text:
|Publication number
|Publication type
|Application number
|Publication date
|Jun 8, 2006
|Filing date
|Dec 28, 2005
|Priority date
|Oct 26, 1998
|Publication number
|Birinder Boveja, Angely Widhany
|Original Assignee
|Boveja Birinder R, Angely Widhany
|Export Citation
|BiBTeX, EndNote, RefMan
|Patent Citations (12), Referenced by (47), Classifications (17)
|External Links: USPTO, USPTO Assignment, Espacenet
This is a Continuation of application Ser. No. 10/195,961 which is a Continuation of application Ser. No. 09/752,083 (now U.S. Pat. No. 6,505,074) which is a Continuation-in Part of application Ser. No. 09/178,060 now U.S. Pat. No. 6,205,359 having a filing date of Oct. 26, 1998. Priority is claimed from these applications, and the prior applications being incorporated herein by reference.
The present invention relates to electrical neuromodulation therapy for medical disorders, more specifically pulsed electrical neuromodulation therapy for urological disorders and/or fecal incontinence utilizing rectangular and/or complex electrical pulses.
Biomedical and clinical research has shown utility of electrical nerve stimulation (neuromodulation) of sacral nerves or branches for urinary and fecal incontinence, and a broad group of urological disorders. This invention is directed to method and system for providing pulsed electrical stimulation/blocking therapy for urological disorders, and fecal incontinence. The urological disorders comprise urinary incontinence, overflow incontinence, stress incontinence, idiopathic chronic urinary retention, interstitial cystitis, neuro-urological disorder, vesico-urethral dysfunctions, bladder inflammation, bladder pain, pelvic pain, constipation, and genito-urinary disorders such as prostatitis, prostatalgia, and prostatodynia.
Pulse generator system to provide therapy for urinary incontinence and urological disorders are known in the art. But, pulse generator systems can be designed in different ways, and a particular type may be more suitable for an individual patient. For example, for patients requiring high stimulation outputs, an external stimulator which works in conjunction with an implanted stimulus-receiver would be appropriate, since a fully implantable system would have a short service life for such a patient. For patients requiring low stimulation outputs, an implantable system may be appropriate because of its convenience, and for patient compliance. This Application discloses six distinct types of pulse generator systems that can be used to provide therapy for urinary incontinence and/or fecal incontinence.
The seven types of systems disclosed in this Application to provide pulsed electrical stimulation to a patient, to provide therapy for urinary/fecal incontinence, and other urological disorders, are:
a) an implanted stimulus-receiver with an external stimulator;
b) an implanted stimulus-receiver comprising a high value capacitor for storing charge, used in conjunction with an external stimulator;
c) a programmer-less implantable pulse generator (IPG) which is operable with a magnet;
d) a programmable implantable pulse generator (IPG);
e) a combination implantable device comprising both a stimulus-receiver and a programmable IPG; and
f) an IPG comprising a rechargeable battery.
In one aspect, a patient may be implanted with more than one type of pulse generator system over time, utilizing the same implanted lead. For example, a patient may be initially implanted with an implanted stimulus-receiver and the stimulation performed with an external stimulator, since an external stimulator can be adjusted by the patient, within the limits prescribed by the physician. This simple and inexpensive system can be used to evaluate a patient's response to neuromodulation therapy. If the patient responds well and neuromodulation therapy is to be continued, at a future time, the implanted stimulus-receiver can be exchanged with an implanted pulse generator (IPG), using the same lead.
In another example, a patient implanted with an implanted pulse generator (I PG) finds that the stimulation thresholds have increased, or the patient does better with high outputs, such that the battery is depleting prematurely. In such a patient, at replacement an IPG comprising rechargeable battery may be used, or an implantable stimulus-receiver may be implanted, and an external pulse generator may be used. Again, without replacing the original lead.
The external components of these systems may be networked over a wide area network, as disclosed in a co-pending application. These external components are either the external pulse generator, or the programmer for an implanted pulse generator.
In one aspect, since the pulse generator system and the patient can be monitored and remotely controlled, the appropriate therapy for each patient can be "customized" without the patient having to visit the clinic, for each adjustment or programming of the device.
With reference to prior art, U.S. Pat. No. 5,562,717 (Tippey et al.) teaches an external system comprising a portable electrical stimulator which can be coupled to one or more electrodes for applying electrical stimulation signals to a patient. The signal generator being responsive to the instruction storage or programming device.
U.S. Pat. No. 6,393,323 B1 (Sawan et al.) teaches a selective stimulation system which is composed of an internal stimulator implanted in the patient and operated with an external hand-held controller. The system being used to prevent bladder hyeperreflexia combined with a voiding signal generator generating a voiding signal for voiding the bladder.
U.S. Patent Applications 2004/0193228 (Gerber), 2005/0033372 (Gerber), 2005/0033374 (Gerber), and 2005/0010259 (Gerber) are generally directed to applying electrical stimulation signals, and/or infusing one or more drugs to the patients's pelvic floor for treating various disorders.
U.S. Pat. No. 6,505,074 B2 (Boveja et al.) is directed to an implanted stimulus receiver coupled with an external stimulator for providing neuromodulation therapy. U.S. Pat. No. 6,449,512 B1 (Boveja) is directed to an implantable pulse generator for providing electrical stimulation therapy for urological disorders. The implanted pulse generator, though convenient, has the disadvantage that the internal battery will not last for a desired period of time, which can lead to repeated surgeries for generator replacement. The inductively coupled implanted stimulus receiver overcomes the disadvantage of implanted battery replacement, but patient convenience is an issue since a primary coil has to be kept in close proximity to an implanted secondary coil.
It would be desirable to have the advantages of both an IPG system and an inductively coupled system. The system and method disclosed, provides an improved method and system for adjunct therapy by providing a system that has the benefits of both systems, and has additional synergistic benefits not possible in the prior art. In the system of this invention, the patient can choose when to use an external inductively coupled system to conserve the battery life of the implanted module and receive higher levels of therapy.
In considering the background of urinary urge incontinence,
When sufficiently activated, the mechanorecptors trigger a coordinated micturition reflex via a center in the upper pons 388, as depicted schematically in
A great advantage of the positive feedback system is that it ascertains a complete emptying of the bladder during micturition. As long as there is any fluid left in the lumen, the intravesical pressure will be maintained above the threshold for the mechanoreceptors and thus provide a continuous driving force for the detrusor. A drawback with this system is that it can easily become unstable. Any stimulus that elicits a small burst of impulses in mechanoreceptor afferents may trigger a full-blown micturition reflex. To prevent this from happening during the filling phase, the neuronal system controlling the bladder is equipped with several safety devices both at the spinal and supraspinal levels.
The best-known spinal mechanism is the reflex control of the striated urethral sphincter 90, which increases its activity in response to bladder mechanoreceptor activation during filling. An analogous mechanism is Edvardsen's reflex, which involves machanoreceptor activation of inhibitory sympathetic neurons to the bladder 89. The sympathetic efferents have a dual inhibitory effect, acting both at the postganglionic neurons in the vesical ganglia and directly on the detrusor muscle of the bladder 89. The sphincter and sympathetic reflexes are automatically turned off at the spinal cord level during a normal micturition. At the supraspinal level, there are inhibitory connections from the cerebral cortex and hypothalamus to the pontine micturition center 88. The pathways are involved in the voluntary control of continence. Other inhibitory systems seem to originate from the pontine and medullary parts of the brainstem with at least partly descending connections.
Bladder over-activity and urinary urge incontinence may result from an imbalance between the excitatory positive feedback system of the bladder 89 and inhibitory control systems causing a hyperexcitable voiding reflex. Such an imbalance may occur after macroscopic lesions at many sites in the nervous system or after minor functional disturbances of the excitatory or inhibitory circuits. Urge incontinence due to detrusor instability seldom disappears spontaneously. The symptomatic pattern also usually is consistent over long periods.
