Ectatic and Occlusive Diseases of the Venous Drainage System of Cerebral Arteriovenous Malformations (AVMs) - with Emphasis on Spectacular Shrinking Neurological Deficits after Embolization.

During reviewing cases with AVM, the author noticed that stenotic and occlusive changes of the draining veins are commonly seen in high flow cerebral AVMs. However, little attention has been paid to these venous diseases until ectatic veins, generated in the upstream of the venous system, cause mass effect to the surrounding structures, or redistribution and shunting toward regional veins became insufficient after they are markedly overloaded or occluded. Cases with such venous abnormality are clinically important because of the possibility of dramatic improvement of neurological deficits after embolization of AVMs. Following presenting treatment results of 177 AVM case, the author is going to present five cases with abnormality in the Galenic venous system and two cases with abnormality in cortical veins associating with high flow cerebral AVMs. Consideration will be made on symptomatology and pathophysiologic mechanism of venous abnormalities associating with high flow cerebral AVMs.