US 20050149146 A1
A method and system for providing electrical pulses to splanchnic nerve(s) and/or around celiac ganglion for selective sympathetic stimulation of a patient, to provide therapy for obesity or to induce weight loss comprises implantable and external components. The implantable components are a lead and an implantable pulse generator, comprising rechargeable lithium-ion or lithium-ion polymer battery. The external components are a programmer and an external recharger. In one embodiment, the implanted pulse generator may also comprise stimulus-receiver means, and a pulse generator means with rechargeable battery. The implanted stimulus-receiver is adapted to work in conjunction with an external stimulator. In another embodiment, the implanted pulse generator is adapted to be rechargeable, utilizing inductive coupling with an external recharger. The implanted system may also use a lead with one or more electrode(s), for sympathetic nerve(s) modulation with selective stimulation and/or blocking. In another embodiment, the external stimulator and/or programmer may comprise an optional telemetry unit. The addition of the telemetry unit to the external stimulator and/or programmer provides the ability to remotely interrogate and change stimulation programs over a wide area network, as well as other networking capabilities.
1. A method of providing electrical pulses with a rechargeable implantable pulse generator for stimulation and/or blocking of sympathetic nerve(s), or its branches, or part thereof in a patient for treating, controlling, or alleviating the symptoms for at least one of obesity, eating disorders, and inducing weight loss, comprising the steps of:
providing said rechargeable implantable pulse generator, comprising a microcontroller, pulse generation circuitry, rechargeable battery, battery recharging circuitry, and a coil;
providing a lead with at least one electrode(s) adapted to be in contact with said sympathetic nerve(s) or its branches or part thereof, and in electrical contact with said rechargeable implantable pulse generator;
providing an external power source to charge said rechargeable implantable pulse generator; and
providing an external programmer to program said rechargeable implantable pulse generator.
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11. A method of treating, controlling, or alleviating the symptoms for at least one of obesity, eating disorders, and inducing weight loss by providing electrical pulses to at least one of splanchnic nerve, greater splanchnic nerve, celiac ganglia or other portion(s) of sympathetic nerve plexus in the gastric region or their branch(s) or part thereof in a patient, comprising the steps of:
providing an implantable rechargeable pulse generator, wherein said implantable rechargeable pulse generator comprises a stimulus-receiver means, and an implantable pulse generator means comprising a microcontroller, pulse generation circuitry, rechargeable battery, and battery recharging circuitry;
providing a lead with at least one electrode(s) adapted to be in contact with said at least one of splanchnic nerve, greater splanchnic nerve, celiac ganglia or other portion(s) of sympathetic nerve plexus in the gastric region or their branch(s) or part thereof in a patient, and in electrical contact with said implantable rechargeable pulse generator;
providing an external power source to charge rechargeable implantable pulse generator; and
providing an external programmer to program the said rechargeable implantable pulse generator.
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16. A system for providing electrical pulses for stimulation and/or blocking of sympathetic nerve(s) or its branches or part thereof for treating or alleviating the symptoms for at least one of obesity, eating disorders, and inducing weight loss, comprising:
a rechargeable implantable pulse generator, comprising a microprocessor, pulse generation circuitry, rechargeable battery, battery recharging circuitry, and a coil;
a lead with at least one electrode(s) adapted to be in contact with said sympathetic nerve(s) or its branches or part thereof and in electrical contact with said implantable rechargeable pulse generator;
an external power source to charge said rechargeable implantable pulse generator; and
an external programmer to program said rechargeable implantable pulse generator.
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This application is a continuation of application Ser. No. 11/035,374 filed Jan. 13, 2005, entitled “Method and system for providing electrical pulses for neuromodulation of vagus nerve(s) using rechargeable implanted pulse generator”, which is a continuation of application Ser. No. 10/841,995 filed May 8, 2004, which is a continuation of application Ser. No. 10/196,533 filed Jul. 16, 2002, which is a continuation of application Ser. No. 10/142,298 filed on May 9, 2002. The prior applications being incorporated herein in entirety by reference, and priority is claimed from these applications.
