Fig. 1

Extreme delta brush (EDB) on the first electroencephalography and magnetic resonance imaging. The beta activity of EDB weakened when the patient closed her eyes (a; blue arrow) and the occipital alpha rhythms occasionally reappeared (b; blue box). Conversely, the beta activity was enhanced when the patient opened her eyes (a; red arrow). EDB markedly weakened during stage II non-rapid eye movement (NREM) sleep (c) and was enhanced during slow-wave sleep (d). The background activity of the second EEG on day 11 was worse than that on day 2, and EDB was observed in bilateral brain regions (e). On day 30, the background activity in the third EEG recording was better than that on day 11. Compared to the initial EDB pattern on day 2, the EDB in the right brain regions was decreased (f). High-pass filter: 0.5 Hz; low-pass filter: 45 Hz. Sensitivity: 100µV/cm. FLAIR and T2 images were normal (g, h). Arterial spin labeling showed high blood flow in the right frontal and temporal regions (i)