Symptomatic thrombosed venous aneurysm after stereotactic radiosurgery for brain arteriovenous malformation: Case report of a late complication mimicking radiation necrosis.

Late complications of radiosurgery for brain arteriovenous malformation include cystic formation, chronic encapsulated hematoma and radiation-induced tumors. Other complications are rarely reported. We present a case of an adult patient who received radiosurgery for treatment of an unruptured parietal arteriovenous malformation. He was followed-up for 10 years and angiographic cure was documented. Fifteen-years after radiosurgery, he complained of new-onset progressive focal seizures associated with a thrombosed venous aneurysm with persistent arteriovenous shunt angiographically occult but evidenced intraoperatively. After resection of the lesion, symptoms disappeared. This case depicts a symptomatic thrombosed venous aneurysm presenting as a rare delayed complication of radiosurgery for the treatment of brain arteriovenous malformation, which can be associated with angiographically-occult persistent arteriovenous shunt.