U.S. patent application number 16/536101 was filed with the patent office on 2019-11-28 for method and apparatus for treating sleep apnea.
The applicant listed for this patent is Invicta Medical, Inc.. Invention is credited to Laurence Wylie Harter, Harold Byron Kent, Steven Thomas Kent, Karena Yadira Puldon.
Application Number | 20190358449 16/536101 |
Document ID | / |
Family ID | 53494433 |
Filed Date | 2019-11-28 |
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United States Patent
Application |
20190358449 |
Kind Code |
A1 |
Kent; Steven Thomas ; et
al. |
November 28, 2019 |
METHOD AND APPARATUS FOR TREATING SLEEP APNEA
Abstract
An oral appliance is disclosed that provides electrical
stimulation to a patient's tongue in a manner that prevents
collapse of the tongue and/or soft palate during sleep. More
specifically, the appliance may induce a reversible current or
currents in a lateral direction across the tongue in a manner that
shortens the patient's Palatoglossus muscle, which in turn pulls
the patient's soft palate downward towards a base of the tongue
and/or decreases a volume of the tongue.
Inventors: |
Kent; Steven Thomas;
(Portola Valley, CA) ; Harter; Laurence Wylie;
(San Jose, CA) ; Kent; Harold Byron; (Portola
Valley, CA) ; Puldon; Karena Yadira; (Northridge,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Invicta Medical, Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
53494433 |
Appl. No.: |
16/536101 |
Filed: |
August 8, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14981720 |
Dec 28, 2015 |
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16536101 |
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14149689 |
Jan 7, 2014 |
10195426 |
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14981720 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 1/0548 20130101;
A61F 5/56 20130101; A61N 1/3601 20130101; A61B 5/4818 20130101;
A61N 1/36078 20130101; A61B 5/0488 20130101; A61F 5/566 20130101;
A61B 5/0826 20130101 |
International
Class: |
A61N 1/36 20060101
A61N001/36; A61B 5/00 20060101 A61B005/00; A61B 5/08 20060101
A61B005/08; A61F 5/56 20060101 A61F005/56; A61N 1/05 20060101
A61N001/05; A61B 5/0488 20060101 A61B005/0488 |
Claims
1-31. (canceled)
32. A non-invasive device for treating sleep apnea, comprising: an
appliance configured to be positioned in a person's oral cavity; a
first electrode and a second electrode coupled to the appliance,
wherein the first and second electrodes are configured to float at
a location beneath or on either side of the person's tongue; a
control circuit coupled to the appliance, wherein the control
circuit is configured to generate a signal to drive the first and
second electrodes; a power supply coupled to the control circuit to
provide power to the control circuit; and wherein the appliance and
the first and second electrodes comprise a unitary device adapted
to fit entirely within the person's oral cavity.
33. The device of claim 32 wherein the first and second electrodes
are arranged to contact tissue proximate to the lateral posterior
regions at which the palatoglossus muscle inserts into the person's
tongue.
34. The device of claim 32 wherein at least a portion of the first
and second electrodes are adapted to be positioned posterior to a
last molar location of the person.
35. The device of claim 32 wherein the control circuit is
configured to generate the signal to drive one or more reversible
currents to flow in one or more substantially lateral directions
across the tongue.
36. The device of claim 35 wherein at least one of the reversible
currents comprises a zero-sum waveform.
37. The device of claim 35 wherein a pulse length of at least one
of the reversible currents is configured according to a
resistive-capacitive time constant model associated with the
tongue.
38. The device of claim 32 wherein the control circuit is
configured to generate the signal to drive an induced current to
shorten the palatoglossus muscle without targeting the person's
hypoglossal nerve.
39. The device of claim 32, further comprising a sensor.
40. The device of claim 39 wherein the sensor is one of the first
or second electrodes.
41. The device of claim 32 wherein the first and second electrodes
are arranged to cause shortening of the palatoglossus muscle
without targeting the hypoglossal nerve.
42. The device of claim 32 wherein at least one of the first and
second electrodes comprises a respiration sensor.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application, and claims the
benefit of co-pending and commonly owned U.S. patent application
Ser. No. 14/149,689 entitled "METHOD AND APPARATUS FOR TREATING
SLEEP APNEA" filed on Jan. 7, 2014, which is hereby incorporated by
reference in its entirety.
TECHNICAL FIELD
[0002] The present embodiments relate generally to sleep apnea, and
specifically to non-invasive techniques for treating one or more
underlying causes and results of sleep apnea.
BACKGROUND OF RELATED ART
[0003] Obstructive sleep apnea (OSA) is a medical condition in
which a patient's upper airway is repeatedly partially or fully
occluded during sleep. These repeated occlusions of the upper
airway may cause sleep fragmentation, which in turn may result in
sleep deprivation, daytime tiredness, and malaise. More serious
instances of OSA may increase the patient's risk for stroke,
cardiac arrhythmias, high blood pressure, and/or other
disorders.
[0004] OSA may be characterized by the tendency of the soft tissues
of the upper airway to collapse during sleep, thereby occluding the
upper airway. More specifically, OSA is typically caused by the
collapse of the patient's soft palate and/or by the collapse of the
patient's tongue (e.g., onto the back of the pharynx), which in
turn may obstruct normal breathing.
[0005] There are many treatments available for OSA including, for
example: surgery, constant positive airway pressure (CPAP)
machines, and the electrical stimulation of muscles associated with
moving the tongue. Surgical techniques include tracheotomies,
procedures to remove portions of a patient's tongue and/or soft
palate, and other procedures that seek to prevent collapse of the
tongue into the back of the pharynx. These surgical techniques are
very invasive. CPAP machines seek to maintain upper airway patency
by applying positive air pressure at the patient's nose and mouth.
However, these machines are uncomfortable and may have low
compliance rates.
[0006] Some electrical stimulation techniques seek to prevent
collapse of the tongue into the back of the pharynx by causing the
tongue to protrude forward (e.g., in an anterior direction) during
sleep. For one example, U.S. Pat. No. 4,830,008 to Meer discloses
an invasive technique in which electrodes are implanted into a
patient at locations on or near nerves that stimulate the
Genioglossus muscle to move the tongue forward (e.g., away from the
back of the pharynx). For another example, U.S. Pat. No. 7,711,438
to Lattner discloses a non-invasive technique in which electrodes,
mounted on an intraoral device, electrically stimulate the
Genioglossus muscle to cause the tongue to move forward during
respiratory inspiration. In addition, U.S. Pat. No. 8,359,108 to
McCreery teaches an intraoral device that applies electrical
stimulation to the Hypoglossal nerve to contract the Genioglossus
muscle, which as mentioned above may prevent tongue collapse by
moving the tongue forward during sleep.
