Enhanced percutaneous nerve evaluation (ePNE) of sacral nerve stimulation (SNS) using a double-blinded sham-controlled crossover test for idiopathic constipation: Quantitative and Qualitative enquiries.
(The TiLTS-cc and Essence studies)

Abstract

Abstract
Introduction: Sacral nerve stimulation (SNS) has been increasingly utilised as a clinical treatment for chronic constipation (CC), but only a small subgroup of patients seem to respond to costly long-term treatment and the peripheral nerve evaluation test (PNE) appears less accurate than in other conditions. The lived experience of patients receiving SNS treatment, within a trial or in routine practice for any condition, is also unknown.
Methods: Two systematic reviews were conducted to evaluate i) the efficacy of SNS testing, and ii) the patient experience. This was followed by a randomised sham-controlled crossover trial of a newly devised enhanced peripheral nerve evaluation (ePNE) test for SNS (the TiLTS-cc study), and a qualitative study of experiences of receiving SNS treatment for CC (the Essence study).
Results: A total of 45 people were randomised, from which 29 (64%) were responders and 27 were implanted with a permanent pulse generator. At 6 month follow up there was no evidence of a difference in response between ePNE discriminate responders (60%) or ePNE indiscriminate responders (57%) (P=0.76, sensitivity 75%, specificity 15%). The study was terminated early (45/75) due to concerns regarding safety, with an infection rate of 22%. Qualitative findings, with a total of 8 people, demonstrate a constant pursuit for control over the disease, a willingness to participate in an invasive trial motivated by desire for a curative treatment, and perceptions of symptom benefit that trial definitions of benefit did not fully capture.
Conclusion: The ePNE test of SNS cannot be recommended for any condition due to the high infection risk. The effect of SNS in treating CC may simply be a placebo effect, or sub-sensory SNS may be ineffective for CC. Because of patient willingness to participate in highly invasive and intrusive trials, trial design in this population should carefully monitor ongoing patient burden and patient perceptions of benefit.