected p value of 0.05/2=0.025. On the
NIH-SSS scale, five of the ten participants had increased risk with
motor levels of stimulation (FIG. 19), while on the Pen-Asp equal
numbers of participants increased or decreased with motor levels of
stimulation (FIG. 20). FIG. 19 is auto scaled to the range of the
data in the condition. Therefore FIG. 19 is on a larger scale than
FIG. 20. FIG. 19 shows that high motor levels of electrical
stimulation (>8 mA) do not benefit swallowing in some subjects
with swallowing disorders. FIG. 20 is auto scaled to the range of
the data in the condition. Therefore, FIG. 16 is on a larger scale
than FIG. 20. FIG. 20 shows that high motor levels (>8 mA) of
stimulation do not benefit swallowing.
[0186] 7. Relationship Between Severity of Dysphagia and Changes in
Swallowing with Stimulation
[0187] The Pearson correlation coefficient between participants'
initial severity on the Pen-Asp scale and change in swallowing with
sensory stimulation was not significant (/=0.142, p=0.737).
Similarly, participants' initial severity and change in swallowing
with sensory stimulation on the NIH-SSS (/=0.701, p=0.053) was not
significant using a Bonferroni corrected a value of 0.025 for
statistical significance. A Pearson correlation coefficient between
both the participants' initial severity on the Pen-Asp scale and
change in swallowing with motor stimulation was not significant
(/=-0.501, p=0.140), nor was the correlation between participants'
initial severity on the NIH-SSS and change in swallowing with motor
stimulation (/=-0.190, p=0.599), using a Bonferroni corrected a
value of 0.025 for statistical significance.
[0188] 8. Relationship of Movement During Stimulation at Rest with
Changes in Swallowing with Stimulation
[0189] Pearson correlation coefficients were computed between the
extent to which the hyoid was pulled down in the neck during
stimulation at rest and the change in swallowing on the Pen-Asp and
the NIH-SSS using a Bonferroni corrected o value of 0.025 for
statistical significance. No significant relationship was found
between the degree of improvement on the NIH-SSS and the degree to
which the hyoid bone was depressed during motor levels of
stimulation at rest (r=-0.388, n=9, P=0.302). The improvement in
the Pen-Asp scale during motor stimulation was significantly
inversely related to the degree to which the hyoid bone was
depressed during motor levels of stimulation at rest (r=-0.828,
n=9, p=0.006). The relationship demonstrated that those with the
greatest hyoid depression at rest had the greatest reduction on the
Pen-Asp scale during motor levels of stimulation while
swallowing.
[0190] Discussion
[0191] One purpose of this study was to determine the physiological
effects of surface electrical stimulation on the position of the
hyoid and larynx in the neck. It was predicted that when both the
submental and laryngeal electrode pairs were stimulating at the
participants' maximal tolerated levels, the hyoid bone would be
pulled downward, most likely due to stimulation of the sternohyoid
muscle. The data supported this hypothesis; as all but two of the
participants had depression of the hyoid bone by as much as 5 mm to
10 mm during stimulation at rest. It was also predicted that the
hyoid bone might be pulled posteriorly; however, limited
anterior-posterior movement occurred in the hyoid bone. Three
participants had hyoid anterior movement, by as much as 5 mm in one
case, while the others had minimal movement in the posterior
direction. Whereas minimal ascending movement (2-3 mm) occurred in
the larynx in two participants, none of the other participants
experienced any appreciable laryngeal movement and the 2-3 mm
changes were potentially due to measurement variation. To summarize
these findings, the only appreciable motoric effects of surface
electrical stimulation was to cause the hyoid bone to descend in
the neck, producing movement in the opposite direction from that
required for swallowing.
[0192] These results suggest that when surface stimulation was
applied to the neck at rest, stimulation was either too weak or not
deep enough to stimulate axons innervating the muscles that produce
hyoid and laryngeal elevation such as the mylohyoid and the
thyrohyoid muscles respectively. No change in laryngeal position
was observed with surface stimulation at rest.
