Ramsay Hunt syndrome is caused by herpes zoster infection of geniculate ganglion; distinguished from Bell's palsy by a vesicular eruption in pharynx and external auditory canal, and by frequent involvement of eighth cranial nerve. Acoustic neuromas often compress the seventh nerve. Infarcts, demyelinating lesions of multiple sclerosis, and tumors are common pontine causes. Bilateral facial weakness may occur in Guillain-Barré syndrome, sarcoidosis, Lyme disease, and leprosy. Hemifacial spasm may occur with Bell's palsy, compression and/or demyelination of the nerve by tumor, infection or multiple sclerosis (MS), or as an idiopathic disorder. Blepharospasm consists of involuntary recurrent spasms of both eyelids, usually occurring in the elderly and sometimes with associated facial spasm; may subside spontaneously. Hemifacial spasm or blepharospasm can be treated by injection of botulinum toxin into the orbicularis oculi.