Fig. 1

Electroencephalogram, voltage topography and magnetic resonance imaging findings. a An electroencephalogram (EEG) on Day 5 showing repeated low-voltage ictal discharges from the right occipital region (red line). Note that the sensitivity of EEG recording is displayed at approximately three-times higher than the ordinary sensitivity (AV, averaged reference). Atrial fibrillation was also observed on electrocardiogram (ECG). b Voltage topography demonstrates the negativity of the ictal discharges to be located at O2, P4, and T6 of the International 10–20 EEG system. c A subsequent magnetic resonance image with fluid-attenuated inversion recovery sequence showed no epileptogenic lesion or abnormal edema. d EEG on Day 11 depicting the disappearance of paroxysmal discharges. The dominant rhythm of the α-ranged wave can be observed on both sides