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Interstim
Sacral Nerve Stimulation
(Medtronic InterStim® Therapy for Urinary Control)
Study Results
Medtronic conducted an international, multi-center clinical study using Medtronic InterStim Therapy. Patients included in the study had symptoms of urge incontinence, urgency-frequency or retention.
The study showed that the InterStim Therapy successfully treated the symptoms of urge incontinence, urgency-frequency or retention. The results of the study are summarized in Figure 7.

Figure 7 - Interstim
Figure 7. Clinical Study Results
*The multi-center study included 23 centers worldwide. A total of 581 patients were studied with 219 of them receiving InterStim Therapy.
**In patients with a baseline degree of >7 voids per day.
***Success is defined as increased voided volume with the same or reduced degree of urgency.
Problems or Complications
As with any surgical procedure, problems can occur. These problems may be resolved with reprogramming of the system, medications or surgery. The InterStim System can always be removed, if necessary.The following events and approximate rate of occurrence occurred during the InterStim Therapy clinical study: pain where the neurostimulator is placed (15%), new pain (9%), movement of the lead (8%), infection (6%), sudden and brief increase in stimulation - sometimes described as shocking or jolting - (6%), pain at lead site (5%), significant change in bowel function (3%) and other1 (16%).
The following problems each occurred less than 2% of the time: technical problems, suspected device problem, change in menstrual cycle, adverse change in voiding function, persistent skin irritation, suspected nerve injury, and device rejection. The following problems each occurred less than 0.5% of the time: change in sensation of stimulation, grand mal seizure, hematoma or seroma, urinary hesitancy, neurostimulator turns on or off, lack of orgasm, lack of efficacy, numbness and tingling, foot/leg movement, strong anal sensation, unable to perceive stimulation, stress urinary incontinence, swollen feeling in abdomen, vaginal cramps, superficial connection, and possible skin perforation at neurostimulator.
You should be aware that none of these problems in the clinical study resulted in permanent injury to patients. Additional information on clinical studies can be found at "www.interstim.com".
It is important to note that since this clinical study was conducted, changes in InterStim Therapy and surgical techniques have been made. For instance, the neurostimulator is now commonly placed in the upper buttock, rather than in the abdomen as in the original study. In addition, a new lead was developed which made the procedure much less invasive.
Candidates for SNS Therapy
Who Are Candidates for SNS Therapy?
SNS is intended for patients who have failed or could not tolerate more conservative treatments. Bladder control problems that may improve with SNS therapy include:
Overactive bladder (includes urge incontinence and urgency frequency-alone or in combination)
- Urge incontinence – The involuntary loss of urine associated with a sudden, strong desire to void (urgency).
- Urgency-frequency– Frequent, uncontrollable urges to urinate (urgency) and voiding often in very small amounts (frequency).
Urinary retention – The inability to empty the bladder
Interstitial cystitis patients with urgency/frequency, bladder pain, pelvic pain
Pelvic pain patients secondary to neuropathic disorders (pudendal neuropathy)
Patients suffering from fecal incontinence
Who Are Not Candidates for SNS Therapy?
InterStim Therapy is not intended to treat:
- symptoms of stress incontinence. People with stress incontinence lose urine when they exercise, sneeze, cough, or laugh.
- mechanical obstructions such as enlarged prostate (benign prostatic hypertrophy/BPH), cancer or narrowing of the urethra (urethral strictures). Safety and effectiveness of InterStim Therapy has not been studied for stimulation with two leads, or for patients who are pregnant, have diabetes, neurological diseases or multiple sclerosis, or are under 16 years old.
What Other Limitations Apply to SNS Therapy?
Some known limitations for this therapy include: a failed test stimulation, or inability to use the patient programmer. Patients with other stimulation devices such as a pacemaker may also not be candidates for SNS. Inform anyone treating you that you CANNOT have any shortwave diathermy, microwave diathermy or therapeutic ultrasound diathermy (all now referred to as diathermy) anywhere on your body because you have an implanted neurostimulation system. Energy from diathermy can be transferred through your implanted system, and can cause tissue damage, resulting in severe injury or death.
Is SNS a Cure for Bladder Control Problems?
As with any therapy, your own individual results may vary. While many patients implanted with InterStim Therapy experienced relief of many of their symptoms, the therapy will not result in complete improvement or a cure.
You should know that many patients have experienced positive results and experienced an improved quality of life after having the InterStim Therapy implanted. To learn more about the therapy, visit "www.interstim.com" or ask your doctor for the Medtronic patient manual and a brochure to read stories from patients who decided to have the InterStim System implanted.
