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Hemifacial Spasm

By Michael Rubin, MDCM, Professor of Clinical Neurology; Attending Neurologist and Director, Neuromuscular Service and EMG Laboratory, Weill Cornell Medical College; New York Presbyterian Hospital-Cornell Medical Center

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 two thirds 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 facial 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 and look like a seizure.


  • Symptoms

  • Magnetic resonance imaging

Hemifacial spasm is diagnosed when doctors see the spasms.

Magnetic resonance imaging (MRI) should be done to rule out tumors, other structural abnormalities, and multiple sclerosis, which can cause similar symptoms. Also, MRI can usually detect the abnormal loop of artery pressing against the nerve.


  • Botulinum toxin

  • Sometimes surgery

Botulinum toxin is the drug of choice for hemifacial spasm. 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.

Taking the Pressure Off a Nerve

When pain results from an abnormally positioned artery pressing on a cranial nerve, the pain can be relieved by a surgical procedure called vascular decompression.

The procedure for the facial nerve in people with hemifacial spasm is similar to that for the trigeminal nerve (shown below).

If the trigeminal nerve is compressed, an area on the back of the head is shaved, and an incision is made. The surgeon cuts a small hole in the skull and lifts the edge of the brain to expose the nerve. Then the surgeon separates the artery from the nerve and places a small sponge between them.

A general anesthetic is required, but the risk of side effects from the procedure is small. Usually, this procedure relieves the pain.

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