[0007] Moving a patient's tongue forward during sleep may cause the
patient to wake, which is not desirable. In addition, existing
techniques for electrically stimulating the Hypoglossal nerve
and/or the Genioglossus muscle may cause discomfort and/or pain,
which is not desirable. Further, invasive techniques for
electrically stimulating the Hypoglossal nerve and/or the
Genioglossus muscle undesirably require surgery and introduce
foreign matter into the patient's tissue, which is undesirable.
[0008] Thus, there is a need for a non-invasive treatment for OSA
that does not disturb or wake-up the patient during use.
SUMMARY
[0009] This Summary is provided to introduce in a simplified form a
selection of concepts that are further described below in the
Detailed Description. This Summary is not intended to identify key
features or essential features of the claimed subject matter, nor
is it intended to limit the scope of the claimed subject
matter.
[0010] A method and apparatus for reducing the occurrence and/or
severity of a breathing disorder, such as OSA, are disclosed
herein. In accordance with the present embodiments, a non-invasive
and removable oral appliance is disclosed that may provide
electrical stimulation to a lateral and/or sublingual portion of a
patient's oral cavity (mouth) in a manner that prevents a collapse
of the patient's tongue and/or soft palate during sleep without
disturbing (e.g., without waking) the patient. For at least some
embodiments, an electric current induced by the appliance may
stimulate the patient's Palatoglossus muscle in a manner that
causes the Palatoglossus muscle to stiffen and shorten, which in
turn may pull the patient's soft palate and/or palatal arches in a
downward direction towards a base of the patient's tongue so as to
prevent the soft palate from collapsing and/or from flapping
against the back of the patient's throat. Stiffening and/or
shortening the Palatoglossus muscle may also cause the patient's
tongue to contract and/or stiffen in a manner that prevents
collapse of the tongue in a posterior direction (e.g., towards the
patient's pharynx).
[0011] In addition, stimulating the Palatoglossus muscle using
techniques described herein may also lower a superior surface of
the tongue T, thereby causing the tongue to cinch downward (e.g.,
to "hunker down") in a manner that further prevents obstruction of
the patient's upper airway. By simultaneously preventing collapse
of the patient's soft palate and tongue, patency of the patient's
upper airway may be maintained in a non-invasive manner. For some
embodiments, the appliance may stimulate the patient's
Palatoglossus muscle without moving the patient's tongue in an
anterior direction. For at least one embodiment, stimulation of the
patient's Palatoglossus muscle may also elevate a posterior portion
of the patient's tongue, which in turn may further prevent collapse
of the tongue onto the back of the patient's pharynx.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The present embodiments are illustrated by way of example
and are not intended to be limited by the figures of the
accompanying drawings, where like reference numerals refer to
corresponding parts throughout the drawing figures.
[0013] FIG. 1A is a side sectional view depicting a patient's upper
airway.
[0014] FIG. 1B is a front plan view of the patient's oral
cavity.
[0015] FIG. 1C is an elevated sectional view of the patient's
tongue.
[0016] FIG. 1D is a side sectional view of the patient's
tongue.
[0017] FIG. 2A is a top plan view of a device, situated over a
patient's lower teeth, in accordance with some embodiments.
[0018] FIG. 2B is an elevated perspective view of the device of
FIG. 2A.
[0019] FIG. 2C is a top plan view of a device, situated over a
patient's lower teeth, in accordance with other embodiments.
[0020] FIG. 2D is an elevated perspective view of the device of
FIG. 2C.
[0021] FIG. 3A is a side sectional view depicting a patient's upper
airway during disturbed breathing.
[0022] FIG. 3B is a side sectional view depicting the patient's
upper airway in response to electrical stimulation provided in
accordance with the example embodiments.
[0023] FIG. 4 is a block diagram of the electrical components of
the device of FIGS. 2A-2B.
[0024] FIG. 5 is a circuit diagram illustrating an electrical model
of the patient's tongue.
[0025] FIG. 6 is an illustrative flow chart depicting an example
operation in accordance with some embodiments.
[0026] FIG. 7A is an elevated perspective view of a device in
accordance with other embodiments.
[0027] FIG. 7B is an elevated perspective view of the device of
FIG. 7A situated over a patient's teeth.
[0028] FIG. 7C is a rear plan view of the device of FIG. 7A
situated over a patient's teeth.
[0029] FIG. 7D is a front plan view of the device of FIG. 7A
situated over a patient's teeth.
DETAILED DESCRIPTION
[0030] A non-invasive method and apparatus for treating sleep
disorders, such as obstructive sleep apnea (OSA) and/or snoring,
are disclosed herein. In the following description, numerous
specific details are set forth to provide a thorough understanding
of the present disclosure. Also, in the following description and
for purposes of explanation, specific nomenclature is set forth to
provide a thorough understanding of the present embodiments.
However, it will be apparent to one skilled in the art that these
specific details may not be required to practice the present
embodiments. In other instances, well-known circuits and devices
are shown in block diagram form to avoid obscuring the present
disclosure. The term "coupled" as used herein means connected
directly to or connected through one or more intervening
components, circuits, or physiological matter. Any of the signals
provided over various buses described herein may be
time-multiplexed with other signals and provided over one or more
common buses, or may be wirelessly transmitted between a number of
component, circuits, sensors, and/or devices of the example
embodiments. Additionally, the interconnection between circuit
elements or software blocks may be shown as buses or as single
signal lines. Each of the buses may alternatively be a single
signal line, and each of the single signal lines may alternatively
be buses, and a single line or bus might represent any one or more
of a myriad of physical or logical mechanisms for communication
between components. Further, the logic levels and timing assigned
to various signals in the description below are arbitrary and/or
approximate, and therefore may be modified (e.g., polarity
reversed, timing modified, etc) as desired.
[0031] As used herein, the term "substantially lateral direction"
refers to a direction across the patient's oral cavity in which the
direction's lateral components are larger than the direction's
anterior-to-posterior components (e.g., a substantially lateral
direction may refer to any direction that is less than
approximately 45 degrees from the lateral direction, as defined
below with respect to the drawing figures). Further, as used
herein, the term "reversible current" means a current that changes
or reverses polarity from time to time between two controllable
voltage potentials.
