Predictive factors of PNE success in a contemporary series: A single institution experience

Peripheral nerve evaluation (PNE) permits a trial of sacral neuromodulation to determine candidates for single stage implant. Before routine fluoroscopy, PNE success rates were 40%-50% compared to approximately 77% with staged procedures. There are limited data on PNE success rates with the use of fluoroscopy and improved techniques. We evaluated a contemporary series of PNE patients to determine predictors of PNE success and persistent functional response following permanent implantation.

A retrospective review of PNE patients at a large academic center from 2015 to 2019 was performed. Patients with urgency-frequency, urge incontinence, and/or fecal incontinence (FI) were included. Rates of permanent implant after successful PNE trial and continued improvement at ≥1 month were reviewed. Multivariable logistic regression determined predictors of PNE success and continued response at follow-up.

A total of 102 PNE patients were included. A total of 78 patients (76.5%) were PNE responders. Predictors of PNE success included younger age (p = .014), urgency incontinence (p = .021), FI (p = .017), absence of a neurologic diagnosis (p = .04), presence of bellows and toe responses (p = .038), and perineal sensation (p = .027). A total of 68 of 78 PNE responders (87.2%) maintained optimal responses at ≥1 month. Absence of a neurologic diagnosis was predictive of persistent success at follow-up (p = .013).

This contemporary PNE series revealed screening success equivalent to a two-staged approach. A small proportion of patients demonstrate suboptimal responses following permanent implant. Conversion from testing to permanent implant may not be the ideal outcome as it may overestimate success, and evaluation for persistent improvement should be investigated further as a more reliable indicator of successful screening.