Surgical treatment of transitional internal carotid aneurysms

Ten transitional internal carotid aneurysms are presented. Necks and domes of these aneurysms were located in both the intradural subarachnoid and extradural intracavernous spaces across the carotid dural ring. Seven aneurysms were small, 2 were large, and 1 was giant. Two patients had subarachnoid haemorrhage (SAH), 2 compressive symptoms, 5 SAH from rupture of associated lesions (aneurysms or AVM) and 1 case was an incidental finding. Direct clipping was performed successfully in all patients. The overall surgical outcome was excellent in all patients, with transient complications in 4 cases. It is suggested these aneurysms should be treated with direct clipping whether ruptured or not because of the risk of SAH. A classification of paraclinoidal region aneurysms including cavernous sinus aneurysms extending into the intradural subarachnoid space is proposed.