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Causes of Hemifacial Spasm

Last Updated: September 25, 2023

Hemifacial spasm can cause serious stress and anxiety. The abnormal facial movements they can create can make daily tasks such as eating or talking difficult. The sudden uncontrollable twitching can alter facial expressions and cause discomfort in public and social situations. But what exactly is the cause of this frustrating condition? In this article, we discuss hemifacial spasm and its origins.  

What Is Hemifacial Spasm?

Hemifacial spasm is a condition in which the muscles on one side of the face periodically contract. This uncontrollable and painless spasm initially affects the muscles around the eye and can gradually involve the entire half of the face. Over time, the twitches can increase in frequency to the point at which it becomes difficult to see out of the affected eye.

Whom Does It Affect?

Hemifacial spasm more commonly affects adults 40 to 60 years of age and females more than males. If the spasms occur at an earlier age, they could be an indication of an underlying neurological condition (for example, multiple sclerosis). 

What Causes Hemifacial Spasm?

The condition is caused most commonly by compression to the facial nerve from an adjacent blood vessel, which causes the nerve to misfire and leads to uncontrollable muscle contractions. Compression from other structures, such as a tumor, cyst, or bone deformity, can also cause hemifacial spasm. In some cases, hemifacial spasm can occur after facial paralysis from a condition called Bell’s palsy. In other cases, no specific cause is ever found.

                                            Figure 1: Magnetic resonance image of the brain showing a loop of blood vessel (black arrow) near the root of the facial nerve.

Figure 1: Magnetic resonance image of the brain showing a loop of blood vessel (black arrow) near the root of the facial nerve.

Magnetic resonance imaging (MRI) studies are often performed to determine if a tumor or other large structure is causing the symptoms. Sometimes, MRI can reveal the presence of a blood vessel pressing against the facial nerve. However, in most cases, the images may appear normal, and the offending blood vessel is seen only during surgery. Fortunately, surgical decompression of the nerve often provides a lasting cure. 


Although stress is often associated with hemifacial spasm, there is currently no evidence that it causes the condition. Rather, stress and anxiety can trigger the spasms or worsen symptoms by increasing how often it occurs or the number of facial muscles involved.

It is common for patients with hemifacial spasm to suffer from anxiety because of the nature of the disease and its impact on the face, which is an important aspect of our physical appearance. Meditation, breathing exercises, yoga, and autogenic training (visual imagery and body awareness to move to a state of relaxation) are commonly used relaxation methods. Sharing information about your condition to family and friends can also help to alleviate anxiety and promote understanding and consideration.


Some vitamin deficiencies are linked to various physiological and neurological problems. Deficiency in vitamin D can be associated with muscle spasms. However, these muscle spasms are generally more widespread than just hemifacial spasms. Vitamin D deficiency also manifests with other signs and symptoms such as muscle pain, bone pain, and fractures, whereas the muscle twitching with hemifacial spasm is painless and usually affects only one side of the face.

Vitamin B12 deficiency has also been associated with hemifacial spasm. This vitamin plays an important role in the nervous system, and a low level can cause nerve damage and muscle spasms.


Most cases of hemifacial spasm occur as a sporadic condition without a hereditary component. Hemifacial spasm in family members is rarely reported, and the exact gene(s) involved and how it may be passed down are unclear.

How Do Hemifacial Spasms Progress?

Hemifacial spasm often begins with twitching of the facial muscles around the eye, which can cause periodic squinting or closure of one eye, making it difficult to see. Over time, the twitching spreads to other facial muscles on the same side of the face. Severe simultaneous contractions of all the facial muscles on one side of the face can pull at the corners of the eye and mouth, leading to an abnormal grimace. Although rare, 2% of patients can experience spasms on both sides of their face.

Key Takeaways

  • Hemifacial spasm is caused most commonly by compression of the facial nerve by a blood vessel at the brainstem.
  • Hemifacial spasm usually begins during the fourth or fifth decade of life.
  • Stress, anxiety, and fatigue are common triggers of these spasms.