[0032] To more fully understand the present embodiments, the
dynamics of OSA are first described with respect to an illustration
100 of a patient's oral cavity shown in FIGS. 1A-1D, which
illustrate the anatomical elements of a patient's upper airway
(e.g., including the nasal cavity, oral cavity, and pharynx of the
patient). Referring first to FIGS. 1A-1B, the hard palate HP
overlies the tongue T and forms the roof of the oral cavity OC
(e.g., the mouth). The hard palate HP includes bone support BS, and
thus does not typically deform during breathing. The soft palate
SP, which is made of soft material such as membranes, fibrous
material, fatty tissue, and muscle tissue, extends rearward (e.g.,
in a posterior direction) from the hard palate HP towards the back
of the pharynx PHR. More specifically, an anterior end 1 of the
soft palate SP is anchored to a posterior end of the hard palate
HP, and a posterior end 2 of the soft palate SP is un-attached.
Because the soft palate SP does not contain bone or hard cartilage,
the soft palate SP is flexible and may collapse onto the back of
the pharynx PHR and/or flap back and forth (e.g., especially during
sleep).
[0033] The pharynx PHR, which passes air from the oral cavity OC
and nasal cavity NC into the trachea TR, is the part of the throat
situated inferior to (below) the nasal cavity NC, posterior to
(behind) the oral cavity OC, and superior to (above) the esophagus
ES. The pharynx PHR is separated from the oral cavity OC by the
Palatoglossal arch PGA, which runs downward on either side to the
base of the tongue T.
[0034] Although not shown for simplicity, the pharynx PHR includes
the nasopharynx, the oropharynx, and the laryngopharynx. The
nasopharynx lies between an upper surface of the soft palate SP and
the wall of the throat (i.e., superior to the oral cavity OC). The
oropharynx lies behind the oral cavity OC, and extends from the
uvula U to the level of the hyoid bone HB. The oropharynx opens
anteriorly into the oral cavity OC. The lateral wall of the
oropharynx consists of the palatine tonsil, and lies between the
Palatoglossal arch PGA and the Palatopharyngeal arch. The anterior
wall of the oropharynx consists of the base of the tongue T and the
epiglottic vallecula. The superior wall of the oropharynx consists
of the inferior surface of the soft palate SP and the uvula U.
Because both food and air pass through the pharynx PHR, a flap of
connective tissue called the epiglottis EP closes over the glottis
(not shown for simplicity) when food is swallowed to prevent
aspiration. The laryngopharynx is the part of the throat that
connects to the esophagus ES, and lies inferior to the epiglottis
EP.
[0035] Referring also to FIGS. 1C-1D, the tongue T includes a
plurality of muscles that may be classified as either intrinsic
muscles or extrinsic muscles. The intrinsic muscles, which lie
entirely within the tongue T and are responsible for altering the
shape of the tongue T (e.g., for talking and swallowing), include
the superior longitudinal muscle SLM, the inferior longitudinal
muscle ILM, the vertical muscle VM, and the transverse muscle TM.
The superior longitudinal muscle SLM runs along the superior
surface SS of the tongue T under the mucous membrane, and may be
used to elevate, retract, and deviate the tip of the tongue T. The
inferior longitudinal muscle ILM lines the sides of the tongue T,
and is attached to the Styloglossus muscle SGM. The vertical muscle
VM is located along the midline of the tongue T, and connects the
superior and inferior longitudinal muscles together. The transverse
muscle TM divides the tongue at the middle, and is attached to the
mucous membranes that run along the sides of the tongue T.
[0036] The extrinsic muscles, which attach the tongue T to other
structures and are responsible for re-positioning (e.g., moving)
the tongue, include the Genioglossus muscle GGM, the Hyoglossus
muscle HGM, the Styloglossus muscle SGM, and the Palatoglossus
muscle PGM. The Genioglossus muscle GGM may be used to protrude the
tongue T and to depress the center of the tongue T. The Hyoglossus
muscle HGM may be used to depress the tongue T. The Styloglossus
muscle SGM may be used to elevate and retract the tongue T. The
Palatoglossus muscle PGM may be used to depress the soft palate SP
and/or to elevate the back (posterior portion) of the tongue T.
Referring also to FIGS. 1A and 1B, the Palatoglossus muscle PGM
connects the tongue T to both sides of the Palatoglossus arch PGA,
and inserts into lateral posterior regions 101 of the base of the
tongue T.
[0037] It is noted that all of the muscles of the tongue T, except
for the Palatoglossus muscle PGM, are innervated by the Hypoglossal
nerve (not shown for simplicity); the Palatoglossus muscle PGM is
innervated by the pharyngeal branch of the Vagus nerve (not shown
for simplicity).
[0038] During awake periods, the muscles of the upper airway (as
well as the hypoglossal nerve) are active and stimulated, and may
maintain upper airway patency by preventing the soft palate SP from
collapsing and/or by preventing the tongue T from prolapsing onto
the back of the pharynx PHR. However, during sleep periods, a
relative relaxed state of the soft palate SP may allow the soft
palate SP to collapse and obstruct normal breathing, while a
relative relaxed state of the tongue T may allow the tongue T to
move in a posterior direction (e.g., onto the back of the pharynx
PHR) and obstruct normal breathing.
[0039] Accordingly, conventional electrostimulation treatments for
OSA typically involve causing the tongue T to move forward in the
anterior direction during apnea episodes so that the tongue T does
not collapse in the posterior direction. More specifically, some
conventional techniques (e.g., disclosed in U.S. Pat. Nos.
5,190,053 and 6,212,435) electrically stimulate the Genioglossus
muscle to move the tongue forward in an anterior direction during
apnea episodes, while other conventional techniques (e.g.,
disclosed in U.S. Pat. No. 8,359,108) electrically stimulate the
Hypoglossal nerve, which in turn causes the tongue to move forward
in the anterior direction by innervating the Genioglossus
muscle.
