PMC9813673_01
Upper part: median PET cortical metabolism superimposed on 3D Freesurfer pial model shows abnormal right perisylvian gyration and hypometabolism compared to the left hemisphere (color palette coldtohot: blue, lower metabolism, red, higher metabolism). Bottom part: T1-weighted anatomical MRI superimposed with SEEG electrodes disclosed diffuse perisylvian polymicrogyria involving the right temporal, frontal and parietal cortex. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
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MRI Brain revealed extensive right perisylvian polymicrogyria and an FDG-PET scan showed concordant right perisylvian hypometabolism (Fig. 1). The exploration aimed to better delineate the real epileptogenic area within the malformation and its relationship to functional areas, and possibly to plan resective surgery or at least perform RF-TC (Fig. 1, Fig. 2a).
A: implantation scheme on the 3D model. B: 30-seconds SEEG trace shows low-voltage fast activity over K 5-6 and P 3-4 preceding typical subjective sensation warning. C 120-second SEEG trace shows low voltage fast activity over K electrodes with a fast propagation over mesial temporal structures (B, C); after 2 s all temporal lobe and perisylvian area are involved in the discharge. D: MRI position of P internal contact (upper) and K internal contact (lower) where RF-TC were performed. SEEG contacts position. B2-3: para-hippocampal gyrus; B5-6: hippocampus head; B13-14: middle temporal gyrus; C3-4:hippocampus body; C11-12 = posterior middle temporal gyrus; Z2-3: fusiform gyrus; K2-3 5-6: lower precuneus; Y10-11: inferior parietal gyrus; U5-6: superior temporal gyrus; P3-4: higher precuneus; P11-12: inferior parietal gyrus; N6-7: post-central gyrus; S6-7: parietal operculum; L10-11: pre-central gyrus; M2-3: supplementary motor area; R2-3: posterior short insular gyrus; X3-4: frontal operculum; F9-10: middle frontal gyrus.
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During monitoring, the patient reported typical subjective sensations associated with short-duration low-voltage discharges recorded independently from multiple areas, encompassing the temporal pole, opercular region, and precuneus (Fig. 2b). A typical spontaneous seizure was recorded associated with rapid low-voltage activity on the K electrode exploring the precuneus, with rapid propagation over the mesial temporal structures and, after a few seconds, over the temporal lobe and perisylvian areas (Fig. 2c). RF-TCs were performed on K 1-4 and 5-6, P 2-5 (Fig. 2d). RF-TCs were performed to ablate the most epileptogenic area and, eventually, to perform a second step surgery.