OnabotulinumtoxinA in the Management of Pain in Adult Patients with Spasticity: A Systematic Literature Review

Many patients with spasticity report pain which can be debilitating. Numerous studies have shown onabotulinumtoxinA (onabotA) is efficacious in the management of spasticity but comprehensive data on its impact on spasticity-associated pain is limited. This systematic review aimed to assess the published evidence on the efficacy of onabotA in the management of pain in adults with spasticity. Search strategies were conducted from 1990 to 2023 for journal publications and from 2020 to 2023 for congress proceedings to identify relevant studies on onabotA in adults with spasticity where pain was a reported outcome. Of 665 records identified, 31 unique studies from 33 publications were included (2740 patients). Twenty-seven studies demonstrated a reduction in pain compared to baseline following treatment with onabotA in adults with spasticity (n = 2740). Of these, 12 studies reported a statistically significant reduction in pain with onabotA versus baseline. Sixteen studies reported a clinically meaningful reduction in pain (≥30% reduction). The reduction in pain with onabotA was consistent across etiologies and a range of pain measures. There was a high level of heterogeneity in the design and quality of the studies identified, which limited statistical analysis; however, the published evidence overall shows a consistent positive trend for the use of onabotA in reducing spasticity-related pain in adults.