U.S. patent application number 12/417529 was filed with the patent office on 2009-10-08 for system and method of bladder and sphincter control.
This patent application is currently assigned to CASE WESTERN RESERVE UNIVERSITY. Invention is credited to Narendra Bhadra, Timothy M. Bruns, Kenneth J. Gustafson, Timothy Y. Mariano.
Application Number | 20090254144 12/417529 |
Document ID | / |
Family ID | 41133958 |
Filed Date | 2009-10-08 |
United States Patent
Application |
20090254144 |
Kind Code |
A1 |
Bhadra; Narendra ; et
al. |
October 8, 2009 |
System and Method of Bladder and Sphincter Control
Abstract
A method and system for bladder control are disclosed. In
embodiments, a method for bladder control is provided that
comprises coupling an electrode to an afferent nerve that is
related to the bladder. Applying a plurality of pulse burst
stimulations via the electrode causes voiding of urine from the
bladder. In embodiments, the plurality of pulse burst stimulations
to the afferent nerve reduces external urethral sphincter (EUS)
contractions and evokes bladder contractions to expel urine from
the subject. In embodiments, the plurality of pulse burst
stimulations to the afferent nerve evokes bladder contractions
alone to expel urine from the subject. In embodiments, a system for
bladder control is provided that comprises an electrode for
applying a pulse burst stimulus to an afferent nerve or dermatome
to reduce reflex contractions and a signal generator for generating
the pulse burst stimulus.
Inventors: |
Bhadra; Narendra;
(Chesterland, OH) ; Gustafson; Kenneth J.; (Shaker
Heights, OH) ; Bruns; Timothy M.; (Cleveland Heights,
OH) ; Mariano; Timothy Y.; (Framingham, MA) |
Correspondence
Address: |
THOMPSON HINE L.L.P.;Intellectual Property Group
P.O. BOX 8801
DAYTON
OH
45401-8801
US
|
Assignee: |
CASE WESTERN RESERVE
UNIVERSITY
Cleveland
OH
|
Family ID: |
41133958 |
Appl. No.: |
12/417529 |
Filed: |
April 2, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61041753 |
Apr 2, 2008 |
|
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|
Current U.S.
Class: |
607/41 |
Current CPC
Class: |
A61N 1/36007
20130101 |
Class at
Publication: |
607/41 |
International
Class: |
A61N 1/36 20060101
A61N001/36 |
Claims
1. A method for bladder control, comprising: electrically coupling
an electrode to an afferent nerve that is anatomically related to
the bladder; stimulating said afferent nerve via said electrode
with a plurality of pulse burst electrical stimulations, wherein
said pulse burst electrical stimulations have an inter-burst
frequency of about 0.25 to about 50 Hz, wherein each of said pulse
burst electrical stimulations comprises between 2 and 20 individual
pulses, wherein each of said pulse burst electrical stimulations
has a width of about 10 to about 300 microseconds, and wherein each
of said individual pulses has an intra-burst pulse frequency of
about 10 Hz to about 250 Hz; and voiding urine from the bladder via
the urethra through an external urethral sphincter.
2. The method of claim 1, further comprising: modulating one of
said pulse burst electrical stimulations, said modulating selected
from the group consisting of modulating an inter-burst frequency,
modulating an inter-burst amplitude, modulating an intra-burst
pulse frequency, modulating an intra-burst pulse amplitude, and
modulating to create a patterned pulse burst electrical
stimulation.
3. The method of claim 1, wherein said stimulating said afferent
nerve reduces contractions of said external urethral sphincter and
further comprising: stimulating a second nerve anatomically related
to the bladder with a second pulse burst electrical stimulation
synchronized with said plurality of pulse burst electrical
stimulations to induce a contraction of the bladder.
4. The method of claim 3, further comprising: wherein said second
pulse burst electrical stimulation occurs during a portion of one
of said plurality of pulse burst electrical stimulations.
5. The method of claim 3, wherein said second nerve is selected
from the group consisting of an afferent nerve for exciting a
reflex contraction of the bladder, an efferent nerve, an intradural
nerve, a sacral ventral root, an extradural nerve, a motor nerve, a
pelvic nerve, a sacral foraminal nerve, and a dermatome.
6. The method of claim 1, further comprising: initiating a
contraction of the bladder.
7. The method of claim 1, wherein said afferent nerve is selected
from the group consisting of an intradural nerve, a sacral dorsal
root, an extradural nerve, a sensory nerve, a pelvic nerve, a
sacral foraminal nerve, a pudendal nerve, and a dermatome.
8. The method of claim 1, wherein said stimulating is performed
subcutaneously using an electrode selected from the group
consisting of a cuff electrode, a subcutaneous electrode, a spiral
electrode, a helical electrode, and a needle electrode.
9. The method of claim 1, wherein said stimulating is performed to
the dermis using an electrode selected from the group consisting of
a surface electrode, and a subcutaneous needle electrode.
