Hemifacial spasm is painless involuntary twitching of one side of the face due to malfunction of the 7th cranial nerve (facial nerve). This nerve moves the facial muscles, stimulates the salivary and tear glands, enables the front part of the tongue to detect tastes, and controls a muscle involved in hearing.
Hemifacial spasm affects men and women but is more common among middle-aged and older women.
The spasms may be caused by an abnormally positioned artery or loop of an artery that compresses the 7th cranial nerve where it exits the brain stem.
Muscles on one side of the face twitch involuntarily, usually beginning with the eyelid, then spreading to the cheek and mouth. Twitching may be intermittent at first but may become almost continuous. The disorder is essentially painless but can be embarrassing.
Diagnosis and Treatment
The diagnosis is made when doctors see the spasms. Magnetic resonance imaging (MRI) should be done to check for a tumor, other structural abnormalities, and evidence of multiple sclerosis. Usually, MRI can detect the abnormal loop of artery pressing against the nerve.
Botulinum toxin is the drug of choice. It is injected into the affected muscles. The same drugs used to treat trigeminal neuralgia—carbamazepine, gabapentin, phenytoin, baclofen, and tricyclic antidepressants (see Table: Drugs Used to Treat Depression)—may be tried but are usually not helpful. If drug treatment is unsuccessful, surgery may be done to separate the abnormal artery from the nerve by placing a small sponge between them (see Sidebar 2: Taking the Pressure Off a Nerve).
Last full review/revision September 2012 by Michael Rubin, MDCM