[A rare case of developmental venous anomaly with diffuse arteriovenous shunt in the posterior fossa presented as massive cerebellar hemorrhage].

Developmental venous anomalies(DVAs), that have been previously called venous malformation, are extreme variations of normal transmedullary veins that are necessary for the drainage of white and gray matter. They are becoming the most commonly encountered intracranial vascular lesions in central nervous system imaging. Most DVAs are asymptomatic or uncomplicated, and surgery is no longer considered necessary. The author describes a rare case of an 8-year-old patient presenting with massive cerebellar hemorrhage due to DVA with diffuse arteriovenous(A-V)shunt. Cerebral angiography demonstrated diffuse A-V shunt from the basilar artery runs into the bilateral basal vein of Rosenthal through the enlarged transpontine vein. Caput medusae-like appearance was visualized, although the finding of nidus was not obvious. Moreover, three-dimensional computed tomography angiography demonstrated stenosis in part of the drainage routes. Then, we supposed that this lesion was a transitional form between a DVA and an arteriovenous malformation, and massive cerebellar hemorrhage might be caused by secondary venous hypertension due to venous stenosis. A careful follow-up should be made, because the prognosis of DVA with A-V shunt has not been fully elucidated.