Improving neuromodulation technique for refractory voiding dysfunctions: two-stage implant

Neuromodulation is a new technique that uses electrical stimulation of the sacral nerves for patients with refractory urinary urge/frequency or urge-incontinence, and some forms of urinary retention. The limiting factor for receiving an implant is often a failure of the percutaneous nerve evaluation (PNE) test. Present publications mention only about a 50% success score for PNE of all patients, although the micturition diaries and urodynamic parameters are similar. We wanted to investigate whether PNE results improved by using a permanent electrode as a PNE test. This would show that improvement of the PNE technique is feasible.

In 10 patients where the original PNE had failed to improve the micturition diary parameters more than 50%, a permanent electrode was implanted by operation. It was connected to an external stimulator. In those cases where the patients improved according to their micturition diary by more than 50% during a period of 4 days, the external stimulator was replaced by a permanent subcutaneous neurostimulator.

Eight of the 10 patients had a good to very good result (60% to 90% improvement) during the testing period and received their implant 5 to 14 days after the first stage.

The good results of the two-stage implant technique we used indicate that the development of better PNE electrodes may lead to an improvement of the testing technique and better selection between nonresponders and technical failures.