Hemodynamic changes in drainage systems following treatment of cerebral arteriovenous malformations.

SUMMARY: The authors studied 61 patients undergoing effective embolization for cerebral arteriovenous malformations (AVMs) and analyzed the hemodynamic changes in their drainage systems following embolization. The changes were classified into following 5 types: type A, disappearance of all the draining veins; type B, disappearance of a part of the cortical veins; type C, disappearance of a part of the deep-seated veins; type D, combined type Band C patterns; type E, disappearance of reflux into normal cortical veins. Each case was evaluated on the basis of these criteria from comparing pre- and post-embolization angiograms. The delay and reduction of shunt were observed in all cases. Forty-nine of them showed obvious hemodynamic changes in the draining systems including type A change in 9, type B in 19, C in 5, Din 3 and E in 13 cases, respectively. Two cases showed a spontaneous shift in the dominance of the main drainers. Thirteen of 15 cases showing successful results in subsequent radiosurgery exhibited various changes in draining pattern. Changes in drainage systems may be affected by the compartmentalization of the nidus, reduction in shunt flow, and spontaneous or progressive thromboses. These can be promoted by embolization and may be regarded as one of the indicators of successful pretreatment for radiosurgery.