Migraine and vertebrobasilar ischemia. I studied 9 patients with migraine and posterior circulation ischemia. Inclusion criteria were (1) brainstem or cerebellar infarcts or transient ischemic attacks, (2) satisfactory vertebrobasilar angiograms, and (3) migraine. Excluded were patients with only occipital lobe ischemia, known arteriosclerosis, or other nonmigrainous vascular disease. Two women and 7 men, ages 6 to 58 years (mean, 34.7), had transient attacks only (2), single strokes (4), single stroke followed by attacks (1), or multiple strokes (2). Five had antecedent classic, 2 common migraine, and classic migraine began only after the initial ischemic event in the other two. The 7 stroke patients all had CT- or MRI-documented brainstem (4) or cerebellar (6) infarcts. Angiography was normal (3) or demonstrated basilar artery (BA) narrowing (2) or occlusion (4), or branch occlusion (1). In 3 patients the initially occluded BA later reopened. At follow-up (average 4.3 years, range 1 to 9 years), 5 were normal and 4 had important clinical deficits. I conclude that (1) "basilar migraine" is not always benign; it affects both sexes and a wide age range; (2) the pattern of headaches, attacks, and strokes varies; (3) migraine may appear only after ischemia; (4) some patients have BA occlusion or diffuse narrowing; and (5) BA occlusion can be temporary. 