U.S. patent application number 13/071312 was filed with the patent office on 2011-07-14 for apparatus, system and method for therapeutic treatment of obstructive sleep apnea.
This patent application is currently assigned to IMTHERA MEDICAL, INC.. Invention is credited to Stanley R. Craig, JR., Marcelo G. Lima.
Application Number | 20110172733 13/071312 |
Document ID | / |
Family ID | 38437975 |
Filed Date | 2011-07-14 |
United States Patent
Application |
20110172733 |
Kind Code |
A1 |
Lima; Marcelo G. ; et
al. |
July 14, 2011 |
APPARATUS, SYSTEM AND METHOD FOR THERAPEUTIC TREATMENT OF
OBSTRUCTIVE SLEEP APNEA
Abstract
Provided is an implantable RFID-enabled micro-electronic
neurostimulator system for treating obstructive sleep apnea,
comprising an implant having a top and a bottom layer, the bottom
layer serving as an attachment mechanism such that the bottom layer
of the implant encompasses the hypoglossal nerve and attaches to
the top layer of the implant; a printed circuit board (PCB)
attached to the top layer of the implant, the PCB having a first
and a second opposing sides; a neural interface attached to the
second side of the PCB; a core subsystem (CSS) attached to the
first side of the PCB and electrically connected to the neural
interface; and a radio frequency (RF) interface attached to the
first side of the PCB and electrically connected to the CSS,
wherein the implant is powered and controlled by an external
programmable controller.
Inventors: |
Lima; Marcelo G.; (San
Diego, CA) ; Craig, JR.; Stanley R.; (Westport,
MA) |
Assignee: |
IMTHERA MEDICAL, INC.
San Diego
CA
|
Family ID: |
38437975 |
Appl. No.: |
13/071312 |
Filed: |
March 24, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12752931 |
Apr 1, 2010 |
7937159 |
|
|
13071312 |
|
|
|
|
11707053 |
Feb 16, 2007 |
7725195 |
|
|
12752931 |
|
|
|
|
60774039 |
Feb 16, 2006 |
|
|
|
60774040 |
Feb 16, 2006 |
|
|
|
60774041 |
Feb 16, 2006 |
|
|
|
Current U.S.
Class: |
607/42 |
Current CPC
Class: |
A61N 1/0556 20130101;
A61N 1/0531 20130101; A61N 1/37223 20130101; A61N 1/3787 20130101;
A61N 1/321 20130101; A61N 1/37288 20130101; A61N 1/0541 20130101;
A61N 1/0534 20130101; A61N 1/0551 20130101; A61N 1/3601 20130101;
A61N 1/37247 20130101; A61N 1/37205 20130101 |
Class at
Publication: |
607/42 |
International
Class: |
A61N 1/36 20060101
A61N001/36; A61F 5/56 20060101 A61F005/56 |
Claims
1-44. (canceled)
45. An implantable neurostimulator for treating obstructive sleep
apnea in a patient comprising: an implantable nerve cuff configured
to at least partially wrap around a segment of a Hypoglossal nerve
(HGN), the nerve cuff including a plurality of electrodes each
oriented and configured to contact the HGN at different radial
locations of the segment of the HGN; an implantable core subsystem
electrically coupled to the nerve cuff; and an external controller
in communication with the implantable core subsystem and configured
to control electrical stimulation applied to the HGN through the
plurality of electrodes.
46. The implantable neurostimulator of claim 45, wherein the core
subsystem includes a printed circuit board (PCB).
47. The implantable neurostimulator of claim 46, wherein the core
subsystem includes a radio frequency (RF) interface electrically
coupled to the PCB and in RF communication with the controller.
48. The implantable neurostimulator of claim 45, wherein the
controller is configured to initiate a stimulation cycle of the
HGN.
49. The implantable neurostimulator of claim 48, wherein the
initiation of the stimulation cycle is conditional on one or more
of activity and posture of the patient determined by a sensor in
communication with the controller.
50. The implantable neurostimulator of claim 45, wherein the core
subsystem is configured to report completion of a stimulation state
to the controller and then go to an idle state.
51. The implantable neurostimulator of claim 45, wherein at least
two of the plurality of electrodes are arranged at different
longitudinal positions with respect to the HGN when the nerve cuff
is wrapped around the HGN.
52. The implantable neurostimulator of claim 45, wherein the nerve
cuff is configured to completely radially wrap around the segment
of the HGN.
53. The implantable neurostimulator of claim 45, wherein the
plurality of electrodes are configured to provide continuous open
loop electrical stimulation to the HGN during sleep hours.
54. The implantable neurostimulator of claim 45, wherein the nerve
cuff is configured to deliver multiple modes of stimulation.
55. The implantable neurostimulator of claim 45, wherein the
plurality of electrodes are configured to provide bi-phasic
stimulation of the HGN.
56. The implantable neurostimulator of claim 45, wherein the
controller is configured to stimulate patient specific nerve
physiology and stimulation parameters.
57. The implantable neurostimulator of claim 45, wherein the
plurality of electrodes are programmable to maximize rate of
airflow and stability of the upper airway.
58. The implantable neurostimulator of claim 45, wherein the
plurality of electrodes are configured to provide stimulation to
different fascicles of HGN at preprogrammed conditions.
59. The implantable neurostimulator of claim 45, wherein each of
the plurality of electrodes is oriented and configured to contact a
different web of nerve fascicles of the HGN.
60. The implantable neurostimulator of claim 45, wherein the
plurality of electrodes are configured and arranged to enable
selective stimulation of both lateral HGN branches.
61. The implantable neurostimulator of claim 45 further comprising:
a multiplexer electrically coupled to the plurality of electrodes,
the multiplexer being programmable and configured to enable
selective stimulation of particular areas of the HGN.
