Indication of Pterional Approach for Basilar Artery Aneurysm of Lower Position

The direct approach to a basilar artery aneurysm of lower position is one of the most difficult operations. The choice of approach should depend on the distance from an aneurysm to the posterior clinoid process and the clivus. Pterional approach is a common and easy procedure but aneurysm was hidden by the ipsilateral posterior clinoid process. Two patients with lower basilar artery aneurysm were operated upon via pterional approach. Case 1: A 46-year-old female had a ruptured basilar bifurcation aneurysm and a non-ruptured right anterior inferior cerebellar artery (AICA) aneurysm. The right AICA aneurysm was located 10mm below the posterior clinoid process. Both aneurysms were clipped after partial removal of the posterior clinoid process via right pterional approach. Postoperatively, mild right hemiparesis developed due to the obstruction of right AICA by the clip. Case 2: A 32-year-old male with a ruptured superior cerebellar artery (SCA) aneurysm. This aneurysm was located 10mm below the posterior clinoid process. Via left pterional approach, an aneurysm was clipped after removal of the posterior clinoid process and clivus. Postoperative course was uneventful and angiogram.showed successful clipping. In this maneuver, the posterior clinoid process and clivus should be drilled out widely, and if necessary, the tentorium should be incised. Another approach should be selected if aneurysm is located more than 10mm below the posterior clinoid process.