Which clinical history findings are characteristic of absence seizures?

Updated: Sep 25, 2018
  • Author: Scott Segan, MD; Chief Editor: Selim R Benbadis, MD  more...
  • Print


Children with idiopathic generalized epilepsies may present with a history of staring spells, but infrequent absence seizures may not be diagnosed until a generalized tonic-clonic seizure has occurred.

Other symptoms, such as behavioral problems, may be the presenting complaint. [31] Whether this is a comorbid condition or a result of brief, unrecognized attacks that cause lapses of awareness and interferes with attention is unknown.

Decline in school performance may be an indication of the onset or breakthrough of absence seizures.

In symptomatic generalized epilepsies, atypical absence seizures often occur in the setting of developmental delay or mental retardation. (See Table 1, below, for features of typical and atypical absence seizures.)

Other seizure types can be present in the patient, such as myoclonic, tonic, atonic, tonic-clonic, and even partial seizures.

Table 1. Clinical and EEG Findings in Typical and Atypical Absence Seizures* (Open Table in a new window)

Type of Clinical Seizure

EEG Findings

Typical absence

Impairment of consciousness only

Usually regular and symmetrical 3 Hz, possible 2- to 4-Hz spike-and-slow-wave complexes, and possible multiple spike-and-slow-wave complexes

Mild clonic components

Atonic components

Tonic component


Autonomic components

Atypical absence

Changes in tone more pronounced than those of typical absence seizure

EEG more heterogeneous than in typical absence; may include irregular spike-and-slow-wave complexes, fast activity, or other paroxysmal activity; abnormalities bilateral but often irregular and asymmetrical

Nonabrupt onset or cessation abrupt

*May be seen alone or in combination.

Adapted from Dreifuss FE. Classification of epileptic seizures. In: Engel J Jr, Pedley TA, eds. Epilepsy: A Comprehensive Textbook. Philadelphia, PA: Lippincott-Raven;1997.

Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!