62. An implantable neurostimulator system for treating obstructive
sleep apnea, comprising: an implant configured to at least
partially surround a portion of a Hypoglossal nerve (HGN); a
printed circuit board (PCB) electrically coupled to the implant; a
neural interface electrically coupled to the PCB; a core subsystem
(CSS) electrically coupled to the PCB and electrically connected to
the neural interface, the core subsystem being configured to select
a trained waveform from memory and start stimulation by providing
an electrical signal to the neural interface upon receiving a
request to enter into a stimulation state, the core subsystem being
configured to report completion of a stimulation state to the
controller via an RF communication and go to an idle state; a radio
frequency (RF) interface electrically coupled to the PCB and
electrically coupled to the CSS; and an external programmable
controller configured to power and control the implant.
63. An implantable neurostimulator system for treating obstructive
sleep apnea, comprising: an implant configured to and at least
partially surround a portion of the Hypoglossal nerve (HGN); a
printed circuit board (PCB) electrically coupled to the implant; a
neural interface electrically coupled to the PCB; a core subsystem
(CSS) electrically coupled to the PCB and electrically coupled to
the neural interface, the core subsystem being included in a
silicon chip placed on the PCB with the chip connected to the
neural interface via traced wires printed on the PCB; a radio
frequency (RF) interface attached to the first side of the PCB and
electrically coupled to the CSS; and an external programmable
controller configured to power and control the implant.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Applications 60/774,039, 60/774,040, and 60/774,041 filed on Feb.
16, 2006, which are expressly incorporated herein by reference in
their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to an apparatus, system, and
method for implantable therapeutic treatment of obstructive sleep
apnea.
BACKGROUND OF THE INVENTION
[0003] Sleep apnea is a physiological condition affecting millions
of people worldwide. It is described as an iterated failure to
respire properly during sleep. Those affected by sleep apnea stop
breathing during sleep numerous times during the night. There are
two types of sleep apnea, generally described in medical literature
as central sleep apnea and obstructive sleep apnea. Central sleep
apnea is a failure of the nervous system to produce proper signals
for excitation of the muscles involved with respiration.
Obstructive sleep apnea (OSA) is cause by physical obstruction of
the upper airway channel (UAW).
[0004] Obstruction of the upper airway is associated with a
depression of the respiratory system caused by a loss of tone of
the oropharyngeal muscles involved in maintaining UAW patency. As
those muscles lose tone, the tongue and soft tissue of the upper
airway collapse, blocking the upper airway channel. Blockage of the
upper airway prevents air from flowing into the lungs. This creates
a decrease in blood oxygen level, which in turn increases blood
pressure and heart dilation. This causes a reflexive forced opening
of the UAW until the patient regains normal patency, followed by
normal respiration until the next apneic event. These reflexes
briefly arouse the patient from sleep (microarousals).
[0005] Current treatment options range from non-invasive approaches
such as continuous positive applied pressure (CPAP) to more
invasive surgical procedures such as uvulopalatopharyngoplasty
(UPPP) and tracheostomy. In both cases patient acceptance and
therapy compliance is well below desired levels, rendering the
current solutions ineffective as a long term solution-for
therapeutic treatment of OSA.
[0006] Implants are a promising alternative to these forms of
treatment. Pharyngeal dilation via hypoglossal nerve (XII)
stimulation has been shown to be an effective treatment method for
OSA. The nerves are stimulated using an implanted electrode. In
particular, the medial XII nerve branch (i.e., in. genioglossus),
has demonstrated significant reductions in UAW airflow resistance
(i.e., increased pharyngeal caliber).
[0007] Reduced UAW airflow resistance, however, does not address
the issue of UAW compliance (i.e., decreased UAW stiffness),
another critical factor involved with maintaining patency. To this
end, co-activation of both the lateral XII nerve branches (which
innervate the hyoglossus (HG) and styloglossus (SG) muscles) and
the medial nerve branch has shown that the added effects of the HG
(tongue retraction and depression) and the SG (retraction and
elevation of lateral aspect of tongue) result in an increased
maximum rate of airflow and mechanical stability of the UAW.
[0008] While coarse (non-selective) stimulation has shown
improvement to the AHI (Apnea+Hypopnea Index) the therapeutic
effects of coarse stimulation are inconclusive. Selective
stimulation of the functional branches is more effective, since
each branch-controlled muscle affects different functions and
locations of the upper airway. For example, activation of the GH
muscle moves the hyoid bone in the anterosuperior direction
(towards the tip of the chin). This causes dilation of the pharynx,
but at a point along the upper airway that is more caudal (below)
to the base of the tongue. In contrast, activation of the HG
dilates the oropharynx (the most commonly identified point of
collapse, where the tongue and soft palate meet) by causing tongue
protrusion. Finally, the tongue retractor muscles (HG and SG) do
not themselves generate therapeutic effects, but they have been
shown to improve upper airway stability when co-activated with the
HG muscle.
[0009] While electrical stimulation of the hypoglossal nerve (HGN)
has been experimentally shown to remove obstructions in the UAW,
current implementation methods require accurate detection of an
obstruction, selective stimulation of the correct tongue muscles,
and a coupling of the detection and stimulation components.
Additionally, attempts at selective stimulation have to date
required multiple implants with multiple power sources, and the
scope of therapeutic efficacy has been limited. A need therefore
exists for an apparatus and method for programmable and/or
selective neural stimulation of multiple implants or contact
excitation combinations using a single controller power source.
SUMMARY OF THE INVENTION
[0010] The present invention relates to an apparatus, system; and
method for selective and programmable implants for the therapeutic
treatment of obstructive sleep apnea.
[0011] In one embodiment, an implantable RFID-enabled
micro-electronic neurostimulator system for treating obstructive
sleep apnea includes an external subsystem and an internal
subsystem. In this embodiment, the internal subsystem includes an
implant having a top and a bottom layer, the bottom layer serving
as an attachment mechanism such that the bottom layer of the
implant encompasses the HGN and attaches to the top layer of the
implant. A printed circuit board (PCB) is attached to the top layer
of the implant, with the PCB having first and second opposing
sides. A neural interface attaches to the second side of the PCB. A
core subsystem (CSS) attaches to the first side of the PCB and
electrically connects to the neural interface. An internal radio
frequency (RF) interface attaches to the first side of the PCB and
is electrically connected to the CSS. The power may be supplied by
RF energy emitted from the external subsystem.
