Incontinence treatment device

127481/2

INCONTINENCE TREATMENT DEVICE BIO CONTROL MEDICAL LTD. C:32729 32729S2

INCONTINENCE TREATMENT DEVICE

FIELD OF THE INVENTION

The present invention relates generally to medical electronic devices, and specifically to implantable electrical muscle controllers.

BACKGROUND OF THE INVENTION

Urinary stress incontinence affects millions of people, causing discomfort and embarrassment, sometimes to the point of social isolation. Stress incontinence results from weakness or inability of pelvic muscles to hold back urinary flow from the bladder when abdominal pressure increases due to everyday events such as coughing, laughing or mild physical exertion. Muscles involved in controlling the urinary flow include the urethral sphincter and the levator ani. In the United States, it is estimated that 10-13 million patients seek medical care for incontinence each year, of whom about 35% suffer from stress-type incontinence.

Stress incontinence is typically associated with either or both of the following anatomical conditions: • Urethral hypermobility - Weakness of or injury to pelvic floor muscles causes the bladder to descend during abdominal straining or pressure, allowing urine to leak out of the bladder. This is the more common source of stress incontinence. • Urethral intrinsic sphincter deficiency - In this condition, the urethral musculature is unable to completely close the urethra or keep it closed during stress. A large variety of products and treatment methods are available for personal and medical care of incontinence. Most patients suffering from mild to moderate incontinence use diapers or disposable absorbent pads. These products are not sufficiently absorbent to 1 32729S2 be effective in severe cases. They are uncomfortable to wear, and cause skin irritation, as well as unpleasant odors. Other non-surgical products for controlling incontinence include urethral inserts (or plugs) and externally-worn adhesive patches, and drugs are also used in some cases.

Various surgical procedures have been developed for bladder neck suspension, primarily to control urethral hypermobility by elevating the bladder neck and urethra. These procedures typically use bone anchors and sutures or slings to support the bladder neck. The success rates for bladder neck suspension surgery in controlling urinary leakage are typically in the 60-80% range, depending on the patient's condition, the surgeon and the procedure that is used. The disadvantages of surgery are its high cost, need for hospitalization and long recovery period, and high frequency of complications.

For serious cases of intrinsic sphincter deficiency, artificial urinary sphincters have been developed. For example, the AMS 800 urinary sphincter, produced by American Medical Systems Inc., of Minnetonka, Minnesota, includes a periurethral inflatable cuff, used to overcome urinary incontinence when the function of the natural sphincter is impaired. The cuff is coupled to a manually-operated pump and a pressure regulator chamber, which are implanted in a patient’s body together with the cuff. The cuff is maintained at a constant pressure of 60-80 cm of water, which is generally higher than the bladder pressure. To urinate, the patient releases the pressure in the cuff by pressing on the implanted pump, which pumps the fluid out of the cuff to the chamber. Aspects of this system are described in U.S. Patent 4,222,377, whose disclosure is incorporated herein by reference.

This artificial sphincter has several shortcomings, however. The constant concentric pressure that the 2 32729S2 periurethral cuff exerts on the urethra results in impaired blood supply to tissue in the area, leading to tissue atrophy, urethral erosion and infection. Furthermore, the constant pressure in the cuff is not always sufficient to overcome transient increases in bladder pressure that may result from straining, coughing, laughing or contraction of the detrusor muscle, for example. In such cases, urine leakage may result. U.S. Patents 4,571,749 and 4,731,083, whose disclosures are incorporated herein by reference, describe an artificial sphincter device whose pressure can vary in response to changes in abdominal or intravesical (bladder) pressure. The device includes a periurethral cuff with subdermal pump and pressure regulator, with the addition of a hydraulic pressure sensor. This system is complicated, however, and requires manual manipulation of the subdermal pump and cuff control.

