Improved longevity and efficacy of sacral nerve stimulation by simple adjustments at follow‐up

Abstract

Aim Sacral nerve stimulation (SNS) for faecal incontinence (FI) at subsensory amplitudes as low as 50% of the sensory threshold has been found to be effective at 3 months’ follow‐up. Furthermore, alternative pacemaker settings may improve functional outcome in patients with suboptimal treatment efficacy. In this work we aim to explore if sub‐sensory stimulation as low as 50% of sensory threshold is effective at 1‐year follow‐up. We also aimed to investigate if 31 Hz (frequency) or 90 µs (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 frequency settings or pulse width (31 Hz or 90 µs). Patients were follow‐up after 12 months and evaluated by a visual analogue scale (VAS) for patient satisfaction, the Cleveland Clinic Continence Score (CCCS), Rockwood Faecal Incontinence Quality of Life Scale (QoL) and a bowel habit diary. Results Two hundred and nineteen patients were contacted, with a response rate of 71% (n = 155). Those who were successfully contacted comprised 110 (71%) patients classed as satisfied and 45 (29%) as dissatisfied. Seventy‐five (68%) of the satisfied patients agreed to have their stimulation amplitude reduced. At 1‐year follow‐up the median amplitude had reduced from 1.5 V [interquartile range (IQR) 0.85–2.0 V] to 0.75 V (IQR 0.45–1.4 V) (P‐value < 0.001) representing an overall reduction of 39% (6.6–62.5%). There were no significant differences in VAS, CCCS or QoL despite subsensory stimulation at 1‐year follow‐up. In 28% of the dissatisfied patients alternative pacemaker settings improved VAS to satisfactory levels. Conclusion Subsensory stimulation is as effective as stimulation at or above the sensory threshold. High‐frequency stimulation (31 Hz) can improve functional outcome in patients with loss of efficacy.

Stimulation Parameters for Sacral Neuromodulation on Lower Urinary Tract and Bowel Dysfunction–Related Clinical Outcome: A Systematic Review

“…An additional 4042 papers were excluded after title and abstract screening. Screening of the 83 full papers resulted in exclusion of 45 additional papers, resulting in 38 papers that were included, of which 17 were clinical papers (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33).…”

“…In detail, 11 papers included were RCTs with a crossover design (17,18,20,21,23,25,26,28,(30)(31)(32). One paper used a RCT design with parallel groups (22) and five papers were based on case series analysis (19,24,27,29,33), of which four prospectively (19,27,29,33) and one retrospectively (24). Eight papers studied the effect of cycling vs. continuous stimulation on urinary and bowel dysfunction (17)(18)(19)(20)(21)(22)(23)(24).…”

“…Standard, conservative settings for SNM frequency and pulse width are 7-20 Hz and 100-300 μsec, respectively. The effect of low (<7 Hz) and high frequency (>20 Hz), and narrow (<100 μs) and wide (>300 μs) pulse width on SNM efficacy in both urinary tract dysfunction and bowel dysfunction were studied (25)(26)(27)(28)(29).…”

“…However, there is no scientific evidence to back up setting SNM amplitude at this level. The effect of subsensory stimulation, as compared to SNM at sensory threshold, was analyzed in three studies (29,32,33).…”

Anorectal angle at rest predicting successful sacral nerve stimulation in idiopathic fecal incontinence—a cohort analysis

“…In order to preclude heterogeneity of the study cohort and intermixing different causes of FI, only patients with idiopathic FI were included. Patients were classified as having idiopathic FI if there was no history of disorders of the central nervous system such as stroke or incomplete spinal cord injury, no diabetic neuropathy, and no larger sphincter injury (> 45°) or any defect of the pelvic floor in endoanal ultrasound [ 11 ]. Further exclusion criteria were low anterior resection syndrome (LARS) and male gender for obtaining a homogeneous patient population.…”