[0012] In some embodiments, the external subsystem includes a
controller. The controller may include a port for interfacing with
a computer. A computer may interface with the controller through
the port to program patient-specific nerve physiology and
stimulation parameters into the controller. The controller may be
shaped for placement around a patient's ear. The controller may
identify an implant having a unique ID tag, communicate with an
implant having the unique ID tag, and send a signal to a
transponder located in the implant. In some embodiments, the
transponder is a passive RFID transponder. In other embodiments,
the transponder is an active transponder. In still further
embodiments, the controller provides an RF signal to the implant,
senses and records data, and interfaces with a programming device.
The controller may also communicate with the implant at
preprogrammed intervals. In other embodiments, the controller
initiates a stimulation cycle by making a request to the CSS, the
request being in the form of an encoded RF waveform including
control data. The request may be encrypted.
[0013] In some embodiments, the implant provides continuous open
loop electrical stimulation to the HGN. In other embodiments, the
implant provides closed loop stimulation. The stimulation may be
constant, or it may be at preprogrammed conditions. Stimulation may
be applied during sleep hours, or it may be applied while the
patient is awake. The stimulation may be bi-phasic stimulation of
the HGN, with a stimulation pulse width of about 200 microseconds
and a stimulation frequency of about 10-40 Hertz. The implant may
be hermetically sealed. In other embodiments, the implant delivers
multiple modes of stimulation. The stimulation can be in multiple
dimensions.
[0014] Stimulation may be provided by a neural interface. This
stimulation may be applied to the HGN. In certain embodiments, the
neural interface includes a plurality of individual electrodes. In
further embodiments, the neural interface electrodes include an
array of anodes and cathodes, which in some embodiments are a
plurality of exposed electrode pairs serving as anode and cathode
complementary elements. In certain other embodiments, the
electrodes are spot welded to the PCB and include material selected
from the group consisting of platinum and iridium. In certain
embodiments, the neural interface includes no external wires or
leads. In still further embodiments, the neural interface includes
a matrix of platinum electrodes coupled to the fascicles of the
hypoglossal nerve (HGN). In some embodiments, the neural interface
senses neural activity of the nerve it interfaces with, and
transmits that sensed neural activity to the core subsystem.
[0015] In some embodiments, the core subsystem (CSS) of the implant
is included in a silicon chip placed on the top of the printed
circuit board PCB, with the chip connected to the neural interface
via traced wires printed on the PCB. The chip may be powered by and
receive a customized electrode stimulation program protocol from
the controller. Upon receiving a request to enter into a
stimulation state the CSS selects a trained waveform from memory
and starts stimulation by providing an electrical signal to the
neural interface. In some embodiments, the core subsystem reports
completion of a stimulation state to the controller via an RF
communication and optionally goes to an idle state.
[0016] Methods for treating obstructive sleep apnea are also
disclosed. In one method, a hypoglossal nerve (HGN) is selectively
stimulated. A neural interface is implanted in a fascicle of the
HGN. The neural interface senses and records neural activity, and
feeds the sensed neural activity information into a parameterized
control algorithm. In certain embodiments, an external subsystem
inductively coupled to an RFID senses and records the neural
activity. The algorithm compares the sensed information to a
reference data set in real time, transmits in real time an output
of the parameterized control algorithm from an external RF
interface to an internal RF interface, and from the internal RF
interface to a microprocessor. Stimulus information may be
calculated and communicated between the external RF interface and
the internal RF interface in real time. In another method,
bi-phasic electrical stimulation is applied to individual fascicles
of the hypoglossal nerve using selectively excitable individual
electrodes arranged in a planar field.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention, and together with the description serve to explain
the principles of the invention. In the drawings:
[0018] FIG. 1 shows an embodiment of an internal subsystem.
[0019] FIG. 2 shows an embodiment of an internal subsystem with the
core subsystem and internal RF interface in a silicon package.
[0020] FIG. 3 shows a hypoglossal nerve an implant.
[0021] FIG. 4 shows multiple embodiments of neural interface
electrode arrays.
[0022] FIG. 5 shows an embodiment of an internal subsystem
implant.
[0023] FIG. 5A is a breakout view of FIG. 1.
[0024] FIG. 6A shows an embodiment of an internal subsystem with
the neural interface electrodes on the bottom layer of the
implant.
[0025] FIG. 6B shows an embodiment of an internal subsystem with
the neural interface electrodes on the top and bottom layers of the
implant.
[0026] FIG. 7 shows an embodiment of an external subsystem with a
controller.
[0027] FIG. 8 shows two embodiments of the external controller.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings.
[0029] One embodiment the present invention includes an external
subsystem and an internal subsystem. In certain embodiments, the
external subsystem includes one or more of (1) a controller, (2) an
external RF interface, and (3) an optional power source. The
internal subsystem may include an implant. In certain embodiments,
the implant includes one or more of (1) a neural interface which
can include an array of electrodes where at least one electrode
contacts a nerve, (2) a core subsystem, and (3) an internal RF
interface. In some embodiments, the neural interface may further
include a digital to analog signal converter and a multiplexer.
[0030] In some embodiments the core subsystem may include a
microprocessor. The microprocessor may have a micrologic CPU and
memory to store protocols selective to a patient. The
microprocessor may be part of an integrated silicon package. In
still further embodiments, the internal RF interface may include
one or more of a transponder, internal antenna, modulator,
demodulator, clock, and rectifier. The transponder can be passive
or active. In some embodiments, one or more of a controller,
external RF interface, and optional power source are positioned on
the skin of a user/patient, typically directly over or in close
proximity to, an implant.
[0031] In certain embodiments, the external subsystem controller
can be in the form of an earpiece or patch including any one or
more of the controller, external RF interface, and optional power
source, e.g., a battery, AC to DC converter, or other power sources
known to those skilled in the art. In certain embodiments, the
external subsystem can send and receive control logic and power
using an external RF interface. In such embodiments, the external
subsystem can further include one or more of a crypto block, data
storage, memory, recording unit, microprocessor, and data port. In
some embodiments the microprocessor may have a micrologic CPU and
memory to store protocols selective to a patient. The
microprocessor may be part of an integrated silicon package.
