Cerebral arteriovenous malformation and the primitive trigeminal artery.

A 27-year-old woman with a small cerebral arteriovenous malformation and a primitive trigeminal artery had subarachnoid hemorrhage. This case and a review of the literature suggest that some of the "spontaneous" subarachnoid hemorrhages reported in patients with a primitive trigeminal artery may have been due to rupture of an unrecognized small arteriovenous malformation or aneurysm.