Chronic encapsulated expanding hematoma after stereotactic radiosurgery of cerebral arteriovenous malformation

Stereotactic radiosurgery has become excellent alternative treatment for cerebral arteriovenous malformations (AVM). This technique has expanded to treatment of larger AVM which is not amenable to surgical management. However, its variable adverse effects should be also taken into considerations sincerely because of radiobiological characteristics such as delayed onset and progressive neurological deteriorations. Herein, we report a case in which progressively expanding hemorrhagic cyst with repeated bleedings so called chronic encapsulated expanding hematoma was developed on several years after radiosurgery treatment. Neurological and radiological findings were improved by surgical removal.