[0040] Unfortunately, repeatedly moving the tongue T forward (e.g.,
in the anterior direction) to prevent its prolapse into the back of
the pharynx PHR may undesirably wake-up the patient, which defeats
the very purpose of OSA treatments and may also abrade the tongue
on the teeth. Indeed, electrically stimulating the relatively large
Genioglossus muscle may cause discomfort or pain. In addition,
because the Hypoglossal nerve innervates every tongue muscle except
the Palatoglossus muscle PGM, electrically stimulating the
Hypoglossal nerve may stimulate not only the Genioglossus muscle
GGM but also the superior longitudinal muscle SLM, the inferior
longitudinal muscle ILM, the vertical muscle VM, the transverse
muscle TM, the Hyoglossus muscle HPM, and/or the Styloglossus
muscle SSM. Stimulating multiple tongue muscles at the same time,
in an attempt to move the tongue forward during apnea episodes, may
not only over-stimulate the patient's tongue muscles but may also
cause the tongue T to behave erratically (e.g., repeatedly
protruding and retracting). For example, simultaneously stimulating
the Genioglossus muscle GGM and the Styloglossus muscle SGM may
cause the tongue T to repeatedly protrude and retract,
respectively, which is likely to disturb the patient's sleep
patterns or even wake-up the patient.
[0041] Applicant has discovered that OSA may be more effectively
treated by targeting the Palatoglossus muscle PGM for electrical
stimulation (e.g., rather than targeting the Genioglossus muscle
GGM or the Hypoglossal nerve for electrical stimulation). More
specifically, Applicant has discovered that application of one or
more voltage differentials across selected portions of the
patient's lateral or sublingual tissue may induce a current across
the tongue to electrically stimulate the Palatoglossus muscle PGM
in a manner that causes the Palatoglossus muscle PGM to shorten
(e.g., to decrease its length). For at least some embodiments, the
induced current may flow in a lateral direction across a base
portion of the patient's tongue (e.g., proximate to the lateral
points at which the Palatoglossus muscle inserts into the tongue
T). Shortening the Palatoglossus muscle, using techniques described
herein, may (1) stiffen and reduce the volume of the tongue T and
(2) may cause the Palatoglossal arch PGA to pull down (e.g., in a
downward direction) towards the base of the tongue T.
[0042] As described in more detail below, reducing the volume of
the tongue T using techniques described herein may prevent the
tongue T from prolapsing onto the back of the pharynx PHR, and
pulling down the Palatoglossal arch PGA using techniques described
herein may prevent the soft palate SP from collapsing onto the back
of the pharynx PHR. In addition, stimulating the Palatoglossus
muscle PGM using techniques described herein may also lower the
superior surface SS of the tongue T, thereby causing the tongue to
cinch downward (e.g., to "hunker down") in a manner that further
prevents obstruction of the patient's upper airway.
[0043] Perhaps equally important, because the present embodiments
do not target either the Hypoglossal nerve or the Genioglossus
muscle GGM for electrical stimulation, the present embodiments may
not cause the tongue T to move forward in the anterior direction
during application of the electrical stimulation, which in turn may
reduce the likelihood of undesirably waking-up the patient. Indeed,
for at least some embodiments, the voltage differential may be
applied across the patient's sublingual or lateral lingual tissues
in a manner that maintains the patient's tongue in a substantially
stationary position while shortening the patient's Palatoglossus
muscle PGM. In this manner, the present embodiments may maintain a
patient's upper airway patency in a subtle yet therapeutic manner.
Although electrical stimulation of the Palatoglossus muscle PGM
using techniques described herein is not intended to stimulate the
Genioglossus muscle GGM, any inadvertent stimulation of the
Genioglossus muscle GGM will be relatively small and, at most, may
serve to maintain the tongue T in a substantially stationary
position.
[0044] FIGS. 2A-2B show a removable oral appliance 200 that, in
accordance with at least some embodiments, may be used to treat OSA
by using electrical stimulation of the Palatoglossus muscle PGM to
prevent collapse of the tongue T and soft palate SP into the back
of the pharynx PHR. The appliance 200 is shown in FIGS. 2A-2B as
including an appliance body 205 upon which a number of electrodes
210(1)-210(2), a control circuit 220, and a power supply 230 may be
mounted (or otherwise attached to) so as to form a unitary and
removable device that may fit generally within a patient's oral
cavity OC (see also FIGS. 1A-1B). For such embodiments, there are
no components external to the patient's body, and therefore the
appliance 200 may not be associated with wires or other connectors
that protrude from the patient's mouth or body. For some
embodiments, the oral appliance 200 may be fitted over a patient's
lower teeth and positioned to fit within a sublingual portion of
the patient's oral cavity OC, for example, as depicted in FIG. 2A.
For other embodiments, appliance 200 may be of other suitable
configurations or structures, and the electrodes 210(1)-210(2) may
be provided in other suitable positions. For some embodiments,
there may be a minor portion of the oral appliance that protrudes
slightly outside the lips or mouth. For other embodiments, the
control circuit 220, power supply 230, and/or other components may
be detached from the appliance 200 and located outside the
patient's mouth. For such embodiments, the control circuit 220,
power supply 230, and/or other components may be electrically
coupled to the electrodes 210(1)-210(1) using wired connections
(e.g., conductive wires).
[0045] Although only two electrodes 210(1)-210(1) are shown in
FIGS. 2A-2B, it is to be understood that the appliance 200 may, in
other embodiments, include a greater or fewer number of electrodes.
For example, in other embodiments, the appliance 200 may include
four or another number of electrodes 210 arranged in opposing
(e.g., "X") patterns with respect to the patient's sublingual
tissues, wherein pairs of the electrodes may be selectively enabled
and disabled in a manner that alternately induces two or more
currents across the patient's sublingual tissues. For such other
embodiments, each of such electrodes may be turned on and/or off
independently of the other electrodes, for example, to determine a
pair (or more) of electrodes that, at a particular moment for the
patient, correlate to optimum electrical stimulation. The
determined pair of electrodes may be dynamically selected either by
(1) directly correlating electrical stimulation and immediate
respiratory response or by (2) indirectly using the oral appliance
200 "to look for" the lowest impedance electrode "pair(s)." The
determined electrodes may or may not be at the ends of an "X"
pattern, and may be opposing one another.
[0046] The first electrode 210(1) and the second electrode 210(2),
which may be formed using any suitable material and may be of any
suitable size and/or shape, are connected to the control circuit
220 by wires 221. The wires 221 may be any suitable wire, cable,
conductor, or other conductive element that facilitates the
exchange of signals between control circuit 220 and the electrodes
210(1)-210(2). The control circuit 220 and electrodes 210(1)-210(2)
are electrically coupled to power supply 230 via wires 221. Note
that the wires 221 may be positioned either within or on an outside
surface of the appliance body 205, and therefore do not protrude
into or otherwise contact the patient's tongue or oral tissue. The
power supply 230 may be mounted in any of several locations and may
be any suitable power supply (e.g., a battery) that provides power
to control circuit 220 and/or electrodes 210(1)-210(2).
