Familial hemifacial spasm.

Three male patients in successive generations of the same family developed acquired left-sided hemifacial spasm. Magnetic resonance imaging of the proband demonstrated a pontine vertebral artery anomaly near the root of the affected facial nerve. This family and a similar family that was recently presented illustrate several interesting features: (1) hemifacial spasm, from whatever cause, may be autosomal dominant; (2) the spasms involve the same side of the face in affected individuals within an affected family; and (3) the age of onset in familial cases may be younger than in nonfamilial cases.