Based on clinical experience, subtypes of urinary incontinence include, Phasic detrusor instability and uninhibited overactive bladder. Phasic detrusor instability is characterized by normal or increased bladder sensation, phasic bladder contractions occurring spontaneously during bladder filling or on provocation, such as by rapid filling, coughing, or jumping. This condition results from a minor imbalance between the bladder's positive-feedback system and the spinal inhibitory mechanisms. Uninhibited overactive bladder is characterized by loss of voluntary control of micturition and impairment of bladder sensation. The first sensation of filling is experienced at a normal or lowered volume and is almost immediately followed by involuntary micturition. The patient does not experience a desire to void until she/he is already voiding with a sustained detrusor contraction and a concomitant relaxation of the urethra, i.e., a well-coordinated micturition reflex. At this stage, she/he is unable to interrupt micturition voluntarily. The sensory disturbance of these subjects is not in the periphery, at the level of bladder mechanoreceptors, as the micturition reflex occurs at normal or even small bladder volumes. More likely, the suprapontine sensory projection to the cortex is affected. Such a site is consistent with the coordinated micturition and the lack of voluntary control. The uninhibited overactive bladder is present in neurogenic dysfunction.
Since bladder over-activity results from defective central inhibition, it seems logical to improve the situation by reinforcing some other inhibitory system. Patients with stress and urge incontinence are difficult to treat adequately. Successful therapy of the urge component does not influence the stress incontinence. While an operation for stress incontinence sometimes results in deterioration of urgency component. Electro stimulation using pulsed electrical stimulation is a logical alternative in mixed stress and urge incontinence, since the method improves urethral closure as well as bladder control. Drug treatment often is insufficient and, even when effective, does not lead to restoration of a normal micturition pattern.
Neuromodulation is a technique that applies pulsed electrical stimulation to the sacral nerves. A general diagram of spinal cord and sacral nerves 54 is shown in
The rationale of this treatment modality is based on the existence of spinal inhibitory systems that are capable of interrupting a detrusor 392 contraction. Inhibition can be achieved by electrical stimulation of afferent anorectal branches of the pelvic nerve, afferent sensory fibers in the pudendal nerve and muscle afferents from the limbs. Most of these branches and fibers reach the spinal cord via the dorsal roots of the sacral nerves 54. Of the sacral nerve roots the S3 root is the most practical for use in chronic pulsed electrical stimulation, although S4 and S2 along with S3 may be stimulated.
In addition to urinary incontinence, pulsed electrical stimulation of sacral nerve(s) and/or pudendal nerve(s) also provides therapy or alleviates symptoms for a broad group of urological or genito-urinary disorders such as prostatitis, prostatalgia and prostatodynia. Therapy may be provided using bilateral stimulation (
Interstitial cystitis is a painful and frequently debilitating condition of the urinary bladder. There are an estimated 700,000 cases of interstitial cystitis in the United States. Its symptoms include pelvic pain, dyspareunia, urinary urgency and frequency, nocturia, and small voided volumes with small bladder capacity. A prospective study that evaluated sacral neuromodulation for the treatment of refractory interstitial cystitis found that 94% of subjects implanted demonstrated a sustained improvement in symptoms. It was also shown that sacral neuromodulation decreased narcotic requirements in refractory interstitial cystitis. Also, in this study patients were overwhelmingly satisfied with the results of their trial of neuromodulation compared with their prior therapies.
Fecal incontinence is a common disorder with a prevalence that rises with age. Individuals suffering from fecal incontinence find it distressing and socially incapacitating. The prevalence is estimated to be 3.5% for women and 2.3% for men. It has been shown that between four and six percent of women having a vaginal delivery will suffer from fecal incontinence.
Dietary manipulation, pharmacological drugs, pelvic floor physiotherapy as well as surgery are often used as combination treatment for patients suffering from fecal incontinence. A stoma (colostomy or ileostomy) is reserved for patients with end-stage fecal incontinence where available treatments have failed or are inappropriate due to comorbidities. While a stoma is successful in controlling fecal incontinence, it is associated with significant psychosocial and economic issues and stoma-related complications. Sacral nerve stimulation (SNS) is an innovative treatment for end-stage fecal incontinence and could obviate the need for a stoma.
The neural supply to the anorectal region is both somatic and autonomic. The superficial perineal nerve (branch of pudendal nerve) provides sensory fibers to the perineum, external genitalia as well as anal canal mucosa. Motor nerve supply to the pelvic floor and external anal sphincter is from the sacral plexus (S2-S4 level). The levator ani and puborectalis muscles are supplied on both the pelvic and perineal surfaces by direct branches from the nerve roots. The external anal sphincter receives its motor supply from the inferior rectal nerve (a branch of the pudendal nerve) and the deep perineal nerve (also a branch of the pudendal nerve) supplies the transverse perineal muscle and urethral sphincter.
The autonomic nerve supply is from both the sympathetic and parasympathetic systems. The sympathetic system is mainly inhibitory to colonic motility and excitatory to the internal anal sphincter. The supply is from the L1-L2 level via the hypogastric nerves. The parasympathetic supply is distributed via the sacral nerves (S2-S4) via the pelvic plexus and is excitatory to colonic motility as well as inhibitory to the internal anal sphincter. There is also an intrinsic nervous system of the colon and rectum with cell bodies within the colonic wall, but these can be affected by the autonomic system and local factors.
There appears to be a dual peripheral nerve supply (branches of the pudendal nerve and direct branches of sacral nerves) to the continence mechanism and the sacral spinal nerve is the most distal common location of this dual supply. Therefore, stimulation at this level can potentially excite both nerves. The basis for sacral nerve stimulation (SNS) is that by stimulating these sacral nerves, additional residual function of an inadequate pelvic floor musculature and pelvic organs can be recruited.
During SNS treatment for patients with urinary incontinence, some patients noticed improvement in any concurrent fecal incontinence also. The medical investigators found increased anorectal junction angulation, as well, as increased anal canal closure pressure as potential mechanisms to account for improvement of fecal continence.
One clinical study reported on the use of SNS in treating three patients with fecal incontinence. After 6 months, two patients regained complete continence while the third improved significantly. He noticed that the maximal anal squeeze pressure increased after stimulation. This improved continence was attributed to a direct nervous stimulation of the external anal sphincter. It was hypothesized that SNS stimulated the conversion of fast twitch, fatiguable type II muscle fibers in the external sphincter and pelvic floor to slow twitch type I fibers, based on the findings in previous studies.
Subsequent studies showed that mean resting anal pressure is raised after successful SNS treatment, suggesting that SNS might have an effect on the autonomic nervous system as well. In one study the rectal blood flow by laser Doppler flowmetry showed increased rectal blood flow after stimulation, and attributed this to modulation of the autonomic system that affects the blood vessels. More recent studies have shown reduced rectal sensory threshold and improved balloon expulsion time. These findings suggest SNS modulates the normal anorectal reflexes, as well as, stimulated the sacral nerve motor outflow.
In summery, sacral nerve stimulation achieves its effect through several physiological mechanisms. It stimulates the motor output from the sacral nerves and pudendal nerve, modulates the local spinal reflex arcs, and modulates the autonomic supply to the rectum and pelvic floor as well as spinal tracts to the higher center in the brain.
In one aspect of the invention, peripheral nerve evaluation (PNE) may be used to determine the feasibility of implanting an electrode into the sacral foramina (acute stage) and to assess the benefits after a period of stimulation (subchronic stage) of the sacral nerves. Screening of patients with fecal incontinence through PNE allows preselection of patients who are likely to have a good response to SNS. Acute PNE serves to locate the optimal sacral spinal nerve that will elicit contractions of the striated pelvic floor muscles, thus establishing the integrity of the sacral spinal nerves.
The procedure can be done under local or general anesthesia. During the procedure, with the patient lying prone, sheathed needles are inserted into the dorsal foramina of S2, S3 and S4 bilaterally under sterile conditions, such that the electrodes are placed close to where the sacral spinal nerves enter the pelvic cavity through the ventral sacral foramina and proximal to the sacral plexus. Intermittent stimulation with graduated amplitudes is applied to a needle until a muscle contraction is obtained. If acute peripheral nerve evaluation (PNE) successfully elicits the required reaction, an electrode is inserted for the subchronic stage of PNE.
