Commentary

The study of the proximal distal dural ring has been of interest to skull base surgeons for many years. Numerous reports attempt to characterize these structures and to relate them to the surrounding anatomy. The evolution of skull base surgery, which includes less invasive techniques to treat aneurysms or radiosurgery for skull base tumors, applies even greater pressure for skull base surgeons to minimize the complications associated with surgery. This outstanding anatomical study by Beretta and coworkers helps skull base surgeons to fulfill this challenging obligation.

We use computed tomographic (CT) angiography to identify whether an aneurysm is located intradurally or extradurally. Of course, the traditional method for discriminating between an intra- or extradural aneurysm is to use the ophthalmic artery and anterior clinoid process as landmarks. However, the origin of the ophthalmic artery varies considerably so this vessel is an unreliable indicator. In our experience, the anterior clinoid process should not be used to define the location of aneurysms in this region either. Based on anatomic dissections and correlations with CT angiography, we have found that the optic strut, as identified on CT, is a reliable landmark for accurately distinguishing intra- and extradural aneurysms.