Classification of Anterior Communicating Aneurysms as a Basis for Surgical Approach

T HE anterior communicating arterial complex provides one of the most common sites for the development of saccular aneurysms. Estimates of frequency of involvement of this area vary from Dandy's early report of 18.8% (25 of 133 cases) to Riggs's report of 60% (79 of 131 cases found in 1437 consecutive autopsies) . 3,~,9,1~-1~,'9 The figure of 27.4% (485 of 1769 aneurysms) in McKissock's series as reported by Bull is probably a representative statistic? The development of this aneurysm when untreated is disastrous; conservative management is associated with a 40% to 70% mortality rate. 1~-15 For this reason various methods of surgical treatment have been advocated and instituted. Successful treatment of aneurysms by intracranial surgery requires careful planning of the surgical approach. Berry aneurysms are most commonly saccular in configuration and most often rupture at their fundi. It is logical, therefore, that they can best be treated if the neck is isolated from the circulation without disturbing the dome. Aneurysms of the anterior communicating complex more than aneurysms of any other location can project in a myriad of directions. Since the area of the anterior communicating artery can be approached from several different directions, it is desirable to separate these aneurysms into groups appropriate to the method by which they can best be attacked. Following this basic philosophy, anterior communicating artery aneurysms are treated by two very distinct approaches at Walter Reed General Hospital. As a result, the preoperative arteriogram has become a key to planning the operative approach. In aneurysms that project superiorly, a subfrontal approach to the anterior communicating complex is used. However, all aneurysms