The effectiveness and safety of botulinum toxin injections for managing motor disorders of patients with Parkinson's disease: A meta-analysis of randomized controlled trials

This study aimed to assess the effectiveness and safety of botulinum toxin (BTX) injections for managing motor disorders in patients with Parkinson's disease (PD). An electronic search was conducted based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data from available randomized controlled trials (RCTs) assessing BTX injections for motor disorders in PD patients were extracted for meta-analysis. Ultimately, 215 patients from eight RCTs were enrolled. Pooled analyses indicated that BTX was more effective than placebo in improving tremor (standardized mean difference [SMD] = 0.96, 95% CI [0.34, 1.58], p < 0.01), whereas no notable differences were observed between BTX and placebo regarding freezing of gait (SMD = 0.66, 95% CI [-0.26, 1.58], p = 0.162), United Parkinson's Disease Rate Scale (UPDRS) III score (SMD = -0.20, 95% CI [-1.17, 0.76], p = 0.68) and clinical global impression (CGI) score (SMD = 0.84, 95% CI [-0.74, 2.42], p = 0.298). Adverse events related to BTX injections were comparable to placebo (OR = 1.74, 95% CI [0.59, 5.14], p = 0.32). The current evidence suggests that BTX is effective and safe in treating PD tremor but fails to provide therapeutic benefits for freezing of gait and motor functional scores in PD patients. Furthermore, the limited number of included studies and heterogeneity in BTX intervention protocols suggest more research is needed, with additional standardized RCTs, to better understand and optimize BTX injections for motor disorders in PD.