Urodynamic changes and response rates in patients treated with permanent electrodes compared to conventional wire electrodes in the peripheral nerve evaluation test

Abstract

Sacral neuromodulation having become established as an essentially effective new therapeutic modality, both in patients with anticholinergic-therapy refractory overactive bladder (OAB) and with chronic urinary retention. It is important to establish which patients might profit from this kind of therapy in order to ensure, by means of a peripheral nerve evaluation (PNE) test, that the implantation of a permanent stimulating device is effective. In a retrospective study we compared the urodynamic outcome of two different techniques (implantation of the permanent neurostimulation electrodes so-called "two-stage-implantation" vs. conventional PNE). We performed a sacral nerve stimulation in 53 patients (30 urinary retention, 23 OAB syndrome). In 42 patients, we performed a conventional PNE, 11 patients received "two-stage-implantation" with implantation of the permanent electrodes. In 20 cases the conventional PNE-test (cPNE) was successful (47.6% of all cPNE). The response rate of "two-stage-implantation" (permanent electrodes) was 81.8%. In patients with overactive bladder the bladder capacity was increased by 30% with cPNE (P = 0.068) versus 52% when permanent electrodes were used (P = 0.017). Bladder instabilities were reduced by ca. 75%. In urinary retention, the cPNE versus permanent electrodes led to an increase of the maximum detrusor pressure by 68 versus 94% with reduction of residual urine by 71% (P = 0.068) versus 66% (P = 0.042). The results of this study show that application of permanent quadripolar electrodes during PNE prior to chronic neuromodulator implantation leads to significantly higher responder rates and enables more efficient patient selection.