Epileptic Disorders


Temporal lobe epilepsy with a contralateral parietal seizure-onset zone Volume 23, issue 5, October 2021

Figure 1

(A) Axial CT image demonstrating peripherally calcified lesion in the paramedian right parietal lobe without surrounding edema. (B) Sagittal MRI double-inversion recovery (DIR) sequence showing lesion in the cuneus gyrus with mild surrounding gliosis. (C) Axial MRI T2 sequence showing lesion as T2 hyperintense suggesting a cystic nature. (D) Postoperative axial MRI T1 sequence demonstrating the resection cavity from a posterior midline approach and a thin rim of blood products. (E) Coronal co-registered PET/MRI showing decreased activity in the left temporal lobe. (F) Axial MRI diffusion tensor imaging (DTI) through the level of the lesion demonstrating asymmetric appearance and color pattern of the parietal lobar white matter (squares) lateral to the lesion with the contralateral (left) side, showing the more expected appearance and predominantly green color of the anteroposterior direction of the fiber tracts. (G) A region of interest (ROI) drawn sagittally, immediately lateral to the lesion, showing fiber tracts that trace into the splenium of the corpus callosum and eventually to the contralateral side. (H) Drawing of a sagittal ROI in the midline splenium of the corpus callosum showing the asymmetric white matter tracts on each side near the lesion, highlighting additional and abnormal peri-lesional tracts of the right tracing from the corpus callosum.

Figure 2

(A) Lateral and anterior-posterior x-rays depicting locations of the depth and subdural strip electrodes. Left panel: depth electrodes are inserted in the amygdala (1), hippocampus (2), secondary somatosensory area (3), entorhinal cortex (4), insula (5), and posterior cingulate gyrus (6). Additionally, three strips (7) sampled the left lateral and inferior temporal lobe, extending medially to the parahippocampal gyrus. Right panel: depth electrodes targeting the hippocampus (8) and precuneus with medial contacts near the neurocysticercosis lesion (9). Two subdural strips sampled the lateral parietal lobe (10) and medial parietal lobe (11) adjacent to the lesion. (B) Scalp (upper panel) and concurrent intracranial (lower panel) recording of an electroclinical seizure. The scalp EEG shows a clinical onset of rapid blinking, annotated on the top left corner. The red arrow marks the transition of the right-sided parieto-occipital polyspikes to low-voltage fast activity, representing the ictal onset. The blue arrow represents the onset of ictal patterns over the left hippocampus and amygdala depth electrodes. Note the delay between clinical onset and left intracranial onset, as well as scalp onset (gray arrow). Relevant electrode locations are represented as right and left SEEG contacts, as well as subdural strips (SDS).