[Craniotomy side for neck clipping of the anterior communicating aneurysm via the pterional approach].

The safety and reliability of neck clipping of the anterior communicating artery (Acom) aneurysm via the pterional approach was evaluated in terms of craniotomy side in 39 consecutive cases operated on by the senior surgeon from April 1991 through March 2000. These aneurysms were approached in principle via the side where the proximal A2 portion of the anterior cerebral artery was located posteriorly, for the purpose of easier identification of all five arteries involved, i.e., A1 and A2 portions of the anterior cerebral arteries of both sides and Acom. All aneurysms were clipped safely irrespective of the approach side because it was possible prior to aneurysmal dissection to prepare both A1 portions of the anterior cerebral arteries for temporary clipping, but not as far as the place where the aneurysm projects inferiorly and its fundus adheres firmly to the optic chiasm. The security of perforating arteries, however, could not be confirmed even after the completion of neck clipping in 9 cases. Clipping was impossible in the other 2 cases. In 2 of these 11 aneurysms the difficulty in clipping was not based on what side was used for craniotomy but on their large size. In the remaining 9 aneurysms, the necks of which were all situated on the posterior wall of the Acom, the craniotomy side turned out to be inappropriate when they were approached via the side where the proximal A2 portion of the anterior cerebral artery was located posteriorly. It was concluded that the craniotomy side should be selected so that the surgeon can observe directly the neck of the aneurysm.