A simple, real time, differential operator based spike detection algorithm has been described, which can efficiently detect seizure spikes in noisy ECoG signals. Simultaneous spikes and inverted spikes have been detected across all focal ECoG channels during preictal, ictal and postictal periods. Out of 79 seizures recorded from 21 patients, about 80% showed more occurrence of simultaneous spikes and inverted spikes across focal channels after the seizure offset than during the seizure in 0–40Hz range, where the duration studied after the offset is equal to the duration of the seizure. This is an important finding because this goes contrary to the prevailing wisdom that epileptic seizure is a hyper-synchronous phenomenon. 
Simultaneous multi-channel spikes and inverted spikes in focal epileptic ECoG are more after offset than during the seizure