Botulinum Toxin in Pain-Related Post-Stroke Limb Spasticity: A Meta-Analysis of Early and Late Injections

Spasticity is a common complication associated with stroke, and around 72% of stroke patients will develop pain during the disease. Botulinum toxin (BoNT) is a safe and efficacious treatment for spasticity and can improve associated complications, including pain. Hence, this meta-analysis aims to establish whether BoNT can reduce pain-related post-stroke spasticity (pPSS) in the early treatment period (<12 weeks post-stroke) or in the late period (>12 weeks post-stroke) based on the available evidence. This study also aims to establish the dose–response relationship of BoNT-A in pPSS. Based on pooled data from multiple studies, there is no significant difference in the scores measuring pPSS between patients who received early BoNT-A injections and those who received a placebo. This finding suggests that within the early treatment period, BoNT-A may not be more effective than a placebo in reducing pPSS. However, it is important to note that the data for early BoNT-A injections are limited, indicating that research is needed to draw definitive conclusions [z = 3.90 (p < 0.0001)]. While BoNT-A appears somewhat more effective than a placebo in the late phase, as indicated by the small to moderate positive z value, there is not enough evidence to confidently claim superiority over a placebo [z = 1.48 (p = 0.14)].