Risk of rebleeding in arteriovenous malformations due to impaired venous drainage after radiosurgery.

A 27-year-old woman presented with rebleeding from an intracranial arteriovenous malformation (AVM) 6 years after radiosurgery. Cerebral angiography demonstrated venous drainage change into a single drainer and cortical reflux due to drainage occlusion into the superior sagittal sinus. During surgery, multiple small feeders thought to be occluded on preoperative angiography caused brain swelling, hindering resection of the AVM border plane. Flow changes after radiosurgery, especially impaired venous drainage, may have increased the tendency to rebleeding of the AVM. Scheduled angiography after radiosurgery is recommended, and retreatment for residual AVMs is preferable, especially if venous drainage change occurs.