The effect of pulse rate changes on the clinical outcome of sacral neuromodulation

We evaluated the effect of pulse rate changes on the clinical response to and stimulation related pain symptoms of sacral neuromodulation treatment.

In this pilot study we evaluated the effect of 4 pulse rates, including 5.2, 10, 21 and 40 Hz, in patients with a suboptimal response to sacral neuromodulation. The effect of each frequency was evaluated during a 6-day test period. To avoid the carryover effect stimulation was discontinued for 24 hours between consecutive test periods. On the last 3 days of each test period a voiding diary and questionnaire were completed. Changes in the clinical response and pain symptoms were compared between the 4 pulse rates using multivariate analysis.

Of the 50 patients included in the study 40 (80%) were female. Mean ± SD age was 55.5 ± 12.3 years. Of the patients 41 (82%) had overactive bladder symptoms and 9 (18%) were in chronic nonobstructive urinary retention. No significant difference was found in clinical outcome on the voiding diary and questionnaire between the pulse rates and none of the 4 rates was significantly related to sacral neuromodulation associated pain. However, individuals appeared to benefit from changing the pulse rate in terms of treatment efficacy and stimulation related pain.

On the group level none of the 4 pulse rates appeared to have a significantly different effect on clinical outcome or sacral neuromodulation related pain. However, an individualized approach to optimize treatment efficacy by changing the pulse rate appears to be useful.