What Is Hemifacial Spasm?

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Hemifacial spasm (HFS) is a movement disorder that causes involuntary muscle contractions on one side of the face. HFS typically starts with painless but annoying twitching around one eye. Over time, muscle spasms may spread down the same side of the face that initially experienced eyelid twitching. Hemifacial spasms can tug the mouth and other facial muscles to one side, which makes a person's face asymmetrical and can give someone with HFS an involuntary grimacing facial expression.

This article discusses the symptoms, causes, diagnostic tools, and treatment options for both types of hemifacial spasms.

Doctors looking at brain scans

Tashi Delek / Getty Images

Types of Hemifacial Spasm

Hemifacial spasms are involuntary facial twitching or muscle spasms on one side or half of the face. There are two types of hemifacial spasms: typical and atypical.

Typical hemifacial spasm usually starts with an involuntary tic or twitching near the eye. Over time, typical HFS progresses down the same side of the face that initially presented symptoms near one eye. The vast majority of hemifacial spasms are classified as "typical."

Atypical hemifacial spasms start lower on one side of the face and progress up the same side of a person's face. Atypical hemifacial spasm often starts in the orbicularis oris muscle around the lips or the buccinator muscle in the cheekbone area. Fewer than one in 10 people with hemifacial spasm experience atypical spasm progression from the lower to the upper face.

Hemifacial Spasm Affects Half the Face

Hemifacial spasms usually affect one-half of the face. When hemifacial spasm affects both sides of the face, it’s called bilateral hemifacial spasm. An estimated 0.6–5% of hemifacial spasm patients experience involuntary muscle spasms on both sides of the face.

Hemifacial Spasm Symptoms

The involuntary twitching and uncontrollable muscle contractions caused by hemifacial spasm aren't physically painful, but they can make a person feel self-conscious or embarrassed. The psychological pain of hemifacial spasm is one of its symptoms. As it progresses, physical symptoms can also interfere with a person's ability to perform daily tasks.

For example, hemifacial spasms around the eye area can interfere with a person's vision and eyesight by causing the eye to shut involuntarily. The uncontrollable twitching of one eyelid is a common symptom that can make it difficult to perform everyday tasks and disrupts the quality of life.

When hemifacial spasm affects one side of the mouth, it can disrupt a person's ability to control mouth movements when speaking or eating. Over time, the constant tugging of facial muscles around the mouth can create an unintentional grimacing expression due to facial asymmetry, which can have social repercussions.

Not Every Eye Twitch Is Hemifacial Spasm

Eyelid twitching (myokymia) isn't always caused by a neurological disease or movement disorder like hemifacial spasm. Stress, lack of sleep, and too much caffeine can all cause eyelid myokymia.

Causes

Hemifacial spasm also called tic convulsive, is characterized by painless, involuntary contractions or tics in facial muscles controlled by cranial nerve 7, also known as the facial nerve. The seventh cranial nerve is responsible for moving facial muscles. When the facial nerve malfunctions or is damaged, it can trigger involuntary facial twitches associated with hemifacial spasms.

For example, if a blood vessel presses against the seventh nerve, this vascular compression causes the facial nerve to malfunction, which can cause hemifacial spasms. Facial nerve compression by a blood vessel is the most common cause of hemifacial spasms. Head and neck tumors can also press against the facial nerve and cause involuntary facial twitching or spasms.

Damage to the facial nerve from an inflammatory demyelinating disease such as multiple sclerosis (MS) is another potential cause, but it's rare. That said, in some cases, hemifacial spasm is the first symptom experienced by someone with MS.

When the cause of someone's facial twitching can't be pinpointed or diagnosed, the involuntary muscle contractions are classified as idiopathic (i.e., the cause is unknown) hemifacial spasm.

Diagnosis

Facial twitching can appear as a part of other disorders, including seizures and certain muscle disorders. Anyone experiencing symptoms of hemifacial spasm should speak to a healthcare provider immediately. After an initial consultation, your general healthcare provider may refer you to a neurologist who specializes in nervous system disorders like hemifacial spasms.

The first step for getting a hemifacial spasm diagnosis is to have a neurological exam. The second diagnostic step involves magnetic resonance imaging (MRI).

The neuroimages created by an MRI can show if a patient’s involuntary movements on one side of the face are caused by a tumor or blood vessel pressing against cranial nerve 7, which controls facial muscles.

Treatment

Hemifacial spasm is typically caused by blood vessels pressing against the facial nerve (cranial nerve 7) at its root entry zone (REZ) in the brainstem.

The best treatment for hemifacial spasms involves removing the REZ source of pressure against the facial nerve at its source via neurosurgery. A surgical procedure called microvascular decompression (MVD) lifts pressure-causing blood vessels away from the facial nerve, which allows cranial nerve 7 to function normally and stops involuntary twitching on one side of the face.

A non-surgical treatment option for hemifacial spasms involves injecting Botox (botulinum toxin) into affected facial muscles. Botox blocks signals that cause muscles to contract, which stops the involuntary twitching of facial muscles in those experiencing hemifacial spasms. One disadvantage of using Botox to treat hemifacial spasms is that injections need to be repeated every three to four months.

Coping

Although hemifacial spasms aren't painful and this movement disorder doesn't have life-threatening consequences, people affected by involuntary facial twitching can experience psychological pain.

Hemifacial spasms can be a severe psychosocial stressor that can lead to social anxiety disorder and increases the risk of major depressive disorder. Early diagnosis and treating hemifacial spasm before the disease progresses can make coping with this movement disorder less challenging.

Summary

Hemifacial spasm is characterized by involuntary muscle contractions and twitching on one side of someone's face. These painless spasms are usually triggered by a blood vessel pressing against the facial nerve (cranial nerve 7), which causes vascular compression and nerve malfunction.

Although targeted Botox injections can stop hemifacial spasms for a few months and provide short-term relief, microvascular decompression is the neurosurgical treatment of choice and the most effective long-term remedy for hemifacial spasm.

A Word From Verywell

Hemifacial spasm may not be life-threatening, but this movement disorder can feel very serious. The psychological toll of involuntary facial twitching is often much more painful than the actual spasms, which are technically "painless."

If you are living with uncontrollable muscle contractions on one side of your face, speak to a healthcare provider as soon as possible. The sooner you get an accurate diagnosis, the sooner you can get treatment for these spasms, which could dramatically improve your quality of life and overall sense of well-being.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Christopher Bergland
Christopher Bergland is a retired ultra-endurance athlete turned medical writer and science reporter.