Monday, October 15, 2007

INTERSTIM, Part II

Neuromodulation of lower urinary tract problems has to do with the "gated theory" of bladder signals.
Simply put, the gentle electrical current that is delivered to the S3 root modulates or gates the signal in/out of the bladder that we try to treat. In OAB patients, the overactive signal is modulated, that is, lowered. The sense of urgency, frequency and incontinence that goes along with OAB is dimished often by 50-75%.

Conversely, Interstim is also indicated for urinary retention that is not due to obstruction (such as prostate enlargement in men). The electric signal stimulates the bladder to contract where it otherwise doesn't (or, blocks an inhibitory signal to the bladder that then allows the bladder to contract.)

Either way, its a fascinating technology that can vastly improve patients lives.

It is most often placed in a 2 stage procedure.

The first stage consists of placing the temporary lead through the skin in the back under x-ray guidance in the operating room. The patient is awake but sedated. The patient helps identify proper placement of the lead by what they sense: where they sense the "tingle".

Once the lead is placed, the patient goes home to see how well it works. The lead is hooked up to a small battery-operated pulse generator and can dial up or down the amplitude of the signal.

About 2/3 of patients respond. They go on to have the permanent lead and generator placed.

About 1/2 of non-responders to Stage I can be salvaged by redoing it.

Even once placed, the amplitude and width of the electrical signal can be adjusted depending on sensation and need.

No comments: