Urinary Incontinence
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InterStim™
The InterStim Continence Control System is a minimally invasive therapy that has been approved by the Food and Drug Administration for the treatment of intractable urgency (Over Active Bladder), urge incontinence, as well as non-obstructive urinary retention.
Urinary urge incontinence is quite common, with a prevalence of 20-25% in men and women between the ages of 50 and 70 years old. In individuals over than 70, the incidence has been estimated at 40%. The incidence of Over Active Bladder (OAB) is even higher.
The usual treatment regimen for the symptoms of urgency, frequency and urge incontinence include fluid management, behavioral management (timed voiding) as well as pelvic floor physiotherapy, and pharmacologic intervention. The drugs that are commonly used are known as antimuscarinic agents. The number of these drugs is increasing, with at least 4 new agents coming to market within the last 2 years. While some individuals will have success with one or more of these drugs, they are not the panacea for which we had hoped. This is primarily due to side effects including dry mouth, constipation, and even cognitive changes.
Attempts at finding newer and more effective modalities to treat this common symptom complex have been ongoing, and have included use of neurotoxins, such as botulinum. While success has been noted, the use of this agent is limited by the need to reinject every 4-6 months to maintain efficacy. It is also limited by the fact that the required dosage may vary from individual to individual, with some trial and error involved in finding the correct amount to inject. Furthermore, it is not yet approved by the FDA for use in the bladder.
InterStim utilizes electrical stimulation of the sacral nerves via an electrode that is implanted in the 3rd Sacral neural foramen, and connected to an intermittent pulse generator (IPG). This battery may last 6 to 10 years before a change is required.
While originally promoted as the treatment of last resort, InterStim is becoming another major step in the treatment algorithm for individuals with severe symptoms. The change in its use has been attributed to the advances made in the method of implantation. One or two leads can be placed percutaneously and attached to a temporary battery pack for a test period lasting from 1-2 weeks. If the test is successful, the IPG is then implanted. If there is no improvement, the leads are removed.
Multicenter studies have shown that the greatest success has been achieved in women under the age of 55. In one study 40% of women remained dry after 1 year. The remainder of the study participants sustained a greater than 50% improvement in their symptoms. In another study, with women older than 55, only 17% were totally dry after the implant. Once again, the remainder of participants achieved greater than 50% improvement in their symptoms. (Siegel, Groen,Spinelly,Amundsen)
Another use for InterStim has been for the treatment of idiopathic urinary retention. In these cases, obstruction must be ruled out, and there can be no obvious neurological cause for the urinary retention. The stimulation of the sacral nerves is thought to turn off the abnormally elevated excitatory activity in the urethra, which allows for normal voiding to resume. In studies presented to the FDA by Medtronic, 61% of individuals were able to eliminate the use of catheters. 16% experienced greater than 50% reduction in the catheterized urine volume.
More information can about InterStim and its effectiveness may be obtained from your physician, who will arrange a visit with a Medtronic Clinical Technician. This individual can review details involved in the entire test and implant procedure, as well as arrange contact with a person who has already undergone the procedure.