Abstract
An autopsy case of intracranial vertebral dissecting aneurysm associated with medial mucoid degeneration is reported and 54 cases of vertebro-basilar dissecting aneurysm in the literature are reviewed. A 37-year-old man with history of hypertension was admitted in a semicomatose state. Computed tomographic scan showed severe subarachnoid hemorrhage (SAH), especially in the posterior fossa with ventricular reflux, and vertebral angiography disclosed a fusiform dilatation with proximal narrowing of the left vertebral artery and narrowing in the midportion of the basilar artery. Continuous ventricular drainage was performed, but the patient died from rebleeding on the 14th hospital day. Autopsy revealed massive SAH around the brain stem and a fusiform aneurysm of the left vertebral artery. Microscopic examination demonstrated a local thickening of the wall with tearing of the intima and the media. A hematoma between the media and the adventitia communicated with the true lumen of the artery. The muscular layer was replaced by myxomatous connective tissue. The basilar artery had mild fibrous thickening of the intima and duplication of the internal elastica. The medial mucoid degeneration was discovered by iron-colloid stain in the intracranial arteries, especially in the vertebro-basilar system. However, arteriosclerotic change was minimal. The authors emphasize that SAH as initial symptom and hypertension as predisposition occur more frequently in vertebro-basilar dissecting aneurysms than previously described.