This invention relates generally to electrical stimulation therapy for medical disorders, more specifically to providing electrical pulses for neuromodulation therapy for obesity and other medical disorders, by selectively modulating sympathetic nervous system with rechargeable implantable pulse generator.
Obesity is a significant health problem in the United States and many other developed countries. Obesity results from excessive accumulation of fat in the body. It is caused by ingestion of greater amounts of food than can be used by the body for energy. The excess food, whether fats, carbohydrates, or proteins, is then stored almost entirely as fat in the adipose tissue, to be used later for energy. Obesity is not simply the result of gluttony and a lack of willpower. Rather, each individual inherits a set of genes that control appetiete and metabolism, and a genetic tendency to gain weight that may be exacerbated by environmental conditions such as food availability, level of physical activity and individual psychology and culture. Other causes of obesity include psychogenic, neurogenic, and other metabolic related factors.
Obesity is defined in terms of body mass index (BMI), which provides an index of the relationship between weight and height. The BMI is calculated as weight (in Kilograms) divided by height (in square meters), or as weight (in pounds) times 703 divided by height (in square inches). The primary classification of overweight and obesity relates to the BMI and the risk of mortality. Obesity has reached epidemic proportions globally. In the U.S., it is estimated that 64% of adults are overweight or obese, and 4.7% or 14-16 million Americans are morbidly obese (BMI≦40 Kg/m2). Furthermore, the number of overweight adolescents is also rapidly increasing.
Treatment of obesity depends on decreasing energy input below energy expenditure. Treatment has included among other things various drugs, starvation and even stapling or surgical resection of a portion of the stomach. Surgery for obesity has included gastroplasty and gastric bypass procedure. Gastroplasty which is also known as stomach stapling, involves constructing a 15- to 30 mL pouch along the lesser curvature of the stomach. A modification of this procedure involves the use of an adjustable band that wraps around the proximal stomach to create a small pouch. Both gastroplasty and gastric bypass procedures have a number of complications.
Advantageously, electrical pulse therapy can be safely provided by delivering electrical pulses to the parasympathetic nerves such as the vagus nerve(s) or the sympathetic nerves such as the splanchnic nerves (or greater splanchnic nerve).
In commonly assigned disclosures Ser. No. 10,079,21 now U.S. Pat. No. ______, and U.S. Pat. No. 6,611,715 B1 (Boveja) electrical pulsed neuromodulation therapy for obesity and other medical conditions is provided by delivering electrical pulses to the parasympathetic nerves such as the vagus nerve(s). Therapeutic effects on obesity may also be achieved by providing electrical pulses (or modulating) the sympathetic nervous system. The apparatus disclosed in U.S. Pat. No. 6,611,715 B1 (Boveja) can also be used in neuromodulating the sympathetic nervous system, of course the stimulating electrodes would by placed on the splanchnic nerves or celiac ganglia (as shown in
The rationale for this is shown in conjunction with
In the Applicant's U.S. Pat. No. 6,611,715 B1 electrical pulses are provided to the vagal pathway as shown in conjunction with
Shown in conjunction with
The gastrointestinal tract has a nervous system all its own called the enteric nervous system 20. This is shown in conjunction with
As depicted in conjunction with
Sympathetic innervation of the gastrointestinal (GI) tract is mainly via postganglionic adrenergic fibers whose cell bodies are located in pre-vertebral and parabertabral ganglia. The celiac, superior and inferior mesenteric, and hypogastric plexus provide sympathetic innervation to various segments of the GI tract. Activation of the sympathetic nerves usually inhibits the motor and secretory activities of the GI system.
Parasympathetic innervation of the GI tract down to the level of the transverse colon is provided by branches of the vagus nerves (10th cranial nerve). Excitation of parasympathetic nerves usually stimulates the motor and secretory activities of the GI tract.
