PMC8042546_01
The bipolar montages (double banana) of electroencephalography (EEG) and magnetic resonance imaging (MRI) of patient 1: (a), (b) periodic epileptiform discharges (thin arrows) are observed in the right frontotemporal area, followed by paroxysmal fast activity (thick arrows), evolving to medium- to high-voltage rhythmic theta and delta activity. The sensitivity of the EEG is 70 microV/cm and the display speed is 15 mm/s. The high frequency filter is set to 70 Hz and the low frequency filter to 1.0 Hz, (c) after 2 weeks of treatment, the EEG became normal, except for inter-ictal spikes in the right temporal area (arrowheads). The axial view of (d) diffusion-weighted imaging, (e) apparent diffusion coefficient map, and (f) fluid-attenuated inversion recovery (FLAIR) shows high signal intensities in the right insular cortex, and (g) Follow-up axial FLAIR imaging shows no abnormality.
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On EEG, continuous seizure activity was observed in the right frontotemporal area, including continuous periodic sharp waves intervened by rhythmic activity with spatiotemporal evolutions (Figure 1a and b), which met the Salzburg Consensus Criteria for NCSE, including periodic epileptiform discharges (PEDs) with rhythmic activity with spatiotemporal evolutions. Brain MRI, including DWI, was performed 18 h after visiting Emergency Department, which revealed high signal intensities with diffusion restriction in the right insular cortex (Figure 1d and f). An apparent diffusion coefficient (ADC) map showed low signal intensities in the area of diffusion restriction (Figure 1e). The seizure activity normalized, except for inter-ictal spikes in the right temporal area (Figure 1c, arrowheads). The follow-up brain MRI, which was performed 2 months after the initial evaluation, was also normal (Figure 1g).
PMC8042546_02
The bipolar montages (double banana) of electroencephalography (EEG) of patient 2: (a), (b) intermittent rhythmic delta activity is observed in the left temporal area (thin arrow), evolving to high amplitude rhythmic delta activity and spreading to the right frontal area, and (c) the amplitude of seizure activity gradually decreases and disappears in the left temporal area (thick arrow). Background EEG shows no abnormality. The sensitivity of the EEG is 70 microV/cm and the display speed is 15 mm/s. The high frequency filter is set to 70 Hz and the low frequency filter to 1.0 Hz.
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The symptoms and EEG abnormalities disappeared in a day after the administration of valproate (loading dose of 25 mg per kg and maintenance doses of 6 mg per kg) (Figure 2b).
PMC8042546_03
The bipolar montages (double banana) of electroencephalography (EEG) of patient 2: (a), (b) intermittent rhythmic delta activity is observed in the left temporal area (thin arrow), evolving to high amplitude rhythmic delta activity and spreading to the right frontal area, and (c) the amplitude of seizure activity gradually decreases and disappears in the left temporal area (thick arrow). Background EEG shows no abnormality. The sensitivity of the EEG is 70 microV/cm and the display speed is 15 mm/s. The high frequency filter is set to 70 Hz and the low frequency filter to 1.0 Hz.
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The symptoms and EEG abnormalities disappeared in a day after the administration of valproate (loading dose of 25 mg per kg and maintenance doses of 6 mg per kg) (Figure 2b).
The bipolar montages (double banana) of electroencephalography (EEG), brain magnetic resonance image (MRI), and single-photon emission tomography (SPECT) of patient 3: (a) intermittent rhythmic delta activity superimposed by quasi-rhythmic fast activity is observed in the frontotemporal area bilaterally, with fluctuating frequency, and amplitude (thick and thin arrows), (b) the rhythmic activity disappears after the administration of an antiepileptic drug. The sensitivity of the EEG is 70 microV/cm and the display speed is 15 mm/s. The high frequency filter is set to 70 Hz and the low frequency filter to 1.0 Hz, (c) the axial fluid-attenuated inversion recovery and (d) the coronal T1 MRI shows the diffuse atrophy of bilateral cortices and hippocampi, and (e) the SPECT image obtained after seizure control shows decreased perfusion in the left frontotemporal area (white arrows).
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On EEG, intermittent rhythmic delta activity superimposed by quasi-rhythmic fast activity was observed in the frontotemporal area bilaterally, with fluctuating frequency and amplitude (Figure 3a), which was compatible with possible NCSE. On brain MRI, diffuse atrophy of the cerebral cortex was observed (Figure 3c and d). Brain single-photon emission tomography performed after the control of ASE showed decreased perfusion in the left frontotemporal area (Figure 3e).