The Effect of Pulse Rate Changes on Clinical Outcome in Sacral Neuromodulation

Objectives: To evaluate the effect of pulse rate changes on the clinical response and stimulation related pain symptoms in sacral neuromodulation (SNM) treatment.

Materials and Methods: This pilot study evaluated the effect of 4 different pulse rates (5.2Hz-10Hz-21Hz-40Hz) in patients with suboptimal response to SNM. The effect of each frequency was evaluated over test period of 6 days. To avoid carry over effect, stimulation was kept off for 24 hours between consecutive test periods. The last 3 days of every test period, a voiding diary (VD) and questionnaire was filled in. The changes on clinical response and pain symptoms were compared between the four pulse-rates using multivariate analysis.

Results: Fifty patients were included of which 40 (80%) were female. Mean age was 55.5yr (SD 12.3). Forty-one patients (82%) had overactive bladder symptoms and 9 (18%) had chronic non-obstructive urinary retention. No significant difference was found regarding clinical outcome (VD and questionnaire) between the different pulse rates. Furthermore, none of the four pulse rates was significantly related to the occurrence of SNM-related pain. However, on individual basis, patients appear to benefit from changing the pulse rate concerning both treatment efficacy and stimulation related pain.

Conclusions: On group level, none of the four pulse rates in this study appears to have a significantly different effect on clinical outcome or SNM-related pain. However, a tailor-made approach for optimizing treatment efficacy by changing the pulse rate might be useful.