Additionally in terms of reflex control, shown in conjunction with
The stomach 5 (shown in
Parasympathetic innervation to the stomach 5 is also supplied by the vagus nerves, while sympathetic innervation to the stomach is provided by the celiac plexus. In general, parasympathetic nerves stimulate gastric smooth muscle motility and gastric secretions, whereas sympathetic activity inhibits these-function. Numerous sensory afferent fibers leave the stomach in the vagus nerves; some of these fibers travel with sympathetic nerves. Other sensory neurons are the afferent links between sensory receptors and the intramural plexuses of the stomach. Some of these afferent fibers relay information intragastric pressure, gastric distention, intragastric pH, or pain.
When a wave of esophageal peristalsis begins, a reflex causes the LES to relax. This relaxation of the LES is followed by receptive relaxation of the fundus and body of the stomach 5. The stomach 5 will also relax if it is filled directly with gas or liquid. The nerve fibers in the vagi are a major efferent pathways for reflex relaxation the stomach 5.
The emptying of gastric contents is regulated by both neural and hormonal mechanisms. The duodenal and jejunal mucosa contain receptors that sense acidity, osmotic pressure, certain fats and fat digestion products, and peptides and amino acids This is depicted in
Shown in conjunction with
In most other excitable tissues, the resting membrane potential remians rather constant. In gastrointestinal smooth muscle, the resting membrane potential characteristically varies or oscillates, this is depicted in
Slow waves are generated by interstitial cells. These cells are located in a thin layer between the longitudinal and circular layers of the muscularis externa. Interstitial cells have properties of both fibroblasts and smooth muscle cells. Their long processes form gap junction with longitudinal and circular smooth muscle cells. These gap junctions enable the slow waves to be conducted rapidly to-both muscle layers. Because gap junctions electrically couple the smooth muscle cells of both longitudinal and circular layers, the slow wave spreads throughout the smooth muscle of each segment of the gastrointestinal tract.
The amplitude and, to a lesser extent, the frequency, of the slow waves can be modulated by the activity of intrinsic and extrinsic nerves and by hormones and paracrine substanes. In general, sympathetic nerve activity decreases the amplitude of the slow waves or ablolshes them completely, wheras stimulation of parasympathetic nerves increases the size of the slow waves.
If the peak of the slow wave exceeds the cell's threshold to fire action potentials, one or more action potentials may be triggered during the peak of the slow wave (
Action potentials: Action potentials in gastrointestinal smooth muscle are more prolonged (10 to 20 msec) than those of skeletal muscle and have little or no overshoot. The rising phase of the action potentials is caused by ion flow through channels that conduct both Ca++ and Na+ and are relatively slow to open. Ca++ that enters the cell during the action potential helps to initiate contraction.
When the membrane potential of gastrointestinal smooth muscle reaches the electrical threshold, typically near the peak of a slow wave, a train of action potentials (1 to 10/sec) is fired (
Slow waves that are not accompanied by action potentials elicit weak contractions of the smooth muscle cells (
Between trains of action potentials the tension developed by gastrointestinal smooth muscle falls, but not to zero. This nonzero resting, or baseline, tension of smooth muscle is the tone. The tone of gastrointestinal smooth muscle is altered by neuroeffectors, hormones, paracrine substances, and drugs.
Control of the contractile and secretory activities of the gastrointestinal tract involves the central nervous system, the enteric nervous system, and hormones and paracrine substances. The autonomic nervous system typically only modulates the patterns of muscular and secretory activity; these activities are controlled more directly by the enteric nervous system.
