PMC6384302_01
Case 1. Initial EEG (a) and EEG 6 h after PER (b). Referential (common average) montage (sensitivity: 10 muV/mm; 0.5-70 Hz; 20-s epoch length). (a) Initial EEG shows SE with periodic discharges and superimposed fast and/or rhythmic activity (LPDs, LPDs + F, LPD + R, LPDs + FR). (b) EEG after initiation of PER shows absence of epileptiform discharges and background improvement with an asymmetric alpha activity.. Axial FLAIR (C), DWI (D) and arterial spin labeling perfusion (E) MR images. The lesions in the right occipital lobe are seen as a hyperintense area on FLAIR and DWI. Hyperperfusion is showed in peripheral areas. These findings correspond to the stroke-like episode. Distribution of the stroke-like lesions is incongruent with a defined vascular territory and hyperperfusion is seen in the affected brain regions in patients with MELAS.. LPD, lateralized periodic discharges; R= superimposed rhythmic activity; F= superimposed fast activity; FR= superimposed fast and rhythmic activity; FLAIR, T2-weighted fluid-attenuated inversion recovery; DWI, diffusion weighted imaging; MR, magnetic resonance.
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Six hours later, the patient had improved clinically, and an EEG monitoring showed resolution of the SE episode (Fig. 1). Shortly after cessation of SE, the patient underwent magnetic resonance imaging (MRI), showing a hyperintense area in the right occipital lobe consistent with metabolic infarction (Fig. 1).
PMC6384302_02
PMC6384302_03