[0193] Another purpose of this study was to determine the immediate
effects of surface stimulation on swallowing in participants with
chronic pharyngeal dysphagia. Based on previous use of sensory
stimulation in the oral and pharyngeal cavities to augment
subjects' volitional control of swallowing, sensory levels of
electrical stimulation just above the participants' sensory
threshold were compared for detecting a tingling sensation on the
skin, and showed a significant improvement during swallowing on the
NIH-SSS scale (FIG. 18). The improvement on the NIH-SSS tended to
be related to higher initial scores; that is the more severely
affected subjects were those who had the greatest improvement with
stimulation. Because the NIH-SSS captures pharyngeal pooling and
failed esophageal entry in contrast with the Pen-Asp scale, which
only measures aspiration and penetration, sensory stimulation may
be somewhat helpful in those patients who have reduced ability to
clear the bolus from the airway.
[0194] Based on the expected lowering of the hyoid with motor
levels of stimulation, it was hypothesized that the group would
have increased penetration and aspiration during swallowing with
motor stimulation. No group change in aspiration was noted on
either scale with motor levels of stimulation. When the degree of
improvement on the Pen-Asp scale with motor levels of stimulation
was examined relative to the degree of hyoid depression, an
unexpected relationship indicated that subjects with the greatest
hyoid depression during motor levels of stimulation at rest had the
greatest improvement during swallowing with the same levels of
stimulation. When the hyoid was depressed with stimulation, a
subject probably experienced a greater resistance to hyolaryngeal
elevation during swallowing. Perhaps those subjects who felt a
greater downward pull on the hyoid, when stimulation was turned on
at maximal levels, made a greater effort to elevate the
hyolaryngeal complex when swallowing in an attempt to overcome the
effects of the stimulation. It could also be the case that those
subjects who had greater residual power in their hyolaryngeal
muscles would have not only experienced greater hyoid descent with
stimulation but could also have greater residual power that they
could recruit for hyolaryngeal elevation to counteract the
stimulation induced descent during swallowing.
[0195] This study also addressed the immediate physiological
effects of the use of surface electrical stimulation at rest and
during swallowing. This study suggests that electrical stimulation
should be used judiciously dependent upon a subject's type and
degree of difficulty with swallowing. In those subjects who already
have some ability to raise the hyolaryngeal complex, hyoid
depression with stimulation may serve as "resistance" during
therapy. On the other hand, if a subject is unable to produce any
hyolaryngeal elevation, and therefore would not be able to resist
the hyoid depression induced by stimulation, stimulation might put
such a subject at greater risk of aspiration as the hyolaryngeal
complex is held down during swallowing. This may have occurred in
some of the more severely affected subjects who increased in
severity on the Pen-Asp and NIH-SSS with motor levels of
stimulation, while those less impaired did not change (FIGS. 19 and
20).
[0196] In this study, both submental and laryngeal pairs of
electrodes were used simultaneously, as is recommended for
VitalStim.RTM. Therapy. It is likely that the simultaneous
stimulation resulted in hyoid lowering because the stronger
stimulation to the more superficial and larger sternohyoid and
sternothyroid muscles overcame any action that might have been
induced by stimulation of the mylohyoid muscle in the submental
region or the thyrohyoid muscle beneath the sternohyoid in the
throat region. Some have proposed using submental stimulation alone
to activate the anterior belly of the digastric and the mylohyoid
muscles to pull the hyoid bone upward. However, elevation of the
hyoid bone without simultaneous stimulation of the thyrohyoid to
raise the larynx would leave the larynx down resulting in further
opening of the vestibule and increased risk of aspiration. Only if
the mylohyoid and thyrohyoid muscles are activated together,
without contraction of the sternohyoid, would both the hyoid and
larynx be raised together as has previously been shown with
intramuscular stimulation. This cannot be achieved using surface
electrical stimulation because the larger sternohyoid muscle
overlies the thyrohyoid and pulls the hyoid downward.
[0197] The finding that the group as a whole improved with sensory
levels of stimulation alone on the Pen-Asp scale was unexpected.