10. A system for bladder control, comprising: an electrode for
applying a pulse burst electrical stimulus to an afferent nerve to
inhibit reflex contractions; and a signal generator for generating
said pulse burst electrical stimulus to be applied by said
electrode, said pulse burst electrical stimulus comprising between
2 and about 20 individual pulses, said pulse burst electrical
stimulus having a width of about 50 to about 300 microseconds, and
each of said individual pulses having an intra-burst pulse
frequency of about 10 Hz to about 250 Hz.
11. The system of claim 10, wherein said electrode is selected from
the group consisting of a cuff electrode, a subcutaneous electrode,
a spiral electrode, a needle probe, a dermal surface electrode, and
a surface mounted needle.
12. The system of claim 10, wherein said afferent nerve is selected
from the group consisting of an intradural nerve, a sacral dorsal
root, an extradural nerve, a sensory nerve, a pelvic nerve, a
sacral foraminal nerve, a pudendal nerve, and a dermatome.
13. The system of claim 10, wherein said pulse burst electrical
stimulus reduces contractions of an external urethral sphincter,
and wherein a contraction of the bladder is initiated using a
mechanical technique selected from the group consisting of
distention, pressing on a skin region near the bladder, and tapping
on a skin region near the bladder, and wherein said contraction of
the bladder induces micturition through said external urethral
sphincter.
14. The system of claim 10, wherein said signal generator is
adapted to generate a plurality of pulse burst electrical stimuli
having an inter-burst frequency of about 0.25 to about 50 Hz.
15. The system of claim 14, wherein said pulse burst electrical
stimulus is modulated using a modulation selected from the group
consisting of an inter-burst frequency modulation, an inter-burst
amplitude modulation, an intra-burst pulse frequency modulation, an
intra-burst pulse amplitude modulation, and a pattern
modulation.
16. The system of claim 10, wherein said pulse burst electrical
stimulus reduces contractions of an external urethral sphincter,
and further comprising: a second electrode for applying an
electrical stimulus, said electrical stimulus synchronized with
said plurality of pulse burst electrical stimuli, wherein said
electrical stimulus occurs during a portion of said pulse burst
electrical stimuli, and wherein said electrical stimulus induces
contractions of the bladder.
17. The system of claim 16, wherein said electrical stimulus is a
second pulse burst stimulus comprising between 2 and 20 individual
pulses, said pulse burst electrical stimulus having a width of
about 50 to 300 microseconds and an inter-burst frequency of about
0.25 to about 50 Hz, and each of said individual pulses having an
intra-burst pulse frequency of about 10 Hz to about 250 Hz; and
wherein said second pulse burst stimulus is modulated using a
modulation selected from the group consisting of a consistent
modulation, an inter-burst frequency modulation, an inter-burst
amplitude modulation, an intra-burst pulse frequency modulation, an
intra-burst pulse amplitude modulation, and a pattern
modulation.
18. The system of claim 16, wherein said electrical stimulus is
applied to an afferent nerve to excite reflex contractions of the
bladder, and wherein said afferent nerve is selected from the group
consisting of an intradural nerve, a sacral ventral root, an
extradural nerve, a motor nerve, a pelvic nerve, a sacral foraminal
nerve, and a dermatome.
19. The system of claim 16, wherein said electrical stimulus is
applied to an efferent nerve selected from the group consisting of
an intradural nerve, a sacral ventral root, an extradural nerve, a
motor nerve, a pelvic nerve, a sacral foraminal nerve.
20. A method for bladder control, the method comprising: applying a
plurality of pulse burst electrical signals to a sensory nerve that
causes the reduction or elimination of urethral sphincter (EUS)
contractions, the sensory nerve being at least one of an intradural
nerve, an extradural nerve, a pudendal nerve, pelvic nerves, a
foraminal nerve and a dermatome; and applying a stimulus to evoke
bladder contractions to expel urine from the subject, the stimulus
being at least one of a non-quasitrapezoidal pulse burst electrical
stimulus.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S.
Provisional Patent Ser. No. 61/041,753 filed Apr. 2, 2008, entitled
"METHODS FOR BLADDER CONTROL," the entire disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to electrical stimulation of
the nervous system, and particularly relates to a system and method
for urinary bladder and sphincter control utilizing electrical
stimulation.
BACKGROUND
[0003] Retention of urine, leading to complications such as urinary
tract infection and urinary calculi, remains a major factor leading
to morbidity in individuals with neurologic disorders or injury
such as spinal cord injury. In high cord injury, with upper motor
neuron damage, the lower nerve pathways to the bladder are intact.
The aim of micturition control in these individuals is to enable
them to contract the bladder musculature without direct or reflex
activation of structures in the urethra that may impede urine flow.
The procedure should leave an acceptable post-void residual volume
within the bladder and should also be able to prevent overflow
incontinence.
[0004] Previously, electrical stimulation has been applied to
control the bladder and bowel. These previous attempts have
predominantly focused on activation of the detrusor by sacral root
or nerve stimulation, activating either motor or sensory nerves.
