AIM: This randomized single-blinded crossover study aimed to investigate whether bilateral sacral nerve stimulation (SNS) is more efficient than unilateral stimulation for faecal incontinence (FI).

METHOD: Patients with FI who responded during a unilateral test stimulation, with a minimum improvement of 50% were eligible. Twenty-seven patients who were accepted to enter the trial were bilaterally implanted with two permanent leads and pacemakers. Patients were randomized into three periods of 4 weeks' stimulation including unilateral right, unilateral left and bilateral stimulation. Symptoms scores and bowel habit diaries were collected at baseline and in each study period. A 1-week washout was introduced between each study period.

RESULTS: Twenty-seven (25 female) patients with a median age of 63 (36-84) years were bilaterally implanted from May 2009 to June 2012. The median number of episodes of FI per 3 weeks significantly decreased from 17 (3-54) at baseline to 2 (0-20) during stimulation on the right side, 2 (0-42) during stimulation on the left side and 1 (0-25) during bilateral stimulation. The Wexner incontinence score improved significantly from a median of 16 (10-20) at baseline to 9 (0-14) with right-side stimulation, 10 (0-15) with left-side stimulation and 9 (0-14) with bilateral stimulation. The differences between unilateral right or unilateral left and bilateral stimulation were non-significant, for FI episodes (P = 0.3) or for Wexner incontinence score (P = 0.9).

CONCLUSION: Bilateral SNS therapy for FI is not superior to standard unilateral stimulation in the short term. Equal functional results can be obtained regardless of the side of implantation.