hypsarrhythmia

noun

hyps·​ar·​rhyth·​mia

variants or hypsarhythmia

ˌhips-ā-ˈrit͟h-mē-ə 

: an abnormal encephalogram that is characterized by slow waves of high voltage and a disorganized arrangement of spikes, occurs especially in infants, and is indicative of a condition that leads to severe intellectual disability if left untreated

hypsarrhythmic adjective

or hypsarhythmic

-mik