Giant carotid-ophthalmic artery aneurysms: direct clipping utilizing the "trapping-evacuation" technique.

The authors have devised a "trapping-evacuation" technique to facilitate direct clipping of giant aneurysms in the paraophthalmic region of the internal carotid artery (ICA). The giant aneurysm is collapsed by first trapping the aneurysm by temporary occlusion of the cervical common carotid and external carotid arteries, along with temporary clipping of the intracranial ICA distal to the aneurysm. Thereafter, intra-aneurysmal blood is simultaneously aspirated through a catheter placed in the cervical ICA. Exposure of the proximal end of the aneurysm neck is mandatory for successful clipping. This is accomplished by extensive unroofing of the optic canal, removal of the anterior clinoid process, opening of the anterior part of the cavernous sinus, and exposure of the most proximal intradural (C2) and genu (C3) portions of the ICA. Four cases of giant aneurysms of the paraophthalmic ICA were successfully treated by this technique and the postoperative outcome was good in all cases. Preoperative magnetic resonance imaging for evaluation of the anatomical details, balloon occlusion test of the ICA, and intraoperative measurement of cortical blood flow were important to the success of the operation. Intraoperative digital subtraction angiography via the catheter placed in the cervical ICA was useful in confirming successful clipping.