Sacral Neuromodulation (SNM)
InterStim therapy is indicated for people with urinary retention, overactive bladder with or without urgency urinary incontinence, and anal incontinence or accidental bowel leakage. The therapy utilizes an innovative and implantable neurostimulator about the size of a stop watch. This device sends mild electrical signals to a nerve located just above the tail bone. This sacral nerve activates or inhibits muscles and smaller nerves that contribute to urinary and bowel control. It also provides signals to the brain about these organs.
How does SNM work?
SNM alters the function of the sacral nerves and the signals they send to the brain regarding bladder and bowel sensations. If the brain and sacral nerves are not communicating effectively, the pelvic organs (bladder and bowel) are not able to function correctly. SNM restores the “normal” communication between the sacral nerves and brain by delivering electrical pulses to the sacral nerves. The electrical stimulation provided by the implantable device helps to modulate signals to the bladder and bowel and may eliminate or reduce bladder and bowel control problems.
How is SNM performed?
In brief, a small stimulator device is placed underneath the skin near the back of your hip. This is connected to a wire which is located near the sacral nerves and delivers the electrical pulses. Finally, a small hand-held device communicates with the stimulator and allows you to adjust the level of stimulation or turn the device on and off.
Before you undergo SNM, you must complete a baseline bladder and/or bowel diary. This provides you and your urogynecologist with valuable baseline information. Next, SNM therapy is delivered in two procedures. The first is the test stage to see if the therapy will work for you. A test stage is used before implantation of the device to see what the effect of the stimulation is on your symptoms. If this test stage produces positive results for you, the lead will stay in place, and you will proceed to the permanent implant.
How long will SNS last?
The lifetime of the battery ranges from 5-10 years. You and your urogynecologist will know when the battery life is low (as indicated on the controller), and at that time we will place a new battery. Most times, the wire does not need to be adjusted. Occasionally, women fall or have an accident which might affect the placement of the wire. If this happens, your urogynecologist will evaluate the location of the wire and might have to revise its location.
What are the potential risks associated with SNS?
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. Although rare, some risks include infection, pain, and lead movement.
Women who have InterStim devices implanted are unable to undergo most MRI studies. If you need to have an MRI, the wire and battery will likely need to be removed.
If at any time your SNM device needs to be removed, this is an easy procedure which is performed in the operating room.
When does a woman choose to pursue this treatment?
Many women find that treatments such as drugs, behavior modification, diet changes, pelvic floor exercises or the use of a catheter to empty the bladder do not effectively treat their symptoms. SNM is a great option for women who have not had adequate symptom control with other therapies.
How should I prepare for SNM?
You will need to fill out a bladder or bowel diary before and during the test phase (your urogynecologist will give this to you). It is very important that you fill out this diary honestly and completely as this will serve as your baseline prior to the examination. You will be given specific instructions regarding the preparation for surgery.