Shown in conjunction with
Most nerves in the human body are composed of thousands of fibers of different sizes. This is shown schematically in
In a cross section of peripheral nerve it is seen that the diameter of individual fibers vary substantially, as is also shown schematically in
The diameters of group A and group B fibers include the thickness of the myelin sheaths. Group A is further subdivided into alpha, beta, gamma, and delta fibers in decreasing order of size. There is some overlapping of the diameters of the A, B, and C groups because physiological properties, especially in the form of the action potential, are taken into consideration when defining the groups. The smallest fibers (group C) are unmyelinated and have the slowest conduction rate, whereas the myelinated fibers of group B and group A exhibit rates of conduction that progressively increase with diameter.
Nerve cells have membranes that are composed of lipids and proteins, and have unique properties of excitability such that an adequate disturbance of the cell's resting potential can trigger a sudden change in the membrane conductance. Under resting conditions, the inside of the nerve cell is approximately −90 mV relative to the outside. The electrical signaling capabilities of neurons are based on ionic concentration gradients between the intracellular and extracellular compartments. The cell membrane is a complex of a bilayer of lipid molecules with an assortment of protein molecules embedded in it, separating these two compartments. Electrical balance is provided by concentration gradients which are maintained by a combination of selective permeability characteristics and active pumping mechanism.
A nerve cell can be excited by increasing the electrical charge within the neuron, thus increasing the membrane potential inside the nerve with respect to the surrounding extracellular fluid. The threshold stimulus intensity is the value at which the net inward current (which is largely determined by Sodium ions) is just greater than the net outward current (which is largely carried by Potassium ions), and is typically around −55 mV inside the nerve cell relative to the outside (critical firing threshold). If however, the threshold is not reached, the graded depolarization will not generate an action potential and the signal will not be propagated along the axon. This fundamental feature of the nervous system i.e., its ability to generate and conduct electrical impulses, can take the form of action potentials, which are defined as a single electrical impulse passing down an axon. This action potential (nerve impulse or spike) is an “all or nothing” phenomenon, that is to say once the threshold stimulus intensity is reached, an action potential will be generated.
To stimulate an excitable cell, it is only necessary to reduce the transmembrane potential by a critical amount. When the membrane potential is reduced by an amount ΔV, reaching the critical or threshold potential. When the threshold potential is reached, a regenerative process takes place: sodium ions enter the cell, potassium ions exit the cell, and the transmembrane potential falls to zero (depolarizes), reverses slightly, and then recovers or repolarizes to the resting membrane potential (RMP). For a stimulus to be effective in producing an excitation, it must have an abrupt onset, be intense enough, and last long enough.
Cell membranes can be reasonably well represented by a capacitance C, shunted by a resistance R as shown by an electrical model in
When the stimulation pulse is strong enough, an action potential will be generated and propagated. As shown in
A single electrical impulse passing down an axon is shown schematically in
The information in the nervous system is coded by frequency of firing rather than the size of the action potential. In terms of electrical conduction, myelinated fibers conduct faster, are typically larger, have very low stimulation thresholds, and exhibit a particular strength-duration curve or respond to a specific pulse width versus amplitude for stimulation, compared to unmyelinated fibers. The A and B fibers can be stimulated with relatively narrow pulse widths, from 50 to 200 microseconds (μs), for example. The A fiber conducts slightly faster than the B fiber and has a slightly lower threshold. The C fibers are very small, conduct electrical signals very slowly, and have high stimulation thresholds typically requiring a wider pulse width (300-1,000 μs) and a higher amplitude for activation. Because of their very slow conduction, C fibers would not be highly responsive to rapid stimulation. Selective stimulation of only A and B fibers is readily accomplished. The requirement of a larger and wider pulse to stimulate the C fibers, however, makes selective stimulation of only C fibers, to the exclusion of the A and B fibers, virtually unachievable inasmuch as the large signal will tend to activate the A and B fibers to some extent as well.
As shown in
In the methodology of the current disclosure, it will usually be desired to stimulate the A-fibers and B-fibers and not the c-fibers (since the c-fibers carry pain). Advantageously, this can be readily accomplished using the system and methodology of the current disclosure.
