Figure. Ictal EEG (patient 1) using extended 10–20 system with surface sphenoidal (zygomatic) electrodes, displaying a combination of circular and longitudinal bipolar montages.

The arrow indicates the onset of movement, which occurred after a generalized EEG electrodecremental event (EDE). The onset of EDEs could precede by as much as 500 msec the onset of the more prolonged abnormal movements, indicating that the motor events were indeed epileptic tonic seizures.