What Is Hemifacial Spasm?

Hemifacial spasm is a disorder of the facial nerve (also known as cranial nerve VII) characterized by painless involuntary twitching of the muscles on one side of the face. These spasms can be distressing in social settings or even disturb sleep and vision.

Hemifacial spasm is most common in middle-aged and elderly women. In most cases, it is caused by compression of the facial nerve from a nearby blood vessel. Although patients might tolerate this condition for years, treatment options are available, and surgery can provide a cure.

Hemifacial spasm is a rare condition, affecting approximately 11 in 100,000 individuals. While typically not painful, hemifacial spasms can be difficult for patients to cope with and can impact their quality of life.  

What is a hemifacial spasm? Below, we answer this question, detail its symptoms, and provide an overview of how this condition is diagnosed and treated.

Patients typically experience a painless twitching of the muscles on one side of their face that they cannot control. The muscles of the eyelid are often the first affected, with other muscles lower on the same side of the face typically becoming involved with time. Stress, fatigue, and use of the facial muscles for actions such as speaking can worsen hemifacial spasm symptoms.

Over months to years, the disorder can progress from occasional twitching to an almost constant spasm of all face muscles on the affected side, leading to a periodic grimace or other abnormal facial expressions. This condition can be embarrassing in social situations and cause discomfort at work. Other symptoms related to hemifacial spasm include the following:

• Poor sleep quality from spasms during sleep.
• Impaired vision caused by periodic squinting.
• Hearing a “ticking” sound from the twitching of a tiny muscle inside the ear.
• Difficulty speaking or drinking because of spasms pulling at the corner of the mouth.

These symptoms can feel frustrating or embarrassing and make daily tasks that require focus and clear vision, such as driving, difficult. Very rarely, a patient might experience hemifacial spasm on both sides of the face, with twitching occurring independently on each side.

At first, twitches might be barely noticeable or limited to only one area of the face, such as the eyelids. However, hemifacial spasm is a progressive disorder, and over time, most patients will experience worsening symptoms without treatment.

Twitching can spread to other muscles controlled by the facial nerve, such as those around the mouth or even inside the ear, causing more disruptive symptoms.

Hemifacial spasm is typically caused by the facial nerve being compressed by a nearby structure, which results in the nerve sending abnormal signals to the facial muscles without input from the brain, causing an uncontrollable twitch. The most common cause of hemifacial spasm is pressure on the facial nerve from a neighboring blood vessel as it leaves its origin in the brainstem. The start of the nerve near the brainstem is the most sensitive to compression because it has less of its protective covering at this location.

Hemifacial spasm can also be caused by damage to the facial nerve, such as from an injury or inflammation. In some cases, a specific cause for the spasm cannot be found.

A brain tumor can occasionally cause hemifacial spasm, but such tumors are almost always benign. Symptoms can arise because the tumor takes up precious space within the skull and compresses surrounding structures such as the facial nerve, causing it to send accidental signals to the facial muscles and lead to spasms.

Also having hearing loss or balance issues might suggest that a tumor is causing the symptoms. Imaging tests, such as magnetic resonance imaging (MRI), can help determine whether a tumor is present. When feasible, surgical removal of the tumor can often resolve the spasms.

Hemifacial spasm is more common in elderly women and people of Asian descent. Estimates suggest that approximately 11 in 100,000 people are affected by this disorder. Patients usually first notice symptoms in their fourth or fifth decade of life.

Unfortunately, hemifacial spasm is commonly misdiagnosed, and patients tend to experience symptoms for an average of 8 years before receiving a proper diagnosis that can guide treatment.

A doctor will complete a physical exam and ask questions about your symptoms to help diagnose the condition. No tests currently exist to confirm the diagnosis besides careful history and physical examination. Sometimes the blood vessel or tumor pressing on the nerve can be seen with imaging such as MRI.

Hemifacial spasm is often misdiagnosed, and patients can experience symptoms for many years before receiving a diagnosis. Many similar movement disorders of the face can mimic this disorder, which can delay accurate diagnosis and appropriate treatment. To understand the differences between them, we must first discuss the interactions between nerves and muscles.

Motor neurons are specialized cells of the nervous system that use electrical and chemical signals to transmit information from the brain to our muscles, leading to muscle contractions.

Each motor neuron can supply information to several muscle fibers. This single motor neuron and its muscle fibers are considered a motor unit. Conditions like hemifacial spasm can differ by the number of motor units involved.

Many people experience occasional uncontrollable small muscle movements, such as an eye twitch. These small twitches are called fasciculations, and they sometimes last for days or weeks. Simple fasciculations, caused by a miscommunication in the muscle’s signal to contract, are harmless.

Fasciculations involve a single motor unit or part of a motor unit and are signs of nerve irritability. These twitches can be caused by a variety of factors such as certain medications, caffeine, electrolyte imbalance, exhaustion, or stress. However, fasciculations might indicate a more serious condition if they are associated with weakness or muscle wasting.

