Localizing focal epileptiform discharges

(A) EEG 10-second epoch, longitudinal bipolar montage. Focal spike and slow wave epileptiform discharge localized to T3 based on the phase reversal of the discharge (arrowhead).

(B) EEG 10-second epoch, Cz referential montage. The same focal spike and slow wave epileptiform discharge from panel A, localized to T3 based on the highest amplitude of the discharge (arrowhead).

ECG: electrocardiography; EEG: electroencephalography.