To determine the long term outcomes of a cohort of patients implanted with a sacral nerve stimulator for the treatment of  constipation

A series of patients with severe medically refectory constipation were implanted with SNS devices between 2011 and 2016. The long term clinical outcomes of patients who underwent permanent SNS from this cohort were analysed. Fifteen patients with severe medically refractory constipation were identified to be suitable for SNS therapy. SNS was performed by the standard 2-stage technique (temporary then permanent implantation).  Long term clinical outcomes of all these patients were studied. Reportable events were collected prospectively on 'open label'. Study endpoints were selected from a previous study by Maeda et al. [1] of clinical outcomes and reportable events in SNS patients treated for faecal incontinence. Outcomes were classified into three ordinal categories: good, acceptable and suboptimal. Reportable events included suboptimal therapeutic responses, adverse events and other events related to the SNS that required additional clinical management.

12 of 15 patients who originally underwent peripheral nerve evaluation had further permanent implantation of the device. At median follow up of 8 (6-12) years, 4 (33%) had a good outcome; 4 (33%) had an adequate outcome; 4 (33%) had a suboptimal outcome.  At last follow up, 9 (75%) implantable devices were in situ. Three devices had been explanted for suboptimal outcomes. 31 reportable events requiring intervention by the team were documented. This led to 35 clinical interventions (28 conservative interventions and 8 operative interventions). Operative interventions included: 5 repositioned leads, 3 device removals, 1 stimulator exchange and 1 procedure to reposition the lead and revise the stimulator site within the same operation. Of all these interventions 5 patients had complete resolution of their reportable events.

Although our series contains only 12 patients, the findings suggest that SNS therapy for patients with constipation provide good effective long term clinical outcomes for about a third of patients. In another third of patients the treatment can be effective but requires multiple clinical interventions to maintain some effectiveness of the therapy. This could lead to rising overall costs.

Up to two thirds of the patients having SNS therapy for constipation can benefit from the therapy but there may be multiple interventions required to maintain effectiveness which led to high costs for intervention and clinician time. SNS therapy for constipation does not seem to be as effective as long term data for faecal incontinence, particularly for urge faecal incontinence.

Maeda, Y., et al., Suboptimal outcome following sacral nerve stimulation for faecal incontinence. Br J Surg, 2011. 98(1): p. 140-7.