[An anatomical and technical note for microsurgery of the MCA aneurysm (author's transl)].

Several basic anatomical and technical principles helpful in selecting and planning the surgical treatment of the aneurysm of middle cerebral artery were discussed. 1. Superficial sylvian vein (SSV) usually runs on the temporal opercular bank, therefore, frontal opercular side may be preferred in opening the sylvian fissure(SF). In approximately 10% of specimens, there are two separate SSV lying close together in the SF which only rarely have communicating channels to each other. It should be kept in mind a vein of the one opercular bank may course to the surface, pass beneath the nearest sylvian vein on its side of the fissure and join the more distally located sylvian vein. 2. Deep sylvian vein (deep middle cerebral vein) which closely accompanies the trunk of MCA must be preserved. Surgical occlusion of this venous pathway may result in unanticipated serious postoperative complication, such as consciousness deterioration, hemiparesis or aphasia. 3. Perforators leaving the M1 over its posterosuperior surface form a loop which hang anteriorly. The loop occasionally comes forward and extends quite anteriorly where the sylvian fissure opens and therefore is in danger of injury. It is important to avoid tearing these fine vessels while exposing the middle cerebral artery. 4. The parent artery should be exposed proximally to the aneurysm to allow control of flow to the aneurysm if it ruptures during dissection in any way of approaching the aneurysm. 5. The aneurysm usually points in the direction of the long axis of the prebifurcation segment. 6. After the clip is applied, the area should be inspected to make certain the clip does not kink or obstruct the major vessels and that no perforating branches are included in it.