Moyamoya disease in black adults.

A 40-year-old hypertensive black female, who suddenly developed aphasia, lethargy, and a right hemiparesis, and a 42-year-old non-hypertensive black male, who suddenly developed intractable headache, drowsiness, and vomiting, were found by angiography to have moyamoya disease. This condition is characterized by a decreased caliber of the internal carotid arteries and bilateral occlusion of the anterior and middle cerebral arteries with visualization of an extensive collateral network of tortuous blood vessels of the rete mirabile type at the base of the brain.