Improving the efficacy of sacral nerve stimulation for faecal incontinence by alteration of stimulation parameters

Sacral nerve stimulation (SNS) is an effective treatment for faecal incontinence, but only standard stimulation parameters have been used. This study assessed the clinical impact of altering the parameters.

Twelve patients with partially improved faecal incontinence following SNS underwent acute testing to select optimal stimulation parameters; rectal compliance was used as a surrogate marker. Parameters tested were: stimulation off; frequency 14 (standard), 31 or 6.9 Hz; and pulse duration 210 (standard), 450 or 90 micros. Patients completed a 2-week bowel diary, St Mark's continence score (SMCS) and Rockwood faecal incontinence quality-of-life (FIQL) score before testing using standard settings, and after testing using optimized settings.

Optimal settings, determined by greatest increase in rectal compliance, were shorter pulse width in five patients and higher frequency in seven. Optimized stimulation resulted in a decrease in mean episodes of incontinence from 2.3 to 1.2 per week (P = 0.031), soiling from 3.3 to 1.7 days per week (P = 0.016), faecal urgency from 31 to 18 per cent of all evacuations (P = 0.055) and SMCS from 12.3 to 8.7 (P = 0.008); the FIQL coping/behaviour score improved (P = 0.008).

With a shorter pulse width and higher frequency, clinical efficacy in patients undergoing SNS for faecal incontinence can be improved.