A Case of Recurrent Expansile Cyst Formation after Gamma Knife Radiosurgery for a Cerebral Arteriovenous Malformation: Role of the Residual Nidus: Case Report

ABSTRACT

The authors report a case of recurrent expansile cyst formation after gamma knife radiosurgery(GKRS) for a cerebral arteriovenous malformation where the residual nidus might play an important role. A 28-year-old male patient underwent gamma knife radiosurgery for a left parietal lobe arteriovenous malformation which had manifested with generalized tonic-clonic seizure in November 1992. In March 1999, 76 months after GKRS, the patient presented with headache, dysphasia and right hemiparesis and the computed tomography(CT) and magnetic resonance(MR) image revealed a huge cystic lesion with enhancing nodule at the anterior wall of the cyst. Cerebral angiography showed a small residual nidus. Aspiration and drainage of the cystic fluid via a burr hole was performed and the symptoms improved. One year later, in March 2000, the symptoms recurred, and CT and MR image revealed a new huge cystic lesion anterior to the enhancing nodule. Surgical removal of the residual nidus was performed, and there is no recurrence of the cyst for two years till now.