There are different types of absence seizures. These are mentioned in 1981 ILAE classification, and were accepted terminology. Present classification does not mention these types. These definitely helps in recognising different clinical forms, EEG characteristics and response to therapy.
Simple absences mean brief episodes characterised by transient out of touch with surroundings with fluttering of eyelids. No postictal phenomenon are seen. Usually these are associated with typical EEG abnormality of 3 Hz spike and wave activity. These patients respond well to ethosuximide (Zarontin syrup).
Complex absences are associated with various other components such as smacking of lips, propulsion, retropulsion, some automatisms similar to CPS. This need to be differentiated from CPS. Duration is very short usually few seconds, no post ictal phenomenon are seen and a number of episodes occur in a day. EEG shows atypical features with 3.5 - 4.5 Hz spike and wave activity. These patients respond to sodium valproate or clonazepam.
There are other types of absences - myoclonic absences, eneuric absences. These are different types of absences based on clinical features.