[0032] Each of the components of various embodiments of the claimed
invention is described hereafter. In certain embodiments, the
present invention is an open loop system. In other embodiments the
present invention is a closed loop system. The components of the
embodiments can be rearranged or combined with other embodiments
without departing from the scope of the present invention.
[0033] The Internal Subsystem
[0034] In certain embodiments, the internal subsystem includes an
implant, which includes one or more of (1) a core subsystem, (2) a
neural interface, and (3) an internal RF interface. Certain
embodiments of the implant components and component arrangements
are described below.
[0035] Implant Components
[0036] The following paragraphs describe embodiments of the implant
of the present invention, which includes one or more of a core
subsystem, neural interface, and internal RF interface
components.
[0037] The Core Subsystem
[0038] FIG. 1 shows an embodiment of the internal subsystem 100. In
certain embodiments the internal subsystem 100 includes an implant
105 (non-limiting representative embodiments of implant 105 are
shown in FIGS. 3, 5, 5A, 6A, 6B, and 8) which may have a core
subsystem 140. The middle portion of FIG. 1 shows a detailed view
of an embodiment of the core subsystem 140. The core subsystem 140
may include one or more of a power module 144, microprocessor 141,
crypto block 142, and input output buffer 143. In certain
embodiments, the microprocessor 141 may have a micrologic CPU, and
may have memory to store protocols selective to a patient. In the
embodiment shown, the core subsystem includes a power module 144, a
core subsystem microprocessor 141 for managing communication with
an external RF interface 203, at least one I/O buffer 143 for
storing inbound and outbound signal data, and a core subsystem
crypto block 142. In some embodiments, the core subsystem
microprocessor 141 communicates with the external RF interface 203
in full duplex. The core subsystem microprocessor 141 may generate
signals for controlling stimulation delivered by the neural
interface 160, and it may processes signals received from the
neural interface 160. In certain embodiments, the core subsystem
microprocessor logic includes an anti-collision protocol for
managing in-range multiple transponders and readers, a management
protocol for reset, initialization, and tuning of the implant 105,
and a protocol to facilitate the exchange of data with the neural
interface 160. The core subsystem microprocessor 141 is
programmable and may further include an attached non-volatile
memory. The microprocessor 141 may be a single chip 145 or part of
an integrated silicon package 170.
[0039] FIG. 2 shows an embodiment of an internal subsystem 100 with
the core subsystem 140 and internal RF interface 150 in a silicon
package 170. For size comparison, FIG. 2 shows the core subsystem
140, internal RF interface 150, and core subsystem microprocessor
141 next to the silicon package 170.
[0040] The Neural Interface
[0041] The right portion of FIG. 1 shows an embodiment of a neural
interface 160. The neural interface 160 can include an array of
electrodes 161 where at least one electrode 161 contacts a nerve.
In one embodiment, the neural interface 160 includes an array of 10
to 16 electrodes 161. This arrangement is exemplary only however,
and not limited to the quantity or arrangement shown. The core
subsystem 140 connects to the neural interface 160, and controls
neural interface stimulation. In the embodiment shown, the neural
interface 160 is attached to the printed circuit board 130. In some
embodiments, the neural interface 160 may further include a digital
to analog signal converter 164 and a multiplexer 166. In certain
embodiments the multiplexer 166 is included on the printed circuit
board 130. In other embodiments, the multiplexer 166 is included on
a thin layer film or flexible membrane around the surface of the
chip.
[0042] In the embodiment shown, the neural interface 160 receives
power from RF waves received by the implant 105. In one embodiment,
the D/A converter 164 uses the RF waves to power one or more
capacitors 165, which may be located in the converter 164. In
certain embodiments, the capacitors 165 are arranged in an array on
a microfilm. These capacitors 165 store charges, which are used to
generate analog burst pulses for delivery by the neural interface
160. In embodiments including a multiplexer 166, the multiplexer
166 may be used to deliver power to multiple capacitors 165, and
can be used to deliver power to multiple electrodes 161 in the
neural interface 160. In still further embodiments, the multiplexer
166 is programmable.
[0043] In certain embodiments, the neural interface 160 is
physically located on the opposite side of the printed circuit
board 130 to which the core subsystem 140 is attached. In other
embodiments, the one or more electrodes 161 are physically
separated from the core subsystem 140 by the printed circuit board
130. Each electrode 161 connects to the core subsystem 140 through
wires 133 (e.g., traced wires) on the printed circuit board 130.
This layered approach to separating the core subsystem 140 from the
electrodes 161 has significant benefits in the bio-compatible
coating and manufacturing of the implant. By minimizing the area
exposed to the HGN, the bio-compatible coating is only required in
the area surrounding the exposed parts of the electrodes 161.
[0044] The electrodes 161 may be manufactured with biocompatible
material coating. In certain embodiments, the electrodes may
include embedded platinum contacts spot-welded to a printed circuit
board 130 on the implant 105. The electrodes 161 may be arrayed in
a matrix, with the bottoms of the electrodes 161 exposed for
contact to the HGN. Since the electrodes 161 attach to the top
portion of the core subsystem 140 through leads on the printed
circuit board, there is no need for wire-based leads attached to
the contact points, allowing for miniaturization of the electrodes
161.
[0045] FIG. 3 shows a hypoglossal nerve implanted with a neural
interface 160. In one embodiment, exposed portions of the neural
interface 160 deliver selective stimulation to fascicles of the
HGN. Selective stimulation allows co-activation of both the lateral
HGN branches, which innervate the hypoglossus (HG) and styloglossus
(SG), and the medial branch. This selective stimulation of HG
(tongue retraction and depression) and the SG (retraction and
elevation of lateral aspect of tongue) results in an increased
maximum rate of airflow and mechanical stability of the upper
airway (UAW). Selective stimulation is a unique approach to nerve
stimulation when implanted on the hypoglossal nerve (HGN). The
neural interface 160 may also sense the neural activity of the
nerve it interfaces with and may transmit that sensed activity to
the core subsystem microprocessor 141.
