The efficacy and safety of the ganglion impar block in chronic intractable pelvic and/or perineal pain: a systematic review and meta-analysis

Background: The ganglion impar is an unpaired sympathetic structure located at the level of the sacrococcygeal joint. It is controversial regarding the effect of ganglion impar block (GIB) in the treatment of chronic intractable and/or perineal pain. This meta-analysis is to provide a comprehensive assessment of the efficacy and safety concerning GIB for chronic intractable pelvic and/or perineal pain, with all the existing trials. Methods: Electronic searches were conducted in Pubmed, Embase and the Cochrane Central Register of Controlled Trials, up to May 2015. The reference lists of the relevant articles were also searched. Selecting criterion is that GIB was used in one group as a treatment of chronic intractable pelvic and/or perineal pain. The effective data were gotten from 245 patients with chronic intractable pelvic and/or perineal pain. We analyzed the overall effective rate and the visual analogue scale (VAS: 0-10) (the baseline, post- treatment and one month later) to conclude the comprehensive effect. Results: GIB can significantly improve the condition of chronic intractable pelvic and/or perineal pain, with the overall response rates (Odds Ratio (OR) = 0.01; 95% confidence interval (CI): 0.00 to 0.02; P<0.00001). There was a significant statistic difference between pre-and post-procedure of GIB (Mean Difference (MD) = -5.98; 95% CI: -7.14 to -4.81; P<0.00001). The subgroup analysis deduced the same excellent results, with pain region (pelvic area (pooled OR = 0.01; 95% CI: 0.00 to 0.05; P<0.00001) and perineal area (pooled OR = 0.01; 95% CI: 0.00 to 0.02; P<0.00001)) and method (GIB alone group (pooled OR = 0.01; 95% CI: 0.00 to 0.03; P<0.00001) and the combined group (pooled OR = 0.01; 95% CI: 0.00 to 0.03; P<0.00001)). What's more, the effect was continued to one month later (MD = -5.56; 95% CI: -6.93 to -4.18; P<0.00001). However, only few complications such as transient paresthesia and pain on injection were found. Conclusions: GIB has a evident effect on chronic intractable pelvic and/or perineal pain. This method should be used in treating chronic intractable pelvic and/or perineal pain.