Hemifacial Spasm

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Hemifacial spasm

Definition

A hemifacial spasm is an involuntary contraction of the muscles of facial expression, resulting in eyelid closure and upturning of the corner of the mouth and accompanied by facial weakness.

Description

Hemifacial spasm results in involuntary contraction of the facial muscles limited to one side of the face. The eyelids are involved, and upturning of the corner of the mouth is observed. The patient may have facial twitching during periods of sleep. If left untreated, the twitching may worsen and extend to other facial muscles.

Demographics

Females are affected more than males, regardless of race. Typically, patients afflicted with hemifacial spasm are in their 40s or 50s.

Causes and symptoms

The cause of hemifacial spasm has been linked to overactivity of the seventh cranial nerve nucleus that signals facial muscle movement. In other instances, hemifacial spasm may be caused by compression by a mass or abnormal blood vessel or by a lack of blood supply (ischemia) of the seventh cranial nerve at its origin or by the nucleus itself. It is thought that compression by a convoluted cerebral artery is the most common cause. In some patients, no underlying cause can be detected, which is termed an idiopathic hemifacial spasm. In younger patients, multiple sclerosis may be the cause.

Patients will usually report involuntary twitching of one side of the face (hemifacial), lasting seconds to minutes. Family members may observe facial twitching while the patient sleeps. Pain or numbness is usually not reported.

Diagnosis

When a clinical diagnosis has been established, imaging of the brain is required to rule out ischemia, mass lesions, or abnormal vasculature. Magnetic resonance imaging (MRI) of the brain, with and without contrast, as well as MRI-angiography, are advised. Blood tests are not required for patients believed to have hemifacial spasm.

Treatment team

Ophthalmologists, neuro-ophthalmologists, and neurologists are physicians who can diagnose and treat hemifacial spasm. If surgery is indicated as a form of treatment, it is usually performed by a neurological surgeon.

Treatment

The mainstay of treatment is injection of botulinum toxin to the face, which results in temporary paralysis of selected muscles of facial expression. Botulinum toxin, commonly known as Botox (Allergen Inc.), is a neuro-toxin produced by the bacterium, Clostridium botulinum. This toxin weakens facial muscles by inhibiting the release of a neurotransmitter, acetylcholine, which results in temporary and partial muscle paralysis. Botulinum toxin has become an accepted and widely used treatment for hemi-facial spasm. Although its use is relatively safe and easily injected, the effect of botulinum toxin is temporary, lasting approximately six months. This necessitates the need for re-injection or increased doses of the toxin, depending on the patient's response.

If botulinum toxin fails to be effective or the patient does not tolerate it well, decompression of the seventh cranial nerve can be attempted. This procedure, performed by a neurosurgeon, entails placing a sponge between the seventh nerve and the vessel compressing the nerve.

Other treatment options include severing branches of the seventh nerve, destruction of eyelid and facial musculature, and oral anti-seizure medications. However, oral medications have proven to be limited in their efficacy and have significant side effects.

Recovery and rehabilitation

There is usually no recovery period following the injection of botulinum toxin. The maximal effects are usually seen four to seven days following injection.

Clinical trials

Currently there are no clinical trials scheduled to study this disorder.

Prognosis

The vast majority of patients responds favorably to injections with a low rate of complications. A small percentage of patients improves spontaneously, and benefits from psychotherapy, surgery, or oral medications.

Special concerns

Support groups and information for patients and families are excellent resources that may improve treatment outcomes and psychosocial ramifications.

Resources

BOOKS

Beers, Mark H., and Robert Berkow, editors. "Cranial Nerve Disorders." The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

Burde, Ronald M., Peter J. Savino, and Jonathan D. Trobe. Clinical Decisions in Neuro-Ophthalmology, 3rd ed. St. Louis, MO: Mosby, 2002.

Liu, Grant T., Nicholas J. Volpe, and Steven L. Galetta. Neuro-Ophthalmology Diagnosis and Management, 1st ed. Philadelphia: W.B. Saunders Company, 2001.