Evaluations allow patients to try sacral neuromodulation delivered by the InterStim™ system to assess its efficacy as well as its sensation, so they can make an educated decision with their physician about whether to proceed with implantation. In general, the evaluation is successful if the patient experiences a significant (50% or greater) reduction in symptoms.
The basic evaluation (also referred to as peripheral nerve evaluation or PNE) is typically used to evaluate patients with bladder control problems. It is initiated through a simple, in-office procedure, during which the lead is placed in the upper buttock.
This lead connects to an external neurostimulator (ENS) that the patient wears on a belt. For approximately 3-7 days (depending on physician guidance) the patient completes a symptom diary that is eventually compared to a baseline (established by using a symptom diary prior to the evaluation).
The advanced evaluation (also referred to as Stage 1) is initiated through an outpatient procedure performed in a hospital or surgical center.
The patient also wears an ENS during the advanced evaluation, which lasts up to 14 days (depending on physician guidance). Symptom diaries are used to measure results.
Both evaluations are reversible. Complications can occur with the evaluation, including movement of the wire, technical problems with the device, and some temporary pain. Patients should be instructed on operating the test device and given other precautions related to the evaluation, including activity restrictions.