Efficacy and safety of botulinum neurotoxin in the treatment of hemifacial spasms: a systematic review and meta-analysis

Background Hemifacial spasm (HFS) is a neuromuscular disorder characterized by unilateral facial muscle spasms, negatively impacts quality of life due to social embarrassment. Botulinum Neurotoxin (BoNT) injections have emerged as a viable therapeutic approach. This systematic review evaluated the efficacy and safety of BoNT injections for HFS management, along with effects on patients' quality of life and mental health. Materials and methods A systematic search for studies on BoNT treatment for HFS published between January 1, 2000, and May 1, 2024, was performed across major databases. Study quality was evaluated using Cochrane and Joanna Briggs Institute (JBI) tools, with data management handled by EndNote X9 and statistical analyses conducted via Review Manager (RevMan 5.4) and STATA 14.0. Results Thirty-five studies met the inclusion criteria: 2 RCTs comprising 83 HFS patients compared the efficacy of perioral injections of botulinum toxin and placebo, while 33 single-arm studies reported outcomes for 2786 patients post-BoNT injection. The selection of 17 single-arm studies focused on the effectiveness rate as the key outcome metric. Pooled estimate signified a remarkably high effectiveness (ES: 0.882, 95% CI: 0.830, 0.926, P < 0.001). Analysis of depression scale (SMD: -0.85, 95% CI: -1.34, -0.35, P < 0.001), anxiety scale (SMD: -1.50, 95% CI: -2.19, -0.80, P < 0.001) and total scale of quality of life (SMD: -0.64, 95% CI: -0.87, -0.41, P = 0.766) showed that BoNT therapy worked well especially in improving mental state and quality of life. Ptosis was considered as the most common adverse reaction during BoNT injections (OR: 0.30, 95% CI: 0.11, 0.81, P = 0.843). Conclusion BoNT injection showed validity and clinical safety in the treatment of HFS, particular for depression relief. Injections around the mouth were only effective for HFS cases with severe symptoms. A standardized strategy for BoNT injections in managing HFS, detailing parameters such as injection sites, doses, and frequencies, remained elusive. Additional RCTs are necessary to further elucidate the interplay between efficacy and these components.