Microsurgical anatomy of anterior communicating artery aneurysms.

The basic anatomy important to surgery of aneurysms of the anterior communicating region was defined in 50 brains. Significant findings were: (1) the recurrent artery of Heubner is frequently exposed before the A-1 segment in defining the neck of the aneurysm because it commonly courses anterior to the A-1 segment. The recurrent artery rose from the A-2 segment of the anterior cerebral artery in 78 percent of hemispheres. (2) The anterior communicating artery frequently gives rise to perforating arteries that terminate in the superior surface of the optic chiasm and anterior hypothalamus. (3) The proximal half of the A-1 segment was a richer source of perforating arteries than the distal half. (4) Aneurysms frequently occur in association with hypoplasia of the A-1 segment and their fundus points in a direction determined by the anatomic principles reviewed in this manuscript. These findings, as they apply to frontotemporal surgical approaches to these aneurysms, are illustrated.