Bi-directional gating techniques may be used to control voltages
and/or currents within wires 221, for example, so that wires 221
may alternately deliver power to electrodes 210(1)-210(2) and
exchange electrical signals (e.g., sensor signals) between
electrodes 240(1)-240(2) and control circuit 220.
[0047] For the example embodiment of FIGS. 2A-2B, the first
electrode 210(1) may include or also function as a sensor 240(1),
and the second electrode 210(2) may include or also function as a
sensor 240(2), which could sense respiration or other functions of
interest. In other words, for some embodiments, one or both of
electrodes 210(1)-210(2) may also function as sensors such as
respiration sensors. For such embodiments, the active function of
the electrodes 210(1)-210(2) may be controlled using bi-directional
gating techniques. For example, when the first electrode 210(1) is
to function as a driven electrode, the bi-directional gating
technique may connect the first electrode 210(1) to the output of a
circuit such as a voltage and/or current driver (e.g., included
within or associated with control circuit 220), for example, to
provide a first voltage potential at the first electrode 210(1);
conversely, when the first electrode 210(1) is to function as the
respiration sensor or other sensor 240(1), the bi-directional
gating technique may connect sensor 240(1) to the input of a
circuit such as an amplifier and/or an ADC (analog to digital)
converter (e.g., included within or associated with control circuit
220), for example, to sense a respiratory function of the patient.
Similarly, when the second electrode 210(2) is to function as a
driven electrode, the bi-directional gating technique may connect
the second electrode 210(2) to the output of a circuit such as a
voltage and/or current driver (e.g., included within or associated
with control circuit 220), for example, to provide a second voltage
potential at the second electrode 210(2); conversely, when the
second electrode 210(2) is to function as the respiration sensor or
other sensor 240(2), the bi-directional gating technique may
connect sensor 240(2) to the input of a circuit such as an
amplifier and/or an ADC (analog to digital) converter (e.g.,
included within or associated with control circuit 220), for
example, to sense a respiratory function of the patient.
[0048] The respiration sensors or other sensors 240(1)-240(2), as
provided within or otherwise associated with the electrodes
210(1)-210(2), may be any suitable sensors that measure any
physical, chemical, mechanical, electrical, neurological, and/or
other characteristics of the patient which may indicate or identify
the presence and/or absence of disturbed breathing. These
respiration sensors 240(1)-240(2) may also be used to detect
snoring. For at least some embodiments, one or both of electrodes
210(1)-210(2) may include electromyogram (EMG) sensor electrodes
that, for example, detect electrical activity of the muscles and/or
nerves within, connected to, or otherwise associated with the oral
cavity. For at least one embodiment, one or both of electrodes
210(1)-210(2) may include a microphone (or any other sensor to
sense acoustic and/or vibration energy) to detect the patient's
respiratory behavior. For other embodiments, one or both of
electrodes 210(1)-210(2) may include one or more of the following
non-exhaustive list of sensors: accelerometers, piezos, capacitance
proximity detectors, capacitive sensing elements, optical systems,
EMG sensors, etc.
[0049] For other embodiments, electrodes 210(1)-210(2) may not
include any sensors. For at least one of the other embodiments, the
electrodes 210(1)-210(2) may continuously provide electrical
stimulation to the patient's Palatoglossus muscle PGM via the
lingual tissues. For an alternative embodiment, a timer (not shown
for simplicity) may be provided on appliance body 205 or within
control circuit 220 and configured to selectively enable/disable
electrodes 210(1)-210(2), for example, based upon a predetermined
stimulation schedule. In another closed-loop embodiment, the
electrodes 210(1)-210(2) may be selectively enabled/disabled based
upon one or more sources of sensor feedback from the patient.
[0050] For the example embodiment of FIGS. 2A-2B, the first and
second electrodes 210(1)-210(2) may be mounted on respective
lateral arms 205(1) and 205(2) of the body 205 of appliance 200
such that when appliance 200 is placed within a sublingual portion
of the patient's oral cavity OC, the first and second electrodes
210(1)-210(2) are positioned on opposite sides of the posterior
sublingual region 207 of the patient's oral cavity OC. For other
embodiments, the first and second electrodes 210(1)-210(2) may be
separate from appliance body 205 but connected to respective
lateral arms 205(1)-205(2), for example, so as to "float" beneath
or on either side of the patient's tongue T, or alternatively
oriented so as to be positioned on opposite sides of the superior
surface of the tongue T. For some embodiments, the first and second
electrodes 210(1)-210(2) are positioned in the posterior sublingual
region 207 of the oral cavity OC such that at least a portion of
each of the first and second electrodes 210(1)-210(2) is proximal
to a molar 209 of the patient. In this manner, the first and second
electrodes 210(1)-210(2) may be in physical contact with the
patient's lingual tissues proximate to the lateral posterior
regions (e.g., points) 101 at which the Palatoglossus muscle PGM
inserts into the tongue T (see also FIGS. 1A-1B). Further, as
depicted in FIGS. 2A-2B, the first and second electrodes
210(1)-210(2) may be angularly oriented with respect to the floor
of the mouth such that the first and second electrodes
210(1)-210(2) substantially face and/or contact opposite sides of
the tongue T proximate to the lateral posterior regions (e.g.,
points) 101 at which the Palatoglossus muscle PGM inserts into the
tongue T (see also FIGS. 1A-1B). For other embodiments, the first
and second electrodes 210(1)-210(2) may be provided in one or more
other positions and/or orientations.
[0051] The control circuit 220 may provide one or more signals to
the first and second electrodes 210(1)-210(2) to create a voltage
differential across the patient's lingual tissues (e.g., across the
base of the tongue) in the lateral direction. For purposes of
discussion herein, the first electrode 210(1) may provide a first
voltage potential V1, and the second electrode 210(2) may provide a
second voltage potential V2. The voltage differential (e.g., V2-V1)
provided between the first and second electrodes 210(1)-210(2) may
induce a current 201 in a substantially lateral direction across
the patient's lingual tissues. For some embodiments, the current
201 is induced in a substantially lateral direction across the
patient's tongue. The current 201, which for some embodiments may
be a reversible current (as described in more detail below),
electrically stimulates the patient's Palatoglossus muscle PGM in a
manner that shortens the Palatoglossus muscle PGM.