Previous research has shown that stimulation of the anterior and
posterior faucial pillars was most effective stimulation for
eliciting a swallow reflex in normal persons. Although not studied
physiologically, stroking the throat region is known to assist with
the spontaneous elicitation of swallowing in infants and some
mammals. Stimulation of either the glossopharyngeal or the superior
laryngeal nerves has been shown to elicit swallowing in animals and
bilateral chemical blockade of the superior laryngeal nerves
disrupts swallowing in normal humans. It has not been observed that
sensory stimulation to the surface of the throat would reflexively
trigger a swallow in adults; however, sensory levels of electrical
stimulation on the skin in the throat may facilitate volitional
triggering of swallowing in dysphagia. These results suggest that
low levels of electrical stimulation on the skin might be
beneficial in some subjects. Because such low levels of electrical
stimulation were not observed to induce hyoid depression, it was
posited that none of the subjects would be put at increased risk
for aspiration using lower sensory levels of stimulation. Before
surface electrical stimulation is used, the subjects should be
carefully screened to determine whether they would be placed at
increased risk of aspiration with a procedure that lowers the
hyoid.
TABLE-US-00001 TABLE 1 PARTICIPANT CHARACTERISTICS AND SURFACE
ELECTRICAL STIMULATION LEVELS Sensory Motor Threshold Threshold
Upper/ Upper/ Time post Lower Lower onset Electrode Electrode
Subject Sex Age Etiology (years) Status (mA) (mA) 1. M 66
hemorrhage in 2.5 PEG, bilateral sensory 3.5/2.0 8.0/8.0
veterbrobasilar loss, pooling, previous circulation aspiration
pneumonia 2. M 66 Parkinson 20 years PEG for 2 years, 6.0/2.5
10.0/10.0 disease duration, swallowed own Severe secretions
dysphagia Recurrent pneumonias 2+ years 3. M 76 Stroke 1 PEG unable
to handle 4.0/2.0 14/7.0 secretions Aspriation pneumonia X 3,
normal sensation 4. M 78 Brain stem 5 PEG, frequent 7.0/7.0 14/14
stroke aspiration pneumonias, sever reductions in UES relaxation,
normal sensation 5. F 47 Left occipital 3 PEG, unable to handle
3.0/4.0 10/10 and brain stem secretions stroke Bilateral sensory
loss 6. M 25 closed brain 2 Aspirations on liquids, 3.5/6.0
16.6/13.0 surgery bilateral sensory loss 7. M 48 Cerebellar 2 PEG,
Unable to handle 3.0/2.5 18.0/18.0 hemorrhage with secretions,
aspiration craniotomy pneumonia, pooling, Normal sensation 8. F 44
Subarchnoid 2 Tracheostomy 4.0/2.0 12.5/9.5 hemorrhage left PEG
tube vertebral artery Normal sensation bilateral Pooling of
secretions 9. M 45 Traumatic brain 3 Chokes on saliva, eats 3.0/4.0
18.0/16.0 injury soft foods, drooling, Bilateral sensory loss 10. M
61 Left hemisphere .5 PEG, Inable to handle 1.5/4.0 13.0/13.0
stroke secretions, Normal sensation on left, pooling, BOTOX .RTM.
in UES 11. M 47 Craniotomy for 4 Severe aspiration, 1.5/1.5* 14/18
brain stem tumor multiple aspiration pneumonias Bilateral sensory
loss *Couldn't study effects of either sensory or motor stimulation
during swallowing due to severe aspiration.
Example 2
Parameters
[0198] Participant selection criteria included healthy volunteers
at the time of the study (e.g., having no difficulty swallowing).
Ten healthy volunteers participated. Two subjects had incomplete
data and had to be deleted from the statistical analyses. Eight
total conditions were compared: 2 control conditions and 6
stimulation conditions. No stimulation was applied during the 2
control conditions. The 6 stimulation conditions included: (1) 30
Hz continuous vibrator motor; (2) 70 Hz continuous vibrator motor;
(3) 110 Hz continuous vibrator motor; (4) 150 Hz continuous
vibrator motor; (5) 70 Hz and 110 Hz hybrid continuous vibrator
motors; and (6) 70 Hz and 110 Hz hybrid pulsed (4 Hz) vibrator
motors. The conditions were randomized across subjects. Each
condition lasted 10 minutes containing 17 stimulation periods.