For the subchronic stage, a tined lead is implanted with the electrodes in the appropriate position, which if successful, will be retained and connected to the permanent implant. The electrodes of the tined lead are connected to a temporary external pulse generator, via an external extension cable. Stimulation is applied, which can be turned off during micturition and defecation. The patient is evaluated typically for a minimum period of 7 days of subchronic PNE for improvement in fecal continence.
Patients who have significant improvement after subchronic PNE can be implanted with a permanent implantable pulse generator (IPG). The spinal nerve site which is chosen is the one that has previously been demonstrated to be therapeutically effective during the test stimulation phase. Using a tined lead during PNE has the advantage that it does not require any change of electrode, which is already in the optimal location in the sacral canal. The electrode is then connected subcutaneously via an extension wire to the implantable pulse generator, which is then placed in a subcutaneous location in the lower abdomen or gluteal area.
As shown in conjunction with
A commonly used nomenclature for peripheral nerve fibers, using Roman and Greek letters, is given in the table below:
External Conduction Group Diameter (μm) Velocity (m/sec) Myelinated Fibers Aα or IA 13-20 80-120 Aβ: IB 10-15 60-75 II 5-15 30-75 Aγ 3-8 15-40 Aδ or III 3-8 10-30 B 1-3 5-15 Unmyelinted fibers C or IV 0.2-1.5 0.5-2.5
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 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. Group B fibers are not present in the nerves of the limbs; they occur in white rami and some cranial nerves.
Compared to unmyelinated fibers, myelinated fibers are typically larger, conduct faster, have very low stimulation thresholds, and exhibit a particular strength-duration curve or respond to a specific pulse width versus amplitude for stimulation. 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. 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.
Stimulation of individual fibers is shown in conjunction with
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 (TP); which is shown in conjunction with
For a stimulus to be effective in producing an excitation, it must have an abrupt onset, be intense enough, and last long enough. These facts can be drawn together by considering the delivery of a suddenly rising cathodal constant-current stimulus of duration d to the cell membrane as shown in
When the stimulation pulse is strong enough, an action potential will be generated and propagated. Immediately after the spike of the action potential there is a refractory period when the neuron is either unexcitable (absolute refractory period) or only activated to sub-maximal responses by supra-threshold stimuli (relative refractory period). The absolute refractory period occurs at the time of maximal Sodium channel inactivation while the relative refractory period occurs at a later time when most of the Na+ channels have returned to their resting state by the voltage activated K+ current. The refractory period has two important implications for action potential generation and conduction. First, action potentials can be conducted only in one direction, away from the site of its generation, and secondly, they can be generated only up to certain limiting frequencies.
Pulsed electrical stimulation induces nerve impulses in the form of action potentials in the nerve fibers. These electrical signals travel along the nerve fibers. The information in the nervous system is coded by frequency of firing rather than the size of the individual action potentials. The bottom portion of
In neuromodulation of the current invention, the entire innervation system should be intact. As shown schematically in
A neurophysiological explanation for the effectiveness of this treatment modality in detrusor instability is based on animal experiments and electrophysiological studies in humans. Electrical stimulation for the treatment of urinary incontinence has evolved over the past 40 years. The mechanism of action of electrical stimulation was investigated initially in animal models. Over 100 years ago, Griffiths demonstrated relaxation of a contracted detrusor during stimulation of the proximal pudendal nerve in the cat model and further work clarified the role of pudendal afferents in relation of the detrusor. Spinal inhibitory systems capable of interrupting a detrusor contraction can be activated by electrical stimulation of afferent anorectal branhes of the pelvic nerve, afferent sensory fibers in the pudendal nerve and muscle afferents from the limbs. The effectiveness of neuromodulation in humans has been objectively demonstrated by urodynamic improvement, especially in light of the fact that such effects have not been noted in drug trials.
Neuromodulation also acts on neural reflexes but does so internally by stimulation of the sacral nerves 54. Sacral nerves 54 stimulation is based on research dedicated to the understanding of the voiding reflex as well as the role and influence of the sacral nerves 54 on voiding behavior. This research led to the development of a technique to modulate dysfunctional voiding behavior through sacral nerve stimulation. It is thought that sacral nerve stimulation induces reflex mediated inhibitory effects on the detrusor through afferent and/or efferent stimulation of the sacral nerves 54.
Even though the precise mechanism of action of electrical stimulation in humans is not fully understood, it has been shown that sensory input traveling through the pudendal nerve can inhibit detrusor activity in humans. It is generally believed that non-implanted electrical stimulation works by stimulating the pudendal nerve afferents, with the efferent outflow causing contraction of the striated pelvic musculature. There is also inhibition of inappropriate detrusor activity, though the afferent mechanism has yet to be clarified. There is consensus that the striated musculature action is able to provide detrusor inhibiton in this setting.
In summary, the rationale for neuromodulation in the management of such patients is the observation that stimulation of the sacral nerves via electrical stimulation can inhibit inappropriate neural reflex behavior.
In the method and system of this invention, pulsed electrical stimulation is provided using both implanted and external components. The pulse generator may be implanted in the body, or may be external to the body. In one aspect the external components may be networked over a wide area network, for remote interrogation and remote programming of stimulation parameters.
The present invention has certain objects. That is, various embodiments of the present invention provide solution to one or more problems exiting in the prior art, including the problems of: a) testing the effectiveness of the therapy with a device and then implanting a different system to provide therapy; b) patient requires periodic surgeries to replace system at the end of battery-life, (typical battery life is 3-6 years); c) patient is not able to easily change between an implanted, external, or integrated system; d) patient is unable to make use of 'cumulative effect' of therapy to reduce/eliminate disorders, in addition to just 'event' based therapy due to limited battery life of exiting systems; e) frequent patient visits to clinics/physician office to monitor the device; f) the titration of therapy is a long and drawn out.
The method and system of current invention provides pulsed electrical stimulation to provide therapy for urinary incontinence, fecal incontinence, and urological disorders. The urological disorders include overflow incontinence, stress incontinence, idiopathic chronic urinary retention, interstitial cystitis, neuro-urological disorder, vesico-urethral dysfunctions, bladder inflammation, bladder pain, pelvic pain, and genito-urinary disorders such as prostatitis, prostatalgia, and prostatodynia. The stimulation is to sacral nerve(s) or its branches or portions thereof, to provide therapy. The method and system comprises both implantable and external components. The power source may also be external or implanted in the body. The system to provide selective stimulation to sacral nerve(s) or branches may be selected from a group consisting of:
a) an implanted stimulus-receiver with an external stimulator;
b) an implanted stimulus-receiver comprising a high value capacitor for storing charge, used in conjunction with an external stimulator;
c) a programmer-less implantable pulse generator (IPG) which is operable with a magnet;
d) a programmable implantable pulse generator (IPG);
e) a combination implantable device comprising both a stimulus-receiver and a programmable IPG; and
f) an IPG comprising a rechargeable battery.
In one aspect of the invention, the selective stimulation is to sacral nerve(s) or branches or parts thereof to provide therapy.
In another aspect of the invention, the electrical pulses to sacral nerve(s) or branches may be provided unilaterally, or bilaterally.
In another aspect of the invention, rectangular and/or complex pulses are used.
In another aspect of the invention, these predetermined/pre-packaged programs may be used to provide therapy.
In another aspect of the invention, predetermined/pre-packaged programs can be modified.
In another aspect of the invention, the stimulation may be unidirectional.
In another aspect of the invention, blocking may be provided to selected branches.
In another aspect of the invention, the pulse generator may be implanted in the body.
In another aspect of the invention, the implanted pulse generator is adapted to be re-chargable via an external power source.
In another aspect of the invention, the external components such as the external stimulator, or programmer comprise telemetry means adapted to be networked, for remote interrogation or remote programming of the device.
In another aspect of the invention, the implanted lead body may be made of a material selected from the group consisting of polyurethane, silicone, and silicone with polytetrafluoroethylene (PTFE).
In yet another aspect of the invention, the implanted lead comprises at least one electrode selected from the group consisting of platinum, platinum/iridium alloy, platinum/iridium alloy coated with titanium nitride, and carbon.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.
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.