This application is also related to co-pending applications entitled “METHOD AND SYSTEM FOR VAGAL BLOCKING WITH OR WITHOUT VAGAL STIMULATION TO PROVIDE THERAPY FOR OBESITY AND OTHER GASRTOINTESTINAL DISORDERS USING RECHARGEABLE IMPLANTED PULSE GENERATOR” and “METHOD AND SYSTEM FOR PROVIDING ELECTRICAL PULSES TO GASTRIC WALL OF A PATIENT WITH RECHARGEABLE IMPLANTABLE PULSE GENERATOR FOR TREATING OR CONTROLLING OBESITY AND EATING DISORDERS.
Prior art is generally directed to adapting cardiac pacemaker technology for nerve stimulation, where U.S. Pat. Nos. 5,263,480 (Wernicke et al.) and 5,188,104 (Wernicke et al.) are generally directed to treatment of eating disorders with vagus nerve stimulation using an implantable neurocybernetic prosthesis (NCP), which is a “cardiac pacemaker-like” device. There is no disclosure for vagal blocking, sympathetic stimulation, or for using a rechargeable implantable device.
U.S. Pat. No. 5,540,730 (Terry et al.) is generally directed to treating motility disorders with vagus nerve stimulation using an implantable neurocybernetic prosthesis (NCP), which is a “cardiac pacemaker-like” device.
U.S. Pat. No. 6,611,715 B1 (Boveja) is generally directed to a system and method to provide therapy for obesity and compulsive eating disorders using an implantable lead-receiver and an external stimulator.
U.S. Pat. No. 6,553,263B1 (Meadows et al.) is generally directed to an implantable pulse generator system for spinal cord stimulation, which includes a rechargeable battery. In the Meadows '263 patent there is no disclosure or suggestion for combing a stimulus-receiver module to an implantable pulse generator (IPG) for use with an external stimulator, for providing modulating pulses to sympathetic nerve(s), as in the applicant's disclosure.
U.S. Pat. No. 6,505,077 B1 (Kast et al.) is directed to electrical connection for external recharging coil. In the Kast '077 disclosure, a magnetic shield is required between the externalized coil and the pulse generator case. In one embodiment of the applicant's disclosure, the externalized coil is wrapped around the pulse generator case, without requiring a magnetic shield.
U.S. Pat. No. 6,622,041 B2 (Terry, Jr. et al.) is directed to treatment of congestive heart failure and autonomic cardiovascular drive disorders using implantable neurostimulator.
The method and system of the current invention overcomes many shortcomings of the prior art by providing method and system for neuromodulation with extended power source either in the form of rechargeable battery, or by utilizing an external stimulator in conjunction with an implanted pulse generator device, to provide therapy for obesity, eating disorders or for inducing weight loss.
Accordingly, in one aspect of the invention, electrical pulses are provided to sympathetic nerves utilizing a rechargeable implantable pulse generator.
In another aspect of the invention, the electrical pulses are provided to at least one of splanchnic nerve, the greater splanchnic nerve, celiac ganglia or other portion of sympathetic nerve plexus in the gastric region or their branch(s) or part thereof.
In another aspect of the invention, the pulse amplitude delivered to sympathetic nervous system can range from 0.25 volt to 15 volts.
In another aspect of the invention, the pulse width of electrical pulses delivered can range from 20 micro-seconds to 5 milli-seconds.
In another aspect of the invention, the frequency of electrical pulses delivered to sympathetic nervous system can range from 5 cycle/second to 200 cycles/second.
In another aspect of the invention, a coil used in recharging said pulse generator is around the implantable pulse generator case, in a silicone enclosure.
In another aspect of the invention, the rechargeable implanted pulse generator comprises two feedthroughs.
In another aspect of the invention, the rechargeable implanted pulse generator comprises only one feedthrough for externalizing the recharge coil.
In another aspect of the invention, the implantable rechargeable pulse generator comprises stimulus-receiver means such that, the implantable rechargeable pulse generator can function in conjunction with an external stimulator, to provide the stimulation and/or blocking pulses to sympathetic nervous system.