[0199] Statistical Analysis
[0200] The number of swallows was measured during the stimulation
period and during intervals between the stimulation periods.
Subjects swallow at different rates, so results between conditions
were compared within each subject. For each condition, including
control conditions, and for each subject, the average number of
swallows during stimulation periods and the average number of
swallows during intervals between stimulation periods were
computed.
[0201] Results
[0202] FIG. 22 is a side-by-side comparison of plots of
vibrotactile stimulation under various conditions compared to
control conditions. The boxes show the range of average swallows in
the subjects, with the horizontal line through the boxes being the
median of those averages. The effects of stimulation on swallowing
differed between conditions (p<0.001). Versus control
conditions, stimulation during Condition 1 (30 Hz continuous
vibrator motor) increased the average number of swallows,
stimulation during Condition 2 (70 Hz continuous vibrator motor)
increased the average number of swallows, stimulation during
Condition 3 (110 Hz continuous vibrator motor) decreased the
average number of swallows, stimulation during Condition 4 (150 Hz
continuous vibrator motor) decreased the average number of
swallows, and stimulation during Condition 5 (70 Hz and 110 Hz
continuous vibrator motors) increased the average number of
swallows. Swallowing was more frequent during Condition 5 than
during Conditions 1, 3, and 4 (p<0.004). The averages between
Condition 2 and Condition 5 were somewhat similar, but Condition 5
was higher and also resulted in fewer subjects having less response
(e.g., every subject experienced at least a 100% increase in
swallowing during stimulation), while Condition 2 resulted in a
spectrum of responses across the subjects from fairly ineffective
to very effective.
[0203] FIG. 23 is a plot of measured continuous vibrotactile
stimulation and pulsed hybrid vibrotactile stimulation in normal
volunteers. The boxes show the range of average swallows between
the subjects, with the horizontal line though the boxes being the
average of those averages. The effects of stimulation on swallowing
differed between continuous and pulsed conditions. Versus control
conditions, stimulation during Condition 5 (70 Hz and 110 Hz
continuous vibrator motors) increased the average number of
swallows, and stimulation during Condition 6 (70 Hz and 110 Hz
pulsed at 4 Hz) increased the average number of swallows. The
averages between Condition 5 and Condition 6 were somewhat
similar.
[0204] FIG. 24 shows a percent change in rate of swallowing for
healthy subjects between control and when hybrid stimulation is
applied. The hybrid stimulation included a first vibrating
frequency of about 70 Hz and a second vibrating frequency of about
110 Hz. Each subject experienced at least a 100% increase in the
rate of swallowing versus control, with some subjects approaching a
200% increase, a 300% increase, or even a 400% increase.
[0205] Discussion
[0206] Vibrotactile stimulation combining a first vibrotactile
stimulator having a vibrating rate of 70 Hz and a second
vibrotactile stimulator having a vibrating rate of 110 Hz has been
shown to increase swallowing in healthy volunteers. It is expected
that vibrotactile stimulation combining a first vibrotactile
stimulator having a vibrating rate of 30 Hz and a second
vibrotactile stimulator having a vibrating rate of 70 Hz would
provide at least as much of an increase in swallowing in healthy
volunteers, for example because vibrating frequencies less than 100
Hz tend to be more beneficial than vibrating frequencies greater
than 100 Hz. A stimulator that has a single vibrating frequency is
not as effective at eliciting swallowing as a stimulator that has
two different vibrating frequencies. The effect of hybrid, two
vibrating frequency, stimulation appears to have a lasting effect
increasing swallowing, also during intervals between stimulation.
The increase in swallowing due to hybrid stimulation is greater and
more uniform than the increase in swallowing due to a single
vibrating frequency. Pulsed and continuous hybrid stimulation are
both effective at eliciting swallowing to similar degrees.