Unlike hemifacial spasms, fasciculations are very small twitches of only a few muscle fibers and might be noticed only while watching the muscles at rest for a while. Since these fasciculations affect only one motor unit, the contractions are not usually strong enough to alter facial expressions.

Facial myokymia presents as a distinct quivering or rippling of facial muscles, typically occurring in various areas across the face at rest. In contrast to the sharp intermittent muscle contractions of hemifacial spasm, facial myokymia presents with subtle, small, continuous flickering of muscles that can resemble worm-like movements under the skin.

Whereas fasciculations involve abnormal firing and contraction of a single motor unit, facial myokymia involves abnormal repetitive signaling from groups of motor units at different rates, leading to the appearance of subtle quivering of muscles.

Unlike the progressive worsening of symptoms in hemifacial spasm, facial myokymia usually resolves on its own within weeks to months. However, for both conditions, underlying conditions such as a tumor or multiple sclerosis can be the cause, so be sure to seek medical attention if you experience any of these symptoms.

Blepharospasm is a condition characterized by uncontrollable and excessive blinking and closure of the eyes.

Although blepharospasm is not usually painful or associated with nerve injury, vision can be impaired and make activities such as reading, watching television, and driving challenging or impossible.

Symptoms of blepharospasm can resemble the initial symptoms of hemifacial spasm. However, blepharospasm is usually confined to the muscles around the eyes and does not progress to involve other muscles.

Also, patients with hemifacial spasm will continue to experience symptoms while they are sleeping, whereas symptoms of blepharospasm disappear during sleep.

Differentiating hemifacial spasm from other movement disorders such as facial myokymia, fasciculations, and blepharospasms requires the clinical judgment and experience of a physician.

The distinct differences, particularly in the observable characteristics of each disorder, can be subtle and are more readily distinguished by someone with a trained eye. Please contact your physician if you are experiencing these symptoms.

Medications, injections of botulinum toxin (a common brand is Botox), and surgery are all treatment options available for hemifacial spasm. Medications and botulinum toxin injections help manage hemifacial spasm symptoms by suppressing the twitching but do not address the root cause of the disorder, but in many cases, surgery can bring a cure by decompressing the facial nerve.

Medications used to treat hemifacial spasm attempt to control symptoms by decreasing the overactivity of nerves, limiting the twitching that patients experience. Medications used include:

• Carbamazepine (Tegretol)
• Clonazepam (Klonopin)
• Baclofen (Gablofen)
• Gabapentin (Neurontin)

Side effects of these medications include fatigue, exhaustion, and poor performance. Unfortunately, many patients do not find relief from their symptoms with these medications and typically explore other treatment options, such as botulinum toxin injections or surgery.

Botulinum toxin injections help manage symptoms for many patients with hemifacial spasm. It can be injected into the face, causing a temporary paralysis of the facial muscles that prevents them from spasming.

This paralysis will wear off by the end of each 3- to 6-month cycle of injections, so patients might feel their spasms return between injections. To find more lasting relief from hemifacial spasm, many patients decide to pursue surgical treatment for their condition.

The surgery used to treat hemifacial spasm is called microvascular decompression surgery (MVD), which effectively eliminates spasms for as many as 80% to 90% of patients who seek treatment by an experienced surgeon.

The surgeon adds cushioning between the facial nerve and the offending blood vessel to take pressure off of the nerve. Twitching symptoms typically decrease shortly after surgery and are eventually absent for many patients.

After a hemifacial spasm diagnosis, you may be left with questions or uncertainties. A second opinion from a qualified medical professional can help resolve your concerns and, importantly, allow you to explore more treatment options for your condition. 

Dr. Aaron Cohen-Gadol is one of the world’s leading neurosurgeons. He is one of only 11 recipients in the history of the Vilhelm Magnus Medal, the highest honor in the field of neurosurgery. 

Apart from his technical acumen, Dr. Cohen-Gadol has also been lauded for his authentic empathy for his patients. He has helped transform the lives of countless patients by providing exceptional surgical care with empathy and compassion. 

Dr. Cohen-Gadol and his team are happy to provide second opinions to patients suffering from hemifacial spasm regarding their questions about their diagnosis or treatment plan. To request a second opinion, please fill out the online form and include details of your case history. 

• Hemifacial spasm is a rare disorder of the facial nerve characterized by painless uncontrollable twitching of facial muscles on one side.
• Hemifacial spasm is often caused by compression of the facial nerve by a nearby blood vessel.
• Medications and injections of botulinum toxin can be used to treat the symptoms of hemifacial spasm, but surgery is the only option that can provide a cure.

• American Association of Neuromuscular & Electrodiagnostic Medicine
• National Institute of Neurological Disorders and Stroke