In another aspect of the invention, the rechargeable battery comprises at least one of lithium-ion, lithium-ion polymer batteries.
In another aspect of the invention, the external programmer or the external stimulator comprises networking capabilities for remote communications over a wide area network for remote interrogation and/or remote programming.
In yet another aspect of the invention, the implanted lead comprises at least one electrode(s) which is/are made of a material selected from the group consisting of platinum, platinum/iridium alloy, platinum/iridium alloy coated with titanium nitride, and carbon.
This and other objects are provided by one or more of the embodiments described below.
For the purpose of illustrating the invention, there are shown in accompanying drawing forms which are presently preferred, it being understood that the invention is not intended to be limited to the precise arrangement and instrumentalities shown.
In the method and system of this invention, the rechargeable implantable pulse generator (RIPG) system, including a lead comprising at least one electrode(s) is/are implanted in the body. The electrode(s) are adapted to make contact with the nerve tissue where the electrical pulses are to be provided. In one embodiment, the electrode(s) may wrap around the nerve tissue to be stimulated (or blocked). Additional electrode(s) may be placed for the purpose of providing blocking pulses. The electrode(s) may be placed using laproscopic surgery, or alternatively surgical incision may be performed for wider exposure of the tissues. The tissue to be stimulated (or blocked) is identified, which is preferably the greater splanchnic nerve 54 or branches, or the tissue around the celiac ganglion 55, or any plexus in the region. Other sites in the region may also be identified for modulation of sympathetic system to provide therapy for obesity. Modulation in this patent disclosure implies any stimulation, blocking, selective stimulation, and selective stimulation of a portion in combination with selective blocking of a portion of the nervous system.
Once the appropriate electrode(s) is/are positioned and attached (shown in conjunction with
Shown in conjunction with
The pulses are provided to the cathode 61 with the return being anode 62 for bipolar mode of stimulation. For unipolar mode of stimulation the pulse generator case acts as the anode (i.e. the return electrode). Switching of stimulation pulses from bipolar mode to unipolar mode is a programmable parameter, and may be performed with the programmer. Bipolar stimulation offers localized stimulation of tissue compared to unipolar stimulation. For the practice of this invention, unipolar mode of stimulation would also have certain advantages such as stimulating an area of tissue comprising ganglion or nerve plexus.
The selective stimulation and/or blocking to the sympathetic nervous tissue can be performed in one of two ways. One method is to activate one of the “pre-determined” programs from the memory. A second method is to “custom” program the electrical parameters which can be selectively programmed, for specific therapy to the individual patient. Additionally, a program may be selected from memory, and selected parameters may be adjusted or “fine-tuned”. The electrical parameters which can be individually programmed, include variables such as pulse amplitude, pulse width, frequency of stimulation, type of pulse (e.g. blocking pulses may be sinusoidal), stimulation on-time, and stimulation off-time. Table two below defines the approximate range of parameters,
The implanted lead component of the system is somewhat similar to cardiac pacemaker leads, except for distal portion 40 (or electrode end) of the lead. The lead terminal preferably is linear, even though it can be bifurcated, and plug(s) into the cavity of the pulse generator means. The lead materials are described later in this disclosure.
Shown in conjunction with
The pulses delivered to the nerve tissue for stimulation therapy are shown graphically in
Because of the rapidity of the pulses required for modulating nerve tissue 54 (unlike cardiac pacing), there is a real need for power sources that will provide an acceptable service life under conditions of continuous delivery of high frequency pulses.
For the practice of the current invention, two embodiments of implantable pulse generators may be used. Both embodiments comprise re-chargeable power sources, such as Lithium-ion polymer battery.
