What Is Hemifacial Spasm?
Involuntary Twitches on One Side of the Face
Medically reviewed by Nicholas R. Metrus, MD
Hemifacial spasm (HFS) is a rare movement disorder that causes involuntary muscle contractions on one side of the face. It 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 and become almost constant.
Hemifacial spasm can tug the mouth and other facial muscles to one side, which makes a person's face asymmetrical and can give someone with HFS a facial expression that looks like a grimace.
This article discusses the symptoms, causes, diagnostic tools, and treatment options for hemifacial spasms.
Hemifacial Spasm Symptoms
In hemifacial spasm, the twitches have these characteristics:
Are typically on one side of the face
Cannot be controlled
Are painless
One eyelid may twitch and pull the eye shut. This can produce tears. Over time, spasms may occur in other areas of the face on the same side, including the cheek and mouth. The spasms can happen during sleep.
The involuntary twitching and uncontrollable muscle contractions caused by hemifacial spasm aren't physically painful, but they can make you feel self-conscious or embarrassed. In some cases, you may feel pain behind the ear and have hearing changes.
As hemifacial spasm progresses, physical symptoms can also interfere with your ability to perform daily tasks. For example, hemifacial spasms around the eye can interfere with eyesight by causing the eye to shut involuntarily. This can make it difficult to perform everyday tasks.
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. Hemifacial spasm is rare, occurring in only 8 to 15 out of 100,000 people in the United States.
Types
Hemifacial spasm may be typical or atypical, with the following characteristics:
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 spasm starts lower on one side of the face and progresses up the same side of a person's face. This type often starts in the orbicularis oris muscle around the lips or the buccinator muscle in the cheekbone area. Fewer than 1 in 10 people with hemifacial spasm experience atypical spasm progression from the lower to the upper face.
Hemifacial Spam Affects Half of the Face
Hemifacial spasm usually affects one-half of the face. This differentiates it from blepharospasm, which usually involves twitches with both eyes at the same time.
When hemifacial spasm affects both sides of the face, it’s called bilateral hemifacial spasm. An estimated 0.6% to 5% of people with hemifacial spasm experience involuntary muscle spasms on both sides of the face.
Causes of Hemifacial Spasm
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 movement of the 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. It can also occur after Bell's palsy, which is inflammation of the facial nerve causing temporary weakness of half the face.
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 hemifacial spasm, meaning the cause is unknown.
What Triggers the Spasms?
While spasms can occur at any time in hemifacial spasm, they can be triggered by voluntary muscle movement, such as pursing the lips, eating, or closing the eyes forcefully. People note that the spasms seem more severe when they are under stress or have fatigue.
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, a medical doctor (M.D.) who specializes in nervous system disorders like hemifacial spasms.
The first step for getting hemifacial spasm diagnosed is to have a neurological exam. The second diagnostic step involves magnetic resonance imaging (MRI).
The neuroimages created by an MRI can show if the 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.
Does Hemifacial Spasm Go Away?
In most cases, hemifacial spasm does not go away. Instead, it progresses and the spasms become worse. Getting treatment early in the condition can help prevent the progression and relieve symptoms.
Treatment for Hemifacial Spasm
Hemifacial spasm is most often caused by blood vessels pressing against the facial nerve (cranial nerve 7) at its root entry zone (REZ) in the brain stem.
The first-line treatment is usually nonsurgical, with Botox (onabotulinumtoxinA) injections 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.
Surgical treatment for hemifacial spasms involves removing the REZ source of pressure against the facial nerve via neurosurgery. Microvascular decompression (MVD) lifts pressure-causing blood vessels away from the facial nerve, which allows the nerve to function normally and stops involuntary twitching on one side of the face.
The prognosis with treatment is good. With Botox, up to 85% of people have improvement. With surgery, 90% have improvement.
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 spasm can be a severe psychosocial stressor that can lead to social anxiety disorder and increase the risk of major depressive disorder.
As the spasms can occur at night, they can lead to sleep disturbances and insomnia. 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 the 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.
Targeted Botox injections can stop hemifacial spasms for a few months and provide short-term relief. Microvascular decompression surgery is an effective long-term remedy for hemifacial spasm caused by a blood vessel compressing the facial nerve.
Read the original article on Verywell Health.
