Re-operation rates after permanent sacral nerve stimulation for refractory voiding dysfunction in women

Objective To describe the development of screening tests and to identify re-operation rates after the permanent implant phase, and its characteristics, of the Interstim (R) (Medtronic, Inc., Minneapolis, MI, USA) device for sacral nerve stimulation (SNS). Patients and Methods We retrospectively reviewed the charts of women who had SNS between January 1998 and December 2005; their demographic, clinical and surgical information was abstracted. Descriptive statistics, chi-square and analysis of variance were used to compare the results. Results In all, 95 patients had 105 test procedures; 30 peripheral nerve evaluation (PNE) and 75 staged tined leads. Response rates were lower in the PNE than in the tined lead (40% vs 67%, P = 0.01). The indication for SNS was associated with the response rate, with urinary retention having the highest response (71%, P = 0.01). For the 55 implanted devices, there were 18 revisions (33%) and eight explants (15%). The main reasons for revision or explants were loss of efficacy (16/26) and pain at the implant site (six of 26). The median (range) time to intervention after implantation was 17 (1.2-75.0) months, and this was significantly associated with the indication. Revisions due to pain at the implant site were within the first year, and re-operations due to loss of efficacy after 1-2 years, whereas battery replacement was required on average 4 years after initial implantation. Conclusion This study confirms the higher response rates of the tined-lead staged technique over PNE. Unobstructive urinary retention had the highest response rates. The reason for revision appeared to be largely predicted by the length of time since implantation.