The methods can suffer from the problem of contraction of the
bladder to expel urine concurrently with contraction of the
external urethral sphincter blocking urine flow. Extensive sacral
dorsal rhizotomy is carried out to solve this problem in
individuals with spinal cord injury. The rhizotomy technique also
results in the loss of sensation and reflexes such as reflex
erection in males. It would be advantageous if reflex contraction
of the sphincter could be reduced or eliminated without the losses
caused by the rhizotomy technique. Using continuous stimulation to
activate sensory nerves to evoke reflex bladder contractions
frequently results in smaller reflex bladder contractions and
reduced efficiency of urine expulsion. It would be advantageous if
reflex contractions of the bladder were more robust.
SUMMARY OF THE INVENTION
[0005] The present disclosure relates to a system and method for
bladder control. In one aspect of the disclosure, the system
comprises an electrode coupled to an afferent nerve of a subject
that applies a pulse burst stimulation to reduce contractions of
the urethral sphincter, and a signal generator for generating the
pulse burst electrical signals. In another aspect of the
disclosure, a second electrode is coupled to an afferent or
efferent nerve of the subject and applies a second pulse burst
stimulation to stimulate contractions of the bladder.
[0006] In another aspect of the disclosure the system and method
comprises stimulating an afferent nerve with pulse burst
stimulations via an electrode to reduce contractions of the
external urethral sphincter while stimulating the bladder to induce
micturition through the urethral sphincter. In another aspect of
the disclosure, the method further comprises manually compressing
the bladder. In another aspect, the system and method stimulates
the bladder with pulse burst stimulations that are synchronized to
the pulse burst stimulations that are applied to the afferent
nerve.
[0007] In another aspect of the disclosure the system and method
comprises coupling a first electrode to an intradural portion of a
sacral dorsal root of a subject and coupling a second electrode to
an intradural portion of a sacral ventral root of the subject. The
system and method further comprises concurrently applying a first
series of intermittent pulse trains to the first electrode and a
second series of intermittent pulse trains to the second electrode,
wherein the first and second series of intermittent pulse trains
are synchronized to mitigate interference with one another and to
reduce or eliminate external urethral sphincter (EUS) contractions
and evoke bladder contractions to expel urine from the subject.
[0008] In another aspect of the disclosure, a system and method are
provided for bladder control comprising coupling at least one
electrode to at least one of an extradural nerve, pelvic nerves, a
pudendal nerve, or a sacral foraminal nerve of a subject, and
applying a series of intermittent pulse trains to the electrode to
concurrently reduce or eliminate EUS contractions and evoke bladder
contractions to expel urine from the subject.
[0009] In yet another aspect of the disclosure, a system and method
for bladder control is provided that comprises attaching a dermal
surface electrode or subcutaneous electrode to a skin region at or
near sacral dermatomes of a subject, applying a series of
intermittent pulse trains to the dermal surface electrode or
subcutaneous electrode to subdue EUS contractions. In another
aspect of the disclosure, a provider/subject initiated mechanical
technique is performed to evoke bladder contractions to expel urine
from the subject.
[0010] In yet a further aspect of the disclosure, a system and
method for bladder control is provided that comprises applying an
electrical signal to a sensory nerve of a subject that causes the
reduction or elimination of EUS contractions and applying a motor
stimulus or sensory stimulus to evoke bladder contractions to expel
urine from the subject, the motor stimulus being at least one of a
non-quasitrapezoidal electrical signal applied to a motor nerve or
a provider/subject initiated mechanical technique.
[0011] In yet another aspect of the disclosure a system and method
for bladder control is provided that comprises stimulation of an
afferent nerve with pulse burst stimulations via an electrode that
causes reflex bladder contractions to induce micturition. In
embodiments, the electrode activates a sacral nerve, a pudendal
nerve, a urethral nerve, or other sensory nerve.
[0012] In yet another aspect of the disclosure, a system and method
for bladder control is provided that comprises applying an
electrical signal to a sensory nerve that causes the reduction or
elimination of EUS contractions, the sensory nerve being at least
one of an intradural nerve, an extradural nerve, a pudendal nerve,
pelvic nerves, a foraminal nerve and a dermatome. The method
further comprises applying a motor stimulus to evoke bladder
contractions to expel urine from the subject, the motor stimulus
being at least one of a non-quasitrapezoidal electrical signal
applied to a motor nerve and a provider/subject initiated
mechanical technique, the motor nerve being at least one of an
intradural nerve, an extradural nerve, a pudendal nerve, pelvic
nerves, a foraminal nerve and a dermatome.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing and other features of the present disclosure
will become apparent to those skilled in the art to which the
present disclosure relates upon reading the following description
with reference to the accompanying drawings, in which:
[0014] FIG. 1 is schematic illustrative embodiment of the portion
of a human body wherein a first and second series of intermittent
pulse trains are employed to evoke bladder contraction and to
subdue EUS contractions in accordance with an aspect of the present
disclosure.