Medtronic Neurological, of Columbia Heights, Minnesota, produces a device known as Interstim for treatment of urge incontinence, which is a different disorder from stress incontinence, associated typically from different sorts of pathologies. Interstim uses an implantable pulse generator, which is surgically implanted in the lower abdomen and wired to nerves near the sacrum (the bone at the base of the spine) in a major surgical procedure under general anesthesia. Electrical impulses are then transmitted continuously to a sacral nerve that controls urinary voiding. The continuous electrical stimulation of the nerve has been found to reduce or eliminate urge incontinence in some patients.

Exercise and behavioral training are also effective in some cases in rehabilitating pelvic muscles and thus reducing or resolving incontinence. Patients are taught to perform Kegel exercises to strengthen their pelvic muscles, which may be combined with electrical 3 32729S2 stimulation of the pelvic floor. Electromyographic, biofeedback may also be provided to give the patients an indication as to the effectiveness of their muscular exertions. But retraining muscles is not possible or fully effective for most patients, particularly when there may be neurological damage or other pathologies involved.

SUMMARY OF THE INVENTION

It is an object of some aspects of the present invention to provide an improved device and method of treatment for incontinence, particularly urinary stress incontinence.

It is a further object of some aspects of the present invention to provide a device and method for enhancing function of muscles associated with urine control.

In preferred embodiments of the present invention, an implantable device for treatment of urinary stress incontinence comprises a control unit and one or more electrodes coupled to the control unit. The electrode or electrodes are implanted in the genital region of a patient so as to contact the one or more of the muscles that are used in regulating urine flow from the bladder. The control unit is preferably implanted under the skin of the abdomen or genital region. Motion of or pressure on or in the area of the bladder generates an electromyographic (EMG) signal in the muscles, which is sensed by the one or more electrodes and analyzed by the control unit. When the control unit determines that the signals are indicative of a condition, such as an increase in abdominal or intravesical pressure, that is likely to cause involuntary urine flow from the bladder, it applies an electrical waveform to the electrode or electrodes, stimulating the contacted muscle to contract and thus to inhibit the urine flow.

Preferably, at least one of the electrodes is 4 32729S2 implanted in or adjacent to the levator ani muscle. Alternatively or additionally, one or more of the electrodes may be implanted in the urethral sphincter or in another of the pelvic muscles that is involved in controlling urinary function. In any case, the present invention differs from electrical muscle stimulators known in the art in that it applies electrical stimulation directly to the muscle when such contraction is actually required, as indicated by intrinsic physiological signals. At other times, stimulation is not applied, and the muscles are allowed to relax. The present invention thus mimics the natural function of the muscles in maintaining urinary continence. Repeated stimulation using the present invention also tends to exercise and strengthen the muscles, thus enhancing their inherent capability to control urine flow. Even in cases of intrinsic sphincter deficiency, as long as the levator ani is viable, stimulation of natural muscular action is preferable to implantation of an artificial sphincter, as described in the above-mentioned U.S. patents, for example. Stimulation of the muscles in accordance with the principles of the present invention is believed to be effective against urine loss due to substantially all common types of stress incontinence.

The stimulation waveform preferably comprises pulses which may be monophasic or biphasic and may have any suitable pulse shape known in the art. The waveform may be applied in a unipolar or a bipolar mode. When unipolar stimulation is used, the control unit preferably includes a metal case which serves as a ground.

In some preferred embodiments of the present invention, the one or more electrodes comprise a single electrode, which both receives the electromyographic signals and applies the stimulation waveform. Alternatively, separate sensing and stimulation electrodes may be used. 5 32729S2

In further preferred embodiments of the present invention, the device also includes one or more other physiological sensors, such as pressure, force, motion or acceleration sensors, which are preferably implanted on, in or in the vicinity of the bladder. The other sensors generate signals responsive to motion or to intravesical or abdominal pressure, which are thus indicative of possible incontinence due to coughing, laughing, or other strain or motion of the abdominal muscles. The control unit processes the signals from the other sensors and uses them to determine when the electrical stimulation should be applied to the muscles.

