Intracavernous aneurysms and carotid-cavernous fistulas. A clinicopathological study.

The location of the original sites of the lesions was studied in 22 non-traumatic and 21 traumatic intracavernous carotid aneurysms in which the neck of the aneurysm was confirmed, and also in 23 traumatic carotid-cavernous fistulas in which the location of the fistula was identified. In the cavernous sinus, common sites of non-traumatic and traumatic carotid aneurysms as well as traumatic carotid-cavernous fistulas were the C3-segment and C4-C5 junction of the internal carotid artery although 27 per cent of non-traumatic carotid aneurysms originated in the C4-segment of the carotid artery. An anatomical study of 37 cavernous sinuses removed from 23 cadavers revealed the following findings. The inner surface of the venous sinus was covered with endothelial cell layers. The size and shape of the venous sinuses vary considerably, but they can be divided into three major groups: 1) the broken (58 per cent) or 2) the unbroken (33 percent) according to the amount of trabeculae and 3) the small scattered venous channel without trabeculation (9 per cent). The third, fourth and fifth cranial nerves ran through the lateral wall without exception, but the sixth cranial nerve was found in the lateral wall in only 48 per cent of the specimens. The internal carotid artery was entirely surrounded by the venous sinus in 72 per cent of the cavernous spaces studied. Based on the above findings, the possibility of direct surgery on aneurysms in the cavernous sinus and carotid-cavernous fistulas is discussed.