Hemifacial spasm associated with dolichomegavertebrobasilar anomaly.

3 patients suffering from long-lasting "cryptogenetic" hemifacial spasm in association with dolichomegavertebrobasilar anomaly, are described. The angiographic examinations confirm the anomaly and put in evidence the patholphysiologic value of segment V4 of the vertebral artery at the same side of the spasm. Classical electromyographic examinations, and methods used to study the blink reflex, seem to rule out the hypothesis of a brain stem involvement as the only and sufficient pathologic mechanism. The peripheral pathogenesis is the most likely one.