[Hemifacial spasm: study using magnetic resonance angiography].

: Nine patients with "idiopathic" hemifacial spasm were evaluated with cranial magnetic resonance imaging and angiography. Alterations of the posterior fossa vasculature, possibly related to the facial nerve irritation, were found in 8 patients (88%). Magnetic resonance angiography is a noninvasive procedure and appears to be a sensitive method to evaluate the hemifacial spasm etiology.