Stereotactic resection of occult vascular malformations.

Angiographically occult vascular malformations can be identified on computerized tomography and magnetic resonance imaging. Surgical excision, when possible, is the treatment of choice in symptomatic lesions. Because these malformations are usually small and can be located in surgically treacherous areas of the brain, stereotactic resection should be considered. Stereotactic resection of a pathologically verified occult vascular malformation was performed in 26 patients in this series (13 females and 13 males, mean age 30 years). Seventeen patients presented with a seizure disorder, four with an intracerebral hemorrhage, and four with a progressive neurological deficit; one patient was asymptomatic. Sixteen patients had normal neurological examinations, nine had neurological signs referable to their lesion, and one had a visual field deficit related to a previous temporal lobectomy. In six patients evidence of acute hemorrhage was found on imaging studies or at surgery, and 11 patients had evidence of previous hemorrhage on imaging studies, determined at surgery or by histological examination. Three patients had evidence of both acute and previous hemorrhage and six patients had no evidence of hemorrhage. Lesions were located in cortical or subcortical areas in 21 patients, in the thalamus or basal ganglia in three, and in the posterior fossa in two. Following stereotactic resection, 24 patients were improved, one patient was unchanged, and one patient was worse. Without stereotaxis or intraoperative ultrasound studies, localization of these lesions at conventional craniotomy can be difficult. A stereotactic craniotomy is ideally suited to the treatment of these benign circumscribed, but potentially devastating lesions.