[0015] FIG. 2a illustrates an exemplary timing diagram of a first
and second series of intermittent pulse trains in accordance with
an aspect of the present disclosure.
[0016] FIG. 2b illustrates an exemplary timing diagram of a
continuous pulse train in accordance with an aspect of the present
disclosure.
[0017] FIG. 2c illustrates an exemplary timing diagram of a pulse
burst stimulus in accordance with an aspect of the present
disclosure.
[0018] FIG. 2d illustrates an exemplary timing diagram of a
frequency modulated pulse burst stimulus in accordance with an
aspect of the present disclosure.
[0019] FIG. 2e illustrates an exemplary timing diagram of an
amplitude modulated pulse burst stimulus in accordance with an
aspect of the present disclosure.
[0020] FIG. 2f illustrates an exemplary timing diagram of a pattern
modulated pulse burst stimulus in accordance with an aspect of the
present disclosure.
[0021] FIG. 3 is schematic illustrative embodiment of the portion
of a human body wherein a single series of intermittent pulse
trains are employed to concurrently evoke bladder contraction and
to subdue EUS contractions in accordance with another aspect of the
disclosure.
[0022] FIG. 4 is schematic illustrative embodiment of the portion
of a human body wherein a series of intermittent pulse trains are
applied to dermatomes to subdue EUS contractions in accordance with
another aspect of the disclosure.
[0023] FIG. 5 illustrates a methodology for bladder control in
accordance with an aspect of the present disclosure.
[0024] FIG. 6 illustrates another methodology for bladder control
in accordance with an aspect of the present disclosure.
[0025] FIG. 7 illustrates another methodology for bladder control
in accordance with an aspect of the present disclosure.
[0026] FIG. 8 illustrates another methodology for bladder control
in accordance with an aspect of the present disclosure.
[0027] FIG. 9a illustrates undesirable EUS activity that can occur
after a motor stimulus excites the bladder.
[0028] FIG. 9b illustrates elimination of undesirable EUS activity
by use of a methodology in accordance with an aspect of the present
disclosure.
[0029] FIG. 10 illustrates a successful use of pulse bursting to
evoke a larger bladder contraction and greater bladder voiding than
occurs using continuous stimulation in accordance with an aspect of
the present disclosure.
DETAILED DESCRIPTION
[0030] The present disclosure relates to a system and method of
stimulating the human nervous system via an electric signal to
achieve a functional result, namely bladder control. The system and
method employs a sensory feedback signal at various nerve regions
of a body of a subject. In one aspect, an electrical signal causes
the reduction or elimination of external urethral sphincter (EUS)
contractions. In another aspect, an electrical signal enhances
contraction of the bladder without encouraging contractions of the
EUS. In yet another aspect, an electrical signal is used to enhance
contraction of the bladder while reducing or eliminating reflexive
EUS contractions. In one embodiment, a sensory feedback signal that
is an artificially generated electrical signal is applied to a
sensory nerve that is associated with EUS contractions, causing
inhibition of natural or dysfunctional sensory signals that cause
the EUS to contract. A variety of techniques for contracting the
bladder in combination with the sensory feedback signal applied to
the EUS are provided to facilitate the expelling of urine from a
subject's body. The subject is a human or other type of species. In
another embodiment, the sensory feedback signals are used to
encourage EUS contractions to reduce or eliminate bladder
contractions for treating incontinence.
[0031] Referring now to FIG. 1, there is shown an illustrative
embodiment of the present disclosure within the environment of a
portion of a human body 10. Urine is expelled from a bladder 4 of
the body 10 of a subject through a bladder neck 11 and urethra 12
and controlled by EUS 13. Bladder 4 and EUS 13 functions are
controlled by action potentials traveling to and from spinal cord 1
primarily, but not limited to, sacral roots which include ventral
sacral roots 14 and dorsal sacral roots 15. Dorsal roots 15 are
primarily sensory (afferent nerves) to transmit sensation to spinal
cord 1, while ventral roots 14 primarily transmit motor pulses
(efferent nerves) from spinal cord 1 to bladder 4 and EUS 13.
Ventral roots 14 and dorsal roots 15 include both intradural nerves
2 and extradural nerves 3. The intradural nerves 2 are coupled to
the spinal cord 1, while the extradural nerves 3 are intertwined
and are coupled to the pelvic nerves 16 and pudendal nerve 5. The
pelvic nerves 16 include ventral nerve fibers that control the
contraction and relaxation of the bladder 4 and sensory nerve
fibers that provide feedback to the central nervous system. The
pudendal nerve 5 also includes sensory nerve fibers that provide
feedback to the central nervous system to control action potentials
flowing along ventral nerve fibers of the pudendal nerve 5 that
cause the EUS 13 to contract, blocking the outlet from urethra
12.