FIGS. 36N and 36-O depict modified square pulses to be used in conjunction with tripolar electrodes.
The method and system of the current invention delivers pulsed electrical stimulation, to provide therapy for urinary incontinence, urological disorders and/or fecal incontinence. The urological disorders include overflow incontinence, stress incontinence, idiopathic chronic urinary retention, interstitial cystitis, neuro-urological disorder, vesico-urethral dysfunctions, bladder inflammation, bladder pain, pelvic pain, and genito-urinary disorders such as prostatitis, prostatalgia, and prostatodynia. The electrical stimulation is delivered usually to S3 (shown in
For implantation of the system, an incision is made and the distal portion of the lead is implanted in the tissue with electrodes in contact with the nerve tissue to be stimulated. The terminal portion of the lead is tunneled subcutaneously to a site where the pulse generator means is implanted, which is usually in the lower abdominal area (or may be in the gluteal region). The pulse generator (or stimulus-receiver) means is connected to the proximal end of the lead, placed in a subcutaneous pocket, and the tissues are surgically closed in layers (
In the method and system of this invention, the pulse generator means may be implanted in the body or may be external to the body. Also, the power source may be external, implantable, or a combination device.
In the method of this invention, a simple and cheap pulse generator may be used to test a patient's response to neuromodulation therapy. As one example only, an implanted stimulus-receiver in conjunction with an external stimulator may be used initially to test patient's response. If the patient responds well, then at a later time, the pulse generator may be exchanged for a more elaborate implanted pulse generator (IPG) model, keeping the same lead. Some examples of stimulation and power sources that may be used interchangeably with the same lead for the practice of this invention, and disclosed in this Application, include:
a) an implanted stimulus-receiver with an external stimulator;
b) an implanted stimulus-receiver comprising a high value capacitor for storing charge, used in conjunction with an external stimulator;
c) a programmer-less implantable pulse generator (IPG) which is operable with a magnet;
d) a programmable implantable pulse generator (IPG);
e) a combination implantable device comprising both a stimulus-receiver and a programmable IPG; and
f) an IPG comprising a rechargeable battery.
As another example, a cheap programmer-less IPG may be implanted initially to test the efficacy of neuromodulation therapy in the patient. If the patient responds well, the simple programmer-less IPG may be replaced with a higher functionality (and more expensive) version of IPG at a future time.
Also as disclosed later, the external components such as a programmer, or the external pulse generator, may comprise a telemetry module for remote communication over a wide area network such as the internet. This would provide means of remotely interrogating the device, or loading or activating new programs from a remote location.
Even though the pulse generator means are interchangeble, the lead(s) is implanted only once. The proximal (or terminal) portion of the lead is plugged into the pulse generator means. The distal portion of the lead comprises two, or three, or four electrodes for delivering electrical stimulation. As described earlier, the pulsed electrical stimulation may be to one of several nerves, however for purposes of describing the system, the stimulation site is referred to as simply "sacral nerves 54". It is to be understood that the "sacral nerves 54" includes sacral nerves S1, S2, S3, S4, pudendal nerve, superior gluteal nerve, lumbo-sacral trunk, inferior gluteal nerve, common fibular nerve, tibial nerve, posterior femoral cutaneous nerve, sciatic nerve, and obturator nerve. Additionally, stimulation may be provided unilaterally or bilaterally via two leads.
For an external power source, a passive implanted stimulus-receiver may be used. The appropriate stimulation of selected nerve fibers in the sacral and pelvic region, as performed by one embodiment of the method and system of this invention is shown schematically in
The carrier frequency is optimized. One preferred embodiment utilizes electrical signals of around 1 Mega-Hertz, even though other frequencies can be used. Low frequencies are generally not suitable because of energy requirements for longer wavelengths, whereas higher frequencies are absorbed by the tissues and are converted to heat, which again results in power losses.
Also, shown in conjunction with
The circuitry contained in the proximal end of the implantable stimulus-receiver 34 is shown schematically in
The circuitry shown in
For therapy to commence, the primary (external) coil 46 is placed on the skin 60 on top of the surgically implanted (secondary) coil 48. An adhesive tape may be placed on the skin 60 and external coil 46 such that the external coil 46, is taped to the skin 60. For efficient energy transfer to occur, it is important that the primary (external) and secondary (internal) coils 46,48 be positioned along the same axis and be optimally positioned relative to each other. In this embodiment, the external coil 46 may be connected to proximity sensing circuitry 50. The correct positioning of the external coil 46 with respect to the internal coil 48 is indicated by turning "on" of a light emitting diode (LED) on the external stimulator 42.
Many different forms of proximity sensing mechanisms may be used. In one embodiment optimal placement of the external (primary) coil 46 may be done with the aid of proximity sensing circuitry incorporated in the system. Proximity sensing occurs utilizing a combination of external and implantable components. The implanted components contains a relatively small magnet composed of materials that exhibit Giant Magneto-Resistor (GMR) characteristics such as Samarium-cobalt, a coil, and passive circuitry. As was shown in conjunction with
The proximity sensors (external) contained in the proximity sensor circuit 50 detect the presence of a GMR magnet 53, composed of Samarium Cobalt, that is rigidly attached to the implanted secondary coil 48. The proximity sensors, are mounted externally as a rigid assembly and sense the actual separation between the coils, also known as the proximity distance. In the event that the distance exceeds the system limit, the signal drops off and an alarm sounds to indicate failure of the production of adequate signal in the secondary implanted circuit 167, as applied in this embodiment of the device. This signal is provided to the location indicator LED 280.
The Siemens GMR B6 (Siemens Corp., Special Components Inc., New Jersey) is used for this function in one embodiment. The maximum value of the peak-to-peak signal is observed as the external magnetic field becomes strong enough, at which point the resistance increases, resulting in the increase of the field-angle between the soft magnetic and hard magnetic material. The bridge voltage also increases. In this application, the two sensors 648, 652 are oriented orthogonal to each other.
The distance between the magnet 53 and sensor 50 is not relevant as long as the magnetic field is between 5 and 15 KA/m, and provides a range of distances between the sensors 648, 652 and the magnetic material 53. The GMR sensor registers the direction of the external magnetic field. A typical magnet to induce permanent magnetic field is approximately 15 by 8 by 5 mm3, for this application and these components. The sensors 648, 652 are sensitive to temperature, such that the corresponding resistance drops as temperature increases. This effect is quite minimal until about 100� C. A full bridge circuit is used for temperature compensation, as shown in temperature compensation circuit 50 of
The signal from either proximity sensor 648, 652 is rectangular if the surface of the magnetic material is normal to the sensor and is radial to the axis of a circular GMR device. This indicates a shearing motion between the sensor and the magnetic device. When the sensor is parallel to the vertical axis of this device, there is a fall off of the relatively constant signal at about 25 mm. separation. The GMR sensor combination varies its resistance according to the direction of the external magnetic field, thereby providing an absolute angle sensor. The position of the GMR magnet can be registered at any angle from 0 to 360 degrees.
In the external stimulator 42 shown in
Also shown in
This method enables any portable computer with a serial interface to communicate and program the parameters for storing the various programs. The serial communication interface receives the serial data, buffers this data and converts it to a 16 bit parallel data. The programmable array logic 264 component of programmable array unit receives the parallel data bus and stores or modifies the data into a random access matrix. This array of data also contains special logic and instructions along with the actual data. These special instructions also provide an algorithm for storing, updating and retrieving the parameters from long-term memory. The programmable logic array unit 264, interfaces with long term memory to store the predetermined programs. All the previously modified programs can be stored here for access at any time, as well as, additional programs can be locked out for the patient. The programs consist of specific parameters and each unique program will be stored sequentially in long-term memory. A battery unit is present to provide power to all the components. The logic for the storage and decoding is stored in a random addressable storage matrix (RASM).
Conventional microprocessor and integrated circuits are used for the logic, control and timing circuits. Conventional bipolar transistors are used in radio-frequency oscillator, pulse amplitude ramp control and power amplifier. A standard voltage regulator is used in low-voltage detector. The hardware and software to deliver the pre-determined programs is well known to those skilled in the art.
