Intra-Cavernosal Injection of Botulinum Toxin in the Treatment of Erectile Dysfunction: a Systematic Review and Meta-Analysis.

[OBJECTIVE] To evaluate the role of botulinum toxin in treating erectile dysfunction as a novel treatment strategy avoiding morbid and irreversible surgeries.

[METHODS] A systematic review of literature was conducted from January 1990 through July 31, 2021. Search engines used included PubMed, Embase and Medline databases, to identify studies investigating botulinum toxin in erectile dysfunction, published in English. Seven studies in total were included in our review including two pre-clinical studies. A meta-analysis was performed on three outcomes included commonly in at least two studies. Among the different parameters assessed were, Erection Hardness Score (EHS), Peak Systolic Velocity in cavernosal artery (PSV) and the Sexual Health Inventory for Men (SHIM) score.

[RESULTS] A clear benefit was noted for intracavernosal injection (ICI) of botulinum toxin (BoNT-A) on PSV with a mean difference (MD) of 10.82 [4.99, 16.65] and a heterogeneity of I2=61%. EHS results favored BoNT-A as well over placebo with a MD of 0.7 [0.47, 0.93] and heterogeneity of I2=94%. As for SHIM score, with a heterogeneity of I2=85%, no statistically significant difference was found (MD 0.58 [-0.03, 1.20]).

[CONCLUSION] Our review and meta-analysis have shown statistical significance for the benefit of BoNT-A in terms of EHS and PSV. However, this statistical significance should be interpreted in light of the given limitations: small sample size, heterogeneity in data collection, patient selection bias, and clinical significance of the measured differences. ICI of BoNT-A should currently be limited to clinical studies to further elucidate its clinical benefit.