Abstract
A case of huge arteriovenous malformation (AVM) with aneurysmal dilatation in the brain stem and thalamus in a 1 3/4-year-old girl is presented. Initial symptoms were Parinaud's syndrome and right hemiparesis, presumably due to mass effect of the AVM on the midbrain. Computed tomography scan disclosed a high density mass in the upper brain stem and thalamus. Cerebral angiography demonstrated a huge aneurysmal AVM (4×4.5×4.5 cm) which was fed by the elongated and dilated posterior thalamoperforators and right superior cerebellar artery, and drained by the superior petrosal, superior cerebellar veins and the great vein of Galen. The patient gradually deteriorated. Craniotomy was carried out through right parieto-occipital interhemispheric approach in order to occlude the feeders. The operative procedure did not disclose the AVM. The feeding artery of the right superior cerebellar artery was coagulated. The patient expired 30 days postoperatively secondary to ventricular hemorrhage and hemorrhage around the AVM. Autopsy specimen showed that the main feeder to the AVM was a large arterial shunt from the left posterior cerebral artery which was not proven preoperatively. It was suggested that definite preoperative clarification of the feeding artery and anatomical correlation between the AVM and the brain stem was essential to distinguish this case from “true” vein of Galen aneurysm. Surgical indications for such a huge AVM in the brain stem and the mechanism of the postoperative hemorrhage are also discussed.