[0046] FIG. 4 shows embodiments of neural interface electrode
arrays. These embodiments are exemplary only, and the arrays are
not limited to the quantity or arrangement of the electrodes shown
in the figure. In one embodiment, at least one electrode 161 is in
contact with a nerve. In certain embodiments, the electrodes 161
may be in the shape of a linear, regular, or irregular array. In
certain embodiments, the electrode 161 array may be in a form
suitable for wrapping around a nerve (e.g., a helical shape or
spring-like shape as shown in FIG. 3). The electrodes 161 may also
be arranged in a planar form to help reshape the nerve and move the
axons closer to the electrodes 161. This facilitates access to
multiple nerve axons, which enables multiple modes of stimulation
for enhanced UAW dilation and stability. With a planar form factor,
stimulation can also be delivered in two dimensions, enabling
optimal excitation of the functional branches of the nerve.
Excitation happens through bi-phasic electrical stimulation of
individual electrodes 161.
[0047] The Internal RF Interface
[0048] The left portion of FIG. 1 shows a detailed view of an
embodiment of the internal RF interface 150. The internal RF
interface 150 may include one or more of a transponder 156,
internal antenna 151, modulator 157, demodulator 158, clock 159,
and rectifier. The transponder 156 can be passive or active. In
certain embodiments, the internal RF interface 150 can send and/or
receive one or more of (1) control logic, and (2) power. In still
further embodiments, the internal RF interface 150 delivers one or
more of power, clock, and data to the implant core subsystem 140.
In certain embodiments the data is delivered via a full duplex data
connection. In some embodiments, the internal RF interface 150
sends data (e.g., function status) of one or more electrodes 161 to
a controller 205, described below, for review by a technician or
physician.
[0049] The internal RF interface 150 operates according to the
principle of inductive coupling. In an embodiment, the present
invention exploits the near-field characteristics of short wave
carrier frequencies of approximately 13.56 MHz. This carrier
frequency is further divided into at least one sub-carrier
frequency. In certain embodiments, the present invention can use
between 10 and 15 MHz. The internal RF interface 150 uses a sub
carrier for communication with an external RF interface 203, which
may be located in the controller 205. The sub-carrier frequency is
obtained by the binary division of the external RF interface 203
carrier frequency. In the embodiment shown, the internal RF
interface 150 is realized as part of a single silicon package 170.
The package 170 may further include a chip 145 which is a
programmable receive/transmit RF chip.
[0050] In certain embodiments, the internal RF interface 150 also
includes a passive RFID transponder 156 with a demodulator 158 and
a modulator 157. The transponder 156 uses the sub carrier to
modulate a signal back to the external RF interface 203. In certain
embodiments, the transponder 156 may further have two channels,
Channel A and Channel B. Channel A is for power delivery and
Channel B is for data and control. The transponder 156 may employ a
secure full-duplex data protocol.
[0051] The internal RF interface 150 further includes an inductive
coupler 152, an RF to DC converter 155, and an internal antenna
151. In certain embodiments, the internal antenna 151 includes a
magnetic component. In such embodiments, silicon traces may be used
as magnetic antennas. In other embodiments, the antenna may be a
high Q coil electroplated onto a silicon substrate. A parallel
resonant circuit 153 may be attached to the internal antenna 151 to
improve the efficiency of the inductive coupling. The internal
antenna 151 may be realized as a set of PCB traces 133 on the
implant 105. Size of the antenna traces is chosen on the basis of
power requirements, operating frequency, and distance to the
controller 205. Both the internal RF interface 150 and the core
subsystem microprocessor 141 are powered from an RF signal received
by the internal antenna 151. A shunt regulator 154 in the resonant
circuit 153 keeps the derived voltage at a proper level.
[0052] Implant Component Arrangement
[0053] The implant 105 may be located on any suitable substrate and
may be a single layer or multi-layer form. FIG. 5 shows an implant
105 constructed as a single integrated unit, with a top layer 110
and a bottom layer 110 which may be implanted in proximity to, in
contact with, or circumferentially around a nerve, e.g., the
hypoglossal nerve. FIG. 5A is a breakout view of FIG. 5.
[0054] In certain embodiments, implant components are layered on a
nerve. This alleviates the need for complex wiring and leads. In
FIGS. 5 and 5A, the top layer 110 includes a core subsystem 140, an
internal RF interface 150, and a neural interface 160. The top
layer 110 serves as the attachment mechanism, with the implant
components on the bottom layer 110. The neural interface 160 may be
surface bonded to contacts on a printed circuit board 130. The
bottom layer 110 is complementary to the top layer 110, and serves
as an attachment mechanism so that the implant 105 encompasses the
HGN. Although conductive parts in contact with the HGN may be
located at any suitable position on the implant 105, in the
embodiment shown in FIGS. 5 and 5A, the bottom layer 110 has no
conductive parts.
[0055] In the embodiment shown in FIGS. 5 and 5A, and as described
above, the core subsystem 140 is included in a silicon package 170
(FIG. 2) attached to a printed circuit board (PCB) 130 on the top
layer 110. The PCB 130 has a first side 131 and a second side 132.
The silicon package 170 is placed on a first side 131 of the
printed circuit board 130. In certain embodiments the PCB 130 may
be replaced with a flexible membrane substrate. In the embodiment
shown, the silicon package 170 further includes the internal RF
interface 150. The neural interface 160 attaches to the second side
132 of the PCB 130. In this embodiment, the neural interface 160
(FIG. 6B) further includes a plurality of neural interface
electrodes 161 (FIG. 4) arranged into anode and cathode pairs
162/163, shown in this embodiment as an array of 10 to 16 elements.
