Abstract
A modified microsurgical bifrontal interhemispheric approach (small trephine craniotomy) for clipping of aneurysms of the anterior communicating artery (ACoA) is described. This approach has been used in a series of 23 patients with ACoA and 2 patients with distal anterior cerebral artery aneurysms. Feasibility, indications and problems related to this approach to ACoA aneurysms are assessed.