Effects of Appropriate Prolonged Sacral Neuromodulation Testing in Improving Implantation Rate of a Permanent Implantable Pulse Generator in Patients with Refractory Lower Urinary Tract Dysfunctions in Mainland China

BACKGROUND Sacral neuromodulation (SNM) has become an effective method for treating lower urinary tract voiding dysfunction during the past 20 years. Because of the expensive cost, the number of implantable pulse generator (IPG) implantations per year in China is far lower than that in Western developed countries since 2012. This study was to summarize the effects of the appropriate prolonged SNM testing time in improving the implantation rate of a permanent IPG in patients with refractory lower urinary tract symptoms (LUTS) in mainland China. METHODS From January 2013 to June 2016, 51 patients with refractory LUTS received SNM therapy. In this study, we compared the conversion rate 2 weeks after the Stage I test and final actual conversion rate. We also observed the complications (such as pain, infection, and electrode displacement) and effectiveness. We tried to improve an appropriate prolonged test time which was favorable for improving the SNM conversion rate while ensuring safety and effectiveness. RESULTS Among 51 patients receiving SNM therapy, 19 patients (mean age 45.0 ± 16.9 years) had poor Stage I test results, and on an average, the electrode was removed 27.4 ± 9.6 days after the surgery. In one patient, the electrode was removed within 2 weeks; when the remaining 18 patients were questioned 2 weeks after testing, none of the patients wanted to terminate the test, and all the 18 patients desired to prolong the testing time to further observe the treatment effect. The remaining 32 patients (mean age 46.7 ± 15.3 years) received Stage II permanent implantation at 19.6 ± 10.4 days after the surgery. The overall Stage I-II conversion was 62.7% (32/51) in this study. Within 2 weeks after the surgery, only eight patients received Stage II permanent implantation, and the conversion rate was only 15.7% (8/51), which was much lower than the overall conversion rate of 62.7%. Nearly 84.4% (27/32) of the patients received Stage II implantation within 4 weeks. None of the patients had incision infections. In one patient, the entire system was removed 1 month after Stage II implantation due to pain in the implantation site. CONCLUSIONS Appropriate extension of the Stage I testing time of an SNM-barbed electrode could significantly improve the Stage II permanent implantation rate in Chinese refractory LUTS patients; there were no wound infections, and the postoperative complication rate was low. This study recommended that Stage I period of SNM therapy should be 4 weeks according to safety and successful conversion rate.