Duelund-Jakobsen J¹, Buntzen S¹, Laurberg S¹, Lundby L¹. Colorectal Dis. 2019 Oct 13. doi: 10.1111/codi.14874. [Epub ahead of print]

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1 Pelvic Floor Unit, Department of Surgery, Aarhus University Hospital, Palle Juul-Jensens, Boulevard 99, 8200, Aarhus N, Denmark.

Abstract

Sacral nerve stimulation (SNS) for faecal incontinence (FI) at sub-sensory amplitude as low as 50% of sensory threshold has been found to be effective at 3-months follow-up. Furthermore, alternative pacemaker settings may improve functional outcome in patients with sub-optimal treatment efficacy.

AIM: To explore if sub-sensory stimulation as low as 50% of sensory threshold is effective at one-year follow-up. This study also aimed to investigate if 31Hz (frequency) or 90µsec (pulse-width) stimulation improved treatment efficacy in dissatisfied patients.

METHOD: All patients in whom the stimulation was effective in controlling FI (satisfied group ) were encouraged to have the stimulation amplitude reduced. Those in whom the device was less effective (dissatisfied group) were offered alternative amplitude and frequency settings (31Hz or 90µsec). Patients were follow-up after 12-months and evaluated by VAS for patient satisfaction, Cleveland Clinic Continence score (CCCS), Rockwood QoL and bowel habit diary.

RESULTS: 219 patients were contacted with a response rate of 71% (n=155). Those successfully contacted comprise 110 (71%) patients were classed as satisfied and 45 (29%) as dissatisfied. Seventy-five(68%) of the satisfied agreed to have their stimulation amplitude reduced.. At one-year follow-up the median amplitude had reduced from 1.5 (0.85-2.0) to 0.75 (IQR: 0.45-1.4) volts (P-value: <0.001) representing an overall reduction of 39 (IQR:6.6-62.5) %. There was no significant differences in VAS, CCCS or QoL despite sub-sensory stimulation at one year follow-up. In 28% of the dissatisfied patient Alternative pacemaker settings improved VAS to satisfactory levels in those patients initially classed as dissatisfied.

CONCLUSION: Sub-sensory stimulation is as effective as stimulation at or above the sensory threshold. High frequency stimulation (31Hz) can improve functional outcome in patients with loss of efficacy.