Familial hemifacial spasm: report of cases and review of literature.

We describe clinical characteristics of 10 patients (five families) with familial hemifacial spasm, with reviews of 13 patients hitherto reported in the literature. There is no clear difference in clinical manifestations between sporadic and familial hemifacial spasms. There is no definite inheritance pattern, but may be autosomal dominant with low penetrance. The ages of onset of familial hemifacial spasm are variable, but occasionally can occur at early years of life. There is a left-side predominance with respect to the affected side of cases with familial hemifacial spasm. Similar to sporadic hemifacial spasm, vascular decompression was effective, suggesting that vascular compression is involved in generating hemifacial spasm even in the familial cases. Familial hemifacial spasm may not be a rare disorder, but may possibly be overlooked. Clarifying the role of genetic susceptibility in pathophysiological mechanisms underlying hemifacial spasm is an important approach toward better understanding of the pathogenesis of cranial rhizopathies.