MICRO-ANATOMICAL STUDY OF THE CAROTID CAVE

The surgical treatment of aneurysms located in the carotid cave is oft en hazardous and difficult. We studied the micro-anatomy of the caroti d cave and its neighbourhood by microscopic observation and histologic al examination using 50 sides from 25 autopsy cases. The carotid caves were found in 34 out of the 50 sides (68%) examined and were usually located in the posteromedial aspect of the carotid dural ring. They we re classified into three types according to the topographic micro-anat omy: the slit-type (17/50, 34%) which showed a small, thin recess of t he dura mater with fine connective tissue loosely adhered to the carot id wall; the pocket-type (12/50, 24%) which had a definite dural pouch with the apex attached to the vessel wall; and the mesh-type (5/50, 1 0%) which formed a slit-or pocket-type dural cave covered with a mesh- like dural roof. The remaining 16 sides (32%) showed tight dural attac hment without any caval structure around the dural ring. The posterome dial portion of the carotid dural ring had no contact with any bony st ructure, and this distinct anatomical feature thus appear to facilitat e the formation of the carotid cave. Furthermore, the availability of this potential space and the closely situated origin of the superior h ypophyseal artery as well as the haemodynamic effect of the internal c arotid artery may allow the development of the carotid cave aneurysm.