Sacral Neuromodulation for Non-Obstructive Urinary Retention: A Meta-Analysis

Objective. The object of this study is to systematically review the literature regarding the efficacy of sacral neuromodulation (InterStim®) for treatment of non-obstructive urinary retention. Methods. Eligible studies were selected through an electronic literature search of PubMed, Cochrane Collaboration, EMBASE, Web of Science and Scopus databases from January 1980 to August 2008. Two investigators independently reviewed all studies to assess methodological quality and inclusion criteria. Eligible studies evaluated sacral neuromodulation using implanted generators with permanent lead placement for treating non-obstructive urinary retention. The primary outcomes assessed were the change in pre- and postoperative post-void residual and voided volume. Exclusion criteria were neurogenic etiology (i.e. spinal cord injury) for urinary retention and non-English studies. The lead authors of all selected studies were contacted to identify ongoing or unpublished research, as was Medtronic, Inc. (Minneapolis, MN). Data were extracted from the selected studies and analyzed using RevMan 5 (Review Manager, Cochrane Collaboration, 2008). The mean difference with a 95% confidence interval was the effect of interest. Results. A total of 14 articles met all inclusion criteria for the systematic review. This included one randomized control trial (RCT) and thirteen observational studies. Outcome data was available from a total of 7 studies and used in the final analysis. After implantation, the mean difference in post-void residual decreased 236ml (95% CI: 219-253, p < 0.00001) and voided volume increased by 299ml (95% CI: 280-318, p < 0.00001). The randomized control trial alone (n = 51) showed a mean decrease in postvoid residual volume in the implanted group compared to control of 270ml (95% CI: 180-360, p < 0.00001) and a mean increase in voided volume of 104 ml (95% CI: 55-152, p < 0.0002). Conclusion. Based on the available literature, sacral neuromodulation is an effective therapy for treatment of nonobstructive urinary retention. Non-obstructive urinary retention is caused either by bladder dysfunction or from urethral obstruction. Bladder dysfunction may be caused by a weak or acontractile bladder muscle. The etiology of this disorder may be due to a myogenic, neurogenic or psychogenic origin. The multifactorial nature of this disorder contributes to the difficulty in finding an effective treatment modality. Traditional management has included pharmacotherapy and urethral dilation neither of which has been particularly successful. Individuals suffering from this disorder often need to learn how to perform clean 22 intermittent self-catheterization (CISC). Furthermore, individuals who cannot perform CISC due to physical limitations require an indwelling catheter. Although the mechanism of sacral neuromodulation was and remains unclear, the FDA approved its use for non-obstructive urinary retention in 1999.