Pathophysiology of hemifacial spasm.

Abstract

Hemifacial spasm (HFS) is characterized by attacks of spasm on one side of the face that usually begin as small contractions around the eye and that over several years increase in intensity while progressing down the face as the intensity of the spasm increases [4, 5]. The attacks also occur during sleep and can be precipitated by emotional factors. Between attacks, the facial muscles seem to function normally, except for synkinesis of facial muscles and maybe a slight weakness of facial muscles in individuals who have had HFS for a long time [4, 5]. The incidence of HFS is very low (0.74 per 100 000 in white men in the USA and 0.81 per 100000 in white women) [3]. HFS is believed to be caused by vascular compression of the intracranial portion of the facial nerve at its root exit zone (REZ). Microvascular decompression (MVD) of the facial nerve offers a high rate of success for total cure [16, 17, 19] with little side effects, but there is no known medical treatment effective in curing HFS [34].