The number and arrangement of anode and cathode pairs 162/163 is
exemplary only, and not limited to the embodiment shown. The
silicon package 170 (FIG. 2) connects to the anode and cathode
pairs 162/163 via traced wires 133 printed on the PCB 130.
[0056] In other embodiments, such as the one shown in FIG. 6A, the
neural interface electrode anode and cathode pairs 162/163 are
located on the bottom layer 110 of the implant 105. In still other
embodiments, such as the one shown in FIG. 6B, the neural interface
electrode anode and cathode pairs 162/163 are located on both the
top and the bottom layers 110/120. The matrix arrangement of
electrodes 161 provides multiple nerve stimulating points, and has
several advantages. The matrix arrangement allows a web of nerve
fascicles of the hypoglossal nerve to be accessed, enabling
selective stimulation of particular areas of the nerve. In some
embodiments, power is delivered to the matrix of electrodes 161
from the D/A converter 164 to capacitors 165 via a multiplexer
166.
[0057] The implant 105 may further include an isolation layer 112
(FIG. 6A). In certain embodiments a protective coating 114 (FIGS.
6A and 6B) may be applied to the top and bottom layers 110/120 of
the implant 105. The implant 105 may further be coated with a
protective coating 114 for biological implantation. Further, in
certain embodiments all or a portion of the device may be encased
in a biocompatible casing. In such embodiments, the casing may be a
material selected from the group consisting of one or more titanium
alloys, ceramic, and polyetheretherketone (PEEK).
[0058] The External Subsystem
[0059] In certain embodiments, the external subsystem 200 may
include one or more of (1) a controller, (2) an external RF
interface and (3) an optional power source. An embodiment of an
external subsystem 200 including these elements is shown in FIG. 7.
Typically the external subsystem 200 is located externally on or
near the skin of a patient.
[0060] The Controller
[0061] FIG. 7 shows an embodiment of an external subsystem 200 with
a controller 205. The controller 205 controls and initiates implant
functions. In other embodiments, the controller 205 may be part of
the internal subsystem 100 instead of external subsystem 200, and
in still further embodiments, portions of the controller 205 may be
in both the external and internal subsystems 200/100. In certain
embodiments, the controller 205 may further have one or more of a
controller crypto block 201, data storage 206, a recording unit
207, and a controller microprocessor 204. In some embodiments the
controller microprocessor 204 may have a micrologic CPU and memory
to store protocols selective to a patient. The controller
microprocessor 204 is programmable and may further include an
attached non-volatile memory. The microprocessor 204 may be a
single chip or part of an integrated silicon package.
[0062] In certain embodiments, the controller may further include
includes one or more of an external RF interface having RF transmit
and receive logic, a data storage that may be used to store patient
protocols, an interface (e.g., a USB port), a microprocessor, an
external antenna, a functionality to permit the controller to
interface with a particular implant, and an optional power source.
In certain embodiments, the controller electronics can be either
physically or electromagnetically coupled to an antenna. The
distance between the external RF interface antenna (not shown) and
the implant 105 may vary with indication. In certain embodiments,
distance is minimized to reduce the possibility of interference
from other RF waves or frequencies. Minimizing the distance between
the external antenna and the implant 105 provides a better RF
coupling between the external and internal subsystems 200/100,
further reducing the possibility of implant activation by a foreign
RF source. An encrypted link between the external and internal
subsystems 200/100 further reduces the possibility of implant
activation by foreign RF. In other embodiments, one or more of the
internal antenna 151 and external antennas 209 are maintained in a
fixed position. Potential design complexity associated with
internal RF interface antenna 151 orientation is minimized through
the ability to position the external RF interface antenna in a
specific location (e.g., near the patient's ear). Even if the
patient moves, the internal RF interface antenna 151 and controller
205 remain coupled.
[0063] In certain other embodiments, the controller 205 can also
serve as (1) a data gathering and/or (2) programming interface to
the implant 105. The controller 205 has full control over the
operation of the implant 105. It can turn the implant 105 on/off,
and may be paired to the implant 105 via a device specific ID, as
described herein below with respect to use of the implant 105 and
controller 205 of the present invention. In still further
embodiments, the controller microprocessor 204 calculates stimulus
information. The stimulus information is then communicated to the
implant 105. The implant 105 then provides a calculated stimulus to
a nerve. In another embodiment, the controller 205 preloads the
implant 105 with an algorithmic protocol for neural stimulation and
then provides power to the implant 105.
[0064] External RF Interface
[0065] In the embodiment shown in FIG. 7, the external subsystem
200 includes an external RF interface 203 that provides an RF
signal for powering and controlling the implant 105. The external
RF interface 203 can be realized as a single chip, a plurality of
chips, a printed circuit board, or even a plurality of printed
circuit boards. In other embodiments, the printed circuit board can
be replaced with a flexible membrane. The external RF interface 203
may include one or more of a transponder 208 (not shown), external
antenna (not shown), modulator 210 (not shown), and demodulator 211
(not shown), clock 212 (not shown), and rectifier 213 (not shown)
(not shown). The external RF interface transponder 208 can be
passive or active. In certain embodiments, the external RF
interface 203 can send and/or receive one or more of (1) control
logic, and (2) power. In still further embodiments, the external RF
interface 203 delivers one or more of power, clock, and data to one
or more of the external subsystem controller 205 and the internal
subsystem 100 via the internal RF interface 150. In certain
embodiments the data is delivered via a full duplex data
connection. In an embodiment, the external RF interface 203
operates at a carrier frequency of approximately 13.56 MHz. In
certain embodiments, the external RF interface 203 can operate
between 10 and 15 MHz. This carrier frequency is further divided
into at least one sub-carrier frequency. The sub-carrier frequency
is obtained by binary division of the external RF interface 203
carrier frequency. The external RF interface 203 uses the sub
carrier for communication with the internal RF interface 150. The
external RF interface transponder 208 (not shown) uses the sub
carrier to modulate a signal to the internal RF interface 150. The
transponder 208 (not shown) may further have two channels, Channel
A and Channel B. Channel A is for power delivery and Channel B is
for data and control. The transponder 208 (not shown) may employ a
secure full-duplex data protocol.
