hypsarrhythmia

Full Definition

An abnormal electroencephalographic pattern characterized by chaotic, high-voltage slow waves interspersed with spikes and sharp waves that appear asynchronously and independently from both hemispheres. This distinctive EEG pattern is most commonly associated with West syndrome and infantile spasms, though it can be seen in other severe epileptic encephalopathies. The term derives from Greek words meaning 'high' and 'irregular rhythm,' reflecting the disorganized nature of the brain activity.

In Context

• "The EEG demonstrated classic hypsarrhythmia with chaotic high-amplitude activity." — EEG interpretation report
• "Resolution of hypsarrhythmia was observed following successful treatment with vigabatrin." — Follow-up neurology note