[0032] When the bladder 4 is to be emptied, the flow of action
potentials through the motor nerve fibers of the pudendal nerve 5
are reduced or eliminated in response to a change in the feedback
of the sensory nerve fibers, which allows the EUS 13 to relax. It
is to be appreciated that levator and other support muscles can
also contribute to EUS 13 control. Motor nerve fibers of the pelvic
nerves 16 usually carry no action potentials until the person
desires to evacuate the bladder 4. At this point, action potentials
are sent along the motor nerve fibers of the pelvic nerves 16
concurrently with the stopping of action potentials along the motor
nerve fibers of the pudendal nerve 5, causing EUS 13 to relax and
allowing bladder neck 11 to open concurrently with bladder 4
muscles contracting, thus expelling urine from the subject.
[0033] Spinal cord injuries and various other medical conditions
can cause a loss of control of bladder function. To reinstitute
this control, a variety of methodologies for bladder control are
provided in accordance with various aspects of the disclosure. In
one aspect of the disclosure, a first electrode 19 is coupled to
the intradural nerves 2 of the sacral ventral root 14 and a second
electrode 20 is coupled to the intradural nerves 2 of the sacral
dorsal root 15. The first and second electrodes 19 and 20 are, for
example, a cuff electrode, a surface mounted needle, a needle
probe, or a variety of other electrode types. The electrodes 19 and
20 are, for example, coupled to respective implanted receiver
stimulators that are powered and controlled by one or more signal
generators 28 of FIG. 4 to provide a first series of intermittent
pulse trains 17 to the first electrode 19 and a second series of
intermittent pulse trains 18 to the second electrode 20. The first
series of intermittent pulse trains 17 provide a motor signal to
contract the bladder 4 and the second series of intermittent pulse
trains 18 provide a sensory feedback signal to inhibit natural or
dysfunctional signals to contract the EUS 13. The first and second
series of intermittent pulse trains 17 and 18 are applied
concurrently to the first and second electrodes 19 and 20 to
provide electric stimulation on the sacral ventral root 14 to evoke
bladder contraction and to provide electrical feedback to the
sacral dorsal root 15 to subdue EUS 13 contractions.
[0034] The one or more signal generators 28 are tunable to vary one
or more parameters of the motor signal and/or sensory feedback
signal based on a particular subject and/or species. An exemplary
signal generator 28 for performing experimental tests is the Pulsar
6bp made by FHC of Bowdoinham, Me. In embodiments, the signal
generator 28 is a Pulsar 6bp combined with a DS7A made by Digitimer
of Welwyn Garden City, UK. In embodiments, the signal generator 28
comprises customized or off-the-shelf parts adapted by those of
ordinary skill in the art to generate the desired pulse trains 17,
18. In embodiments, the signal generator 28 is created using
microcontrollers, microprocessors, or programmable logic devices
with associated signal conditioning electronics. In embodiments,
the signal generator 28 is an implantable pulse generator.
[0035] In one aspect of the disclosure, the first and second series
of intermittent pulse trains 17 and 18 are synchronized to mitigate
coupling interference with one another during bladder evacuation.
Synchronizing the first and second series of intermittent pulse
trains 17 and 18, produces the least urethral 12 resistance while
generating sufficient bladder drive to achieve bladder 4 emptying.
FIG. 2a illustrates a timing diagram 22 of first and second series
of intermittent pulse trains 17 and 18 in accordance with an aspect
of the present disclosure. The first series of intermittent pulse
trains 17 provides a motor signal with each pulse train 17
comprising bursts of between 2 and about 20 individual pulses 32
with pulse widths 29 of about 50 microseconds to about 300
microseconds and an inter-burst frequency 33 of about 0.25 Hz to 50
Hz. In another aspect, the individual burst comprises between 3 and
about 20 discrete pulses. In yet another aspect, the individual
burst comprises between 4 and about 20 discrete pulses. Each of the
individual pulses within a burst has a pulse frequency 30 between
about 10 Hz to about 250 Hz. The second series of intermittent
pulse trains 18 provides a sensory signal with each pulse train 18
comprising bursts of 2-20 individual pulses with pulse widths 29 of
about 50 microseconds to about 300 microseconds and an inter-burst
frequency 33 of about 0.25 Hz to 50 Hz. Each of the individual
pulses has a pulse frequency 30 of about 10 Hz to about 250 Hz. In
embodiments, the pulse trains 17, 18 use identical pulse burst
stimuli. In embodiments, the pulse trains 17, 18 each use
differently configured pulse burst stimuli. In embodiments, the
amplitudes of the first and second series of intermittent pulse
trains 17 and 18 are between two and four times the nerve
activation threshold.
[0036] Referring now to FIG. 2b a continuous stimulus is presented.
