Abstract: PD54-03
Sources of Funding: SUFU neuromodulation grant

Introduction

Current practice at our high-volume tertiary referral hospital aims to optimize lead placement at the superior medial aspect of the S3 foramen and achieve lead thresholds under 2mA for all four electrodes sites. This analysis aims to summarize our experience with optimized technique, and evaluate the impact of baseline factors on progression to stage 2 SNM implant.

Methods

This is a cross sectional analysis of all stage 1 lead placement SNM cases from August 2014-October 2016. After a 2 week trial period, patients received a stage 2 SNM pulse generator implant if voiding diaries reflected ≥50% symptom improvement. Otherwise, the lead was removed. We performed univariate analysis on demographic, clinical and intraoperative factors comparing patients who progressed to stage 2 with those whose leads were removed after the trial period. Multivariate analysis with logistic regression was performed using R version 3.2.1.

Results

89% of the total 108 stage 1 lead placements progressed to stage 2. 91% of subjects were female. Cumulative indications for SNM were 95% refractory urgency/urgency incontinence, 16% idiopathic urinary retention, and 29% fecal incontinence. Several factors were associated with progression to stage 2 implant (see table 1). Multivariate analysis revealed that history of prior failed 3rd line therapy was independently associated with lead removal (OR 17, CI 2.9-132, p=0.003), and there was a trend toward significance for pelvic pain (OR 4.8, CI 0.9-27, p=0.06).

Conclusions

Optimized lead placement technique can achieve motor and sensory thresholds <2mA in all electrodes and 89% conversion rate to stage 2 SNM. Our analysis was limited by small lead removal group size, but history of pelvic pain and prior SNM implant appear to be associated with lead removal after the 2 week trial.

Funding

SUFU neuromodulation grant