Megalencephaly secondary to occlusion and stenosis of sigmoid sinuses.

Bilateral, idiopathic, essentially asymptomatic but hemodynamically significant stenosis or occlusion of the sigmoid sinuses is extremely rare. We report a child with the angiographic features of occlusion of the right sigmoid sinus and severe stenosis on the contralateral side, presenting with megalencephaly and a cranial bruit. Cranial computed tomographic scans demonstrated increased subarachnoid spaces and borderline ventricular enlargement.