[Bipolar stimulation may improve the efficacy of the percutaneous nerve evaluation test of sacral neuromodulation]

Purpose This study evaluates the hypothesis that bipolar stimulation of the S3 and S4 sacral roots may enhance the efficacy of the percutaneous nerve evaluation (PNE) test. Material and Methods In this case-control-study, we enrolled 43 patients undergoing bipolar PNE and 57 controls undergoing unipolar PNE. For bipolar PNE, four test electrodes were placed at the bilateral S3 and S4 roots. The electrodes at the S3 and S4 roots of each side were connected to obtain bipolar stimulation. The test protocol over eight days included unilateral and bilateral stimulation of the S3 and S4 sacral roots. Eight days after implantation, the electrodes were removed and test results from bladder diaries were collected. Results The unipolar test procedure was successful in 47 % (27/57) of cases. The bipolar test procedure was successful in 58 % (25/43). In the bipolar group, 63 % (12/19) of patients with neurogenic tract dysfunction profited from treatment, vs. 57 % (13/23) in the unipolar group. Patients without a neurologic disease had a successful test in 58 % (14/24) of cases treated with bipolar PNE vs. 41 % (14/24) treated with unipolar PNE. Multivariate analysis did not reveal a statistically significant difference between groups. Conclusion Although not significant in this population, bipolar PNE may improve efficacy compared to the unipolar test procedure. Similar observations were made in subgroups of neurogenic and non-neurogenic bladder dysfunctions.