Facial pain in a case of cranial dystonia: a case report.

A 76-year-old man had shown sustained excruciating facial pain in the maxillary region for more than 30 years. Since he was suffering from blepharospasm, facial electromyography was performed and revealed a perioral dystonia. This possible cause of facial pain might have been overlooked had dystonia not been considered and electromyographical studies performed. Repeated intramuscular perioral injections of botulinum toxin brought about complete pain relief. This case shows that involuntary activity of facial muscles can cause a severe chronic pain syndrome. Possible mechanisms include irritation of ascending trigeminal fibers, muscle ischemia due to compression of blood -vessels, or release of pain-producing substances.