Clipping of basilar apex aneurysms: resurgence of the microsurgical era

Basilar apex aneurysms have been considered challenging due to their deep location, intricate perforator anatomy, and large size and wide necks. However, advancements in skull base exposure and microvascular techniques, especially the extended pretemporal transcavernous approach, have proven to be indispensable in treating these aneurysms. In this article we aimed to assess the safety, efficacy, durability, and functional outcomes of microsurgical clipping of basilar apex aneurysms using the pretemporal transcavernous approach.

A retrospective review was conducted of all patients who underwent surgical treatment of basilar apex aneurysms performed by the senior author using the pretemporal transcavernous approach. Surgical exposure proceeded in a stepwise extraduralintradural manner, including anterior and posterior clinoidectomy, mobilization of CNs III to V, and systematic enlargement of the carotidoculomotor and oculomotortentorial windows. Temporary clips were applied to the basilar trunk at a perforator-free zone and on bilateral P1 segments. A sequential "pilot" clip followed by a definitive "smart" clip and bipolar dome remodeling were used to achieve occlusion while preserving perforators.

From 1998 to 2024, 191 patients with 200 basilar apex aneurysms underwent microsurgical repair; 67.5% had unruptured aneurysms. Most of these aneurysms were complex, with 61% measuring > 7 mm. Early postoperative imaging in 105 patients demonstrated complete aneurysm obliteration in 102 (97%). Thirteen patients (6.8%) experienced minor ischemic events with no later sequelae, and 2 experienced lasting neurological deficits. Transient oculomotor palsy was universal but resolved in 92% of patients by 6 months and 99% by 1 year. Among patients with unruptured aneurysms, hospital mortality was 0.8%, and a good functional outcome (modified Rankin Scale score 0-2) was achieved in 88% at discharge and 97% at the final followup. The overall recurrence rate was 1.5%, with only 1 patient (0.8%) requiring retreatment.

The pretemporal transcavernous approach with microsurgical clipping yielded durable obliteration of basilar tip aneurysms with minimal morbidity and mortality, even in anatomically complex lesions. These findings reaffirm the continued relevance of the approach and, in many cases, the superiority of expert microsurgical clipping alongside endovascular techniques for treating these aneurysms.