[0207] Although this invention has been disclosed in the context of
certain embodiments and examples, the invention extends beyond the
specifically disclosed embodiments to other alternative embodiments
and/or uses of the invention and obvious modifications and
equivalents thereof. In addition, while several variations of the
embodiments of the invention have been shown and described in
detail, other modifications, which are within the scope of this
invention, will be readily apparent based upon this disclosure.
Various combinations or sub-combinations of the specific features
and aspects of the embodiments may be made and still fall within
the scope of the invention. Various features and aspects of the
disclosed embodiments can be combined with, or substituted for, one
another in order to form varying modes of the embodiments of the
disclosed invention. Thus, it is intended that the scope of the
invention herein disclosed should not be limited by the particular
embodiments described above.
[0208] The ranges disclosed herein also encompass any and all
overlap, sub-ranges, and combinations thereof. Language such as "up
to," "at least," "greater than," "less than," "between," and the
like includes the number recited. Numbers preceded by a term such
as "about" or "approximately" include the recited numbers. For
example, "about 30 Hz" includes "30 Hz." Terms or phrases preceded
by a term such as "substantially" include the recited term or
phrase. For example, "substantially perpendicular" includes
"perpendicular."
Example Embodiments
[0209] The following example embodiments identify some possible
permutations of combinations of features disclosed herein, although
other permutations of combinations of features are also
possible.
[0210] 1. A device comprising: [0211] a first vibrotactile
stimulator configured to operate at a first vibrating rate; [0212]
a second vibrotactile stimulator configured to operate at a second
vibrating rate different than the first vibrating rate; and [0213]
a collar configured to position the first vibrotactile stimulator
and the second vibrotactile stimulator over a neck of a
subject.
[0214] 2. The device of Embodiment 1, further comprising a switch
configured to activate the first vibrotactile stimulator and the
second vibrotactile stimulator, the switch configured to be
volitionally operated by the subject.
[0215] 3. The device of Embodiment 1 or 2, further comprising an
automatic clock configured to activate the first vibrotactile
stimulator and the second vibrotactile stimulator.
[0216] 4. The device of any one of Embodiments 1-3, wherein the
first vibrotactile stimulator and the second vibrotactile
stimulator are configured to operate at partially
simultaneously.
[0217] 5. The device of any one of Embodiments 1-4, wherein the
first vibrating rate is between about 30 Hz and about 60 Hz and the
second vibrating rate is between about 60 Hz and about 80 Hz.
[0218] 6. The device of any one of Embodiments 1-4, wherein the
first vibrating rate is between about 50 Hz and about 90 Hz and the
second vibrating rate is between about 90 Hz and about 130 Hz.
[0219] 7. The device of any one of Embodiments 1-4, wherein the
first vibrating rate is about 30 Hz and the second vibrating rate
is about 70 Hz.
[0220] 8. The device of any one of Embodiments 1-4, wherein the
first vibrating rate is about 70 Hz and the second vibrating rate
is about 110 Hz.
[0221] 9. A method for stimulating swallowing in a subject, the
method comprising: [0222] applying a first vibrotactile stimulation
to a throat area of the subject, the first vibrotactile stimulation
having a first vibrating property; and [0223] applying a second
vibrotactile stimulation to the throat area of the subject, the
second vibrotactile stimulation having a second vibrating property
different than the first vibrating property.
[0224] 10. The method of Embodiment 9, wherein applying the first
vibrotactile stimulation and applying the second vibrotactile
stimulation includes the subject voluntary activating a first
vibrational transducer and a second vibrational transducer.
[0225] 11. The method of Embodiment 9 or 10, wherein applying the
first vibrotactile stimulation and applying the second vibrotactile
stimulation includes automatically activating a first vibrational
transducer and a second vibrational transducer.
[0226] 12. The method of Embodiment 11, wherein automatically
activating the first vibrational transducer and the second
vibrational transducer includes coordinating automatically
activating the first vibrational transducer and the second
vibrational transducer with a monitored bodily parameter.
[0227] 13. The method of any one of Embodiments 9-12, wherein
applying the first vibrotactile stimulation is at least partially
simultaneous with applying the second vibrotactile stimulation.