In one embodiment, the implanted device comprises a stimulus-receiver module and a pulse generator module. Advantageously, this embodiment provides an ideal power source, since the power source can be an external stimulator coupled with an implanted stimulus-receiver, or the power source can be from the implanted rechargeable battery. Shown in conjunction with
In this embodiment, as shown in
The system of this embodiment provides a power sense circuit 728 that senses the presence of external power communicated with the power control 730, when adequate and stable power is available from an external source. The power control circuit controls a switch 736 that selects either implanted battery power 740 or conditioned external power from 726. The logic and control section 732 and memory 744 includes the IPG's microcontroller, pre-programmed instructions, and stored changeable parameters. Using input for the telemetry circuit 742 and power control 730, this section controls the output circuit 734 that generates the output pulses.
Shown in conjunction with
The stimulus-receiver portion of the circuitry is shown in conjunction with
As shown in conjunction with
In one embodiment, the coil may also be positioned on the titanium case as shown in conjunction with
A schematic diagram of the implanted pulse generator (IPG 391R), with re-chargeable battery 694 of the preferred embodiment, is shown in conjunction with
The operating power for the IPG 391R is derived from a rechargeable power source 694. The rechargeable power source 694 comprises a rechargeable lithium-ion or lithium-ion polymer battery. Recharging occurs inductively from an external charger to an implanted coil 48B underneath the skin 60. The rechargeable battery 694 may be recharged repeatedly as needed. Additionally, the IPG 391R is able to monitor and telemeter the status of its rechargable battery 691 each time a communication link is established with the external programmer 85.
Much of the circuitry included within the IPG 391R may be realized on a single application specific integrated circuit (ASIC). This allows the overall size of the IPG 391R to be quite small, and readily housed within a suitable hermetically-sealed case. The IPG case is preferably made from titanium and is shaped in a rounded case.
Shown in conjunction with
A simplified block diagram of charge completion and misalignment detection circuitry is shown in conjunction with
The indicator 706 may similarly be used as a misalignment indicator. In normal operation, when coils 46B (external) and 48B (implanted) are properly aligned, the voltage Vs sensed by voltage detector 704 is at a minimum level because maximum energy transfer is taking place. If and when the coils 46B and 48B become misaligned, then less than a maximum energy transfer occurs, and the voltage Vs sensed by detection circuit 704 increases significantly. If the voltage Vs reaches a predetermined level, alignment indicator 706 is activated via an audible speaker and/or LEDs for visual feedback. After adjustment, when an optimum energy transfer condition is established, causing Vs to decrease below the predetermined threshold level, the alignment indicator 706 is turned off.
The elements of the external recharger are shown as a block diagram in conjunction with
As also shown in
Referring now to
Once the lead is fabricated, coating such as anti-microbial, anti-inflammatory, or lubricious coating may be applied to the body of the lead.
In one aspect of the invention, in addition to selective stimulation of the sympathetic system, selective portions of the nervous system may be blocked. Typically when a nerve pathway is stimulated, the stimulation is conducted in both the Afferent (towards the brain) and Efferent (away from the brain) direction. Shown in conjunction with
Selective Efferent block can also be obtained and is depicted in conjunction with
Blocking can be generally divided into 3 categories: (a) DC or anodal block, (b) Wedenski Block, and (c) Collision block. In anodal block there is a steady potential which is applied to the nerve causing a reversible and selective block. In Wedenski Block, the nerve is stimulated at a high rate causing the rapid depletion of the neurotransmitter. In collision blocking, unidirectional action potentials are generated anti-dromically. The maximal frequency for complete block is the reciprocal of the refractory period plus the transit time i.e. typically less than a few hundred hertz. The use of any of these blocking techniques is considered within the scope of this invention.
Shown in conjunction with
The telecommunications component of this invention uses Wireless Application Protocol (WAP). WAP is a set of communication protocols standardizing Internet access for wireless devices. Previously, manufacturers used different technologies to get Internet on hand-held devices. With WAP, devices and services inter-operate. WAP promotes convergence of wireless data and the Internet. The WAP Layers are Wireless Application Envirnment (WAEW), Wireless Session Layer (WSL), Wireless Transport Layer Security (WTLS) and Wireless Transport Layer (WTP).
