Progressive dilatative arteriopathy

This 36-year-old athletic female, without known vascular risk factors, presented during the third trimester of pregnancy with headache, slurred speech, and “twisted mouth.” Head CT scan showed an extra-axial mass compressing the left cerebral peduncle (A), recognized by CT angiography (B) as a partially thrombosed fusiform aneurysm of the left posterior cerebral artery. There was also tortuosity and ectasia of the basilar and left internal carotid arteries (C). Six years later, the vascular mass had expanded (D), producing severe midbrain compression and hydrocephalus with spastic quadriparesis. She was treated with ventricular drainage and clipping of the left posterior cerebral artery proximal to the aneurysm. (Contributed by Dr. J Brorson.)