Preferably, the control unit comprises a processor, which is programmed to distinguish between signals indicative of possible incontinence and other signals that do not warrant stimulation of the muscles. In particular, the processor is programmed to recognize signal patterns indicative of normal voiding, and does not stimulate the muscles when such patterns occur, so that the patient can pass urine normally. Preferably, the processor is programmable after implantation of the device, most preferably by means of a wireless communications link, so that the strength and shape of the stimulation waveform and the response of the device to the electromyographic and/or other physiological signals can be adjusted in response to the patient's clinical characteristics and experience with the device.

Although preferred embodiments of the present invention are described with reference to treatment of urinary stress incontinence, it will be appreciated that the principles of the present invention may be applied as well to treat other types of incontinence, such as urge incontinence. In such a case, the device is preferably configured so as to engender relaxation of muscles associated with the bladder, rather than to stimulate muscular contraction as in the present case. The 6 32729S2 principles of the present invention may further be applied to treat and enhance the function of other muscles in the body.

There is therefore provided, in accordance with a preferred embodiment of the present invention, a device for treatment of urinary stress incontinence, including: at least one electrode, which is placed in electrical contact with a pelvic muscle of a patient; and a control unit, which receives signals indicative of abdominal stress in the patient and responsive thereto applies an electrical waveform to the electrode which stimulates the muscle to contract, so as to inhibit involuntary urine flow through the patient's urethra due to the stress.

Preferably, the signals include electromyographic signals received from the at least one electrode, and the device includes a switch between the electrode and an input of the control unit, which switch is opened when the electrical waveform is applied so as to prevent feedback from the electrode to the input.

Preferably, the control unit includes a processor, which analyzes the signals so as to determine when an involuntary urine flow is likely, whereupon the waveform is applied. Further preferably, the processor distinguishes between signals indicative of an involuntary urine flow and signals indicative of voluntary voiding by the patient. Preferably, the processor is programmable to vary one or more parameters associated with the application of the waveform, and the device includes a wireless receiver, which receives data for programming the processor from a programming unit outside the patient's body.

Preferably, the at least one electrode includes a single unipolar electrode or, alternatively or additionally, a pair of bipolar electrodes.

In a preferred embodiment, the device includes a 7 32729S2 physiological sensor coupled to the patient's bladder, which sensor provides at least some of the signals to the control unit. Preferably, the sensor includes a pressure sensor or, alternatively or additionally, an acceleration sensor.

Preferably, the at least one electrode and the control unit are implanted in the body of the patient, and the control unit includes a rechargeable power source. Most preferably, the power source is recharged by inductive energy transfer, substantially without electrical contact between the control unit and any object outside the patient's body.

Preferably, the pelvic muscle includes the levator ani muscle or, alternatively or additionally, the urethral sphincter muscle or another muscle adjacent to the urethral sphincter muscle.

There is further provided, in accordance with a preferred embodiment of the present invention, a method for treatment of urinary patient, including: receiving a signal stress incontinence of from the patient's body waveform to a stimulates the indicative of abdominal stress; and responsive to the signal, applying an electrical pelvic muscle of the patient, which muscle to contract so as to inhibit involuntary urine flow through the urethra due to the stress .

Preferably, applying the electrical waveform includes implanting an electrode in the patient's body in electrical contact with the pelvic muscle, most preferably with the levator ani muscle or, alternatively or additionally, in contact with the urethral sphincter muscle or in proximity thereto.

Further preferably, applying the waveform includes applying a waveform to the electrode in a unipolar mode. Alternatively or additionally, implanting the electrode 8 32729S2

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includes placing at least two electrodes in electrical contact with the muscle, and applying the waveform includes applying a waveform between the electrodes in a bipolar mode.

Preferably, receiving the signal includes receiving an electromyographic signal.

In a preferred embodiment, receiving the signal includes receiving a signal indicative of pressure on the patient's bladder or, alternatively or additionally, receiving a signal indicative of motion of the patient's bladder.

