[Technical tactics to preserve cortical venous drainage in interhemispheric approach for anterior communicating artery aneurysms].

The interhemispheric approach has been selected for clipping of the anterior communicating artery aneurysm located high above the sphenoidal plate, and in a posterior direction. However, this approach is sometimes complicated with postoperative hemorrhagic infarction due to excess brain retraction combined with damages of the cortical bridging veins. We have devised a modification in this approach to eliminate these complications. Our newly devised methods include the following; 1) Small bifrontal craniotomy performed, 2) Continuous ventricular drainage performed to minimize the effect of compression by the spatula during resection of interhemispheric fissure, 3) Bifrontal dural incision made along the frontal skull base, 4) Mobilization of the major cortical vein in the operated field, if necessary, by resection of the overlying arachnoid membrane with or without sacrificing its small tributaries, 5) Gradual dissection of the olfactory nerves according to the process of operation. We analysed the incidence of operative complications in thirteen consecutive cases with this approach. Major frontal ascending veins were carefully preserved in all cases. None showed hemorrhagic infarction, regardless of the cortical venous drainage patterns. The degree of smell preserved in 10% of the examined 11 cases was more than unilateral. In conclusion, this method is useful for the elimination of perioperative complications even in the acute stage of subarachnoid hemorrhage.