Feeling the muscles in your face move without your control can be upsetting. In hemifacial spasm, nerve signals to these muscles become disrupted, so muscles contract when they shouldn't. While there is no cure for this chronic condition, treatments such as medication and surgery can help ease symptoms.
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What Is Hemifacial Spasm?
Hemifacial spasm (HFS) is categorized as a chronic neuromuscular disorder that causes involuntary twitches, also called “tics,” of muscles in one side of the face.
Each side of your face has more than two dozen muscles that you use to chew and show emotions. The 12 cranial nerves send electrical signals from your brain to your upper body. Two of these nerves — the facial nerve and the trigeminal nerve — control how your facial muscles move.
In HFS, these nerves tell muscles on one side of your face to contract or twitch for no reason. These facial tics usually don't hurt. But over time, they may happen more often, even during sleep.
While tics are not life-threatening, they can interfere with daily life as they progress and happen more often. In most cases, only one side of the face is affected (hemi means half), but some people experience the condition on their entire faces.
What are the stages of hemifacial spasm?
HFS typically begins with twitching of the eyelid muscles, which can force the eye closed. While the tics may start off spaced apart, they can progress to more frequent tics or involve other parts of the face, including the mouth and jawbone.
As the condition progresses or worsens, tics can happen very often or continuously. This can affect your ability to keep your eye(s) open, speak, or swallow. Stressful or exhausting situations can worsen symptoms.
How common is hemifacial spasm?
Hemifacial spasms are rare — they happen in less than 1 out of every 100,000 people in the United States.
What causes hemifacial spasm?
For the most part, spasms occur when a blood vessel presses on a facial nerve at the brainstem. The pressure disrupts the nerve impulses that cause muscles to contract.
You may also experience hemifacial spasms if you:
- Have a tumor pressing on facial nerves.
- Have Bell's palsy or ear infections.
- Injure a facial nerve.
Anxiety, fatigue, or stress can also cause the muscles in your face to twitch. Rarely, hemifacial spasm starts for no clear reason. This condition is called idiopathic hemifacial spasm.
Hemifacial spasm risk factors
You are more likely to be diagnosed with hemifacial spasms if you:
- Are female (women are twice as likely to be diagnosed than men).
- Are over 40 years old.
- Are of Asian descent.
Hemifacial spasm is not a hereditary condition, meaning it is not known to run in families.
Complications of hemifacial spasm
If not treated, hemifacial spasm symptoms may get worse, with nearly constant twitches.
What Are the Signs and Symptoms of Hemifacial Spasm?
Symptoms of hemifacial spasm include movements you can't control. These movements typically occur on one side of the face.
You may notice:
- Pulling of your mouth toward one side of your face.
- Twitching in the muscles of your lower face, such as the cheek and jaw.
- Twitching in your eyelid that forces your eye to close.
These symptoms may worsen over time or when you are tired or stressed.
When should I see a doctor about my hemifacial spasm symptoms?
If you are experiencing any involuntary muscle twitches in your face, you should set up an appointment with your primary care physician. Early diagnosis and treatment of hemifacial spasm can help prevent worsening symptoms.
How Do You Diagnose Hemifacial Spasm?
First, you can expect your doctor to ask you a series of questions about your current symptoms and health history. They may perform a physical exam of your face to examine symptoms and muscle contractions.
To formally diagnose hemifacial spasms, you can expect to take certain diagnostic tests.
Tests to diagnose hemifacial spasm
Imaging tests
Imaging tests help doctors see what's going on under your skin. To diagnose HFS, you may undergo an MRI, CT scan, or arteriography, which is an imaging test that uses a special injected dye and x-ray imaging.
These tests help rule out other conditions, such as a benign tumor or vascular malformation, as well.
Electrodiagnostic testing
Specialists use electrodiagnostic medicine techniques, such as an EMG or nerve conduction study, to learn more about how your cranial nerves work. These painless tests are used to find disruptions in how nerves send electrical signals to the muscles in your face.
Hemifacial spasm prognosis
Several factors determine the prognosis of HFS: initial cause, symptom severity, and response to treatment methods. However, for most people, a successful treatment method removes most or all symptoms. Continued treatment may be needed down the line if spasms return.
For other people, symptoms can continue to be severe and may affect their mental health and daily lives.
How Do You Treat Hemifacial Spasm?
The appropriate treatment method for HFS depends on the symptom severity and patient’s overall health.
Doctors can treat HFS using:
- Botulinum toxin (Botox®) injections.
- Oral medications.
- Surgery.
Botox® injections to treat hemifacial spasms
The most common and effective treatment method for HFS is Botox® injections. Botox ® is a brand name for botulinum toxin, a neurotoxin known to cause weakening of the muscles. It works by blocking nerve signals that connect to certain muscles, easing them into relaxation.
These injections have a high success rate for weakening the contracting facial muscles in people with HFS. A small needle is injected around the affected muscles in the face. These injections are typically short-term and need to be administered every three to six months.
Oral medications to treat hemifacial spasms
If your HFS symptoms are mild, you may be prescribed an oral medication first. These medications are known to stop the brain from signaling the body to spasm, but can also cause side effects such as drowsiness, nausea, and irritated skin.
Microvascular decompression (MVD) surgery to treat hemifacial spasm
Microvascular decompression (MVD) surgery offers lasting symptom relief for many people with hemifacial spasm caused by a blood vessel putting pressure on the facial nerve.
During microvascular decompression, a surgeon makes an incision behind the ear and removes part of the skull (craniectomy) to access the compressed facial nerve. They will use a small, thin instrument with a magnifying lens (endoscope) to see the area where the blood vessel has compressed the nerve. Once located, they will place a small Teflon cushion between the blood vessel and nerve to move them apart. Once the insertion is complete, they will close the skull using a metal plate and screws.
When large arteries compress nerves, experts place a small loop around the artery and secure it to your skull using the sling technique. This loop lifts the blood vessel and relieves facial nerve compression.
Surgeons check your nerve activity throughout surgery to protect the other cranial nerves.
How effective is treatment?
Injection therapy and oral medications are short-term solutions to HFS and need to be continued over a long period of time. If treatment ends, the spasms may begin again. Surgery is a longer-term solution, but spasms can return, though rarely.
Minimizing stress, anxiety, caffeine, and situations that cause fatigue can also help ease facial spasms.
