Topographic analysis of the gyral patterns of the central area

Great advances in imaging technology allows the surgeon to visualize the entire brain surface during surgery. However, the cerebral convolutions are extremely complex, so that it is often difficult to define the central area precisely. Using the curvilinear reconstruction technique (Gyroview) and MRI, we have analyzed the gyral anatomy of the central area in 20 normal brans and have recognized several patterns of topographic organization and have classified them into several categories. We divided the central area into anterior and posterior subregions with the central sulcus as the main landmark. More specifically, we studied how the pre- and postcentral gyri merge into the frontal and parietal lobe proper by anatomical bridges (roots). We describe three anterior and two main posterior roots which originate from the precentral and the postcentral gyrus, respectively. We found four different types of pattern for the anterior roots and as many as 10 different patterns for the posterior roots. The arterior roots are relatively constant, compared to the posterior ones. The most frequent pattern (type 1) was found in 33 hemispheres among the 40 analyzed (82.5%). Four main posterior root patterns were recognized in 32 hemispheres of the 40 analyzed (80%). Thus, although gyral variability was encountered for the posterior roots, a very constant global pattern was seen for the central area. One of the most important steps of frameless stereotactic-guided epilepsy surgery is the precise localization of the central area. Therefore, a knowledge of gyral patterns of the central area is essential not only for the resective epilepsy surgery, but also for the successful removal of a variety of lesions in the central area.