Assessment of pain relief after four botulinum toxin A injection cycles in patients with post-stroke lower limb spasticity: A prospective, observational study.

Introduction: Spasticity is common after a stroke and is an independent risk factor for developing pain. BotulinumtoxinA injection is the treatment of choice for focal spasticity. We examined the effect of intramuscular botulinumtoxinA on pain relief in patients in routine clinical practice who were experiencing pain as a primary complaint associated with post-stroke lower limb spasticity.

Methods: Prospective, multicentre, post-marketing observational study. The study period was 16 months. The primary effectiveness variable was the mean change from baseline on the pain 0-10 Numerical Rating Scale after four botulinumtoxinA injection cycles. Secondary endpoints included changes from baseline on the pain 0-100 Visual Analogue Scale, Goal Attainment Scale, modified Ashworth Scale, 10-Meter Walk Test, Penn Spasm Frequency Scale, and 36-item Short-Form Health Survey.

Results: Of 186 enrolled patients, 180 (96.8%) received botulinumtoxinA at least once. The mean (standard deviation) pain 0-10 Numerical Rating Scale score decreased significantly (p<0.0001) from 4.9 (2.2) at baseline to 2.5 (2.1) at study end, representing a 50% decrease in pain severity. Relief of pain due to spasticity was supported by improvement from baseline in all secondary variables except the 10-Meter Walk Test. Two adverse events (erysipelas and phlebitis) in one patient were considered likely to be related to botulinumtoxinA injection.

Conclusion: BotulinumtoxinA appears to provide pain relief as an additional benefit of local treatment in patients with post-stroke lower limb spasticity for whom pain relief is a primary therapeutic goal (a Lay Abstract has been provided as Appendix A).