Hemifacial spasm is painless involuntary twitching of one side of the face due to malfunction of the 7th cranial (facial) nerve and/or the area of the brain that controls it (called a center or nucleus). The 7th cranial 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.
Twitching may occur only occasionally at first but may become almost constant.
Doctors diagnose hemifacial spasm based on symptoms but do magnetic resonance imaging to check for other disorders that can cause similar symptoms.
Hemifacial spasm is treated with botulinum toxin or another medication, but if medications are ineffective, surgery may be necessary.
(See also Overview of the Cranial Nerves.)
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 puts pressure on (compresses) the facial cranial nerve where it exits the brain stem
Symptoms of Hemifacial Spasm
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.
Hemifacial spasm is essentially painless but can be embarrassing and look like a seizure.
Diagnosis of Hemifacial Spasm
Neurologic examination
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.
Treatment of Hemifacial Spasm
Botulinum toxin
Sometimes surgery
Botulinum toxin (used to paralyze muscles or to treat wrinkles) is the medication of choice for hemifacial spasm. It is injected into the affected muscles. The same medications used to treat trigeminal neuralgiatricyclic antidepressants—can also be used.
If medications are unsuccessful, surgery (called vascular decompression) may be done to separate an abnormal artery, if present, 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. This procedure may be done to treat trigeminal neuralgia, hemifacial spasms, or glossopharyngeal neuralgia. 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. Side effects include facial numbness, facial weakness, double vision, infection, bleeding, alterations in hearing and balance, and paralysis. Usually, this procedure relieves the pain, but in about 15% of people, pain recurs. |
