Factors affecting the outcome of temporary sacral nerve stimulation for faecal incontinence. The value of the new tined lead electrode

Aim Sacral nerve stimulation (SNS) is an effective but expensive treatment for faecal incontinence. About 50% of the patients are unresponsive for unknown reasons, hence knowledge of any factors predictive of success would be highly desirable. The aim of this study was to analyse the potential factors associated with a successful outcome of the temporary test of electrostimulation. Method Eighty-five patients with faecal incontinence were tested for SNS. The cause was idiopathic in 45, iatrogenic or obstetric in 28, spinal lesion or neurological diseases in nine and anal malformation in three patients; 43 were tested with a unipolar electrode and 42 with a quadripolar electrode. The severity of faecal incontinence was evaluated using the American Medical System (AMS) score and Wexner's score. Results A positive response was obtained in 45 patients (53%); 40 (47%) were implanted with a permanent pulse generator. Responders and nonresponders were comparable in age, duration of incontinence, anal manometry, pudendal nerve terminal motor latency and diabetes. Unipolar electrode test (PNE test) was able to elicit positive responses in 18 of 43 (42%) and the quadripolar in 27 of 42 patients (P < 0.001). Type of incontinence and gender did not affect the success rate. Patients with idiopathic incontinence had a significantly higher response rate (P = 0.022). Multivariate regression analysis indicated use of a quadripolar electrode as the only independent variable predicting the success of SNS (OR = 5.58, P = 0.009). Conclusion Use of the quadripolar electrode is the only factor significantly related to the success of SNS.