case_images: PMC10600519_01
case_images: Timeline and neuroimaging. (A) Preoperative brain-MRI FLAIR slices, displaying no alterations and PET showing an hypometabolism of the right temporal lobe, more marked in the superior temporal gyrus and temporal pole. (B) Post-operative brain-MRI T13D slices, at 6 months, showing the resection cavity, without complications.
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case_images: fig1
case_images: Brain MRI (1.5 Tesla) resulted normal, while a Positron Emission Tomography and Computed Tomography with 18F-fluorodeoxyglucose (18FDG-PET/CT) showed a right temporal hypometabolism, more marked at the level of the temporal pole and superior temporal gyrus (Figure 1A). The patient was operated with a tailored resection within the limits of the right temporal lobe, including the superior gyrus, pole, and mesial structures (Figure 1B).
case_images: Functional MRI and DTI. (A) Functional MRI with language-dedicated tasks (phonemic and semantic fluency in green, auditory comprehension in blue and naming by verbal description in red). On the left side, the preoperative functional MRI showing a right cerebellar lateralization, with only a slight activation at the level of the right inferior frontal gyrus (the other two tasks were inconclusive). (B) The post-thermocoagulations functional MRI confirming the right cerebellar activation with left-side supratentorial activation either at the level of the inferior frontal gyrus for fluency and posterior temporal regions for comprehension. (C) Bilateral tractography representation of the superior longitudinal and arcuate fasciculi (SLF-III/AF) complex. On the left side: 3D surface rendering of each hemisphere and SLF-III/AF complex (in magenta). On the right side: axial and coronal slice of T13D brain-MR with representation of SLF-III/AF complex (in magenta). Left-side fasciculus volume resulted larger than the right-side one.
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case_images: fig2
case_images: A right cerebellar activation was observed during all language tasks (Figure 2A). The study showed the bilateral presence of a white matter tract connecting the inferior frontal gyrus and the superior temporal gyrus (belonging to the superior longitudinal and arcuate fasciculi systems), with asymmetry and a prevalence of the left-sided one (Figure 2C). On the contrary, right cerebellar activation remained similar to that unveiled during the preoperative exam (Figure 2B).
case_images: Seizure onset and propagation in stereo-EEG. (A) Stereo-EEG implantation: right hemisphere (black background) and left hemisphere (blue background). (B) Stereo-EEG recording of spontaneous seizure. It shows an increase of interictal spike on the contacts electrodes that explore the posterior portion of the right superior temporal gyrus (W4-5, W9-10, U4-5, T3-4), followed by low-voltage fast activity in the same region (red star). After 1.5 s, the discharge spreads to the left homologous region (W'7-8, red arrow). Then, after 14 s, it also involves the right temporal pole (I4-5) and hippocampus (C2-3), and immediately it propagates to the left homologous regions (I'7-8, B'2-3). After 26 s from the right ictal onset, a new ictal discharge arises in the left hippocampus (B'2-3) and spreads after 3 s into the right hippocampus (B2-3).
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case_images: fig3
case_images: They were placed bilaterally (Figure 3) in tailored positions to identify the EZ and clarify language lateralization and its relationship with the EZ. Further details on stereo-EEG recordings are reported in Figure 3.
case_images: Analysis of Gamma activity (50-300 Hz) induced by language tasks (4.1) and Connectivity between the two homologous posterior temporal regions (4.2.). (4.1) The Figure depicts the Event-Related Spectral Perturbation (ERPS) in the reading-repeat condition (A-D) and listening condition (G-J) for the leads sampling the cortex of the superior temporal gyrus (W'8 and W8) and inferior frontal gyrus (pars triangularis, X'5 and X4) of the left (A,B,G,H) and the right (C,D,I,J) hemisphere. (E,F,K,L) Compare for each couple of homologous leads the gamma-band (50-300 Hz) time course. Significance between left and right hemisphere has been computed with a paired, two-tailed t-test (p < 0.001) and plotted in green above the traces. Both data processing and statistical analysis were performed with Matlab R2022b and in-build function of EEGLAB package. ERSP has been computed in the frequency interval (10-300 Hz) and baseline corrected (i.e., by subtracting the median in the interval [-500, 0 ms] according to the stimulus onset). (4.2) (A) Cortico-cortical evoked potentials obtained by means of stereo-EEG documented the connection between both posterior temporal regions: the stimulation (1 Hz, 0.5 ms, 5 mA) of the contacts W7-8 (right superior temporal gyrus) generated cortico-cortical evoked potential on contacts W'6; W'7; W'8 (left superior temporal gyrus) shown in monopolar montage. The latency between the stimulus and the evoked potential is 42 milliseconds (amplified below in C). (B) On the left side: 3D surface rendering of both cerebral hemispheres and the tractography-based fasciculus connecting both posterior temporal regions (in green). On the right side: co-registration between of preoperative 3D-T1 MRI, DTI-based "intertemporal fasciculus" representation and post-implantation cone beam CT, showing the intersection of the intertemporal fasciculus with W7-8 and W'6-7-8 contacts.
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case_images: fig4
case_images: A remarkable activation during reading was observed in the left inferior frontal gyrus, congruent with the clinical slowing in reading observed during ESM (Figure 4.1). This last finding was confirmed also using tractography, which documented the interhemispheric structural connectivity among these areas (Figure 4.2 illustrates the connectivity between both superior temporal gyrus).