Surgical Technique of Interhemispheric Approach for Anterior Communicating Artery Aneurysms

It is important to preserve perforators of the anterior communicating artery (A-com) such as the hypothalamic artery in surgery of the A-com aneurysm (A-com AN). Preservation of these arteries is, however, sometimes difficult in the limited space of the small surgical field. We report the efficacy of a technique that provides a wide surgical field by our modified interhemispheric approach (IHA).During the past 5 years, we have experienced 78 cases with A-com AN. We selected 34 cases (44%) to apply IHA according to the results of the angiography and three-dimensional CT angiography.To obtain a wider view and surgical field around A-com AN, the falx is completely resected at its anterior end, the olfactory nerves are completely dissected to free them from the base of the frontal lobe by meticulous arachnoid dissection, the arachnoid membrane is opened even at the Sylvian vallecula as well as at the portion of the bilateral internal carotid artery to the A-com through the horizontal part of the anterior cerebral artery (A1). After these preparations, we open the interhemispheric fissure from the corpus callosum to the frontal base.Our modified IHA made it possible to preserve perforators thoroughly with a much wider surgical field around the A-com than that with the usual pterional approach or traditional IHA. Our modified IHA provides enough space even when using temporary clips for A-com ANs that are relatively difficult to dissect, such as big and/or complexly shaped aneurysms with tight adhesion of surrounding arteries, enabling application of aneurysmal clips from various directions and ensuring safe and complete obliteration of the aneurysmal necks.Our modified IHA is especially useful in the surgical intervention of big and complexly shaped A-com ANs.