Hemifacial spasm (tic convulsif)Open print version

Overview

Hemifacial spasm (HFS) is an involuntary twitching or contraction of the facial muscles on one side of the face. Medication, surgery, and Botox injections are treatment options to stop the spasms and relieve the discomfort. Each treatment offers benefits, but each has limitations. You and your doctor should determine which treatment is best.

What is hemifacial spasm?

Hemifacial spasm (also called tic convulsif) is an involuntary twitching of the facial muscles on one side of the face. The facial muscles are controlled by the facial nerve (seventh cranial nerve), which originates at the brainstem and exits the skull below the ear where it separates into five main branches (Fig. 1). The facial nerve is primarily a motor nerve, meaning it controls muscles that move the eyebrows, close the eyes, and move the mouth and lips.


Figure 1. The facial nerve (7th cranial nerve) originates in the brainstem and exits the skull beneath the ear where it has five main branches that control the muscles of facial expression.

What are the symptoms?

In 92% of cases, the spasm starts near the eye and progresses down the face over time. In the other 8% it starts near the chin and progresses upward. The twitching is usually not painful, but it can be embarrassing and interfere with normal expression and vision.

What causes hemifacial spasm?

Hemifacial spasm can be caused by injury to the facial nerve, a tumor or blood vessel compressing the nerve, or Bell’s palsy. The most common cause is compression of your facial nerve by the anterior inferior cerebellar artery where the nerve begins at your brainstem. The compression causes the nerve to misfire making your facial muscles contract. This condition is related to trigeminal neuralgia—an irritation of the fifth cranial nerve that causes severe facial pain. Both hemifacial spasm and trigeminal neuralgia are caused by nerve compression from a blood vessel, yet differ in whether the sensory nerve or motor nerve is compressed.

Who is affected?

Hemifacial spasm is rare, affecting only 8 people in 100,000 in the US. The average age of onset is 44 years and occurs slightly more in women.

How is a diagnosis made?

First, your doctor will carefully review your medical history and perform a neurological exam. An MRI scan may be ordered to rule out other conditions such as a brain tumor, aneurysm, or AVM that may be causing facial nerve compression. Next, you may have an electromyogram (