The use of botulinum toxin for the treatment of chronic facial pain.

An open label pilot study was conducted to evaluate efficacy of botulinum toxin injections for the treatment of patients with chronic facial pain seeking tertiary care at a pain clinic. Diagnoses included temporomandibular joint syndrome, postsurgical pain syndromes, essential headache, and idiopathic trigeminal neuralgia. Thirty-three (75%) of 44 patients favorably responded, including 8 of 11 patients with trigeminal neuralgia. The duration of beneficial effect ranged from 2 to 4 months, and all responding patients desired further injections. Complications were mild and included temporary facial asymmetry and weakness secondary to neuromuscular effects of botulinum toxin. Doses ranged from 25 to 75 LD 50 units with Hall strain-derived botulinum toxin type A. A small degree of facial edema during pain or erythema seemed to have predictive value when categorically evaluated against response.