High-dose Botulinum Toxin Therapy: Safety, Benefit, and Endurance of Efficacy.

Background: Botulinum neurotoxin therapy (BoNT) is a powerful tool for treating many neurologic disorders. The U.S. Food and Drug Administration (FDA)-approved maximum onabotulinum toxin A (OnaA) dose is 400 units (U) per visit, but higher doses are commonly necessary, particularly when treating multiple body regions. Methods: We collected demographics, OnaA dose, body regions injected and indications, patient-reported efficacy via 7-point Clinical Global Impression Scale (CGIS), and duration of benefit. Results: Sixty-eight patients were identified receiving OnaA >400 U/session. Dystonia (n = 44) and spasticity (n = 24) were the most common indications for high-dose OnaA. Mean duration of benefit was 9 weeks (standard deviation [SD] 3). More than 70% of patients self-reported "very much improved" or "much improved" at 6 month, 1 year, and last visit. No serious adverse effects were reported. Discussion: The majority of patients tolerated >400 U OnaA with continued benefit. OnaA doses >400 U may be safe and effective in appropriate patients.