A Basal Interhemispheric Operative Approach for Anterior Communicating Artery Aneurysms

Abstract

The author herein reports a new operative approach, the basal interhemispheric (BIH) approach, for anterior communicating artery aneurysms (ACo AN). This approach is a modification of the anterior interhemispheric (AIH) approach developed for lesions in and around the anterior third ventricle. The patient is fixed in the supine position and the head is dorsiflexed. A bicoronal skin incision is made behind the hairline and subperiosteal dissection of the skin flap is performed to the nasion and both upper portions of the orbits. The supraorbital nerves must be preserved in this procedure when the nerves penetrate the supraorbital foramina. A bifrontal craniotomy is performed as in the routine AIH approach and then an additional craniotomy is performed in the basal frontal and nasal bones. A small dural incision is made in the mid-basal portion of the right side. Microsurgical dissection of the interhemispheric fissure is performed directly toward the pre and suprachiasmatic areas near the folded portion of the arachnoid membrane, instead of the knee portion of the corpus callosum as in the AIH approach. Thus, the approach to the aneurysm can be performed using a shorter and more limited interhemispheric dissection than with the AIH approach. After the intradural procedure, the dura should be closed water tight, the additional bone flap is fixed, and then the area of the opened frontal sinus is completely covered with periosteum. The bifrontal bone flap is secured at four points and skin and galea are closed in the usual manner. The bifrontal bone flap is removed for external decompression if necessary. Fourteen cases of ACo AN (clear consciousness: 7 cases, drowsy state: 6 cases, semicoma: 1 case) have been operated on up to the present time, and all cases have recovered to a good condition. Furthermore, they don't show any cosmetic problem due to additional midline bone flap. It should be stressed that ACo AN can be approached with minimum brain retraction and dissection of the interhemispheric fissure using this BIH approach. This is a most important point in surgery for ACo AN in the acute stage.