The pulses delivered to the nerve tissue for stimulation therapy are shown graphically in
The selective stimulation to the sacral nerves can be performed in one of two ways. One method is to activate one of several "pre-determined" programs. A second method is to "custom" program the electrical parameters which can be selectively programmed, for specific therapy to the individual patient. The electrical parameters which can be individually programmed, include variables such as pulse amplitude, pulse width, frequency of stimulation, stimulation on-time, and stimulation off-time. Table two below defines the approximate range of parameters,
TABLE 2 Electrical parameter range delivered to the nerve PARAMER RANGE Pulse Amplitude 0.1 Volt-15 Volts Pulse width 20 μS-5 mSec. Frequency 5 Hz-200 Hz On-time 10 Secs-24 hours Off-time 10 Secs-24 hours
The parameters in Table 2 are the electrical signals delivered to the nerve tissue via the two electrodes 61,62 (distal and proximal) at the nerve tissue. It being understood that the signals generated by the external pulse generator 42 and transmitted via the primary coil 46 are larger, because the attenuation factor between the primary coil and secondary coil is approximately 10-20 times, depending upon the distance, and orientation between the two coils. Accordingly, the range of transmitted signals of the external pulse generator 42 are approximately 10-20 times larger than shown in Table 2.
Referring now to
The stimulating electrodes may be made of pure platinum, platinum/Iridium alloy or platinum/iridium coated with titanium nitride. The conductor connecting the terminal to the electrodes 61, 62, 63, 64 is made of an alloy of nickel-cobalt. The implanted lead design variables are also summarized in table three below.
TABLE 3 Lead design variables Proximal Distal End End Conductor (connect- ing Lead body- proximal Elec- Elec- Lead Insulation Lead- and distal trode - trode - Terminal Materials Coating ends) Material Type Linear Polyure- Anti- Alloy of Pure Standard bipolar thane microbial Nickel- Platinum Ball and coating Cobalt Ring elec- trodes Bifur- Silicone Anti- Platinum- Steroid cated Inflam- Iridium eluting matory (Pt/Ir) coating Alloy Silicone Lubricious Pt/Ir with coating coated Polytetra- with fluoro- Titanium ethylene Nitride (PTFE) Carbon
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 embodiment, the implanted stimulus-receiver may be a system which is RF coupled combined with a power source. In this embodiment, the implanted stimulus-receiver contains high value, small sized capacitor(s) for storing charge and delivering electric stimulation pulses for up to several hours by itself, once the capacitors are charged. The packaging is shown in
As shown in conjunction with
The refresh-recharge transmitter unit 460 includes a primary battery 426, an ON/Off switch 427, a transmitter electronic module 442, an RF inductor power coil 46A, a modulator/demodulator 420 and an antenna 422.
When the ON/OFF switch is on, the primary coil 46A is placed in close proximity to skin 60 and secondary coil 48A of the implanted stimulator 490. The inductor coil 46A emits RF waves establishing EMF wave fronts which are received by secondary inductor 48A. Further, transmitter electronic module 424 sends out command signals which are converted by modulator/demodulator decoder 420 and sent via antenna 422 to antenna 418 in the implanted stimulator 490. These received command signals are demodulated by decoder 416 and replied and responded to, based on a program in memory 414 (matched against a "command table" in the memory). Memory 414 then activates the proper controls and the inductor receiver coil 48A accepts the RF coupled power from inductor 46A.
The RF coupled power, which is alternating or AC in nature, is converted by the rectifier 408 into a high DC voltage. Small value capacitor 406 operates to filter and level this high DC voltage at a certain level. Voltage regulator 402 converts the high DC voltage to a lower precise DC voltage while capacitive power source 400 refreshes and replenishes.
When the voltage in capacative source 400 reaches a predetermined level (that is VDD reaches a certain predetermined high level), the high threshold comparator 430 fires and stimulating electronic module 412 sends an appropriate command signal to modulator/decoder 416. Modulator/decoder 416 then sends an appropriate "fully charged" signal indicating that capacitive power source 400 is fully charged, is received by antenna 422 in the refresh-recharge transmitter unit 460.
In one mode of operation, the patient may start or stop stimulation by waving the magnet 442 once near the implant. The magnet emits a magnetic force Lm which pulls reed switch 410 closed. Upon closure of reed switch 410, stimulating electronic module 412 in conjunction with memory 414 begins the delivery (or cessation as the case may be) of controlled electronic stimulation pulses to the sacral nerves 54 (sacral plexus) via a pair of electrodes. In another mode (AUTO), the stimulation is automatically delivered to the implanted lead based upon programmed ON/OFF times.
The programmer unit 450 includes keyboard 432, programming circuit 438, rechargeable battery 436, and display 434. The physician or medical technician programs programming unit 450 via keyboard 432. This program regarding the frequency, pulse width, modulation program, ON time etc. is stored in programming circuit 438. The programming unit 450 must be placed relatively close to the implanted stimulator 490 in order to transfer the commands and programming information from antenna 440 to antenna 418. Upon receipt of this programming data, modulator/demodulator and decoder 416 decodes and conditions these signals, and the digital programming information is captured by memory 414. This digital programming information is further processed by stimulating electronic module 412. In the DEMAND operating mode, after programming the implanted stimulator, the patient turns ON and OFF the implanted stimulator via hand held magnet 442 and the reed switch 410. In the automatic mode (AUTO), the implanted stimulator turns ON and OFF automatically according to the programmed values for the ON and OFF times.
Other simplified versions of such a system may also be used. For example, a system such as this, where a separate programmer is eliminated, and simplified programming is performed with a magnet and reed switch, can also be used.
In one embodiment, a programmer-less implantable pulse generator (IPG) may be used. In this embodiment, shown in conjunction with
In one embodiment, shown in conjunction with
Once the prepackaged/predetermined logic state is activated by the logic and control circuit 102, as shown in
In one embodiment, there are four stimulation states. A larger (or smaller) number of states can be achieved using the same methodology, and such is considered within the scope of the invention. These four states are, LOW stimulation state, LOW-MED stimulation state, MED stimulation state, and HIGH stimulation state. Examples of stimulation parameters (delivered to the sacral plexus) for each state are as follows,
LOW stimulation state example is,
Current output: 0.75 milliAmps.
Pulse width: 0.20 msec.
Pulse frequency: 20 Hz
ON for 5 minutes
LOW-MED stimulation state example is,
Current output: 1.5 milliAmps,
Pulse width: 0.30 msec.
Pulse frequency: 22 Hz
ON for 7.5 minutes
MED stimulation state example is,
Current output: 2.0 milliAmps.
Pulse width: 0.40 msec.
Pulse frequency: 25 Hz
ON for 15 minutes
HIGH stimulation state example is,
Current output: 3.0 milliAmps,
Pulse width: 0.50 msec.
Pulse frequency: 30 Hz
ON for 30 minutes
These prepackaged/predetermined programs are mearly examples, and the actual stimulation parameters will deviate from these depending on the treatment application.
It will be readily apparent to one skilled in the art, that other schemes can be used for the same purpose. For example, instead of placing the magnet 90 on the pulse generator 171 for a prolonged period of time, different stimulation states can be encoded by the sequence of magnet applications. Accordingly, in an alternative embodiment there can be three logic states, OFF, LOW stimulation (LS) state, and HIGH stimulation (HS) state. Each logic state again corresponds to a prepackaged/predetermined program such as presented above. In such an embodiment, the system could be configured such that one application of the magnet triggers the generator into LS State. If the generator is already in the LS state then one application triggers the device into OFF State. Two successive magnet applications triggers the generator into MED stimulation state, and three successive magnet applications triggers the pulse generator in the HIGH Stimulation State. Subsequently, one application of the magnet while the device is in any stimulation state, triggers the device OFF.
The advantage of this embodiment is that it is cheaper to manufacture than a fully programmable implantable pulse generator (IPG).
