Multiple Stereoelectroencephalography-Guided Radiofrequency Thermocoagulations for Polymicrogyria With Startle Seizures: A Case Report

Figures

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  Figure 1. (A) Ictal EEG originated in the left unilateral PMG. The first ictal modifications were characterized by left frontotemporal rhythmic fast activity (red arrow), followed by a focal left temporal alpha rhythm. Ictal clinical signs shown in the image corresponded to sudden sensation of stiffness and rigidity of the right limb; the patient was unable to stand stably. (B) An MRI scan showed a multi-lobar PMG involving the left frontal lobe, temporal lobe, insula, and temporo-parieto-occipital junctions. (C) PET/MRI imaging co-register of the patient showing significant hypometabolism in the middle part of the PMG. (D) Results of fMRI showed a significant increase in BOLD signal over the left PMG when moving the right leg, especially the perisylvian area (from red to yellow, the BOLD signal intensity increased). PMG, polymicrogyria; BOLD, blood oxygen level dependent.

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  Figure 2. (A) A three-dimensional MRI reconstruction of the depth electrodes. (B) Ictal SEEG recording revealed that the first electrodes involved in the seizure were from the cingulate sulcus and insular pole (electrodes D and H, marked by red vertical bars). Then the midcingulate cortex, inferior part of the insula, anterior short gyrus, anterior part of the insula, precuneus, superior temporal gyrus, and operculum quickly became involved (electrodes A, B, E, F, J, N, and O, marked by blue vertical bars). The color of the letters is consistent with the dots in illustration A. (C) The x-axis represents the time of the selected seizure; the y-axis indicates electrodes. The energy ratio (ER) of high-frequency changes was depicted in a color scale (from red to blue, the ER intensity decreased). Quantification of the seizure was consistent with visual analysis, indicating that the cingulate sulcus and insular pole (marked in red) were involved first. SEEG, stereoelectroencephalography.

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  Figure 3. (A) Illustration on the left shows early-onset electrode D (contacts 1–5) and H (contacts 9–15) in which RF-TC was performed first (highlighted with red circles). Illustration on the right shows sites of coagulation in the same region on an MRI image acquired 6 months after the first RF-TC (arrows on the right). The patient was free from startle seizures even when provoked by sudden unexpected sounds or other events during the following 2 weeks of monitoring. (B) The patient did not have a seizure when stimulated by a sudden unexpected sound; SEEG showed a similar pattern of a startle-induced seizure, yet there was no trace of discharges in electrodes D and H after RF-TC. RF-TC, radiofrequency thermocoagulation.

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  Figure 4. Illustration on the left shows secondarily involved electrodes A (contacts 1 and 2), B (contacts 1–10), E (contacts 1–4), F (contacts 1–9), J (contacts 3–10), N (contacts 1–5), and O (contacts 1 and 2) (highlighted with blue circles). All these contacts were subjected to RF-TC 2 weeks after the first thermocoagulation. Illustration on the right shows sites of coagulation in the same region on an MRI image acquired 6 months later (arrows on the right). The diameter of lesions ranged from 4 to 5 mm. RF-TC, radiofrequency thermocoagulation.