Classification of Anterior Communicating Artery Aneurysm with Regard to its Microsurgical Anatomy

Rhee, Chang Hun; Han, Dae Hee

Abstract

One hundred cases of anterior communicating artery aneurysms, operated upon during a 10-year period from 1977 to 1987, were analysed to study the microsurgical anatomy of the aneurysms. All of the cases were operated by direct intracranial approach using a operating microscope. Findings of preoperative four-vessel angiogram, operative microphotographs, operative microvideo tapes, and operator's drawings with narratives were investigated on in order to provide the detaild microsurgical anatomy of the aneurysms to obtain the classification according to it. The results were as follows; 1) The anatomical variations of the anterior portion of circle of Willis were as follows;right A1 hypoplasia in 23 cases, left A1 hypoplasia in 9 cases, left A1 aplasia in 3 cases, duplication of anterior communicating artery in 3 cases, and fenestration of anterior communicating artery in 1 case. 2) The diameter of the aneurysm was as follows;5-10mm in 73% below 5mm in 16%, and over 10mm in 11%. 3) Classification of the anterior communicating artery aneurysms according to its direction were as follows;anterior directions in 65%, posterior directions in 16%, superior directions in 10%, inferior direction in 9%. 4) The frequency of hemorrhage were as follows;One bleeding in 65%, Two bleedings in 25%, more than three bleedings in 10%. 5) The vasospasm was observed in 26%, the hydrocephalus in 44%. 6) The posteriorly directing aneurysms showed worse preoperative state than anteriorly directing ones, and the diameter and the direction of anterior communicating artery aneurysm has no relationship with hydrocephalus, vasospasm, and rebleeding. 7) Overall mortality was 5%. Psychotic disturbance, one of the significant complications of rupture of the anterior communicating artery aneurysms, was observed in 13% and among these 6% were observed after operation. Frontal lobe syndrome, organic brain syndrome, depression, confusion, mutism, memory disturbance were manifestations of psychotic disfurbances.