Role of Extradural Clinoidectomy and Trapping in Giant Superior Hypophyseal Artery Aneurysm

Giant paraclinoid internal carotid artery (ICA) aneurysms are surgically challenging, mainly owing to lack of adequate working space and distortion of the regional anatomy. Anterior clinoidectomy is a vital surgical technique in such cases, allowing optic nerve decompression and exposure of the proximal ICA outside the confines of the arachnoid. While clinoidectomy is generally conducted intradurally, some aneurysms, particularly unruptured and directed medially paraclinoid ICA aneurysms, can allow a completely extradural clinoidectomy. Extradural clinoidectomy avoids bone dust spillage and drill bite related injury from prolonged intradural drilling times. An 18-year-old man with a giant left superior hypophyseal artery aneurysm presented with progressive headache and visual diminution. He had a very good cross-flow from the contralateral ICA and tolerated balloon test occlusion. The aneurysm was exposed after extradural clinoidectomy and optic nerve mobilization. It was a wide-necked aneurysm and involved the distal dural ring. Owing to intraoperative somatosensory evoked potential findings as well as our concern of inadequate neck occlusion in view of the distal dural ring involvement and a possible future aneurysm regrowth, we trapped the aneurysm. The patient made an uneventful recovery with improvement in vision and normal visual fields. This video demonstrates the feasibility and utility of extradural clinoidectomy in adequate exposure of giant paraclinoid aneurysms and the role of aneurysm trapping for definitive aneurysm obliteration when the distal dural ring is involved. Trapping, in contrast to direct clipping, avoids manipulation of the compressed optic nerves, which is necessary for an optimal environment for postoperative visual recovery.