In one embodiment, a fully programmable implantable pulse generator (IPG), capable of generating stimulation and blocking pulses may be used. Shown in conjunction with
As was previously mentioned in the background section, the stimulation to sacral and/or pudendal nerve(s) may be unilateral or bilateral. For bilateral stimulation, a dual channel stimulator with two leads may be utilized. This is shown in conjunction with
In one embodiment, as shown in conjunction with
This embodiment also comprises predetermined/pre-packaged programs. Examples of four stimulation states were given in the previous section, under "Programmer-less Implantable Pulse Generator (IPG)". These predetermined/pre-packaged programs comprise unique combinations of pulse amplitude, pulse width, pulse morphology, pulse frequency, ON-time and OFF-time. Any number of predetermined/pre-packaged programs, even 100, can be stored in the memory of the implantable pulse generator of this invention, and are considered within the scope of the invention.
Examples of additional predetermined/pre-packaged programs for urological disorders are:
Pulse amplitude: 0.5 volts
Pulse width: 0.150 msec.
Pulse frequency: 5 Hz
Cycles: 10 seconds ON-time and 10 seconds OFF-time in repeating cycles.
Configuration: Unipolar
Pulse amplitude: 0.75 volts
Pulse width: 0.160 msec.
Pulse frequency: 7 Hz
Cycles: 12 seconds ON-time and 8 seconds OFF-time in repeating cycles.
Configuration: Unipolar
Pulse amplitude: 1.0 volts
Pulse width: 0.175 msec.
Pulse frequency: 9 Hz
Cycles: 12 seconds ON-time and 6 seconds OFF-time in repeating cycles.
Configuration: Unipolar
Pulse amplitude: 1.5 volts
Pulse width: 0.200 msec.
Pulse frequency: 10 Hz
Cycles: 12 seconds ON-time and 6 seconds OFF-time in repeating cycles.
Configuration: Unipolar
Pulse amplitude: 2.0 volts
Pulse width: 0.225 msec.
Pulse frequency: 10 Hz
Cycles: 12 seconds ON-time and 5 seconds OFF-time in repeating cycles.
Configuration: Unipolar
Pulse amplitude: 2.5 volts
Pulse width: 0.250 msec.
Pulse frequency: 15 Hz
Cycles: 12 seconds ON-time and 4 seconds OFF-time in repeating cycles.
Configuration: Unipolar
Pulse amplitude: 3.5 volts
Pulse width: 0.250 msec.
Pulse frequency: 20 Hz
Cycles: 12 seconds ON-time and 4 seconds OFF-time in repeating cycles.
Configuration: Unipolar
Pulse amplitude: 4.5 volts
Pulse width: 0.250 msec.
Pulse frequency: 20 Hz.
Cycles: 15 seconds ON-time and 3 seconds OFF-time in repeating cycles.
Configuration: Unipolar
Pulse amplitude: 2.0 volts
Pulse width: 0.225 msec.
Pulse frequency: 10 Hz
Cycles: 12 seconds ON-time and 5 seconds OFF-time in repeating cycles.
Configuration: Bipolar
Pulse amplitude: 2.5 volts
Pulse width: 0.250 msec.
Pulse frequency: 15 Hz
Cycles: 12 seconds ON-time and 4 seconds OFF-time in repeating cycles.
Configuration: Bipolar
Pulse amplitude: 1.5 volts
Pulse width: 0.20 msec.
Pulse frequency: 10 Hz
Pulse type: step pulses
Cycles: 10 seconds ON-time and 5 seconds OFF-time in repeating cycles.
Configuration: unipolar
Pulse amplitude: 1.5 volts
Pulse width: 0.20 msec.
Pulse frequency: 12 Hz
Pulse type: step pulses
Cycles: 10 seconds ON-time and 5 seconds OFF-time in repeating cycles.
Configuration: bipolar
Pulse amplitude: 1.5 volts
Pulse width: 0.20 msec.
Pulse frequency: 12 Hz
Cycles: 6 seconds ON-time and 2 seconds OFF-time in repeating cycles.
Pulse amplitude: 2.0 volts
Pulse width: 0.225 msec.
Pulse frequency: 15 Hz
Cycles: 5 seconds ON-time and 1 second OFF-time in repeating cycles.
Pulse amplitude: 2.5 volts
Pulse width: 0.250 msec.
Pulse frequency: 15 Hz
Cycles: 6 seconds ON-time and 1 second OFF-time in repeating cycles.
Pulse amplitude: 4.0 volts
Pulse width: 0.225 msec.
Pulse frequency: 18 Hz
Cycles: 10 seconds ON-time and 1 second OFF-time in repeating cycles.
Pulse amplitude: 6.0 volts
Pulse width: 0.250 msec.
Pulse frequency: 18 Hz
Cycles: 6 seconds ON-time and 2 seconds OFF-time in repeating cycles.
These prepackaged/predetermined programs are mearly examples, and the actual stimulation parameters will deviate from these depending on the treatment application and physician preference. One advantage of predetermined/pre-packaged program is that it can be readily activated by a program number. A simple version of a programmer, adapted to activate only a limited number of predetermined/pre-packaged programs may also be supplied to the patient.
In addition, each variable parameter may be individually adjusted and stored in the memory 394. The range of programmable electrical stimulation parameters include both stimulating and blocking frequencies, and are shown in table four below.
TABLE 4 Programmable electrical parameter range PARAMER RANGE Pulse Amplitude 0.1 Volt-25 Volts Pulse width 20 μS-5 mSec. Stim. Frequency 2 Hz-80 Hz Freq. for blocking DC to 750 Hz On-time 3 Secs-24 hours Off-time 1 Sec.-24 hours Ramp ON/OFF Mode Unipolar, Bipolar
Shown in conjunction with
Most of the digital functional circuitry 350 is on a single chip (IC). This monolithic chip along with other IC's and components such as capacitors and the input protection diodes are assembled together on a hybrid circuit. As well known in the art, hybrid technology is used to establish the connections between the circuit and the other passive components. The integrated circuit is hermetically encapsulated in a chip carrier. A coil 399 situated under the hybrid substrate is used for bidirectional telemetry. The hybrid and battery 397 are encased in a titanium can 65. This housing is a two-part titanium capsule that is hermetically sealed by laser welding. Alternatively, electron-beam welding can also be used. The header 79 is a cast epoxy-resin with hermetically sealed feed-through, and form the lead 40 connection block.
For further details,
The size of ROM 337 and RAM 339 units are selected based on the requirements of the algorithms and the parameters to be stored. The number of registers in the register file 321 are decided based upon the complexity of computation and the required number of intermediate values. Timers 340 of different precision are used to measure the elapsed intervals. Even though this embodiment does not have external sensors to control timing, future embodiments may have sensors 322 to effect the timing as shown in conjunction with
In this embodiment, the two main components of microprocessor are the datapath and control. The datapath performs the arithmetic operation and the control directs the datapath, memory, and I/O devices to execute the instruction of the program. The hardware components of the microprocessor are designed to execute a set of simple instructions. In general the complexity of the instruction set determines the complexity of datapth elements and controls of the microprocessor.
In this embodiment, the microprocessor is provided with a fixed operating routine. Future embodiments may be provided with the capability of actually introducing program changes in the implanted pulse generator. The instruction set of the microprocessor, the size of the register files, RAM and ROM are selected based on the performance needed and the type of the algorithms used. In this application of pulse generator, in which several algorithms can be loaded and modified, Reduced Instruction Set Computer (RISC) architecture is useful. RISC architecture offers advantages because it can be optimized to reduce the instruction cycle which in turn reduces the run time of the program and hence the current drain. The simple instruction set architecture of RISC and its simple hardware can be used to implement any algorithm without much difficulty. Since size is also a major consideration, an 8-bit microprocessor is used for the purpose. As most of the arithmetic calculation are based on a few parameters and are rather simple, an accumulator architecture is used to save bits from specifying registers. Each instruction is executed in multiple clock cycles, and the clock cycles are broadly classified into five stages: an instruction fetch, instruction decode, execution, memory reference, and write back stages. Depending on the type of the instruction, all or some of these stages are executed for proper completion.
Initially, an optimal instruction set architecture is selected based on the algorithm to be implemented and also taking into consideration the special needs of a microprocessor based implanted pulse generator (IPG). The instructions are broadly classified into Load/store instructions, Arithmetic and logic instructions (ALU), control instructions and special purpose instructions.
