Sacral Neuromodulation for Lower Urinary Tract and Bowel Dysfunction in Animal Models: A Systematic Review With Focus on Stimulation Parameter Selection

Objective Conventional sacral neuromodulation (SNM) has shown to be an effective treatment for lower urinary tract and bowel dysfunction, but improvements of clinical outcome are still feasible. Currently, in preclinical research, new stimulation parameters are being investigated to achieve better and longer effects. This systematic review summarizes the status of SNM stimulation parameters and its effect on urinary tract and bowel dysfunction in preclinical research. Materials and Methods The literature search was conducted using three databases: Ovid (Medline, Embase) and PubMed. Articles were included if they reported on stimulation parameters in animal studies for lower urinary tract or bowel dysfunction as a primary outcome. Methodological quality assessment was performed using the SYRCLE Risk of Bias (RoB) tool for animal studies. Results Twenty-two articles were eligible for this systematic review and various aspects of stimulation parameters were included: frequency, intensity, pulse width, stimulation signal, timing of stimulation, and unilateral vs. bilateral stimulation. In general, all experimental studies reported an acute effect of SNM on urinary tract or bowel dysfunction, whereas at the same time, various stimulation settings were used. Conclusions The results of this systematic review indicate that SNM has a positive therapeutic effect on lower urinary tract and bowel dysfunction. Using low-frequency-SNM, high-frequency-SNM, bilateral SNM, and higher pulse widths showed beneficial effects on storage and evacuation dysfunction in animal studies. An increased variability of stimulation parameters may serve as a basis for future improvement of the effect of SNM in patients suffering from urinary tract or bowel dysfunction.