Botulinum toxin for radiation-induced facial pain and trismus

Objective: To report the efficacy of botulinum toxin A for radiation-induced pain, trismus, and masticator spasm in head and neck cancer. Patients and Methods: This prospective nonrandomized study included patients in complete remission with radiation-induced pain and trismus with or without masticator spasms. Fifty units of Botox (Allergan) or 250 units of Dysport (Ipsen) were injected transcutaneously into the masseter muscles. Jaw opening was measured and patients answered 20 questions about jaw opening, pain, and cramps, before injection at 1 month. Results: Nineteen patients (7 women, 12 men) were included. Median time after radiation therapy was 5 years (range, 11 months to 22 years). At 1 month, no significant increase in jaw opening was recorded. Improvement was noted in the functional domain (P = 0.004), for pain (P = 0.002) and cramps (P = 0.004), but not in the social (P = 0.83) or emotional (P = 0.43) domains. No side effects occurred. Conclusions: Botulinum toxin did not improve trismus but significantly improved pain scores and masticator spasms (oromandibular dystonia).