Dissecting basilar artery aneurysm growing during long-term follow up--case report.

A 58-year-old male presented with a dissecting aneurysm of the basilar artery manifesting as dysarthria, left hemiparesis, and numbness of the left side. Angiography revealed a double lumen at the midportion of the basilar artery which was consistent with a diagnosis of dissecting basilar artery aneurysm. The patient was treated conservatively, and remained neurologically stable for a 5-year period following initial presentation, but serial magnetic resonance imaging revealed growth of the aneurysm compressing the brain stem. His condition then worsened. Computed tomography revealed obstructive hydrocephalus. Ventriculoperitoneal shunting was performed and the patient's symptoms improved. However, he died of subarachnoid hemorrhage. Autopsy showed the patient had had a type 3 "dolichoectatic dissecting aneurysm." Surgical treatment should be seriously considered for treating the patients with dissecting basilar artery aneurysm causing brain stem ischemia, especially if the aneurysm is growing. High-flow bypass and proximal occlusion may be the choice in patients with poor collateral circulations.