Unlike pulse burst stimuli, a continuous stimulus does not comprise
clusters or bursts of pulses. Instead, a continuous stimulation
uses a continuous series of pulses, typically at a fixed frequency
to stimulate a nerve. Referring now to FIGS. 2c-2f, various
embodiments of pulse burst stimuli are presented. In FIG. 2c, an
embodiment of a pulse burst stimulus is illustrated with consistent
pulse width 29, pulse frequency 30, also described herein as
inter-pulse interval 30, pulse amplitude 31, burst width 32 or
number of pulses, and inter-burst frequencies 33 (also referred to
herein in the inverse as the inter-burst period). In embodiments
the pulse width 29, pulse frequency 30 and inter-pulse interval 30,
pulse amplitude 31, burst width 32, and/or inter-burst frequencies
33 are varied either intra-burst or inter-burst to produce a
modulation of the pulse burst stimuli or a patterned pulse burst
stimulus. In other embodiments the characteristics of the pulse
burst stimuli (i.e. pulse amplitude 31, inter-pulse interval 30,
pulse width 29, burst width 32, and inter-burst frequency 33 are
selected by one of ordinary skill in the art based on the
characteristics of the electrode--nervous system interaction and
reflex response to achieve the desired physiological response such
as suppression of the EUS reflex response or reflex excitation of
the bladder 4.
[0037] Referring now to FIG. 2d, an embodiment of a pulse burst
stimulus illustrating intra-burst frequency modulation is presented
wherein the inter-pulse interval 30 between individual pulses
within a single burst is varied. Referring now to FIG. 2e, another
embodiment of a pulse burst stimuli illustrating both intra-burst
and inter-burst amplitude 31 modulation is presented.
[0038] In other embodiments, the characteristics of the pulses that
comprise the bursts are modified. In the embodiments depicted in
FIGS. 2a-f a bi-phasic square wave individual pulses that comprise
the bursts. In other embodiments, a quasi-trapezoidal pulse is used
that comprises a square leading edge followed by a plateau and an
exponential trailing edge. Other pulse characteristic waveforms are
readily adapted by one of ordinary skill in the art for use with a
pulse burst stimuli.
[0039] Referring now to FIG. 2f, an embodiment of a pulse burst
stimulus with a pattern modulation is presented. The terms pulse
burst stimulus and pulse burst stimulations are intended to cover
both the consistent and varying embodiments. In embodiments, the
pulse burst stimulus functions as a structured temporal code that
stimulates the nervous system into responding as desired, either by
contracting the bladder, as in the case of the motor signal pulse
train 17 or other sensory pulse trains, or by reducing EUS
contractions, as in the case of the sensory signal pulse train 18.
Although the examples and descriptions herein refer principally to
pulse trains 17, 18, the systems and methods are also applicable to
pulse burst stimuli in general.
[0040] The motor signal 17 and sensory feedback signal 18 are
synchronized in one embodiment such that the pulse trains have
periods such that one period is substantially a positive integer
multiple of the other. For example, the intermittent pulse trains
of the sensory feedback signal are turned on and off in 1 second
intervals, while the intermittent pulse trains of the motor signal
are turned on for 0.5 second and off for 1.5 seconds, such that
both intermittent pulse trains have a period (P) of about 2
seconds. It is to be appreciated that other numbers of pulses,
frequencies, and on and off time durations are employed as long as
both on and off time durations period (P) such that one period is
substantially a positive integer multiple of the other. It is to be
appreciated that the above motor signal and sensory inhibition
signal are but examples of signals that are employed to evoke
bladder contractions and reduce or eliminate EUS contractions.
[0041] FIG. 3 is an illustrative embodiment of the portion of a
human body 10 wherein a single series of intermittent pulse trains
are employed to concurrently evoke bladder contraction and to
subdue EUS contractions in accordance with another aspect of the
disclosure. Electrode(s) 23 are coupled to extradural nerves 3 of
the ventral root 14 and dorsal root 15, the pudendal nerve 5,
pelvic nerves 16, sensory nerves, and/or nerves disposed in a
foramen (i.e., foraminal nerves). A series of intermittent pulse
trains 24 are applied to the electrode(s) 23 to evoke bladder
contraction and to subdue EUS contractions. The pelvic nerves 16
include ventral nerve fibers that control the contractions of the
bladder 4 that extend from the extradural nerves 3 of the ventral
roots 14. The extradural nerves 3 of the ventral root 14 are
intertwined with the extradural nerves 3 of the dorsal roots 15.
The extradural nerves 3 of the dorsal roots 15 and ventral roots 14
extend to the pudendal nerve 5, which includes nerve fibers that
control the contraction of the EUS 13.
[0042] Electrical signals applied to the extradural nerves 3, the
pelvic nerves 16, the pudendal nerve 5, sensory nerves, or to
foraminal nerves can cause signal coupling of the electrical signal
to the other of the dorsal or ventral nerves. Therefore, a single
signal in the form of the series of intermittent pulse trains 24
are employed both to evoke a motor signal for contracting the
bladder 4 and as a sensory feedback signal to subdue EUS
contractions. The effect on the state of the bladder 4 are modified
by tuning one or more parameters associated with the series of
pulse trains. It is also to be appreciated that a separate bladder
drive signal and separate sensory feedback signal are applied to
the extradural nerves 3, the pudendal nerve 5, the pelvic nerves
16, and/or nerves disposed in a sacral foramen.
