Efficacy and safety of botulinum toxin for treating motor dysfunction in patients with Parkinson’s disease: a systematic review and meta-analysis

OBJECTIVE: To evaluate the efficacy and safety of botulinum toxin (BTX) for motor dysfunction in Parkinson’s disease (PD). DESIGN: Systematic review and meta-analysis. DATA SOURCES: Searches of PubMed, EMBASE and the Cochrane Library, from database inception to 20 October 2022. ELIGIBILITY CRITERIA: Studies reported in English with adult PD patients treated with BTX. DATA EXTRACTION AND SYNTHESIS: Primary outcomes were United Parkinson’s Disease Rate Scale Section (UPDRS) III (or its items) and Visual Analogue Scale (VAS). Secondary outcomes were UPDRS-II (or its items), Freezing of Gait Questionnaire (FOG-Q), Timed Up and Go test (TUG) and treatment-related adverse events (TRAEs). Mean difference (MD) or standardised MD (SMD) before and after treatment with 95% CIs were used for continuous variables and risk ratios (RRs) with 95% CIs was used for TRAEs. RESULTS: Six randomised controlled trials (RCTs) and six non-RCTs (case series) were included (n(total)=224 participants, n(RCT)=165). No significant difference was found in pooled results of UPDRS-III (available in four RCTs and two non-RCTs, SMD=−0.19, 95% CI −0.98 to 0.60), UPDRS-II (four RCTs and one non-RCT, SMD=−0.55, 95% CI −1.22 to 0.13), FOG-Q (one RCT and one non-RCT, SMD=0.53, 95% CI −1.93 to 2.98) or the risk of TRAEs (five RCTs, RR 0.87, 95% CI 0.37 to 2.01). Significant decreases were found in pooled VAS score (three RCTs and five non-RCTs, MD=−2.14, 95% CI −3.05 to −1.23) and TUG (MD=−2.06, 95% CI −2.91 to −1.20) after BTX treatment. CONCLUSIONS: BTX may not be associated with motor symptoms alleviation, although it benefits pain alleviation and functional mobility improvement.