The characteristic EEG feature of absence seizures:
The electrophysiologic hallmark of typical absence seizures is a generalized, symmetric, 3-Hz spike-and-wave discharge that begins and ends suddenly, superimposed on a normal EEG background. Hypsarrhythmia is an abnormal pattern, consisting of high amplitude and irregular waves and spikes in a background of chaotic and disorganized activity seen on EEG, and frequently encountered in infantile spasms. Ref: Harrisons principles of internal medicine, 18th edition, Chapter 159
3 Hz spike & wave
1-2 Hz spike & wave
Generalized polyspikes
Hypsarrythmia