Giant aneurysm of the proximal (A1) anterior cerebral artery.

BACKGROUND

Aneurysms arising from the proximal (A1) segment of the anterior cerebral artery are quite rare. A giant aneurysm in this location is a true exception. METHOD-FINDINGS: A 66-year-old man who presented with drowsiness and confusion was diagnosed to harbor a giant ovoid (30 x 25 mm) aneurysm originating from the right A1. The aneurysm arose from the mid 3/5th of the artery and there was no neck. There was good cross-flow through the anterior communicating artery. Instead of trapping, the flow through the A1 was maintained by connecting the axis of inflowing A1 and outflowing A1 segments using a fenestrated clip. The sac was finally decompressed. The patient is alive and well 3 years postoperatively with complete resolution of the pre-operative hydrocephalus.

INTERPRETATION: A review of the literature revealed 14 such cases. The presentation, management and the outcome of these rarities differ from routine A1 aneurysms or other paraclinoid giant aneurysms and are briefly reviewed.