Sacral neuromodulation, which is also called interstim, acts in providing a small amount of electrical stimulation to the nerves that run through the tailbone (sacrum) to the bladder. For reasons we did not understand well that this can improve or eliminate bladder overactivity and urinary leakage. Another application of this therapy is for patients that develop urinary retention and cannot urinate effectively. This therapy can be thought of as a bladder pacemaker. The electrical stimulation is usually not something that causes pain or discomfort.
Who Should Have This Treatment?
One of the best applications of this therapy is for those women who have overactive bladder. In this condition with aging the bladder begins to give inappropriate signals to urinate and patients feel urgency and frequency of urination.
This is a condition that affects mostly in aged women. When this condition is severe in women, they will frequently have urinary leakage as a result of the bladder spasms. Another application of the therapy is in women, those who have a condition where their bladder stops working. This is referred to as Fowler’s syndrome. Often there is some precipitating factor like a recent unrelated surgery.
What Are Other Applications Of Sacral Neuromodulation?
There are some other conditions that can respond to the use of sacral neuromodulation:
- Spinal Cord Injury: One of these conditions is found in patients with partial spinal cord injury. Usually a good measure of partial spinal cord injury, which might give response to sacral neuromodulation is a patient with greater than 50 percent motor function below their injury. For instance some patients can walk after a partial spinal cord injury. These patients may respond to sacral neuromodulation and eliminate bladder spasticity or urinary retention.
- Multiple Sclerosis: Another potential application is patients with multiple sclerosis that have good lower extremity function and can walk well. In a similar way to partial spinal cord injured patients, the fact that these patients are ambulatory shows that many of the spinal pathways that are needed for this therapy to work are intact.
How Is Sacral Neuromodulation performed?
Sacral neuromodulation is an outpatient procedure that includes two operations about one to two weeks apart.
Operation 1 : In the first operation patients are in a twilight sleep with anesthetics and will lie on their stomach in the operating room. The locations of the nerves to the bladder are detected and electrodes are placed onto the nerve on both sides. The electrodes are connected internally to temporary small wires that come out of the side of the body. When the patient wakes up a temporary stimulator is connected to these wires. The patient then has the nerves stimulated for one to two weeks from this external unit. If the patient’s urinary problem is improved by 50 percent or resolved with the therapy than the permanent unit is placed.
Operation 2 : In this second operation the permanent electrodes placed in the first operation are connected to a stimulator that is implanted above the buttock and hipbone. This unit will last three to seven years depending upon several factors, like how much stimulation is needed. It can be changed, in the future, when the battery wears out in a small surgery without disturbing the permanent electrode in the nerve.
If the first surgery and the stimulation is not successful than in the second operation the electrodes are removed.