Hypsarrhythmia true true http://www.case.edu/EpSO.owl#Hypsarrhythmia UMLS:C0684276 human_phenotype Hypsarrhythmia by EEG https://www.ncbi.nlm.nih.gov/pubmed/29656099 SNOMEDCT_US:28055006 MSH:D013036 Hypsarrhythmia is abnormal interictal high amplitude waves and a background of irregular spikes. There is continuous (during wakefulness), high-amplitude (>200 Hz), generalized polymorphic slowing with no organized background and multifocal spikes demonstrated by electroencephalography (EEG). HP:0002521 EEG with generalized epileptiform discharges