Efficacy and safety of incobotulinumtoxinA in the treatment of shoulder spasticity due to cerebral causes

Introduction/Background Botulinum neurotoxin is well established for treating upper limb spasticity. However, few studies have assessed efficacy in the shoulder. TOWER ( NCT01603459 ) previously evaluated the safety and efficacy of escalating incobotulinumtoxinA doses (400U– ≤ 800U) in adults with upper- and lower limb spasticity due to cerebral causes (Wissel. Neurology , 2017). This post-hoc analysis assessed the efficacy and safety of incobotulinumtoxinA for treating shoulder spasticity, as part of upper limb treatment. Material and method Patients received three injection cycles (IC) with escalating incobotulinumtoxinA doses on the same body side (400U, 600U and 600–800U; ≤ 600U per limb including optional shoulder dose, planned range 100–250U). Here, patients who had received shoulder treatment were compared with those who had upper limb treatment, without shoulder treatment. Ashworth Scale (AS) scores for shoulder adduction, extension and internal rotation were added to form the AS shoulder sum score (AS-SSS), to fully assess joint function. The incidence of adverse events (AEs) was assessed. Results The number of patients receiving shoulder treatment increased with escalating incobotulinumtoxinA dose at each IC, peaking in IC3 ( n  = 84/140 [60.0%]; mean [SD] shoulder dose 118.4 [60.2] U). From baseline to 4 weeks post-injection in IC1, IC2 and IC3, respectively, the mean (SD) AS-SSS improved by −1.1 (1.9), −1.7 (1.8) and −1.7 (1.8) in patients treated in the shoulder and −0.5 (1.3), −0.8 (1.6) and −0.9 (1.4) in patients who were not. Multiple regression analysis adjusting for IC baseline showed significant improvement in AS-SSS with incobotulinumtoxinA shoulder dose in IC3 ( P  = 0.0081). AEs occurred in 52.1% of patients treated in the shoulder and 61.0% in those who were not. No differences were observed in AE patterns and no unexpected safety concerns were reported with shoulder treatment or higher incobotulinumtoxinA dose. Conclusion Results support the efficacy and safety of incobotulinumtoxinA for treatment of shoulder spasticity as part of upper limb treatment.