[0066] In certain embodiments, the external RF interface 203 may
further include a demodulator 211 (not shown) and a modulator 210
(not shown). In still further embodiments, the external RF
interface 203 further includes an external antenna. In certain
embodiments, the external antenna includes a magnetic component. In
such embodiments, silicon traces may be used as magnetic antennas.
The antenna may be realized as a set of PCB traces. Size of the
antenna traces is chosen on the basis of power requirements,
operating frequency, and distance to the internal subsystem 100. In
certain embodiments, the external antenna may transmit the power
received by internal subsystem 100. In certain other embodiments,
the external antenna may be larger, and have a higher power
handling capacity than the internal antenna 151, and can be
realized using other antenna embodiments known by those skilled in
the art.
[0067] In certain embodiments, the external subsystem 200 is
loosely coupled to an optional power source 215. In one embodiment,
the controller power source 215 is not co-located with the external
RF interface antenna. The external power source 215 may be in one
location, and the external RF interface 203 and optionally the
controller 205 are in a second location and/or third location. For
example, each of the power source 215, controller 205 and external
RF interface 203 can be located in difference areas. In one
embodiment, the power source 215 and the controller 205 and the
external RF interface 203 are each connected by one or more
conductive members, e.g. a flexible cable or wire. Additionally, in
certain embodiments, the controller 205 and optional power source
215 may be co-located, and the external RF interface 203 may be
located elsewhere (i.e., loosely coupled to the controller 205). In
such embodiments, the external RF interface 203 is connected to the
controller 205 by a flexible cable or wire.
[0068] Since the power source 215 may be separately located from
the controller 205 and/or external RF interface antenna, a larger
power source 215 can be externally located but positioned away from
the nerve that requires stimulation. Further, to reduce wasted
power, a larger external RF interface antenna can be used. This
provides the advantage of less discomfort to a user and therefore
enhances patient compliance.
[0069] Such embodiments can also provide power to 2, 3, 4, 5 or
more loosely coupled external RF interfaces 203. Thus, each
external RF interface 203 can be positioned at or near the site of
an implant 105 without the need for a co-located power source 215.
In certain embodiments, each external RF interface 203 draws power
from a single power source 215, and thus a single power source 215
powers a plurality of implants 105. Of course, the amount of power
provided to each implant 105 will vary by indication and distance
between the external RF interface 203 and the implant 105. The
greater the distance between the external RF interface 203 and the
implant 105, the greater the power level required. For example, a
lower power is generally required to stimulate peripheral nerves,
which are closer to the surface of the skin. As apparent to one of
skill in the art, the power received at the implant 105 must be
high enough to produce the desired nerve stimulus, but low enough
to avoid damaging the nerve or surrounding tissue.
[0070] The external RF interface 203 may further include a
programmable receive/transmit RF chip, and may interface with the
controller crypto unit 201 for secure and one-to-one communication
with its associated implant 105. The external RF interface 203
includes a parameterized control algorithm, wherein the
parameterized control algorithm compares the sensed information to
a reference data set in real time. The algorithm may be included in
the controller microprocessor 204. Depending upon the patient's
size and severity of disease state, the algorithm will vary a
number of parameters which include frequency, amplitude of the
signal, number of electrodes involved, etc.
[0071] Interaction with Outside Information Sources
[0072] The external subsystem controller 205 may also interface
with a computer. In some embodiments, the controller interface 202
is a built-in data port (e.g., a USB port). Via the controller
interface 202 a computer may tune (and re-tune) the implant system,
and transfer historical data recorded by the implant 105. The
controller 205 may obtain and update its software from the
computer, and may upload and download neural interface data to and
from the computer. The software may be included in the controller
microprocessor 204 and associated memory. The software allows a
user to interface with the controller 205, and stores the patient's
protocol program.
[0073] External Subsystem Design
[0074] The external subsystem 200 can be of regular or irregular
shape. FIG. 8 shows two embodiments of an external subsystem
controller 205, one with the controller 205 included with an
earpiece much like a Bluetooth earpiece, and one with the
controller 205 included with a patch. In the embodiments shown,
potential design complexity associated with internal RF antenna 151
orientation is minimized through the single and fixed position of
the controller 205. The patient may move and turn without
disrupting the coupling between the controller 205 and the internal
antenna 151. In the embodiment with the controller 205 in an
earpiece, a flexible receive/transmit tip in the earpiece aligns
the controller external RF interface antenna with the implant 105.
In the embodiment with the controller 205 in a patch, the patch is
aligned with the implant 105 and placed skin. The patch may include
one or more of the controller 205, a replaceable adhesive layer,
power and RFID coupling indication LED, and a thin layer
rechargeable battery. Still further embodiments include
incorporation of the external subsystem 200 into a watch-like
device for, e.g., the treatment of arthritic pain, or in a belt.
Yet another range of variations are flexible antennas and the
controller RF chip woven into clothing or an elastic cuff, attached
to controller electronics and remotely powered. Controller 205
designs may be indication specific, and can vary widely. The
controller 205 embodiments in FIG. 8 are exemplary only, and not
limited to those shown.
[0075] Communication with the Implant as a Function of Design
[0076] The distance between this contact area and the actual
implant 100 on a nerve is 1 to 10 cm, typically 3 cm, through human
flesh. This distance, along with the controller crypto unit 201 and
the core subsystem crypto unit 142 in the implant 100, reduces
potential interference from other RF signals.
[0077] Implant and Controller Positioning
[0078] Prior to implantation of the present invention for the
treatment of sleep apnea, patients are diagnosed in a sleep lab,
and an implant 105 is prescribed for their specifically diagnosed
condition. Once diagnosis is complete, the implant 105 is
surgically implanted in the patient's body, typically on or in the
vicinity of a nerve. In certain embodiments, the implant 105 is
implanted on the HGN. In such embodiments, the implant 105 may be
implanted below the ear unilaterally at the sub-mandibular
triangle, encasing the hypoglossal nerve.