The WAP programming model, which is heavily based on the existing Internet programming model, is shown schematically in
The key components of the WAP technology, as shown in
The presently preferred embodiment utilizes WAP, because WAP has the following advantages, 1) WAP protocol uses less than one-half the number of packets that the standard HTTP or TCP/IP Internet stack uses to deliver the same content. 2) Addressing the limited resources of the terminal, the browser, and the lightweight protocol stack are designed to make small claims on CPU and ROM. 3) Binary encoding of WML and SMLScript helps keep the RAM as small as possible. And, 4) Keeping the bearer utilization low takes account of the limited battery power of the terminal.
In this embodiment two modes of communication are possible. In the first, the server initiates an upload of the actual parameters being applied to the patient, receives these from the stimulator, and stores these in its memory, accessible to the authorized user as a dedicated content driven web page. The web page is managed with adequate security and password protection. The physician or authorized user can make alterations to the actual parameters, as available on the server, and then initiate a communication session with the stimulator device to download these parameters.
The physician is also able to set up long-term schedules of stimulation therapy for their patient population, through wireless communication with the server. The server in turn communicates these programs to the neurostimulator. Each schedule is securely maintained on the server, and is editable by the physician and can get uploaded to the patient's stimulator device at a scheduled time. Thus, therapy can be customized for each individual patient. Each device issued to a patient has a unique identification key in order to guarantee secure communication between the wireless server 130 and stimulator device 42 (or programmer 85).
Shown in conjunction with
The standard components of interface unit shown in block 292 are processor 305, storage 310, memory 308, transmitter/receiver 306, and a communication device such as network interface card or modem 312. In the preferred embodiment these components are embedded in the external stimulator 42 and can also be embedded in the programmer 85. These can be connected to the network 290 through appropriate security measures (Firewall) 293.
Another type of remote unit that may be accessed via central collaborative network 290 is remote computer 294. This remote computer 294 may be used by an appropriate attending physician to instruct or interact with interface unit 292, for example, instructing interface unit 292 to send instruction downloaded from central computer 286 to remote implanted unit.
Shown in conjunction with
The telemetry module 362 comprises an RF telemetry antenna 142 coupled to a telemetry transceiver and antenna driver circuit board which includes a telemetry transmitter and telemetry receiver. The telemetry transmitter and receiver are coupled to control circuitry and registers, operated under the control of microprocessor 364. Similarly, within stimulator a telemetry antenna 142 is coupled to a telemetry transceiver comprising RF telemetry transmitter and receiver circuit. This circuit is coupled to control circuitry and registers operated under the control of microcomputer circuit.
With reference to the telecommunications aspects of the invention, the communication and data exchange between Modified PDA/Phone 140 and external stimulator 42 operates on commercially available frequency bands. The 2.4-to-2.4853 GHz bands or 5.15 and 5.825 GHz, are the two unlicensed areas of the spectrum, and set aside for industrial, scientific, and medical (ISM) uses. Most of the technology today including this invention, use either the 2.4 or 5 GHz radio bands and spread-spectrum technology.
The telecommunications technology, especially the wireless internet technology, which this invention utilizes in one embodiment, is constantly improving and evolving at a rapid pace, due to advances in RF and chip technology as well as software development. Therefore, one of the intents of this invention is to utilize “state of the art” technology available for data communication between Modified PDA/Phone 140 and external stimulator 42. The intent of this invention is to use 3G technology for wireless communication and data exchange, even though in some cases 2.5G is being used currently.
For the system of the current invention, the use of any of the “3G” technologies for communication for the Modified PDA/Phone 140, is considered within the scope of the invention. Further, it will be evident to one of ordinary skill in the art that as future 4G systems, which will include new technologies such as improved modulation and smart antennas, can be easily incorporated into the system and method of current invention, and are also considered within the scope of the invention.