[0052] When the Palatoglossus muscle PGM is stimulated and/or
shortened in response to the current 201 induced by the first and
second electrodes 210(1)-210(2), the Palatoglossus muscle PGM
causes the tongue T to stiffen in a manner that decreases the
tongue's volume, and that may also slightly cinch a portion of the
tongue T closer to the floor of the oral cavity OC. One or more of
decreasing the tongue's volume and slightly cinching the tongue T
downward towards the floor of the oral cavity OC may prevent the
tongue T from prolapsing onto the back of the pharynx PHR, thereby
maintaining patency of the patient's upper airway (e.g., without
moving the tongue forward in the anterior direction). The
shortening of the Palatoglossus muscle PGM may also pull the
patient's Palatoglossal arch PGA in a downward direction towards
the base of the tongue T, which in turn may prevent the soft palate
SP from collapsing and obstructing the patient's upper airway.
[0053] For example, FIG. 3A shows a side view 300A of a patient
depicting the collapse of the patient's tongue T and soft palate SP
in a posterior direction towards the back of the pharynx (PHR)
during disturbed breathing. As depicted in FIG. 3A, the patient's
upper airway is obstructed by the tongue T prolapsing onto the back
wall of the pharynx PHR and/or by the soft palate SP collapsing
onto the back wall of the pharynx PHR.
[0054] In contrast, FIG. 3B shows a side view 300B of the patient
depicting the patient's upper airway response to electrical
stimulation provided in accordance with the present embodiments.
More specifically, electrical stimulation provided by one or more
embodiments of the appliance 200 may cause the Palatoglossus muscle
PGM to stiffen and shorten, which in turn may pull the patient's
soft palate SP and/or palatal arches in a downward direction,
thereby preventing the soft palate SP from collapsing onto the back
wall of the pharynx PHR. In addition, stiffening and/or shortening
the Palatoglossus muscle PGM may also cause the patient's tongue T
to contract and/or cinch downward in a manner that prevents
collapse of the tongue T towards the back of the pharynx PHR
without substantially moving the tongue T forward in the anterior
direction.
[0055] The control circuit 220 may be any suitable circuit or
device (e.g., a processor) that causes electrical stimulation
energy to be provided to areas proximate to the base of the
patient's tongue T via the electrodes 210(1)-210(2). More
specifically, the control circuit 220 may generate one or more
voltage waveforms that, when provided as signals and/or drive
signals to the first and second electrodes 210(1)-210(2), primarily
induces a current across (e.g., in a substantially lateral
direction) one or more portions of the patient's upper airway
(e.g., across a lingual portion of the patient's tongue T) in a
manner that causes the patient's Palatoglossus muscle PGM to
shorten. As used herein, inducing a current across one or more
portions of the patient's upper airway refers to a direction
between left and right sides of the patient's oral cavity. The
waveforms provided by control circuit 220 may include continuous
voltage waveforms, a series of pulses, or a combination of both.
The control circuit 220 may be formed using digital components,
analog components, or a combination of analog and digital
components.
[0056] For some embodiments, the control circuit 220 may vary or
modify the waveform in a manner that induces a reversible current
across one or more portions of the patient's upper airway (e.g.,
across a portion of the patient's tongue T). Applicant has
discovered that inducing a reversible current across one or more
portions of the patient's upper airway may decrease the likelihood
of patient discomfort (e.g., as compared with providing a constant
current or current in a single direction). More specifically,
Applicant notes that when a current is induced in the lingual
tissues of the patient, the lingual tissues may experience ion or
carrier depletion, which in turn may require greater voltage
differentials and/or greater current magnitudes to maintain a
desired level of electrical stimulation of the Palatoglossus muscle
PGM. However, inducing greater voltage and/or current magnitudes to
offset increasing levels of ion or carrier depletion may create
patient discomfort. Thus, to prevent ion or carrier depletion of
the patient's sublingual tissues, the control circuit 220 may limit
the duration of pulses that induce the current 201 across the
sublingual tissues and/or may from time to time reverse the
direction (e.g., polarity) of the current 201 induced across the
patient's sublingual tissues.
[0057] For some embodiments, control circuit 220 may generate
and/or dynamically adjust the waveform and/or drive waveform
provided to the first and second electrodes 210(1)-210(2) (and/or
to a number of additional electrodes, not shown for simplicity) in
response to one or more input signals indicative of the patient's
respiratory behavior and/or inputs from other characteristics and
sensing methods. The input signals may be provided by one or more
of the sensors 240(1)-240(2) integrated within respective
electrodes 210(1)-210(2).
[0058] For other embodiments, sensors other than the sensors
240(1)-240(2) integrated within respective electrodes 210(1)-210(2)
may be used to generate the input signals. For example, FIGS. 2C-2D
show a removable oral appliance 270 in accordance with other
embodiments. Appliance 270 may include all the elements of the
appliance 200 of FIGS. 2A-2B, plus additional sensors
240(3)-240(4). For the example embodiment of FIGS. 2C-2D, the
sensor 240(3) may be an oxygen saturation (O.sub.2 sat) sensor that
provides a signal indicative of the patient's oxygen saturation
level, and the sensor 240(4) may be a vibration sensor that
provides a signal indicative of the patient's respiratory activity
(as measured by vibrations detected within the patient's oral
cavity). For other embodiments, sensors 240(3)-240(4) may be other
types of sensors including, for example, sensors that measure air
composition (especially O.sub.2 and CO.sub.2), heart rate,
respiration, temperature, head position, snoring, pH levels, and
others.
[0059] FIG. 4 shows a block diagram of the electrical components of
an appliance 400 that is one embodiment of the appliance 200 of
FIGS. 2A-2B. Appliance 400 is shown to include a processor 410, a
plurality of electrodes 210(1)-210(n), power supply 230, sensors
240, and an optional transceiver 420. Processor 410, which is one
embodiment of the control circuit 220 of FIGS. 2A-2B, includes a
waveform generator 411, a memory 412, and a power module 413. The
power supply 230, which as mentioned above may be any suitable
power supply (e.g., a battery), provides power (PWR) to processor
410. For some embodiments, the processor 410 may use power module
413 to selectively provide power to sensors 240, for example, only
during periods of time that the sensors 240 are to be active (e.g.,
only when it is desired to receive input signals from sensors 240).