[0079] Stimulation of the HGN can act to maintain nerve activity.
Hence in certain embodiments, the present invention can maintain
muscular tone (e.g., in the tongue, thereby preventing apnea).
Therefore, in certain embodiments, controller 205, described in
more detail above, activates implant 105 to stimulate HGN activity
to ameliorate the negative physiological impact associated with
insufficient tone muscles caused by, e.g., insufficient HGN
activity.
[0080] Once implanted, the implant 105 is used to stimulate the
nerve. In embodiments where the device is implanted in a manner to
stimulate the HGN, the implant 105 delivers tone to the tongue.
Maintaining tongue muscle tone stops the tongue from falling back
and obstructing the upper airway. The stimulation may be provided
continuously during sleep hours, or upon preprogrammed
patient-specific intervals. The implant 105 may also sense and
record neural activity.
[0081] Implant and Controller Security
[0082] In certain embodiments, the controller 205 identifies the
patient's unique ID tag, communicates with and sends signals to the
implant 105. In certain embodiments, a controller crypto unit 201
may be installed to ensure that communication between the
controller 205 and the implant 105 is secure and one-to-one. The
controller crypto unit 201 may include the implant's unique ID
tag.
[0083] In particular, the implant 105 may have a unique ID tag,
which the controller 205 can be programmed to recognize. A
controller microprocessor 204 confirms the identity of the implant
105 associated with the controller 205, thereby allowing setting of
the patient's specific protocol. The setting may be accomplished
using a computer interfaced with the controller 205 through an
interface 202 on the controller 205.
[0084] More particularly, once the controller crypto unit 201
establishes a link with the core subsystem crypto unit 142, the
controller 205 communicates a stimulation scenario to the core
subsystem microprocessor 141. The controller 205 initiates a
stimulation cycle by making a request to the core subsystem 140 by
sending an encoded RF waveform including control data via the
external RF interface 203. The core subsystem 140 selects a trained
waveform from memory and transmits the stimulation waveform to the
core subsystem microprocessor 141. Once the core subsystem
microprocessor 141 receives the waveform, the core subsystem 140
generates a stimulating signal for distribution to the neural
interface 160.
[0085] Interaction with the Implant
[0086] In certain embodiments, the controller 205 prevents
self-activation or autonomous operation by the implant 105 by
handshaking. Handshaking occurs during each communications cycle
and ensures that security is maintained. This prevents other
devices operating in the same frequency range from compromising
operation of the implant 105. Implant stimulus will not commence
unless an encrypted connection is established between the external
RF interface 203 and the implant 105. This serves as an
anti-tampering mechanism by providing the implant 105 with a unique
ID tag. The external controller 205 is matched, either at the point
manufacture or by a physician, to a particular ID tag of the
implant 105, typically located in an EPROM of the implant 105. In
certain embodiments, the EPROM may be included in the core
subsystem microprocessor 141. In other embodiments, the EPROM may
be included in the controller microprocessor 204. This prevents
alien RF interference from `triggering` activation of the implant
105. While arbitrary RF sources may provide power to the implant
105, the uniquely matched controller 205 establishes an encrypted
connection before directing the implant 105 to commence stimulus,
thereby serving as a security mechanism.
[0087] System Programming
[0088] Desired system programming is determined by measuring a
patient's tongue activity against predetermined stimulation
protocols. The effectiveness of the neural interface 160
stimulation protocols are measured until a desired tongue
stimulation level is achieved. Once a desired tongue stimulation
level is achieved, those protocols are programmed into the
controller 205. Stimulation may be programmed for delivery in an
open loop or closed loop at a suitable frequency. In certain
embodiments, a stimulation frequency of about 10-40 Hz is used.
Stimulation may also be delivered in pulses, with pulse widths
about 100 to 300 microseconds, more typically 200 microseconds.
Although any suitable pulse width can be used, preferred pulses are
at a width that simultaneously prevent nerve damage and reduce or
eliminate corrosion of neural interface electrodes. After the
controller 205 is programmed, the patient activates the controller
205 at bed time or at desired intervals.
[0089] In certain embodiments, controller 205 can also determine
when the patient is asleep, and stimulate the HGN based on that
determination. In order to determine when the patient is asleep,
controller 205 can include one or more sensors that generate
signals as a function of the activity and/or posture of the
patient. In such embodiments, controller 205 determines when the
patient is asleep based on the signal. Controller 205 can also have
an acoustic sensor, to indicate when snoring starts, and can
determine whether the patient is asleep based on the presence of
snoring. In other embodiments the patient may enter an input into
the controller 205 telling it to commence treatment. However, as
noted above, controller 205 can be activated by a user and then
function in a manner such that the implant is continuously active
until the patient awakens and manually deactivates the controller
by pressing a button on the controller 205 or by moving the
controller 205 out of range of the implant.
[0090] This electrical stimulation provides a signal to the HGN and
starts the treatment of the airway obstruction. Upon completion of
one cycle, the duration of which is determined in the tuning phase
of the implantation procedure, described above, the core subsystem
140 can report completion back to the controller 205 via RF
communication, and optionally goes to an idle state until receiving
another set of instructions.
[0091] As described above, in certain embodiments, the implant 105
is externally powered by near field RF waves, the RF waves are
inductively converted to DC power, which powers the implant 105 and
delivers electrical signals to selected elements of the neural
interface 160. The implant uses between 0.1 to about 1 milliamps,
preferably averaging about 0.5 milliamps of current and about 10 to
30 microwatts of power.
[0092] In some embodiments, the near field RF waves are emitted
from the controller 205. In certain embodiments, controller 205 can
be powered by an optional power source 215, e.g., a battery, AC to
DC converter, or other power source known to those skilled in the
art.
[0093] Other embodiments of the apparatus and methods described can
be used in the present invention. Various alternatives,
substitutions and modifications for each of the embodiments and
methods of the invention may be made without departing from the
scope thereof, which is defined by the following claims. All
references, patents and patent applications cited in this
application are herein incorporated by reference in their
entirety.
* * * * *