Surgical techniques for a combined infratemporal epidural and medial triangle approach to basilar tip aneurysms consists of 1) an orbitozygomatic frontotemporal craniotomy, 2) an infratemporal epidural approach in order to expose the nerve sheathes of the IInd and Ist divisions of the trigeminal nerve and the medial half of the gasserian ganglion, 3) a pterional transsylvian approach for opening the superior wall of the cavernous sinus via the medial triangle and 4) unveiling the cavernous sinus medial to the IInd division of the trigeminal nerve.
Seventeen cases of ruptured basilar tip aneurysms which were operated on via this orbitozygomatic infratemporal transcavernous approach were divided into three groups and the clinical features were reviewed. The fact that out of 4 cases in the early-operation group only one case showed good operative result seems to be attributed to the serious original Hunt and Kosnik Grade of the patients. All 3 cases with Hunt and Kosnik Grades I and II in the relatively early-stage operation group (operated on between Day 6 and Day 10) were good postoperatively. The operative result of 6 out of 8 cases with Grade I or II in the delayed-operation group was good. Conclusion: 1. This transcavernous approach seems to be the preferable approach to the basilar tip aneurysm in the early stage, with several advantages such as 1) wide exposure of the operative field, 2) the shortest possible distance with only slight retraction of the temporal tip with its dura mater, and 3) no division of the Sylvian vein and the spheno-parietal sinus running within the temporal dura propria. 2. Clipping of the basilar tip aneurysm being located either in higher or lower position can be performed successfully without retracting the carotid artery and its tributaries.
