抄録
One of the biggest advantages of the interhemispheric approach to the anterior communicating artery aneurysm is the easy handling of topographical orientation, which makes this approach very useful regardless of anatomical variations or sites of the aneurysm. However, the fact that dissection of the interhemispheric fissure is not an easy procedure has been pointed out as a disadvantage. In this report, several key points in performing the interhemispheric fissure dissection are described from the anatomical viewpoint of arachnoid and subarachnoid cisterns relating to the interhemispheric approach. The origin of the A1 segment of the anterior cerebral artery is located in the carotid cistern, whereas the distal part of the A1, the anterior communicating artery and the proximal part of the A2 are located in the lamina terminalis cistern, and the distal A2 is located in the callosal cistern. Between the cingulate gyrus and the rectal gyrus, which corresponds from the inferior part of the falx to the callosal or the lamina terminalis cisterns, is the most difficult part to dissect. Nevertheless, separation of the right and left cerebral hemispheres is possible without causing any damage by carefully approaching the narrow subarachnoid space around the cortical arteries and by making a sharp dissection where the gyri are closely adhered. On the other hand, the arachnoid around the A1 segment of the anterior cerebral artery which constitutes the walls of the carotid, the chiasmatic, the olfactory and the lamina terminalis cisterns strongly holds the frontal lobes. Therefore, it should be emphasized that a wide operative field without much brain retraction can be obtained only when such arachnoid is divided.