Preferably, applying the waveform includes analyzing the signal to determine when an involuntary urine flow is likely, and applying a waveform dependent on the determination, wherein analyzing the signal preferably includes distinguishing between a signal indicating that the involuntary urine flow is likely and another signal indicative of voluntary voiding.

In a preferred embodiment, applying the waveform includes varying a parameter of the waveform selected from a group including amplitude, frequency, duration, wave shape and duty cycle. Alternatively or additionally, applying the waveform includes applying a pulse burst.The present invention will be more fully understood from the following detailed description of the preferred embodiments thereof, taken together with the drawings in which: 9 32729S2

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic, pictorial view of an implantable muscle stimulation device, in accordance with a preferred embodiment of the present invention;

Fig. 2 is a schematic, partly sectional illustration showing implantation of the device of Fig. 1 in the pelvis of a patient, in accordance with a preferred embodiment of the present invention;

Fig. 3 is a schematic block diagram illustrating circuitry used in the device of Fig. 1, in accordance with a preferred embodiment of the present invention;

Fig. 4 is a schematic block diagram illustrating circuitry used in an implantable muscle stimulation device, in accordance with another preferred embodiment of the present invention;

Fig. 5 is a graph showing a typical waveform applied to the muscle by the device of Fig. 1, in accordance with a preferred embodiment of the present invention; and

Fig. 6 is a graph showing experimental results obtained using an implantable muscle stimulation device, in accordance with a preferred embodiment of the present invention. 10 32729S2

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to Fig. 1, which is a schematic, pictorial illustration of an implantable electronic muscle stimulator device 20, in accordance with a preferred embodiment of the present invention. Device 20 is preferably implanted in the genital region of a patient, as described further hereinbelow, for use in stimulating one or more of the muscles in the region, so as to control and treat urinary stress incontinence.

Device 20 comprises a control unit 22 and an electrode 30, mutually coupled by an electrical lead 24. Electrode 30 preferably comprises gold or has a gold-plated surface, and is formed in the shape of a spiral or hook, as is known in the art, so that the electrode can be easily and permanently anchored in the muscle. The lead is preferably 5-10 cm long and comprises a wire 28 made of any suitable conductive material, preferably a biocompatible metal such as gold, titanium, platinum or stainless steel, which is most preferably plated with gold. Preferably, the wire is a multi-strand wire in the range of 28-30 gauge. The wire is contained in an insulating jacket 26 preferably comprising silicone, polyurethane or other flexible, biocompatible insulating material.

Control unit 22 contains circuitry, described further hereinbelow with reference to Fig. 3, for receiving electrical signals from and applying a waveform to electrode 30 via lead 24. The circuitry is preferably contained in a case 25, made of stainless steel or other suitable biocompatible metal, and is preferably about 20 mm in diameter and 4 mm thick. Alternatively, the case may be made of a plastic material which is coated with a layer ' of biocompatible plastic, such as polymethyl methacrylate (PMMA) or silicone. Although only a single electrode is shown attached to the control unit in Fig. 1, additional electrodes and/or other sensors may 11 32729S2 127481/2 similarly be coupled to the control unit, as described further hereinbelow.

Fig. 2 is a schematic, partly sectional illustration showing the genitourinary anatomy of a female patient 31 in whom device 2 0 is implanted, in accordance with a preferred embodiment of the present invention. Electrode 30 is preferably inserted into the patient's levator ani muscle 32, adjacent to urethra 34 and bladder 36.

The levator ani supports and reinforces the operation of the urethral sphincter and can generally compensate for lost function of the sphincter in controlling urine flow from the bladder, such as may occur in cases of stress incontinence. The electrode may be inserted through the wall of vagina 42 or via any other suitable approach, preferably chosen for ease of access and minimization of tissue trauma.