Selectively providing power to sensors 240 may not only reduce
power consumption (thereby prolonging the battery life of power
supply 230) but may also minimize electrical signals transmitted
along wires 221 to the processor 410. For other embodiments, power
supply 230 may provide power directly to sensors 240.
[0060] The sensors 240, which may include sensors 240(1)-240(2) of
FIGS. 2A-2B and/or sensors 240(3)-240(4) of FIGS. 2C-2D, may
provide input signals to processor 410. The input signals may be
indicative of the respiratory behavior or other functions of the
patient and may be used to detect the presence and/or absence of
disturbed breathing, for example, as described above with respect
to FIGS. 2A-2D.
[0061] The processor 410 may receive one or more input signals from
sensors 240, or sensors located elsewhere, and in response thereto
may provide signals and/or drive signals (DRV) to a number of the
electrodes 210(1)-210(n). As described above, the signals and/or
drive signals (e.g., voltage and/or current waveforms) generated by
waveform generator 411 may cause one or more of the electrodes
210(1)-210(n) to electrically stimulate one or more portions of the
patient's oral cavity OC in a manner that shortens the patient's
Palatoglossus muscle PGM. Shortening the Palatoglossus muscle PGM
in response to electrical stimulation provided by one or more of
the electrodes 210(1)-210(n) may (1) stiffen and reduce the volume
of the tongue T, (2) may cause the tongue to cinch downward, and
(3) may cause the Palatoglossal arch PGA to pull down (e.g., in a
downward direction) towards the base of the tongue T. In this
manner, the electrical stimulation provided by the one or more
electrodes 210(1)-210(n) may prevent the tongue T from prolapsing
onto the back of the pharynx PHR and/or may prevent the soft palate
SP from collapsing onto the back of the pharynx PHR and/or may
prevent the tissues from vibrating.
[0062] As mentioned above, the waveforms generated by the waveform
generator 411, when provided as signals and/or drive signals to the
electrodes 210(1)-210(n), primarily induce a current across the
patient's upper airway in a manner that causes the patient's
Palatoglossus muscle PGM to shorten. The waveforms generated by the
waveform generator 411 may include continuous (analog) voltage
waveforms, any number of pulses that may vary in shape and duration
as a pulse train, or the pulses may be combined to simulate an
analog waveform or a combination of both, and may be dynamically
modified by the waveform generator 411. In other implementations,
the waveforms generated by the waveform generator 411 may be
digital pulses.
[0063] The optional transceiver 420 may be used to transmit control
information (CTL) and/or data, and/or receive control information
and/or data from an external device via a suitable wired or
wireless connection. The external device (not shown for simplicity)
may be any suitable display device, storage device, distribution
system, transmission system, and the like. For one example, the
external device may be a display (e.g., to display the patient's
respiratory behavior or patterns, to alert an observer to periods
of electrical stimulation, to indicate an alarm if breathing stops,
and so on).
[0064] For another example, the external device may be a storage
device that stores any data produced by appliance 200, perhaps
including the patient's respiratory behavior, the electrical
stimulation provided by appliance 200, the waveforms provided by
waveform generator 411, and/or relationships between two or more of
the above. More specifically, for some embodiments, the external
device may store data for a plurality of patients indicating, for
example, a relationship between the application of electrical
stimulation to the patient and the patient's respiratory response
to such electrical stimulation, and may include other information.
Such relationship data for large numbers of patients may be
aggregated, and thereafter used to identify trends or common
components of OSA across various population demographics. The
storage device may be a local storage device, or may be a remote
storage device (e.g., accessible via one or more means and/or
networks including but not limited to such as a wide area network
(WAN), a wireless local area network (WLAN), a virtual private
network (VPN), and/or the Internet). The data and information may
be made available and/or manipulated locally and/or remotely, and
may be utilized immediately and/or preserved for later utilization
and/or manipulation.
[0065] Memory 412 may include a non-transitory computer-readable
storage medium (e.g., one or more nonvolatile memory elements, such
as EPROM, EEPROM, Flash memory, a hard drive, etc.) that may store
the following software modules and/or information: [0066] a
function select module to selectively switch an active function of
the electrodes 210 between an electrode mode (e.g., provided by one
or more of electrodes 210 and a sensor mode (e.g., provided by one
or more of sensors 240); [0067] a control module to selectively
provide signals and/or drive signals to the electrodes 210, for
example, to induce an electric current across a portion of the
patient's oral cavity in accordance with the present embodiments
and/or to receive input signals from the sensors 240; and [0068] a
data collection module to record data indicative of the patient's
respiratory or other behavior and/or to transmit such data to an
external device.
[0069] Each software module may include instructions that, when
executed by the processor 410, may cause appliance 400 to perform
the corresponding function. Thus, the non-transitory
computer-readable storage medium of memory 412 may include
instructions for performing all or a portion of the operations
described below with respect to FIG. 6. The processor 410 may be
any suitable processor capable of executing scripts of instructions
of one or more software programs stored in the appliance 400 (e.g.,
within memory 412). For at least some embodiments, memory 412 may
include or be associated with a suitable volatile memory, for
example, to store data corresponding to the patient's respiratory
functions and/or corresponding to the electrical stimulation
provided by the appliance 200.
[0070] As mentioned above, the control circuit 220 may control the
duration of pulses that induce the current 201 across the patient's
oral cavity, for example, to minimize carrier depletion within the
patient's lingual tissues and/or may from time to time reverse the
direction of the induced current 201, for example, to provide a
zero sum drive waveform (e.g., to minimize or preclude
electrochemical activity and/or to minimize the patient's awareness
of any electrical activity related to oral appliance 200). For at
least one embodiment, the control circuit 220 may select the pulse
lengths (and/or other characteristics of the waveforms) based upon
a resistive-capacitive (RC) time constant model of the patient's
tongue T. For example, FIG. 5 shows an RC time constant model 500
of the patient's tongue T. The model 500 is shown to include a
capacitor C and two resistors, R1 and R2. For an example
embodiment, the capacitor C may be approximately 0.5 uF, the
resistor R1 may be approximately 600 ohms, and the resistor R2 may
be approximately 4,000 ohms. Thus, for the example embodiment, the
time constant .tau.=R1*C may be a value approximately equal to 300
.mu.s. The resistor R2 represents minor "DC current" flow in the
model, where the current stabilizes at a small but non-zero value
after more than 5 time constants or when DC is applied to the
electrodes.
