PMC6657531_01
The first EEG shows 1-2 Hz, polymorphic delta activity over the left hemisphere, with maximum expression over the centro-temporo-parietal region, along with superimposed rhythmic beta activity, which is better expressed over the fronto-centro-parietal region (EDB pattern). (High frequency filter = 70 Hz, low frequency filter = 0.5 Hz, notch filter = off, sensitivity = 10 muV/mm, and display speed = 30 mm/s.)
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A 3 Tesla MRI of the brain was normal (Supplementary Fig. 1). Her EEG revealed polymorphic left hemispheric slow activity, maximally over the left parietal region with EDB morphology (Fig. 1).
Serial EEGs depict the persistence of the left hemispheric polymorphic slow activity and EDB pattern. The EEG dated May 22, 2018 (C), in addition, shows left central spike discharges. (High frequency filter = 70 Hz, low frequency filter = 0.5 Hz, notch filter = off, sensitivity = 7-10 muV/mm, and display speed = 30 mm/s.)
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Brain fluorodeoxyglucose-positron emission tomography (FDG-PET) was normal (Supplementary Fig. 2). Her serial EEGs done at nearly 4-6 month intervals are depicted in Fig. 2. The EEG performed during the same time continued to show EDB (Fig. 2D).