Prevention of Visual Function in the Operation of Paraclinoid Aneurysms

Objective: Paraclinoid aneurysms are aneurysms of the internal carotid artery (ICA) around the anterior clinoid process (ACP), including carotid cave and IC-ophthalmic aneurysms. To treat those aneurysms by direct clipping, it would need the removal of ACP and opening of the external dural ring, which might harm the optic nerves and their function. Then, the endovascular surgery is sometimes recommended especially in the case with carotid cave aneurysm. However, the recent paper reported that the complication and recurrence rates of endovascular surgery are relatively high. This direct surgery is useful, but difficult for the young and middle surgeon because those aneurysms are rare and dangerous lesion. We reviewed our recent cases and assessed the pitfall for prevention of visual function.

Method: A total of eight cases with paraclinoid aneurysms treated in our hospital since December 2012 are assessed.

Result: One case was treated by endovascular and seven were treated by direct surgery. Five cases were completely clipped with the removal of ACP, however, one of five showed visual impairment after surgery. In this case with right carotid cave aneurysm, ICG-VA during the surgery had shown disappearance of aneurysm and patency of ICA and perforators, however, her right vision gradually worsened 2days after surgery. Right ophthalmic artery was patent on her MRI/MRA and 3D-CTA, and her right optic disc was normal. Operative video was assessed, and showed that her right optic was contracted to ICA during the dissection of aneurysm and ophthalmic artery because of incomplete cutting of falcifalm fold, suggesting that this physiological compression to the optic nerve might cause the visual function.

Conclusion: For prevention of visual function in the surgery of paraclinoid aneurysms, the complete opening of dural ring, the removal of optic strut, and the appropriate cutting of falcifalm fold are important as well as the removal of ACP. We emphasize that those techniques are essential as well as the removal of ACP to mobilize the optic nerve and perform the safe surgery.