The instruction format is decided based upon the total number of instructions in the instruction set. The instructions fetched from memory are 8 bits long in this example. Each instruction has an opcode field (2 bits), a register specifier field (3-bits), and a 3-bit immediate field. The opcode field indicates the type of the instruction that was fetched. The register specifier indicates the address of the register in the register file on which the operations are performed. The immediate field is shifted and sign extended to obtain the address of the memory location in load/store instruction. Similarly, in branch and jump instruction, the offset field is used to calculate the address of the memory location the control needs to be transferred to.
Shown in conjunction with
Generally, two or more timers are required to implement the algorithm for the IPG. The timers are read and written into just as any other memory location. The timers are provided with read and write enable controls.
The arithmetic logic unit is an important component of the microprocessor. It performs the arithmetic operation such as addition, subtraction and logical operations such as AND and OR. The instruction format of ALU instructions consists of an opcode field (2 bits), a function field (2 bits) to indicate the function that needs to be performed, and a register specifier (3 bits) or an immediate field (4 bits) to provide an operand.
The hardware components discussed above constitute the important components of a datapath. Shown in conjunction with
In a multicycle implementation, each stage of instruction execution takes one clock cycle. Since the datapath takes multiple clock cycles per instruction, the control must specify the signals to be asserted in each stage and also the next step in the sequence. This can be easily implemented as a finite state machine.
A finite state machine consists of a set of states and directions on how to change states. The directions are defined by a next-state function, which maps the current state and the inputs to a new state. Each stage also indicates the control signals that need to be asserted. Every state in the finite state machine takes one clock cycle. Since the instruction fetch and decode stages are common to all the instruction, the initial two states are common to all the instruction. After the execution of the last step, the finite state machine returns to the fetch state.
A finite state machine can be implemented with a register that holds the current stage and a block of combinational logic such as a PLA. It determines the datapath signals that need to be asserted as well as the next state. A PLA is described as an array of AND gates followed by an array of OR gates. Since any function can be computed in two levels of logic, the two-level logic of PLA is used for generating control signals.
The occurrence of a wakeup event initiates a stored operating routine corresponding to the event. In the time interval between a completed operating routine and a next wake up event, the internal logic components of the processor are deactivated and no energy is being expended in performing an operating routine.
A further reduction in the average operating current is obtained by providing a plurality of counting rates to minimize the number of state changes during counting cycles. Thus intervals which do not require great precision, may be timed using relatively low counting rates, and intervals requiring relatively high precision, such as stimulating pulse width, may be timed using relatively high counting rates.
The logic and control unit 398 of the IPG controls the output amplifiers. The pulses have predetermined energy (pulse amplitude and pulse width) and are delivered at a time determined by the therapy stimulus controller. The circuitry in the output amplifier, shown in conjunction with (
The constant-voltage output amplifier applies a voltage pulse to the distal electrode (cathode) 61 of the lead 40. A typical circuit diagram of a voltage output circuit is shown in
To re-establish equilibrium, the recharge switch 222 is closed, and a rapid recharge pulse is delivered. This is intended to remove any residual charge remaining on the coupling capacitor Cb 229, and the stimulus electrodes on the lead (polarization). Thus, the stimulus is delivered as the result of closing and opening of the stimulus delivery 220 switch and the closing and opening of the RCHG switch 222. At this point, the charge on the holding Ch 225 must be replenished by the stimulus amplitude generator 206 before another stimulus pulse can be delivered.
The pulse generating unit charges up a capacitor and the capacitor is discharged when the control (timing) circuitry requires the delivery of a pulse. This embodiment utilizes a constant voltage pulse generator, even though a constant current pulse generator can also be utilized. Pump-up capacitors are used to deliver pulses of larger magnitude than the potential of the batteries. The pump up capacitors are charged in parallel and discharged into the output capacitor in series. Shown in conjunction with
The prior art systems delivering fixed rectangular pulses provide limited capability for selective stimulation or neuromodulation of sacral nerve(s). A fixed rectangular pulse, whether constant voltage or constant current, will recruit either i) A-fibers, or ii) A and B fibers, or iii) A and B and C fibers. Only one of these three discrete states can be achieved. This form of modulation is severely limited for providing therapy for neurological disorders.
In the method and system of the current invention, the microcontroller is configured to deliver rectangular and complex pulses. Complex pulses comprise non-rectangular, biphasic, multi-step, and other complex pulses where the amplitude is varying during the pulse. Advantageously, these complex pulses provide a new dimension to selective stimulation or neuromodulation of sacral nerve(s) to provide therapy for urological disorders, such as urinary incontinence/fecal incontinence.
Examples of these pulses and pulse trains are shown in
For example in the multi-step pulse shown in
Further, as shown in the examples of
The pulses and pulse trains of this disclosure gives physicians a lot of flexibility for trying various different neuromodulation algorithms, for providing and optimizing therapy for urological disorders (and fecal incontinence) disorders. Furthermore, as shown in conjunction with
The combination of tripolar electrodes and the pulse shapes of FIGS. 36-J to 36-O would not only decrease or prevent the unwanted side effects, but the electrical charge of the pulse is also reduced, which will make this technique safer for long-term clinical applications.
In the tripolar cuff electrodes (
As shown in
Other examples of complex pulses, that may be used with tripolar electrodes are shown in FIGS. 36-L to 36-O.
Since the number of types of pulses and pulse trains to provide therapy can be complex for many physician's, in one aspect pre-determined/pre-packaged program comprise a complete program for the pulse trains that deliver therapy. The advantage of the pre-packaged programs is that the physician may program a complicated program simply by selecting a program number.
Since one of the objects of this invention is to decease side effects, blocking electrodes may be strategically placed at the relevant branches of sacral nerve(s). In one aspect efferent stimulation of selected types of fibers may be substantially blocked, utilizing the "greenwave" effect. In such a case, as shown in conjunction with
Therefore in the method and system of this invention, stimulation without block may be provided. Additionally, stimulation with selective block may be provided. Blocking of nerve impulses, unidirectional blocking, and selective blocking of nerve impulses is well known in the scientific literature. Some of the general literature is listed below and is incorporated herein by reference. (a) "Generation of unidirectionally propagating action potentials using a monopolar electrode cuff", Annals of Biomedical Engineering, volume 14, pp. 437-450, By Ira J. Ungar et al. (b) "An asymmetric two electrode cuff for generation of unidirectionally propagated action potentials", IEEE Transactions on Biomedical Engineering, volume BME-33, No. 6, June 1986, By James D. Sweeney, et al. (c) A spiral nerve cuff electrode for peripheral nerve stimulation, IEEE Transactions on Biomedical Engineering, volume 35, No. 11, November 1988, By Gregory G. Naples. et al. (d) "A nerve cuff technique for selective excitation of peripheral nerve trunk regions, IEEE Transactions on Biomedical Engineering, volume 37, No. 7, July 1990, By James D. Sweeney, et al. (e) "Generation of unidirectionally propagated action potentials in a peripheral nerve by brief stimuli", Science, volume 206 pp. 1311-1312, Dec. 14, 1979, By Van Den Honert et al. (f) "A technique for collision block of perpheral nerve: Frequency dependence" IEEE Transactions on Biomedical Engineering, MP-12, volume 28, pp. 379-382, 1981, By Van Den Honert et al. (g) "A nerve cuff design for the selective activation and blocking of myelinated nerve fibers" Ann. Conf. of the IEEE Engineering in Medicine and Biology Soc., volume 13, No. 2, p 906, 1991, By D. M Fitzpatrick et al. (h) "Orderly recruitment of motoneurons in an acute rabbit model", "Ann. Conf. of the IEEE Engineering in Medicine and Biology Soc., volume 20, No. 5, page 2564, 1998, By N. J. M. Rijkhof, et al. (i) "Orderly stimulation of skeletal muscle motor units with tripolar nerve cuff electrode", IEEE Transactions on Biomedical Engineering, volume 36, No. 8, pp. 836, 1989, By R. Bratta. (j) M. Devor, "Pain Networks", Handbook of Brand Theory and Neural Networks, Ed. M. A. Arbib, MIT Press, page 698, 1998.
