Botulinum toxin treatment for multiple sclerosis and post-stroke spasticity in clinical practice: differences in injection doses and patterns.

Introduction: Botulinum Toxin Type A (BoNT-A) is a safe and effective treatment for spasticity in both multiple sclerosis (MS) and post-stroke spasticity (PSS). This single-center retrospective study compared injection patterns and dosages between these two conditions. Methods: Thirty-three people with MS (PwMS) and 55 people with PSS treated with BoNT-A at our outpatient spasticity clinic were analyzed. Clinical and demographic data, BoNT-A dosages, upper- and lower-limb dosing, patterns of injected muscles, and their respective dosages were collected. BoNT-A treatment doses and injection patterns were compared between groups. Patient-reported benefit was also recorded. Results: PwMS more frequently received treatment in lower limbs and lower total doses of BoNT-A. Patients with PSS were more commonly treated in distal upper-limb muscles. In the lower limbs, PwMS were more frequently treated in the adductor muscles and rectus femoris, while patients with PSS were more often treated in tibialis posterior. In MS, higher Expanded Disability Status Scale (EDSS) scores were associated higher total BoNT-A dosage. Discussion: MS-related spasticity mainly affects the lower limbs and less frequently upper limbs, and requires lower BoNT-A dosages compared with PSS. In contrast, PSS is characterized by more prominent distal spasticity, particularly in the upper limbs. Treatment patterns and BoNT-A dosing are influenced by these differences in spasticity distribution. We hypothesize that the need to preserve residual motor function, particularly in lower limbs, may have contributed to lower BoNT-A doses in MS, although not systematically investigated. Despite being only marginally assessed, treatment efficacy appeared to be similar in both groups.