Multiple electrodes (not shown in Fig. 2). may similarly be implanted at different locations in levator muscle 32, or alternatively or additionally in the sphincter in other pelvic muscles, preferably in the vicinity of the sphincter. Alternatively, the electrode or electrodes may be inserted in one or more of these other muscles, and not in the levator. The precise placement of the electrodes is not essential, and any suitable placement in one or more of the pelvic muscles is considered to be within the scope of the present invention.

Control unit 22 is preferably implanted under the skin in the. genitopelvic region of patient 31. Most preferably, the control unit is implanted inside the patient's labia minora 38 or in the labia majora 40, near muscle 32. .Alternatively, the control unit is not implanted in. the patient's body, but is instead maintained outside the body, connected by lead 24 to the electrode. This configuration is convenient particularly 12 32729S2 for an initial test period, during which the effectiveness of device 20 in treating a given patient is evaluated before permanent implantation.

Fig. 3 is a schematic block diagram showing circuitry used in control unit 22 to receive signals from and apply electrical waveforms to electrode 30, in accordance with a preferred embodiment of the present invention. When stress is applied to the abdomen of patient 31, electrode 30 receives electromyographic (EMG) signals from muscle 32. These signals are conveyed via a switch 46, which is normally closed, to the input of an amplifier 48, preferably a low-noise operational amplifier. Amplified signals output from amplifier 48 are digitized by an analog/digital (A/D) converter 50 and conveyed to a central processing unit (CPU) 52, preferably a microprocessor. CPU 52 analyzes the signals to determine whether they fit a pattern indicative that incontinence, i.e., involuntary urine flow from bladder 36, is likely to result from the stress. The pattern may correspond to coughing, laughing, or other strain or motion of the abdominal muscles. The CPU is programmed to distinguish between incontinence-related patterns and other signal patterns not associated with incontinence, such as signals generated when patient 31 wishes to pass urine voluntarily.

When possible incontinence is detected in this manner, CPU 52 opens switch 4 6 and commands a pulse generator 54 to apply a suitable electrical waveform to electrode 30 so as to stimulate muscle 32 to contract. Switch 46 is opened in order to avoid feedback of the stimulation waveform to amplifier 48, and is closed again after the waveform is terminated. In the embodiment shown in Fig. 3, the waveform is applied to the electrode in a unipolar mode, wherein case 25 of control unit 22 serves as the return (ground) electrode. (This mode can be used only when case 25 comprises a conductive 13 32729S2 material. When control unit 22 has a plastic case, at least two electrodes are generally needed, in order to administer bipolar stimulation.) As muscle 32 contracts, it closes off urethra 34, thus inhibiting the undesired urine flow. Preferably, the waveform is terminated and switch 46 is closed after a predetermined period of time, typically about 5 sec, has passed. If possible incontinence is again detected at this point, the waveform is re-applied.

Power is supplied to the elements of control unit 22 by a battery 56, preferably a rechargeable battery. Alternatively, a super-capacitor, as is known in the art, may be used to store and provide the electrical power. The battery or super-capacitor is preferably recharged via an inductive coil 58 or antenna, which receives energy by magnetic induction from an external magnetic field charging source (not shown) held in proximity to the pelvis of patient 31. The magnetic field causes a current to flow in coil 58, which is rectified by a rectifier 60 and furnished to charge battery 56. A similar inductive arrangement, using a coil antenna 62 coupled to CPU 52, is preferably used to program the CPU, using an external programming device (not shown) with a suitable antenna. Such programming may be used, for example, to set an amplitude or duration of the stimulation waveform applied by pulse generator 54, or to set a threshold level or other parameters according to which the CPU distinguishes between electromyographic signals that are indicative of impending incontinence and those that are not. Such programming may be carried out by medical personnel or by the patient herself, who can similarly turn the implanted control unit on and off as desired.

Although the circuit blocks in control unit 22 are shown as discrete elements, some or all of these blocks are preferably embodied in a custom or semi-custom 14 32729S2 integrated circuit device, as is known in the art.

