Generalized non-motor (absence) seizure Atypical absence seizure Atypical absence An atypical absence seizure is a type of generalized non-motor (absence) seizure characterized by interruption of ongoing activities and reduced responsiveness. In comparison to a typical absence seizure, changes in tone may be more pronounced, onset and/or cessation may be less abrupt, and the duration of the ictus and post-ictal recovery may be longer. Although not always available, an EEG often demonstrates slow (<3 Hz), irregular, generalized spike-wave activity. SNOMEDCT_US:23374007 in 2017 the ILAE Commission for Classification and Terminology recommended classifying a seizure as having focal or generalized onset only when there is a high degree of confidence (over 80%, arbitrarily chosen to parallel the usual allowable beta error) in the accuracy of this determination; see Dialeptic seizure. Atypical absence seizures Atypical petit mal seizures HP:0007270 UMLS:C0595948