Long-term efficacy and safety results of the two-stage implantation technique in sacral neuromodulation.

OBJECTIVE: To assess the long-term efficacy and safety of two-stage sacral neuromodulation with an implantable pulse generator (IPG) in patients treated for urinary urge incontinence (UI) and/or urinary retention (UR).

PATIENTS AND METHODS: The two-stage technique is used if patients have a good response during the acute phase of the percutaneous nerve evaluation (PNE) test, but have a poor response during the following 4-7 days (subchronic phase). In the first stage only the permanent electrode was implanted and connected to a temporary external stimulator, allowing patients to be assessed for longer. If the main symptoms improved by more than half the patient proceeded to the second stage, the insertion of the IPG. We reviewed all patients who underwent two-stage implantation; all had signed an informed consent and were asked to complete voiding diaries and a questionnaire to assess the subjective effects of the therapy. Safety was assessed from relevant medical events, management, and relative to the thera-py and resolution. Residual urine was assessed by self-catheterization. The long-term voiding diary results were compared with baseline estimates and analysed statistically using the two-sided Student's t-test.

RESULTS: Between 1991 and 1998, 15 patients (13 women and two men, mean age 53 years, range 44-66) underwent the two-stage technique; the mean (median, range) follow-up was 4.9 (5.2, 2.5-7.5) years. Seven patients had UI and seven had UR, with one having both. The mean (range) number of PNEs undertaken in each patient was 2.1 (1-4) and these all failed in the subchronic phase. All patients underwent a first- and second-stage implant after a mean (range) screening period of 12.2 (2-29) days. One patient was explanted after implantation of only the first stage, and two others explanted in a later phase because the IPG was ineffective during the follow-up. The voiding diary results of the remaining 12 patients showed improvement in all the main variables, and in the subjective assessment 11 reported an improvement and were satisfied with the therapy. There were 17 adverse events, 14 of which were resolved and seven of which required surgical intervention.

CONCLUSION: The long-term results of the two-stage implantation show clinically and statistically significant improvements, probably because the implantation of the lead (first stage) more closely resembles the final therapy. If a temporary PNE test is not optimal (lead migration, longer testing needed), the two-stage technique can offer a good and safe alternative of comparable efficacy in the long-term. If the two-stage technique had not been available to these 12 patients they would not have been offered neuromodulation.