What is Hemifacial Spasm?

Hemifacial spasm is a neurological movement disorder that causes involuntary twitching, tightening, or contractions of the facial muscles on one side of the face. The word “hemi” means half, and the condition usually affects only one side.

Hemifacial spasm is often related to irritation of the facial nerve, also called cranial nerve VII. This nerve controls many muscles of facial expression, including muscles around the eye, cheek, mouth, and jaw. In many patients, symptoms begin around one eye and may later involve the cheek, mouth, or lower face.

De Novo Brain & Spine evaluates adult patients with suspected hemifacial spasm when symptoms suggest facial nerve irritation, neurovascular compression, skull base disease, tumor, prior facial nerve injury, or another neurological condition that may require neurosurgical review.

Common Signs and Symptoms

Hemifacial spasm symptoms depend on the facial muscles involved, the frequency of spasms, and whether the condition is primary or related to another structural cause.

Common signs and symptoms may include:

• Involuntary twitching on one side of the face
• Eyelid twitching or repeated eye closure
• Spasms that begin around the eye and spread to the cheek or mouth
• Pulling of the mouth to one side
• Facial tightening or cramping
• Twitching that worsens with stress, fatigue, talking, eating, or facial movement in some patients
• Spasms that may continue during sleep in some cases
• Difficulty keeping the eye open during spasms
• Facial asymmetry during a spasm
• Interference with reading, driving, working, eating, or social interaction
• Facial irritation or eye discomfort if frequent blinking or eye closure occurs
• Anxiety or frustration related to visible facial twitching

Seek medical evaluation for new or persistent facial twitching, worsening spasms, facial weakness, facial numbness, hearing changes, dizziness, trouble swallowing, double vision, or symptoms that affect daily function. Seek emergency medical care or call 911 for sudden facial drooping, arm weakness, speech difficulty, sudden vision loss, severe headache, loss of consciousness, or other stroke-like symptoms.

What Causes This Condition?

Hemifacial spasm occurs when the facial nerve becomes irritated or overactive. In many cases, this is related to a nearby blood vessel pressing on the facial nerve near where it exits the brainstem. This is often called neurovascular compression.

Possible causes and related factors may include:

• Neurovascular compression of the facial nerve near the brainstem
• Irritation of the facial nerve, or cranial nerve VII
• Blood vessel contact with the facial nerve root exit zone
• Skull base tumors or lesions in selected cases
• Brainstem or cerebellopontine angle lesions in selected cases
• Prior facial nerve injury in selected patients
• Prior Bell’s palsy or facial nerve recovery changes that may cause spasm-like movements or facial synkinesis
• Multiple sclerosis or other demyelinating conditions in selected cases
• Vascular malformation, aneurysm, or other structural cause in less common cases
• Idiopathic hemifacial spasm, meaning no clear cause is found after evaluation

These causes and related factors do not mean every patient has a tumor or serious structural condition. Treatment planning depends on the symptom pattern, neurological examination, imaging findings, severity of spasms, response to prior treatment, and overall health.

How It Is Diagnosed?

Hemifacial spasm is diagnosed through medical history, physical examination, neurological examination, and imaging when appropriate. The pattern of one-sided facial twitching is an important part of the diagnosis.

Common diagnostic steps may include:

• Medical history and symptom review to understand when twitching began, which facial muscles are involved, triggers, frequency, duration, prior facial weakness, prior Bell’s palsy, and prior treatment
• Neurological examination to evaluate facial movement, facial strength, facial sensation, eye movement, hearing, coordination, balance, and other cranial nerve functions
• Observation of facial spasms during examination when symptoms are present
• MRI of the brain and skull base with and without contrast to evaluate the facial nerve pathway, brainstem, cerebellopontine angle, and possible structural causes
• High-resolution MRI of the facial nerve region in selected cases when neurovascular compression is suspected
• MR angiography, also called MRA, or CT angiography, also called CTA, in selected cases when blood vessel anatomy needs further evaluation
• Electromyography, also called EMG, in selected cases when the diagnosis is unclear or when symptoms may overlap with other facial movement disorders
• Evaluation for other causes of facial movement such as facial tic, blepharospasm, facial myokymia, seizure, medication-related movement disorder, Bell’s palsy recovery changes, or facial synkinesis

The goal of diagnosis is to confirm whether symptoms fit hemifacial spasm, identify whether a structural cause is present, and determine whether medical treatment, injections, observation, or neurosurgical treatment planning may be appropriate.

Treatment Options

Hemifacial spasm treatment depends on symptom severity, facial nerve findings, imaging results, suspected cause, prior treatment response, surgical risk, and the patient’s overall health. Not every patient needs surgery.

Treatment options may include:

• Observation and monitoring when symptoms are mild, infrequent, or not significantly affecting daily life
• Botulinum toxin injections into selected facial muscles to reduce twitching or spasms for a period of time
• Medication trials in selected cases, although oral medications may have limited benefit for many patients
• Treatment of an underlying structural cause when imaging identifies a tumor, vascular lesion, demyelinating disease, or another condition
• Microvascular decompression, also called MVD, in selected patients when neurovascular compression of the facial nerve is suspected and the patient is an appropriate surgical candidate
• Coordination with neurology, ophthalmology, ENT, or pain specialists when symptoms overlap with other facial movement, eye, ear, or cranial nerve conditions
• Eye protection or eye care when frequent blinking or forced eye closure causes irritation or interferes with vision
• Follow-up care to monitor spasm frequency, facial function, treatment response, and imaging findings when appropriate

The purpose of microvascular decompression is to relieve pressure on the facial nerve when a blood vessel is believed to be irritating the nerve near the brainstem. Neurosurgical treatment is not appropriate for every patient with hemifacial spasm, and the safest plan depends on the diagnosis, imaging findings, symptom severity, and individual medical factors.