[0043] FIG. 4 is an illustrative embodiment of the portion of a
human body 10 wherein a series of intermittent pulse trains are
applied to dermatomes 21 to subdue EUS contractions in accordance
with another aspect of the disclosure. One or more dermal
electrodes 26 are coupled to an exterior skin region 27 at a
location where a signal is coupled to the dermatomes 21 underlying
the exterior skin region 27 of a subject. Alternatively or
additionally, one or more subcutaneous electrodes are placed under
the skin, or dermis, to be in contact with a subcutaneous surface.
A series of intermittent pulse trains 25 are applied to the dermal
electrode(s) 26 to subdue EUS contractions employing, for example,
a tunable signal generator 28.
[0044] A variety of motor or reflex techniques are employed to
contract the bladder 4. For example, a variety of different
continuous or intermittent electrical signals are applied at the
intradural nerves 2 and/or extradural nerves 3 of the sacral
ventral root 14, at the pelvic nerve 16, at the pudendal nerve 5 or
the bladder 4 wall to evoke either direct bladder contraction or
indirect reflex bladder contraction. Alternatively, a variety of
provider/subject initiated mechanical techniques are employed to
contract the bladder 4, for example, by distension, pressing or
tapping on the skin of the human body 10 at the location of the
bladder 4.
[0045] FIG. 4 illustrates the pressing or tapping of the bladder 4
employing a human hand 44. In this manner, a provider/subject can
initiate bladder contractions with a non-invasive technique that
requires no surgical procedures. A person can simply place the
dermal electrode 26 onto their skin 27 which applies the sensory
feedback signal to the EUS 13 and evoke bladder contraction simply
by tapping or pressing of the outside of the bladder 4 with the
hand 29, thus evacuating the bladder 4 of urine.
[0046] In view of the foregoing structural and functional features
described above, a methodology in accordance with various aspects
of the present disclosure will be better appreciated with reference
to FIGS. 5-8. While, for purposes of simplicity of explanation, the
methodologies of FIGS. 5-8 are shown and described as executing
serially, it is to be understood and appreciated that the present
disclosure is not limited by the illustrated order, as some aspects
could, in accordance with the present disclosure, occur in
different orders and/or concurrently with other aspects from that
shown and described herein. Moreover, not all illustrated features
may be required to implement a methodology in accordance with an
aspect of the present disclosure.
[0047] FIG. 5 illustrates a methodology for bladder control in
accordance with an aspect of the present disclosure. At 100, a
first electrode is coupled to an intradural portion of a sacral
dorsal root of a subject. At 110, a second electrode is coupled to
an intradural portion of a sacral ventral root of the subject. At
120, a first and second series of intermittent pulse trains are
concurrently applied to the first electrode and the second
electrode, wherein the first and second series of intermittent
pulse trains are synchronized to mitigate interference with one
another and to reduce or eliminate EUS contractions and evoke
bladder contractions to expel urine from the subject.
[0048] FIG. 6 illustrates another methodology for bladder control
in accordance with an aspect of the present disclosure. At 200, at
least one electrode is coupled to at least one of extradural
nerves, the pudendal nerve, pelvic nerves, sensory nerves, and
foraminal nerves of a subject. At 210, a series of intermittent
pulse trains are applied to at least one of the electrodes to
concurrently reduce or eliminate EUS contractions and evoke bladder
contractions to expel urine from the subject.
[0049] FIG. 7 illustrates yet another methodology for bladder
control in accordance with an aspect of the present disclosure. At
300, a dermal surface electrode or subcutaneous electrode is
disposed at a skin region at or near dermatomes of a subject. At
310, a series of intermittent pulse trains are applied to the
electrode to reduce or eliminate EUS contractions. At 320, a motor
or sensory stimulus is applied to a nerve anatomically related to
the bladder 4 to evoke bladder contractions to expel urine from the
subject. The bladder stimulus is provided via a
non-quasitrapezoidal electric signal or a mechanical stimulus. The
mechanical stimulus can be a variety of provider/subject initiated
mechanical techniques such as distension, pressing or tapping on an
outside area over the bladder 4 or a combination thereof.
[0050] FIG. 8 illustrates yet a further methodology for bladder
control in accordance with an aspect of the present disclosure. At
400, an electrical signal is applied to a sensory nerve of a
subject to cause the reduction or elimination of EUS contractions.
The sensory nerve is at least one of an intradural nerve, an
extradural nerve, a pudendal nerve, a pelvic nerve, a foraminal
nerve and a dermatome. At 410, a stimulus is applied to the bladder
4 to evoke bladder contractions to expel urine from the subject.
The bladder stimulus is provided via non-quasitrapezoidal electric
signals to a motor or sensory nerve, or a provider/subject
initiated mechanical technique. The motor or sensory nerve is at
least one of an intradural nerve, an extradural nerve, a pudendal
nerve, a sensory nerve, a pelvic nerve, a foraminal nerve, and a
dermatome. The provider/subject initiated mechanical technique is,
for example, distension, pressing or tapping on an outside area
over the bladder 4 or a combination thereof.
