Table 2

Differences between atypical and typical absence seizures

FeaturesAtypical absencesTypical absences
Onset and terminationUsually gradualAbrupt
ResponsivenessDecreased but not abolishedVaries from mild to severe
Changes in toneUsually pronouncedUsually mild
DurationUsually long sometimes minutesUsually brief; never >30–40 s
Postictal recoveryCognitive impairment may persistImmediately
Interictal EEGBackground often abnormal with frequent discharges of various typesBackground usually normal sometimes with typical IGE discharges
Ictal EEGSlow (<2.5 Hz) spike and waveFast (>2.5 Hz) spike and slow wave
Normal neurological and mental stateExceptionalAs a rule
Other types of seizuresAtonic and tonic seizures of symptomatic generalised epilepsiesDepend on IGE syndrome (myoclonic jerks, GTCS or both)
PrognosisCommonly badCommonly good
  • Adapted from Panayiotopoulos CP. A clinical Guide to Epileptic Syndromes and their treatment 2007.

  • IGE, idiopathic generalised epilepsy, GTCS, generalised tonic clonic seizures.