Early Use of Botulinum Toxin in Post-Stroke Spasticity Has the Potential to Prevent Post-Stroke Upper Limb Pain-A Secondary Analysis of the EUBoSS Randomised Controlled Trial.

Post-stroke upper limb pain is prevalent and challenging to manage once established. Early use of botulinum toxin can reduce spasticity and contracture development and has potential to prevent or reduce pain. A secondary analysis of the EUBoSS study was undertaken to report pain prevalence in people post-stroke with severe upper limb impairment and spasticity in a hyper/acute setting, identify if botulinum toxin Type-A (BoNTA) could prevent pain developing and reduce pain if already present and evaluate differences in analgesic use between BoNTA and placebo groups. Odds ratios (OR) with 95% confidence intervals (CI) were calculated. Ninety-three participants (48F:45M) were randomised at a median of 11 days post-stroke (IQR 8-19) and included in the intention-to-treat analysis. Pain prevalence increased from 29.0% (95% CI [20.1-37.9%]) to 63.4% (95% CI [54.0-72.9%]) at six months. BoNTA treatment may prevent the development of pain at six months (OR = 0.42, 95% CI [0.18 to 1.01]) but not at three months (OR = 0.57, 95% CI [0.25 to 1.32]). The odds ratio for being on at least one analgesic at six months in the BoNTA group was 0.35 ([95% 0.14 to 0.87]). This secondary analysis suggests that early treatment of spasticity with BoNTA may potentially help prevent post-stroke upper limb pain and reduce analgesic use but appears less effective once pain is established. Further prospective studies are required to verify the hypotheses generated from this secondary analysis.