Research Article

The Classical Pathways of Occipital Lobe Epileptic Propagation Revised in the Light of White Matter Dissection

Figure 1

(a) Lateral view of a right hemisphere after the dissection of the superficial white matter layers of temporo-parieto-occipital region. The first bundle identified is the vertical component of the superior longitudinal fasciculus (vSLF/dark blue), which connects the supramarginal gyrus and angular gyrus to the temporo-occipital junction. Posterior to the vSLF, the vertical occipital fasciculus (VO/light blue) connects the superior occipital gyrus to the fusiform gyrus. At the level of the supramarginal gyrus the vSLF partially overlaps with the horizontal component of SLF (hSLF/purple), which runs from the parietal region to the frontal region. (b) After vSLF has been removed the arcuate fasciculus (AF/cyan) is exposed running from the frontal region through the perisylvian region with white matter terminations underneath the temporo-occipital junction and it ends at the level of the middle and inferior temporal gyrus. (c) The temporal terminations of the AF are overlapping with the temporal portion of the dorsal inferior longitudinal fasciculus (dILF/light blue). The AF has been retracted completely exposing the course of dILF. The cuneal (Cu) branch and the dorsolateral occipital cortex portion (DLOC) run in one bundle (dILF) at the level of the temporo-occipital junction lateral to the SSS and straight to the temporal pole area. (d) Medial to the AF, the middle longitudinal fasciculus (MLF/orange) is exposed at the connection between the posterior insular cortex (Ins) and the superior temporal gyrus (STG). This bundle runs from the superior temporal gyrus within the sagittal stratum of Sachs (SSS) to the parieto-occipital sulcus region (POS). At the level of the cuneal region (Cu) the dILF terminations are partially overlapping the MLF terminations. M1: primary motor cortex (precentral gyrus); Ins: insula; TP: temporal pole.