PMC8511771_01
Preoperative and follow-up scalp EEGs. Preoperatively (A) generalized spikes and multiple spike complex were frequently observed with phase reversal at the central region (C3, Cz, C4). Follow-up EEGs [(B) 3-months; (C) 6-months; (D) 12-months after surgery] showed decreased spike frequency, and some small spikes were found to be limited to one hemisphere. However, large spikes were always bilaterally synchronized. Bipolar montages: blue traces are left (F3-C3, C3-O1, F3-T3, T3-O1), greens are midline (Fz-Cz, Cz-Pz), and reds are right (F4-C4, C4-O2, F4-T4, T4-O2). Sensitivity = 15 muV, Time constant = 0.1, High-cut filter = 60 Hz, AC filter = ON.
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F1
Scalp EEG under sedation (Supplementary Data 1.2) revealed frequent spikes and multiple spike complexes were observed on the central regions (C3, C4, Cz) dominantly but synchronized generally (Figure 1A). Although a few spikes were observed in a hemisphere only, most were still synchronized bilaterally (Figures 1B-D).
Preoperative (A) and 12-months postoperative (B) midline sagittal T1-weighted MRI (generated by multiplanar reconstruction from 3D-T1 data). In the postoperative image, the genu of the corpus callosum (arrowhead) left intact and necrotic lesions in the cingulate gyrus (small arrows), which was damaged during the surgery, were observed.
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F2
High-field MRI (3.0T) under general anesthesia (Supplementary Data 1.3) showed no appreciable structural abnormalities in the whole brain (Figure 2A). Follow-up MRI at 3, 6, and 12 months after surgery revealed the bisected CC with the remaining genu, loss of caudal part of the left cingulate gyrus, and old hemorrhagic and a necrotic lesion in the left cingulate gyrus likely related to intraoperative tissue handling as well as vascular damage (Figure 2B).
Changes in averaged daily seizure frequency (seizure/day) for preoperative (Pre) to postoperative 12 months (P1-P12). The preoperative seizure frequency (Pre; 7.22 sz/d) was shown as the average for 3-months before surgery. The average one-year postoperative seizure frequency was 1.7 sz/d (76% reduction). FPS (yellow), fencing posture seizures; GTCS (pink), generalized tonic-clonic seizures; MS (purple), myoclonic seizures including generalized, facial myoclonic, and short tonic seizures.
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F3