Percutaneous Screening Test for Evaluation of Potential Efficacy of Chronic Neurostimulation as a Therapy for Pelvic Floor Dysfunction
Publication Date: 2002-Jan-31
The IP.com Prior Art Database
A method for evaluating whether a patient is suited to chronic nerve stimulation as a therapy for pelvic floor disfunction includes acutely stimulating, for instance, the pudendal nerve, while measuring the response to such stimulation. Measurements may include pudendal nerve terminal motor latency, perineal nerve terminal motor latency, other sensory and motor nerve conduction velocity, first sensation of bladder filling, first urge to void, maximum cystometric capacity, and sacral reflexes, such as bulbocavernosus reflex, the urethral-anal reflex, the bladder-anal reflex, and the clitoral-anal reflex. Based on the results of these measurements, patients may be accepted or rejected for chronic pudendal nerve stimulation to treat pelvic floor dysfunction, such as urinary urgency, frequency, urge incontinence, stress incontinence, fecal incontinence, and pelvic pain.
Background and Summary
Urinary incontinence is a prevalent and costly condition that affects approximately 38% of women over 60 years of age. Incontinence predisposes patients to other health problems, contributes to depression and social isolation, is a significant source of dependency among the elderly, and is widely cited as a factor in nursing home admissions. The costs of incontinence are enormous, accounting for an estimated $16 billion each year. Urge incontinence, the involuntary urine loss associated with a strong sensation to void, is especially common among older women and is usually associated with detrusor instability or reduced bladder capacity. It is often characterized by sudden large-volume urinary accidents that can lead to embarrassment and significant restriction of activities.
Most patients are initially treated conservatively with bladder retraining, pelvic floor exercises and biofeedback. This regimen is often supplemented with drugs. However, about 40% of patients with these forms of lower urinary tract dysfunction do not experience acceptable relief with these forms of treatment, and thus remain a therapeutic problem.
A chronic implantable sacral nerve root neurostimulator is commercially available for the treatment of urge incontinence, which allows women with severe and/or medically refractory urge incontinence to gain significant control over their incontinence symptoms. The mode of action of neuromodulation on detrusor hyperreflexia is still unclear, but it is hypothesized that the neurostimulation modulates reflex pathways involved in the filling and evacuation phase of the micturition cycle. Stimulation of large myelinated fibers of the sacral roots S3 and S4 decreases the spastic behavior of the pelvic floor and enhances the tone of the urethral sphincter. In many subjects, the primary voiding dysfunction appears to begin with unstable urethral activity, which activates the voiding reflexes, leading to detrusor instability and the associated urgency/frequency and incontinence. The inhibitory effect of the enhanced urethral sphincter tone suppresses detrusor instability and stabilizes detrusor activity.
While chronic neurostimulation is an effective therapy for many patients, some respond poorly or not at all. Such patients may demonstrate characteristic differences in certain screening tests vis-à-vis patients who do respond to chronic neurostimulation. Thus, prior to implanting a chronic implantable sacral nerve root neurostimulator, a test is performed, lasting days or even weeks, to determine a patient’s response to the therapy. This test requires both internal and external equipment for percutaneous stimulation, is inconvenient, time-consuming, expensive, and suffers risks of infection and of the electrode being dislodged (e.g., the patient can pull it out...