Abstract
A 52-year-old male sustained subarachnoid hemorrhage and ventricular hemorrhage due to a ruptured anterior communicating artery aneurysm. Ventriculo-peritoneal shunting was performed 3 weeks later. The aneurysm was clipped 1 month after the onset. During the operation, the aneurysm ruptured prematurely causing marked swelling of the brain. Enlargement of the fourth ventricle was detected by computerized tomography (CT) scan the next day. Four days postoperatively the fourth ventricle was opacified by metrizamide injected into the lateral ventricle, showing patency of the aqueduct of Sylvius. However, the fourth ventricle increased in size on serial CT scans. Since the patient was in ataxic respiration and tetraplegia, an external fourth ventricular drainage was placed 5 days postoperatively, and the fourth ventricle became smaller. The patient died of pneumonia 1 month postoperatively.
It is suggested that the mechanism of the trapped fourth ventricle in the present case is the oneway block of the aqueduct, resulting from the ependymal change due to the ventricular hematoma and brain edema compressing the midbrain after the operation for the aneurysm.