[0228] 14. The method of any one of Embodiments 9-13, wherein the
first vibrating property comprises a first vibrating frequency and
the second vibrating property comprises a second vibrating
frequency different than the first vibrating frequency.
[0229] 15. The method of Embodiment 14, wherein the first vibrating
rate is between about 30 Hz and about 60 Hz and the second
vibrating rate is between about 60 Hz and about 80 Hz.
[0230] 16. The method of Embodiment 14, wherein the first vibrating
rate is between about 50 Hz and about 90 Hz and the second
vibrating rate is between about 90 Hz and about 130 Hz.
[0231] 17. The method of Embodiment 14, wherein the first vibrating
rate is about 30 Hz and the second vibrating rate is about 70
Hz.
[0232] 18. The method of Embodiment 14, wherein the first vibrating
rate is about 70 Hz and the second vibrating rate is about 110
Hz.
[0233] 19. The method of any one of Embodiments 7-18, wherein the
first vibrating property comprises a first vibrating frequency
range and the second vibrating property comprises a second
vibrating frequency range different than the first vibrating
frequency range.
[0234] 20. The method of Embodiment 19, wherein the first vibrating
rate range is between about 30 Hz and about 60 Hz and the second
vibrating rate range is between about 60 Hz and about 80 Hz.
[0235] 21. The method of Embodiment 19, wherein the first vibrating
rate range is between about 50 Hz and about 90 Hz and the second
vibrating rate range is between about 90 Hz and about 130 Hz.
[0236] 22. The method of any one of Embodiments 7-21, wherein the
first vibrating property comprises a first wave shape and the
second vibrating property comprises a second wave shape different
than the first wave shape.
[0237] 23. The method of Embodiment 22, wherein the first wave
shape comprises sinusoidal and the second wave shape comprises
saw-tooth.
[0238] 24. The method of Embodiment 22, wherein the first wave
shape comprises sinusoidal and the second wave shape comprises
triangular.
[0239] 25. The method of Embodiment 22, wherein the first wave
shape comprises sinusoidal and the second wave shape comprises
square.
[0240] 26. The method of Embodiment 22, wherein the first wave
shape comprises saw-tooth and the second wave shape comprises
triangular.
[0241] 27. The method of Embodiment 22, wherein the first wave
shape comprises saw-tooth and the second wave shape comprises
square.
[0242] 28. The method of Embodiment 22, wherein the first wave
shape comprises triangular and the second wave shape comprises
square.
[0243] 29. The method of any one of Embodiments 7-28, wherein the
first vibrating property comprises a first vibrating frequency and
the second vibrating property comprises a second vibrating
frequency out of phase with the first vibrating frequency.
[0244] 30. The method of Embodiment 29, wherein the first vibrating
frequency and the second vibrating frequency are between about
150.degree. and about 210.degree. out of phase.
[0245] 31. The method of Embodiment 29, wherein the first vibrating
frequency and the second vibrating frequency are about 180.degree.
out of phase.
[0246] 32. The method of any one of Embodiments 7-31, wherein the
first vibrating property comprises a continuous vibrating frequency
and the second vibrating property comprises a pulsed vibrating
frequency.
[0247] 33. The method of any one of Embodiments 7-32, wherein the
first vibrating property comprises a first direction of mechanical
force and the second vibrating property comprises a second
direction of mechanical force different than the first direction of
mechanical force.
[0248] 34. The method of Embodiment 33, wherein one of the first
direction of mechanical force and the second direction of
mechanical force is substantially perpendicular.
[0249] 35. The method of Embodiment 33 or 34, wherein one of the
first direction of mechanical force and the second direction of
mechanical force is non-perpendicular and non-parallel.
[0250] 36. A device comprising: [0251] a first vibrational
transducer having a first vibrating property; [0252] a second
vibrational transducer having a second vibrating property different
than the first vibrating property; and [0253] a collar configured
to position the first vibrational transducer and the second
vibrational transducer over a neck of a subject.
[0254] 37. The device of Embodiment 36, further comprising a switch
configured to activate the first vibrational transducer and the
second vibrational transducer, the switch configured to be
volitionally operated by the subject.
