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=224 participants, n=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.