Hemifacial Spasm

Last update March 23, 1997

Overview

The Benign Essential Blepharospasm Research Foundation (BEBRF) was organized with the purpose "...to undertake, promote, develop and carry on the search for the cause and a cure for Benign Essential Blepharospasm and other related disorders and infirmities of the facial musculature..." Among these other related disorders is hemifacial spasm.

Hemifacial spasm affects one side of the face, while blepharospasm and Meige syndrome affect both sides. Though these disorders are quite different and have different causes, the patients in their search for diagnosis and treatment generally find the same physicians. Also, botulinum toxin injections are frequently helpful in treating both maladies. Surgical treatment, however, is quite different. Hemifacial spasm is frequently relieved with a surgical procedure called microvascular decompression in which an artery at the level of the brain stem is rerouted to relieve pressure on the facial nerve.

Since, to date, there is no other organization to represent patients with hemifacial spasm and to serve as a clearing house for information about medical and surgical treatments, BEBRF gladly accepts that responsibility. Questions about hemifacial spasm can be addressed to BEBRF

A Technical Description of Hemifacial Spasm

Hemifacial spasm is characterized by paroxysmal bursts of involuntary tonic or clonic activity occurring in muscles innervated by the facial nerve. Between spasms, the face may be normal or slightly weak on the side of the spasms. The condition occurs most often in middle-aged adults, with men and women being equally affected, although I have observed it in two teenagers. It usually begins with involvement of orbicularis oculi muscles and simulates the typical eyelid myokymia that affects most normal persons intermittently throughout life; however, instead of resolving spontaneously after several days to a few weeks, it subsequently spreads to the mid and lower face over months to years. Hemifacial spasm generally persists throughout life, gradually worsening over the years; however, I have seen several patients who experienced spontaneous temporary remissions of the condition that lasted years and others whose remissions were permanent.

Hemifacial spasm usually is painless, but it can be associated with ipsilateral facial pain. It may be exacerbated or activated by cough, fatigue, or stress. The condition is present during sleep and is often associated with both clinical and electromyographic evidence of synkinesis (aberrant regeneration).

The differential diagnosis of hemifacial spasm includes a wide variety of other entities characterized by involuntary facial movements, such as facial myokymia, which is limited to a small area of the face; essential blepharospasm, which is always a bilateral condition and confined to the eyelids and forehead unless associated with Meige syndrome (see above); Meige syndrome, which is not only bilateral but is characterized by a different type of spasms that are not synchronous; Tourette's syndrome, which is only rarely unilateral and usually is associated with purposeless vocalizations; spastic-paretic facial contracture, in which the affected side of the face is truly paretic, rather than slightly weak inferiorly, between spasms; and secondary aberrant regeneration of the facial nerve following peripheral facial nerve palsy, in which the history of a previous acute seventh nerve palsy should suggest the correct diagnosis.

Hemifacial spasm is believed to result from irritation of the seventh nerve at its exit from the brainstem. About 0.1-1% of cases are associated with extra-axial lesions compressing the seventh nerve, such as tumors (epidermoid, acoustic schwannoma, meningioma), aneurysms, arteriovenous malformations, and dolichoectatic basilar arteries. Even fewer cases are caused by damage to the facial nerve by intrinsic brainstem lesions, most often multiple sclerosis. Most cases, however, are associated with (and possibly caused by--see below) a small artery (usually a branch of the posterior inferior cerebellar artery) or a vein that is compressing the seventh nerve.

Because of the small but definite probability that a patient with hemifacial spasm has a mass lesion in the region of the cerebellopontine angle or an infiltrating lesion in the pons, all patients with hemifacial spasm should undergo magnetic resonance imaging (MRI).

Written by:
Neil R. Miller, M.D., F.A.C.S.
Department of Ophthalmology
Johns Hopkins, Baltimore, MD
1996

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