Effectiveness of Botulinum Toxin A Injection for Hemiplegic Shoulder Pain: A Meta-Analysis of Randomized Controlled Trials

Hemiplegic shoulder pain (HSP) is a common post-stroke complication impairing function and quality of life. Botulinum toxin A (BTA), a neurotoxin that inhibits acetylcholine release and reduces spasticity, has been proposed for treating HSP, though its clinical effectiveness remains unclear. This meta-analysis aimed to evaluate BTA's efficacy in managing HSP. Nine randomized controlled trials involving 272 patients were included. Compared to placebo, BTA significantly reduced pain at 1 week (SMD = −0.93; 95% CI [−1.67, −0.19]; p = 0.01) and 4 weeks (SMD = −0.90; 95% CI [−1.51, −0.28]; p < 0.01), but not at 12 weeks. External rotation ROM improved at all time points, peaking at 4 weeks (WMD = 6.20; 95% CI [3.11, 9.30]; p < 0.01). Abduction ROM improved at 4 and 12 weeks. Spasticity decreased significantly throughout, with the largest reduction at 12 weeks (WMD = −0.78; 95% CI [−1.42, −0.14]; p = 0.02). Functional gains were noted at 4 weeks. However, these results should be interpreted cautiously due to small samples and heterogeneous injection protocols across studies. In conclusion, BTA is effective for short-term HSP management, particularly in relieving pain and improving motor function. Further large-scale trials with standardized methods are needed.