[0071] More specifically, Applicant has discovered that a typical
patient's tongue T is often most receptive to a current "pulse
duration" that is equal to or shorter than a time period
approximately equal to .tau.=R1*C.apprxeq.300 .mu.s. After the time
period 3.tau..apprxeq.1 ms expires, the patient's tongue T may
exhibit an even greater increase in impedance, or perhaps
experience ion depletion, which in turn requires greater voltage
levels to continue inducing the current 201 across the patient's
upper airway tissues. As noted above, increasing the voltage levels
to continue inducing the current 201 across the patient's upper
airway tissues may not only waste battery or wired power but also
may cause discomfort (or even pain) to the patient. Indeed, because
current regulators typically utilize their available voltage
"headroom" to increase the drive voltage and maintain a constant
current flow when the load impedance increases or when the
effective drive voltage otherwise decreases, it is important to
dynamically manage the effective drive voltage provided by the
electrodes 210(1)-210(2).
[0072] The effective drive voltage may decrease when there is an
increased impedance, or perhaps ion depletion, in the patient's
tongue, and the drive resistance may increase when one (or both) of
the electrodes 210(1)-210(2) loses contact with the patient's
sublingual tissues, generally causing the control circuit 220 to
increase its drive voltage in an attempt to maintain a prescribed
current flow. Thus, for at least some embodiments, the control
circuit 220 may be configured to limit the drive voltage and/or the
current to levels that are known to be safe and comfortable for the
patient, even if the drive impedance becomes unusually high. In
addition, the control circuit 220 may be configured to from time to
time reverse the polarity or direction of the induced current 201.
The reversal of the current 201 can be performed at any time. The
timing of the reversal of current 201 may be selected such that
there is no net transfer of charge across the patient's sublingual
tissues (e.g., a zero sum waveform).
[0073] FIG. 6 is a flow chart 600 depicting an example operation
for providing electrical stimulation to a patient in accordance
with the present embodiments. Although the flow chart 600 is
discussed below with respect to appliance 200 of FIGS. 2A-2B, the
flow chart 600 is equally applicable to other embodiments discussed
herein. Prior to operation, the appliance 200 is positioned within
a sublingual portion of the patient's oral cavity, for example, so
that the electrodes 210(1)-210(2) are positioned on opposite sides
of the patient's tongue proximate to the lateral posterior regions
(e.g., points) 101 at which the Palatoglossus muscle PGM inserts
into the tongue T (see also FIGS. 1A-1B). Once the appliance 200 is
properly fitted within the patient's oral cavity, the appliance 200
accepts zero or more input signals using a number of sensing
circuits provided on or otherwise associated with appliance 200
(601). As discussed above, the input signals may be indicative of
the respiratory state or other behavior of the patient, and may be
derived from or generated by any suitable sensor. The control
circuit 220 generates a number of control and/or drive signals
based on the input signals. (602).
[0074] In response to the signals and/or drive signals, the
electrodes 210(1)-210(2) induce a current in a lateral direction
across a sublingual portion of the patient's tongue (603). The
current induced across the sublingual portion of the patient's
tongue electrically stimulates the patient's Palatoglossus muscle
(604). As described above, electrically stimulating the patient's
Palatoglossus muscle may shorten the Palatoglossus muscle (604A),
may pull down the patient's soft palate towards the base of the
tongue (604B), may decrease the volume of the tongue (604C), and/or
may prevent anterior movement of the tongue (604D).
[0075] For some embodiments, the induced current may be a
reversible current. For at least one embodiment, the reversible
current may be a zero-sum waveform. For such embodiments, the
control circuit 220 may from time to time reverse a polarity of the
reversible current (605), and/or may adjust the duration and/or
amplitude of voltage and/or current pulses and/or waveforms based
on the RC time constant model of the patient's tongue (606).
[0076] FIGS. 7A-7D show a removable oral appliance 700 in
accordance with other embodiments. The oral appliance 700, which
may be used to treat OSA (and/or other types of disordered
breathing, discussed in more detail below with respect to FIGS.
8A-8B, 9A-9F, and 10A-10F) by providing electrical stimulation to a
patient's sublingual tissues in a manner that causes the
Palatoglossus muscle to shorten, is shown to include an appliance
body 705 (which includes portions 705(1)-705(3), as shown in the
FIGS.) upon which electrodes 210(1)-210(2), control circuit 220,
and power supply 230 may be mounted (or otherwise attached to) so
as to form a unitary and removable device that may fit entirely
within a patient's oral cavity OC (see also FIGS. 1A-1B). The oral
appliance 700, which may operate in a similar manner as the oral
appliance 200 of FIGS. 2A-2B, includes appliance body 705 instead
of appliance body 205 of FIGS. 2A-2B. Specifically, appliance body
705 includes two anchor portions 705(1)-705(2) and a support wire
705(3). The anchor portions 705(1)-705(2) may be fitted over
opposite or approximately opposite molars of the patient, with the
support wire 705(3) connected between anchor portions 705(1)-705(2)
and extending along the patient's gum line. For other embodiments,
the appliance body 705 may be attached, inserted, or otherwise
positioned within the patient's oral cavity in any technically
feasible manner.
[0077] More specifically, for the example embodiments described
herein, the first electrode 210(1) may be attached to or otherwise
associated with the first anchor portion 705(1), and the second
electrode 210(2) may be attached to or otherwise associated with
the second anchor portion 705(2). For other embodiments, one or
both of the anchor portions 705(1)-705(2) may be omitted (e.g., the
appliance body 705 may be a "floating" system in which the
electrodes 210(1)-210(2) are positioned within the patient's oral
cavity without anchors that fit over the patient's teeth. The
control circuit 220 may be attached to support wire 705(3) and/or
the second anchor portion 705(2), and the power supply 230 may be
attached to support wire 705(3) and/or the first anchor portion
705(1) and/or the second anchor portion 705(2). Wires 221 (not
shown in FIGS. 7A-7D for simplicity) may be attached to or provided
within the support wire 705(3).
[0078] In the foregoing specification, the example embodiments have
been described with reference to specific example embodiments
thereof. It will, however, be evident that various modifications
and changes may be made thereto without departing from the broader
scope of the disclosure as set forth in the appended claims. The
specification and drawings are, accordingly, to be regarded in an
illustrative sense rather than a restrictive sense.
* * * * *