Hemifacial spasm: magnetic resonance angiography.

Twenty-three consecutive patients with hemifacial spasm were studied. Magnetic resonance imaging angiography of the brain was performed in 20 patients and 15 controls. The angiograms were evaluated by two independent observers and blinded for side-location of the spasm. Contact between an artery from the vertebrobasilar circulation and the intracranial part of the facial nerve was observed ipsilaterally to the spasm in 17 patients (85%) and in two of 30 control half-brains (7%), respectively. Treatment is discussed. The study confirms that arterial relation to the facial nerve root is the most frequent cause of hemifacial spasm. Magnetic resonance imaging is recommended to exclude mass lesions in the posterior cranial fossa, and magnetic resonance angiography is recommended in preoperative evaluation and in research.