Abstract
We report a classification of juxta-dural ring aneurysms of the internal carotid artery (ICA). These aneurysms are classified into three types according to their relation to the carotid dural ring and the long axis of the ICA: paraclinoid intradural, carotid cave and infraclinoid extradural aneurysms. Another set of classification is made according to their location in relation to the cross section of the ICA as lateral, medial, ventral or dorsal type.
The paraclinoid intradural aneurysms arise from the ICA distal to the origin of the ophthalmic artery and are close to the dural ring, which may include some of so-called carotid-ophthalmic aneurysms. The carotid cave aneurysms are located intradurally in the carotid cave, a dural recess in the infraclinoid carotid groove, and proximal to the origin of the ophthalmic artery. They are located at the angiographical genu angiographically and in the intradural space anatomically. The infraclinoid extradural aneurysms are located extradurally in the infraclinoid segment close to the dural ring.
The infraclinoid extradural aneurysms should be differentiated from aneurysms in the cavernous sinus, because they are located in the infraclinoid carotid groove sinus, which is a peripheral venous space to the cavernous sinus.
Clipping of these aneurysms requires essentially the same surgical techniques: removal of the anterior clinoid process, unroofing of the optic canal, opening of the dural ring and exposure of the infraclinoid segment including the surgical genu and axilla of the ICA via the ipsilateral pterional approach.
