SURGICAL ANATOMY OF THE JUXTA-DURAL RING AREA

Object. The authors report on the surgical anatomy of the juxta-dural ring area of the internal carotid artery to add to the information ava ilable about this important structure. Methods. Twenty sides of cadave r specimens were used in this study. The plane of the dural ring was f ound to incline in the posteromedial direction. Medial inclination was measured at 21.8 degrees on average against the horizontal line in th e anteroposterior view on radiographic studies. Posterior inclination was measured at 20.3 degrees against the planum sphenoidale in the lat eral projection, and the medial edge of the dural ring was located 0.4 mm above the tuberculum sellae in the same projection, The lateral ed ge of the dural ring was located 1.4 mm below the superior border of t he anterior clinoid process. The carotid cave was situated at the medi al or posteromedial aspect of the dural ring; however, two of the 20 s pecimens showed Ilo cave formation. The carotid cave contained the sub arachnoid space in 13 sides, the arachnoid membrane only in three side s, and the extraarachnoid space in two sides, The authors propose that the marker of the medial side of the dural ring, which is more proxim al than the lateral, is the tuberculum sellae in the lateral view on r adiographic studies, Ln the medial aspect of the dural ring the intrad ural space can be situated below the level of the tuberculum sellae be cause of the existence of the carotid cave. Conclusions. An aneurysm a rising from the medial side of the juxta-dural ring area even below th e tuberculum sellae is a potential cause of subarachnoid hemorrhage.