[0255] 38. The device of Embodiment 36 or 37, further comprising an
automatic clock configured to activate the first vibrational
transducer and the second vibrational transducer.
[0256] 39. The device of any one of Embodiments 36-38, wherein the
first vibrational transducer and the second vibrational transducer
are configured to operate at partially simultaneously.
[0257] 40. The device of any one of Embodiments 36-39, wherein the
first vibrating property comprises a first vibrating frequency and
the second vibrating property comprises a second vibrating
frequency different than the first vibrating frequency.
[0258] 41. The device of Embodiment 40, wherein the first vibrating
rate is between about 30 Hz and about 60 Hz and the second
vibrating rate is between about 60 Hz and about 80 Hz.
[0259] 42. The device of Embodiment 40, wherein the first vibrating
rate is between about 50 Hz and about 90 Hz and the second
vibrating rate is between about 90 Hz and about 130 Hz.
[0260] 43. The device of Embodiment 40, wherein the first vibrating
rate is about 30 Hz and the second vibrating rate is about 70
Hz.
[0261] 44. The device of Embodiment 40, wherein the first vibrating
rate is about 70 Hz and the second vibrating rate is about 110
Hz.
[0262] 45. The device of any one of Embodiments 36-44, wherein the
first vibrating property comprises a first vibrating frequency
range and the second vibrating property comprises a second
vibrating frequency range different than the first vibrating
frequency range.
[0263] 46. The device of Embodiment 45, wherein the first vibrating
rate range is between about 30 Hz and about 60 Hz and the second
vibrating rate range is between about 60 Hz and about 80 Hz.
[0264] 47. The device of Embodiment 45, wherein the first vibrating
rate range is between about 50 Hz and about 90 Hz and the second
vibrating rate range is between about 90 Hz and about 130 Hz.
[0265] 48. The device of any one of Embodiments 36-47, wherein the
first vibrating property comprises a first wave shape and the
second vibrating property comprises a second wave shape different
than the first wave shape.
[0266] 49. The device of Embodiment 48, wherein the first wave
shape comprises sinusoidal and the second wave shape comprises
saw-tooth.
[0267] 50. The device of Embodiment 48, wherein the first wave
shape comprises sinusoidal and the second wave shape comprises
triangular.
[0268] 51. The device of Embodiment 48, wherein the first wave
shape comprises sinusoidal and the second wave shape comprises
square.
[0269] 52. The device of Embodiment 48, wherein the first wave
shape comprises saw-tooth and the second wave shape comprises
triangular.
[0270] 53. The device of Embodiment 48, wherein the first wave
shape comprises saw-tooth and the second wave shape comprises
square.
[0271] 54. The device of Embodiment 48, wherein the first wave
shape comprises triangular and the second wave shape comprises
square.
[0272] 55. The device of any one of Embodiments 36-54, wherein the
first vibrating property comprises a first vibrating frequency and
the second vibrating property comprises a second vibrating
frequency out of phase with the first vibrating frequency.
[0273] 56. The device of Embodiment 55, wherein the first vibrating
frequency and the second vibrating frequency are between about
150.degree. and about 210.degree. out of phase.
[0274] 57. The device of Embodiment 55, wherein the first vibrating
frequency and the second vibrating frequency are about 180.degree.
out of phase.
[0275] 58. The device of any one of Embodiments 36-57, wherein the
first vibrating property comprises a continuous vibrating frequency
and the second vibrating property comprises a pulsed vibrating
frequency.
[0276] 59. The device of any one of Embodiments 36-58, wherein the
first vibrating property comprises a first direction of mechanical
force and the second vibrating property comprises a second
direction of mechanical force different than the first direction of
mechanical force.
[0277] 60. The device of Embodiment 59, wherein one of the first
direction of mechanical force and the second direction of
mechanical force is substantially perpendicular.
[0278] 61. The device of Embodiment 59 or 60, wherein one of the
first direction of mechanical force and the second direction of
mechanical force is non-perpendicular and non-parallel.
* * * * *