Fig. 4 is a schematic block diagram illustrating a muscle stimulator device 120, in accordance with an alternative embodiment of the present invention. Device 120 is substantially similar to device 20, except for features described hereinbelow. Device 120 comprises a control unit 74, which is coupled to electrodes 30 and 72, of which electrode 72 serves as the sensing electrode, furnishing electromyographic signals via switch 46 to amplifier 48, as described hereinabove. Alternatively, electrodes 30 and 72 may be coupled as differential inputs to amplifier 48. Pulse generator 54 applies the stimulation waveforms between electrodes 30 and 72 in a bipolar mode.

In addition to or instead of the electromyographic signals received from electrode 72, CPU 52 preferably receives additional signals from other physiological sensors, such as a pressure sensor 76 and/or an acceleration sensor 78, or other types of strain and motion measurement devices, as are known in the art. Pressure sensor 76 is preferably implanted on or in bladder 36, so as to detect increases in abdominal or intravesical pressure that may lead to involuntary urine loss. Similarly, acceleration sensor 78 is preferably implanted so as to detect bladder motion associated with hypermobility, which is similarly associated with urine loss. The additional signals from these sensors are preferably analyzed by the CPU together electromyographic signals in order to accuracy and reliability of detection of impending stress incontinence.

Fig. 5 is a graph that schematically illustrates a waveform 80 applied to electrode 30 by control unit 22, in accordance with a preferred embodiment of the present invention. In clinical trials, waveform 80 was found to be effective, when applied to muscle 32, in stimulating sensors are r with the improve the 15 32729S2

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the muscle to contract and preventing urine loss. In the example shown in Fig. 5, the waveform has a relatively low frequency (given by time T2) of approximately 6 Hz, a duty cycle of about 25% (given by time 1/), and a diphasic form. Values of U+ = 1.5 mV and U- = 1.2 mV led to strong contraction of the patient's urinary control muscles, but without causing pain.

It will be appreciated that other waveforms may similarly be used in place of waveform 80. For example, the waveform may be uniphasic instead of biphasic and may have a higher or lower amplitude, duty cycle and/or frequency. It has been found generally that frequencies in the range between 5 and 200 Hz are effective in engendering contraction of the levator ani, but it may also be possible to use frequencies outside this range. The waveform may comprise a square wave (or a decaying square wave as shown in Fig. 5), sinusoid or sawtooth or have any other shape found to be suitable. Alternatively, the waveform may comprise one or more bursts of short pulses, each pulse preferably less than 1 msec in duration.

Fig. 6 is a graph schematically illustrating experimental results obtained by applying the therapeutic method described hereinabove to a human patient suffering from urinary stress incontinence. An electrode similar to electrode 30 was fixed in one of the patient's pelvic muscles and used both for sensing electromyographic signals and for applying the stimulation waveform to the muscle, as described hereinabove. The upper trace in the figure illustrates the amplitude of the stimulation waveform applied, which was of the general form shown in Fig. 5. The lower trace shows the electromyographic (EMG) signals that were measured. The scales of both upper and lower traces are arbitrary.

Up to a time of approximately 1:35, according to the time axis marked at the bottom of the figure, no stimulus 16 32729S2 was applied to the electrode, with the result that when the patient strained her abdomen, urine passed from her bladder. The patient's abdominal straining, typically induced by coughing, is illustrated by peaks in the EMG signal. Beginning at a point marked "START" in the figure, the stimulation waveform was applied to the electrode. The patient's muscles contracted accordingly, and substantially no urine was lost while the stimulation was applied. A strong EMG signal was measured throughout the period during which the stimulation waveform was applied.

Although preferred embodiments of the present invention are described hereinabove with reference to treatment of urinary stress incontinence, it will be appreciated that the principles of the present invention may be applied as well to treat other types of incontinence, such as urge incontinence, and to treat and enhance the function of other muscles in the body. It will be understood that the preferred embodiments described above are cited by way of example, and the full scope of the invention is limited only by the claims. 17