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 can be applied for the practice of this invention, and all are considered within the scope of this invention.
The programming of the implanted pulse generator (IPG) 391 is shown in conjunction with
The transmission of programming information involves manipulation of the carrier signal in a manner that is recognizable by the pulse generator 391 as a valid set of instructions. The process of modulation serves as a means of encoding the programming instruction in a language that is interpretable by the implanted pulse generator 391. Modulation of signal amplitude, pulse width, and time between pulses are all used in the programming system, as will be appreciated by those skilled in the art.
The reed switch 389 is a magnetically-sensitive mechanical switch, which consists of two thin strips of metal (the "reed") which are ferromagnetic. The reeds normally spring apart when no magnetic field is present. When a field is applied, the reeds come together to form a closed circuit because doing so creates a path of least reluctance. The programming head of the programmer contains a high-field-strength ceramic magnet.
When the switch closes, it activates the programming hardware, and initiates an interrupt of the IPG central processor. Closing the reed switch 389 also presents the logic used to encode and decode programming and telemetry signals. A nonmaskable interrupt (NMI) is sent to the IPG processor, which then executes special programming software. Since the NMI is an edge-triggered signal and the reed switch is vulnerable to mechanical bounce, a debouncing circuit is used to avoid multiple interrupts. The overall current consumption of the IPG increases during programming because of the debouncing circuit and other communication circuits.
A coil 399 is used as an antenna for both reception and transmission. Another set of coils 383 is placed in the programming head, a relatively small sized unit connected to the programmer 85. All coils are tuned to the same resonant frequency. The interface is half-duplex with one unit transmitting at a time.
Since the relative positions of the programming head 87 and IPG 391 determine the coupling of the coils, this embodiment utilizes a special circuit which has been devised to aid the positioning of the programming head, and is shown in
Actual programming is shown in conjunction with
A programming message is comprised of five parts
All of the bits are then encoded as a sequence of pulses of 0.35-ms duration
The serial pulse sequence is then amplitude modulated for transmission
Telemetry data may be either analog or digital. Digital signals are first converted into a serial bit stream using an encoding such as shown in
An advantage of this and other encodings is that they provide multiple forms of error detection. The coils and receiver circuitry are tuned to the modulation frequency, eliminating noise at other frequencies. Pulse-position coding can detect errors by accepting pulses only within narrowly-intervals. The access code acts as a security key to prevent programming by spurious noise or other equipment. Finally, the parity field and other checksums provides a final verification that the message is valid. At any time, if an error is detected, the entire message is discarded.
Another more sophisticated type of pulse position modulation may be used to increase the bit transmission rate. In this, the position of a pulse within a frame is encoded into one of a finite number of values, e.g. 16. A special synchronizing bit is transmitted to signal the start of the frame. Typically, the frame contains a code which specifies the type or data contained in the remainder of the frame.
This embodiment also comprises an optional battery status test circuit. Shown in conjunction with
In one embodiment, the implantable device may comprise both a stimulus-receiver and a programmable implantable pulse generator (IPG) in one device. Another embodiment of a similar device is disclosed in applicant's co-pending application Ser. No. 10/436,006. This embodiment also comprises predetermined/pre-packaged programs. Examples of several stimulation states were given in the previous sections, under "Programmer-less Implantable Pulse Generator (IPG)" and "Programmable Implantable Pulse Generator". These predetermined/pre-packaged programs comprise unique combinations of pulse amplitude, pulse width, pulse frequency, ON-time and OFF-time.
In this embodiment, as disclosed in
The system 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 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 chagneable parameters. Using input for the telemetry circuit 742 and power control 730, this section controls the output circuit 734 that generates the output pulses.
It will be clear to one skilled in the art that this embodiment of the invention can also be practiced with a rechargeable battery. This version is shown in conjunction with
The stimulus-receiver portion of the circuitry is shown in conjunction with
In the unipolar configuration, advantageously a bigger tissue area is stimulated since the difference between the tip (cathode) and case (anode) is larger. Stimulation using both configuration is considered within the scope of this invention.
The power source select circuit is highlighted in conjunction with
In one embodiment, an implantable pulse generator with rechargeable power source can be used. Because of the rapidity of the pulses required for modulating nerve tissue 54 with stimulating and/or blocking pulses, there is a real need for power sources that will provide an acceptable service life under conditions of continuous delivery of high frequency pulses.
This embodiment also comprises predetermined/pre-packaged programs. Examples of several stimulation states were given in the previous sections, under "Programmer-less Implantable Pulse Generator (IPG)" and "Programmable Implantable Pulse Generator". These pre-packaged/pre-determined programs comprise unique combinations of pulse amplitude, pulse width, pulse frequency, ON-time and OFF-time. Additionally, predetermined programs comprising blocking pulses may also be stored in the memory of the pulse generator.
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, 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 a 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
In summary, in the method of the current invention for neuromodulation of sacral nerve(s) 54, to provide adjunct therapy for urinary/fecal incontinence and urological disorders can be practiced with any of the several pulse generator systems disclosed including,
a) an implanted stimulus-receiver with an external stimulator;
b) an implanted stimulus-receiver comprising a high value capacitor for storing charge, used in conjunction with an external stimulator;
c) a programmer-less implantable pulse generator (IPG) which is operable with a magnet;
d) a programmable implantable pulse generator;
e) a combination implantable device comprising both a stimulus-receiver and a programmable IPG; and
f) an IPG comprising a rechargeable battery.
Neuromodulation of sacral nerve(s) with any of these systems is considered within the scope of this invention.
In one embodiment, the external stimulator and/or the programmer has a telecommunications module, as described in a co-pending application, and summarized here for reader convenience. The telecommunications module has two-way communications capabilities.
In one aspect of the invention, the telecommunications component can use Wireless Application Protocol (WAP). The Wireless Application Protocol (WAP), which is a set of communication protocols standardizing Internet access for wireless devices. While previously, manufacturers used different technologies to get Internet on hand-held devices, with WAP devices and services interoperate. WAP also promotes convergence of wireless data and the Internet. The WAP programming model is heavily based on the existing Internet programming model, and is shown schematically in
The key components of the WAP technology, as shown in
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 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.
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
configured to fulfill the role of communication module 292 of the present invention. The Modified PDA/Phone 502 may operate under any of the useful software including Microsoft Window's based, Linux, Palm OS, Java OS, SYMBIAN, or the like.
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 502 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 502 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 502, 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.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. It is therefore desired that the present embodiment be considered in all aspects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.
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|U.S. Classification
|International Classification
|Cooperative Classification
|European Classification


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Very comfortable! Everyone was very nice. I didn't want to leave.
Great place, right next to the tram that head up to he mountain... Pool and jacuzzi were nice. Bedroom was clean and spacious. Bathroom was big, clean, with a large tub.
Don't like Hidden fees... Hotel rates on your website was $159, then after tax and fees and extras came to $199, which I was aware of it when paying they your website. Then for my surprise I still had to pay an EXTRA $27 for some extras fees at the hotel. Couldn't argue neither wasted time with employees but not sure who is doing a bad job here... The hotel or kayak due to the HIDDEN FEES. Not fair.
We really enjoyed the breakfast foods. Nice.
The little town was vey cute and everything was within walking distance; just be prepared to spend 23 dollars On a burger and fries, the pool was heated to 85 so we could swim early before we left, the pillows were fantastic as was the bed, and the staff was helpful and friendly!
The wood burning fireplace in the room was awesome!
The rooftop hot tub after skiing/boarding
unfortunately our friends had to move to a sister hotel and we could not stay in the same hotel as we had planned.
Even with an upgrade at the sister hotel (for the inconvenience) we were not easily together for activities like, grabbing b/fast together, the hot tub or meeting in one lobby... we had to be more organized than that.
Staff was very helpful
Not carzy about $30 per night parking then feeling you have to tip everytime they get your vehicle.
The staff were dedicated to making this a getaway to remember
Wish we could have stayed longer is all.
Great location, beautiful scenery, near national parks.
Going stairs was hard for my elderly mother.
location, price, refrigerator, game room
thin walls, room noisy, towels
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