Hemifacial spasm is a rare neuromuscular disorder that causes the muscles on one side of a person’s face to spasm, tic or twitch. In some cases, these spasms may be mild or nearly unnoticeable. In severe cases, hemifacial spasms can cause embarrassment and disruption of daily life.
While the tics associated with hemifacial spasm can be disruptive, they are usually not painful. They can occur at any time of the day and may even continue while a person is sleeping.
The condition is incredibly rare, affecting only 11 in every 100,000 people. Anyone can develop hemifacial spasm, but it is most common among those of Asian descent and in middle-aged or elderly women.
While researchers are not entirely certain what causes hemifacial spasm, it is believed to result from something irritating the facial nerve. This irritation can come from a variety of sources, including a vein putting pressure on the facial nerve, hereditary defects, a tumor pressing on the facial nerve, or injuries to the facial nerve.
In some cases, hemifacial spasm can be an early symptom of multiple sclerosis, though this is uncommon.
Symptoms of Hemifacial Spasm
Hemifacial spasm usually first shows up in the form of a spasm of the eyelid that may cause the eye to close entirely. While this twitching can affect either eye, it is more commonly found in the left eye.
Over time, hemifacial spasm may spread into other areas of the face, causing uncontrollable spasms on one side of the face. These spasms are particularly common in the muscles of the jaw and mouth and may be accompanied by a clicking noise in the ear.
If left untreated, hemifacial spasm can negatively affect the muscles of the mouth, eventually causing them to align into a permanent frown.
Along with facial spasms, hemifacial spasm can also cause ear pain, changes in hearing and hearing loss. Hearing loss is relatively rare in hemifacial spasm patients.
How Hemifacial Spasm Is Diagnosed
When a person is experiencing tics of any sort, a doctor will review this and other symptoms, carefully analyze the patient’s personal and family medical history, perform a thorough medical exam and make firsthand observations of the spasms.
If hemifacial spasm is diagnosed, imaging tests will be ordered to determine what is irritating the facial nerve. This may include MRI, CT or angiography to capture detailed images of the affected area, looking specifically for tumors or lesions.
If these causes are not visible, it is usually presumed that a blood vessel is the likely source of pressure on the facial nerve.
Treatment for Hemifacial Spasm
Treatment for hemifacial spasm will vary depending on a patient’s individual needs and the severity of symptoms. In most cases, injected botulinum toxin, commonly called Botox, is the first-line treatment for the condition.
These injections into the affected area temporarily paralyze the facial muscles, which stops the twitching. In the vast majority of cases, this treatment option is effective. It does wear off over time, though, so the treatment must be repeated every three to six months.
In the most severe cases, a doctor may recommend surgical treatment of hemifacial spasm. This involves a procedure called microvascular decompression, in which the artery putting pressure on the facial nerve is moved and the nerve is then cushioned with a pad to protect it from future compression.