[0051] In embodiments, a pulse burst stimulus activates a nerve
related to the bladder 4 to inhibit the bladder 4 from voiding to
prevent incontinence. In embodiments, a pulse burst stimulus
activates central pathways, for example the brain and spinal cord.
In embodiments, a pulse burst stimulus activates other afferent or
sensory nerves, or viscera. In embodiments, a pulse burst stimulus
activates pathways for direct or reflex activation of a visceral
function such as the gastro-intestinal tract, urinary tract, sexual
function and hepatic function. In embodiments, a pulse burst
stimulus activates peripheral sensory nerves, for example for
sensory rehabilitation in neurologically impaired persons or
amputees. In embodiments, a pulse burst stimulus activates central
pain suppression pathways, for example in spinal cords and
periphery for treating causalgia or cluster headaches. In
embodiments, a pulse burst stimulus activates central or peripheral
pathways for behavioral, psychiatric, or psychological disorders
such as depression, schizophrenia, tics, and posttraumatic stress
disorder. In embodiments, a pulse burst stimulus activates central
nerve pathways in the brain or spinal cord for deep brain
stimulation, thalamic and hippocampal stimulation, and spinal cord
stimulation. In embodiments, a pulse burst stimulus activates
afferent pathways for feedback or feed-forward control of central
reflexes such as sneezing, coughing, or central pattern
generators.
EXAMPLES
[0052] Reference is now made to the following examples, which
together with the above descriptions; illustrate the invention in a
non-limiting fashion.
[0053] In one exemplary set of experiments that demonstrate an
embodiment of the present system and method, a motor stimulus was
applied to an animal having a spinal cord injury under 15 mg/kg
.alpha.-chloralose anesthesia. The motor stimulus was applied to
sensory dermatomes to affect the EUS in the animal. Referring to
FIG. 9a, when only a motor stimulus 34 was applied, bladder
contractions 35 and EUS contractions 36 occurred during the motor
stimulus 34. After the motor stimulus 34 was terminated,
undesirable reflex EUS contractions 37 occurred as seen between 35s
and 55s on the x-axis. Referring to FIG. 9b, the use of a pulse
bursting stimulus 38 applied on sensory dermatomes 21 in accordance
with an aspect of the disclosure eliminated the undesirable reflex
EUS contractions 37 of FIG. 9a. The best dermatome bursting
patterns in these experiments were a burst of 10 pulses at 20 Hz
with an inter-burst frequency 33 of 1 Hz applied to the sacral
dermatomes 21.
[0054] In another exemplary set of experiments that demonstrate an
embodiment of the present system and method series of experiments,
a stimulus was applied via a nerve cuff electrode to the pudendal
nerve 5 or via an electrode placed near sensory nerves on the
urethral wall in an animal under 15 mg/kg .alpha.-chloralose
anesthesia. The stimulus was either a continuous pulse train
between 0.5 Hz and 100 Hz or a pulse burst stimulus having the same
0.5 Hz and 100 Hz inter-burst frequency 33 but using bursts of 1-25
pulses at 33-1000 Hz instead of the continuous pulse train. Across
experiments, the use of the pulse burst stimulus resulted in an
average increase in evoked bladder pressure of 52.0.+-.44.5% over
the continuous pulse train stimulus. The best average bursting
patterns were using a burst of 2 pulses at 200 Hz with an
inter-burst frequency 33 of 20 Hz, 25 Hz, or 33 Hz, or using a
burst of 5 or 10 pulses at 200 Hz with an inter-burst frequency of
1 Hz, 2 Hz, or 3 Hz depending on the animal and stimulus
location.
[0055] Referring now to FIG. 10, another exemplary experimental
result of an embodiment is shown. In FIG. 10, a 2 Hz continuous
pulse train 39 applied to sensory nerves originating from the
urethra 12 excited 42 the bladder 4 but did not lead to any urine
being expelled from the bladder 4. The subsequent use of pulse
bursting 40, using 10 pulses at 200 Hz with an inter-burst
frequency of 2 Hz, resulted in a larger bladder contraction 43 and
successful expulsion 41 of 29 ml of urine from the bladder 4. The
81% efficiency indicated the percentage of starting volume in the
bladder 4 that was emptied during the experimental trial and is a
clinically desirable result.
[0056] As is appreciated by those of ordinary skill in the art,
certain features of the invention, which are, for clarity,
described in the context of separate embodiments, may also be
provided in combination in a single embodiment. Conversely, various
features of the invention, which are, for brevity, described in the
context of a single embodiment, may also be provided separately or
in any suitable subcombination. Although the invention has been
described in conjunction with specific embodiments thereof, it is
evident that many alternatives, modifications, and variations will
be apparent to those skilled in the art. Accordingly, it is
intended to embrace all such alternatives, modifications, and
variations that fall within the spirit and broad scope of the
appended claims.
* * * * *