Moyamoya syndrome with spherocytosis: effect of splenectomy on strokes.

A 3-year-old male patient with hereditary spherocytosis who developed moyamoya syndrome, presenting hemiplegia, and slurred speech is reported. Transient ischemic attacks occurred repeatedly with hemolytic crises. Magnetic resonance imaging and angiography revealed bilateral occlusion of the internal carotid and middle cerebral arteries with the formation of moyamoya vessels and multiple infarctions in the basal ganglia. Although splenectomy can increase the risk of stroke, no stroke occurred after splenectomy. On aspirin and dipyridamole therapy the patient has been free of neurologic deficits and progression of the vasculopathy for 5 years. This rare observation suggests that anemic hypoxia more greatly contributes to the progression of moyamoya syndrome than postsplenectomy thrombocytosis or reduced deformability of spherocytes.