Is the Method of Screening in Sacral Neuromodulation a Prognostic Factor for Long-term Success?

We evaluated all patients screened for eligibility to receive SNM treatment since the introduction of the tined lead technique in our centre in 2002. In May 2009, all implanted patients were asked to keep a voiding diary to record the effect of SNM on urinary symptoms. Success was defined as more than 50% improvement in at least one of the relevant voiding diary parameters compared to baseline. Chi square analysis was used to evaluate differences in long-term outcome for the separate screening methods.

Results: In total, 92 patients were screened for SNM. Of the 76 patients who were screened with PNE, 35 (46%) met the criteria for permanent implantation, whereas 11 of the 16 patients (69%) who underwent direct screening with TLP had permanent stimulators placed. Of the 41 patients who failed PNE and subsequently underwent screening with TLP, 18 (44%) were implanted with an INS after showing a successful response. The mean follow-up was 53 months (range 35-77 months) at the time of voiding diary analysis. Statistical analysis showed no difference between type of screening and long-term success (p=0.94).

Conclusion: Although first stage TLP is a more reliable screening tool than PNE, the long-term success rate does not seem to be dependent on the screening method. Furthermore, patients who initially failed PNE but responded to prolonged screening with TLP, appear to be at least as successful in the long-term as patients who directly responded to PNE or TLP.