Sacral nerve stimulation induces pan-colonic propagating pressure waves and increases defecation frequency in patients with slow-transit constipation.

ABSTRACT

OBJECTIVE: Colonic propagating sequences are important for normal colonic transit and defecation. The frequency of these motor patterns is reduced in slow-transit constipation. Sacral nerve stimulation (SNS) is a useful treatment for fecal and urinary incontinence. A high proportion of these patients have also reported altered bowel function. The effects of SNS on colonic propagating sequences in constipation are unknown. Our aims were to evaluate the effect of SNS on colonic pressure patterns and evaluate its therapeutic potential in severe constipation. METHOD: In eight patients with scintigraphically confirmed slow-transit constipation, a manometry catheter (16 recording sites at 7.5 cm intervals) was positioned colonoscopically and the tip fixed in the caecum. Temporary electrodes (Medtronic) were implanted in the S2 and S3 sacral nerve foramina under general anaesthesia. In the fasted state, 14 Hz stimulation was administered and four sets of parameters (pulse width 300 or 400 micros; S2 and S3) were tested in four 2-h epochs, in random order, over 2 days. Patients were then discharged home with the sacral wires in situ and a 3-week trial stimulation commenced during which patients completed a daily stool diary. RESULTS: When compared with basal activity, electrical stimulation to S3 significantly increased pan-colonic antegrade propagating sequence (PS) frequency (5.4 +/- 4.2 vs 11.3 +/- 6.6 PS/h; P=0.01). Stimulation at S2 significantly increased retrograde PSs (basal 2.6 +/- 1.8 vs SNS 5.6 +/- 4.8 PS/h; P=0.03). During the subsequent three-week trial (continuous stimulation), six of eight reported increased bowel frequency with a reduction in laxative usage. CONCLUSION: These data demonstrate that SNS induces pan-colonic propagating pressure waves and therefore shows promise as a potential therapy for severe refractory constipation.