Extent of anterior clinoidectomy for clipping of carotid-ophthalmic aneurysms predicted on three-dimensional computerised tomography angiography

We aimed to verify the value of computerised tomography angiography (CTA) on predicting the extent of anterior clinoidectomy that is optimal for particular carotid-ophthalmic aneurysms (COAs). The anterior clinoid process (ACP) often impedes the complex microsurgery of COA. Complete removal of the ACP ensures safe clipping; however, it also may increase the risk of severe complications. The probability of performing a successful partial anterior clinoidectomy could be evaluated by preoperative CTA. 28 patients with either a ruptured (n=4) or unruptured COA were included in this prospective, single-centre, observational study. One aneurysm was giant, two were large, and the rest were smaller. Successful aneurysm clipping was the aim in all cases. The anterior clinoidectomy was preoperatively planned on multiplanar three-dimensional reconstructions of CTA images (3D-CTA) which resembled the typical view of a frontotemporal craniotomy. Finally, the predicted clinoidectomy was compared to the extent of the actual clinoidectomy. 21 aneurysms (75%) projected superolateral or superior. The ACP was completely and selectively resected in 25% (7 of 28) and 67.9% of patients (19 of 28) respectively. Optic nerve (ON) unroofing was always performed in the case of total anterior clinoidectomy, but accompanied only 8 of 19 selective clinoidectomies (p = 0.03). The extent of the actual clinoidectomy was predicted by the 3D-CTA-based preoperative planning in 17 of 27 cases (63.0%). Particularly, prediction of the osteotomy was correct in 85.7% of complete, 62.5% of selective lateral, and 57.1% of medial clinoidectomy. None of the radiological and clinical factors determined the correlation between the planned and the actual extent of ACP removal. There was one incomplete occlusion among 23 obtained follow-up CTAs. The predictive value of 3D-CTA on the extent of anterior clinoidectomy still remains unsatisfactory; it is limited by the individual variability of COA and its surrounding structures. Currently, the role of 3D-CTA planning is restricted to educational purposes only.