Ictal EEG

The term “Ictal” refers to an active phase of a seizure, an epileptic event. EEG is an electrical activity generated by neurons. It is the summation of the excitatory and inhibitory postsynaptic potentials of neurons.

In a healthy brain, the firing of the neurons is desynchronized. During an epileptic event (seizure) there is excessive and synchronous neuronal activity in the brain.

The EEG during a seizure or an ictal phase is evolving rhythmic activity originating with in network of neurons localized in one hemisphere (focal seizure) or in a rapidly engaging bilaterally distributed network of neurons (generalized seizures) (ILAE). It is well proven that the scalp ictal EEG signal compared to normal EEG has higher amplitude, mostly slower frequencies and higher rhythmicity.

This rhythmic activity has variable amplitude (low to high), frequencies (ranging from delta, theta, alpha, beta) , and morphology (spikes, poly-spikes, sharps, spike and wave, poly-spikes and waves, and fast paroxysmal activity). The ictal features vary among the various types of seizures.

​​​​​​​This webinar will explore various ictal patterns and will discuss the appropriate terminology to describe the ictal events.