Hypsarrhythmia with episodes of voltage attenuation.Hypsarrhythmia with a consistent focus of abnormal discharge.Associated with a brain structural abnormality, and does not necessarily predict the affected hemisphere. Characterized by symmetric and synchronized activity, seen in patients with longstanding evolution, especially in those with West syndrome that changes to Lennox-Gastaut syndrome. Hypsarrhythmia with increased interhemispheric synchronization.Through the use of video EEG and continuous monitoring, five variants of the 'classical' hypsarrhythmic pattern have been identified: Hypsarrhythmia rarely persists beyond the age of 24 months. In most cases of infantile spasms, hypsarrhythmia either disappears or improves during a cluster of spasms and/or REM sleep. Occasionally the spike discharge becomes generalized, but it never appears as a rhythmically repetitive and highly organized pattern that could be confused with a discharge of the petit mal or petit mal variant type'. At time they appear to be focal, and a few seconds later they seem to originate from multiple foci. These spikes vary from moment to moment, both in time and in location. Gibbs and Gibbs described hypsarrhythmia (originally spelled with one 'r' ) in 1952 as '.random high voltage waves and spikes. It is an abnormal interictal pattern, consisting of high amplitude and irregular waves and spikes in a background of chaotic and disorganized activity seen on electroencephalogram (EEG), and frequently encountered in infants diagnosed with infantile spasms, although it can be found in other conditions such as tuberous sclerosis. Hypsarrhythmia is very chaotic and disorganized brain electrical activity with no recognizable pattern, whereas a normal brain electrical activity shows clear separation between each signal and visible pattern. Although having this seemingly chaotic EEG, the patient didn't show any clinical seizures while being recorded. In it high amplitude waves and spikes are present, randomly appearing and with no topographical distribution identified also, there is no frequency nor amplitude gradient, indicating a highly disorganized brain activity. The hypsarrhythmia EEG is from a 4-month old girl with cryptogenic West syndrome. A comparison of an awake, resting (with activity), normal EEG with a hypsarrhythmia EEG.

Eeg seizure vs normal