Hemifacial Spasm: Causes, Symptoms and Treatment

01Definition

What hemifacial spasm is

Mayo Clinic describes hemifacial spasm as a nervous system condition that causes muscles on one side of the face to twitch or spasm. The movements cannot be controlled. They usually start around one eye and may spread on that side of the face.

Hemifacial spasms are not life-threatening, but they can be uncomfortable and affect social interaction. They are usually painless. Mayo Clinic notes that, occasionally, they can affect both sides of the face, but not usually at the same time.

02Progression

How it starts and spreads

Mayo Clinic explains that the spasms often start in one eyelid and may then move to the cheek and mouth on the same side. At first, they come and go; over months to years, they may occur almost all the time. How quickly they spread and how often they happen differs from person to person. Common features include muscle movements that:

• affect one side of the face
• cannot be controlled
• spread from the eye area to other areas on the same side
• happen more often over time
• can occur during sleep

03Causes

Causes: facial nerve and blood vessels

The facial nerve controls the muscles of facial expression. Mayo Clinic explains that the most common cause of hemifacial spasm is a blood vessel touching the facial nerve. Less often, a tumor pressing on the nerve or an injury to the nerve is responsible, and sometimes no cause is found. A tumor is an uncommon cause, but it is one reason why a doctor may order imaging.

Some studies suggest that certain factors may increase the risk: high blood pressure, age over 40, female sex, certain genes involved in carrying cholesterol and other fats in the blood, brain lesions or tumors, conditions such as multiple sclerosis, and a history of facial nerve injury or Bell’s palsy.

04Triggers

What makes it worse

Mayo Clinic explains that several things can increase the spasms:

• moving the muscles of the face
• anxiety
• stress
• tiredness

There is no known way to prevent hemifacial spasm, but managing stress, fatigue and anxiety may help reduce symptoms.

05Differences

How it differs from eyelid twitching and blepharospasm

Most people occasionally have brief eyelid twitching that settles on its own. Hemifacial spasm is different: it is persistent, affects one side of the face, tends to spread from the eye to the cheek and mouth on that side, becomes more frequent over time and can continue during sleep.

Blepharospasm is a different condition, a form of dystonia that affects the muscles that close the eyes, usually on both sides. Because these conditions are treated differently, a professional assessment is needed rather than self-diagnosis from how the twitching feels. Not every twitching eyelid is hemifacial spasm, and a tumor is only an occasional cause of hemifacial spasm.

06Diagnosis

How it is diagnosed

Mayo Clinic explains that diagnosis usually starts with your medical history: your symptoms and how long you have had them. Physical and neurological examinations check facial movement and look for other nerve problems.

Imaging such as MRI can show a blood vessel pressing on the facial nerve, as well as tumors or other brain conditions; sometimes magnetic resonance angiography (MRA) is used to show the blood vessels. Mayo Clinic notes that imaging is not always needed and is more likely if symptoms are not typical or surgery is planned. Electromyography (EMG), which measures electrical activity in the facial muscles, may be used but is not commonly needed.

07Injections

Botulinum toxin (no doses)

Mayo Clinic explains that botulinum toxin injections into the affected muscles stop them from moving. This is the most common treatment and controls symptoms in most people. The effect is temporary, so injections are repeated every few months.

The muscles injected, the dose and the interval are decided by the specialist. Possible side effects and expected benefits should be discussed before treatment, as responses vary between people.

08Other treatment

Medicines and surgery

Mayo Clinic explains that some oral medicines, such as anti-seizure medicines and muscle relaxants, can relieve hemifacial spasm in some people, mainly in early or mild cases.

Surgery is an option for some people. Mayo Clinic notes that studies have found microvascular decompression, in which the surgeon places a small pad between the blood vessel and the facial nerve through an incision behind the ear, to be the most effective long-term treatment. Other procedures act on the nerve itself. Surgery is a decision made with a specialist after weighing benefits and risks, and no procedure guarantees a cure. Some studies report benefit from acupuncture, but its effectiveness is uncertain.

09Sources

Where the sources differ

This guide is based on two Mayo Clinic pages (October 2025), one on symptoms and causes and one on diagnosis and treatment, so it reflects a single organization’s view. Within them, Mayo Clinic is cautious: risk factors come from “some studies”, imaging is not always required, EMG is not commonly needed and the evidence for acupuncture is uncertain.

Other sources online sometimes describe injections as entirely non-invasive or surgery as a definitive cure; Mayo Clinic presents surgery as the most effective long-term option for some people, not a guaranteed result. Living with visible spasms can affect confidence and social life, and support and treatment can help. MediBilbao Salud does not treat hemifacial spasm; a neurologist is the right specialist.

10Summary

In summary

Hemifacial spasm causes involuntary twitching on one side of the face, usually starting at the eyelid and spreading to the cheek and mouth, becoming more frequent over time and sometimes present during sleep. It is usually caused by a blood vessel touching the facial nerve. It is painless but can affect social life. Botulinum toxin injections control symptoms in most people; medicines and surgery are other options.

For your appointment, note where the twitching started, how it has spread, how often it occurs, whether it continues during sleep and whether it interferes with vision, reading, driving or sleep. New facial weakness or other neurological symptoms need urgent care.