Absence Epilepsy


Childhood absence epilepsy (CAE) is a form of idiopathic epilepsy with absence seizures and in 10%, generalized tonic-clonic seizures. CAE accounts for 10-15% of childhood epilepsy cases. CAE occurs between the ages of 4 and 14 years of age, and peaks at 6 to 7 years. Children with CAE show typical development and normal IQ. [Bergqvist: 2007] See the CHILDHOOD ABSENCE EPILEPSY diagnosis module for more information.

Absence seizures may also occur in juvenile absence epilepsy and juvenile myoclonic epilepsy; the presence of absence seizures does not automatically mean the child has absence epilepsy.

Characteristics of an absence seizure:
  • Child blanks out from 2 to 20 seconds, but usually less than 10 seconds;
  • Child stares, sometimes blinks, eyes may begin to roll back;
  • INTERRUPTS ACTIVITY (such as drinking from cup, playing);
  • Child isn't aware of surroundings, such as being called by name;
  • Child experiences many a day; at diagnosis children with CAE may be having up to 100/day;
  • Child has no warning, seizure begins and ends suddenly;
  • Child not usually aware of having had seizure; and
  • Absence seizures increase with hyperventilation; this is a good provocative test in the clinic
Although absence seizures occur in normal children, these children have higher rates of behavioral, social, and educational problems; morbidity in educational/social/behavioral situations may be related to the amount of time with abnormal brain activity due to seizures. Declining school performance may be a first sign of absence seizures or a need for increased medication in a child already being treated for absence seizures. There is no mortality unless patient is driving a car, operating dangerous equipment or in water; the seizures themselves aren't fatal, only becoming non-responsive in a dangerous situation.


The etiology of absence epilepsy is genetic with complex multifactorial inheritance. 15-45% of children with CAE have a positive family history and monozygotic twins have a 75% concordance rate. Affected family members may have other forms of idiopathic or generalized epilepsy, such as febrile convulsions and generalized tonic clonic seizures. Absence epilepsy is linked to the GABA receptor gamma 2 subunit and the voltage gated calcium channel alpha 1A subunit. See [Weber: 2008] for more information.


5-50 cases per 100,000 of the population; some studies suggest it is more common in females than males [Jallon: 2005]

Clinical Assessment

Differential Diagnosis
It can be difficult to differentiate between absence seizures, partial complex seizures and daydreaming in normally developing children. Children with daydreaming and absence seizures have normal physical exams, including neurological exams. Daydreaming has no clear start or stop, can be interrupted, and occurs less frequently and in predictable situations (classroom).

Partial complex seizures will often end with the child feeling confused, and these usually occur infrequently (a few times a week or a day compared to many a day). Partial complex seizures are often longer than 20 seconds, and may be accompanied by automatisms (lip smacking, teeth grinding, finger movements).

Diagnosis and Testing
In a child with typical absence epilepsy, including a characteristic EEG, clinical history, and normal development and exam, neuro-imaging is not usually necessary. EEG shows typical (frontally predominant) 3-Hz spike and wave complexes that increase with hyperventilation and have an abrupt beginning and ending. Background activity is normal in children with CAE. Atypical absence seizures may be seen in children with developmental delays/intellectual deficits with 1.5-2.5 Hz sharp-slow complexes on EEG; these represent a different type of symptomatic seizure.


Most experts use valproic acid for CAE, as it treats absence, generalized tonic-clonic, and myoclonic seizures, whereas ethosuximide treats only absence seizures, but not concurrent generalized tonic-clonic seizures. Absence seizures are the only indication for this latter medication.

Lamotrigine may be helpful in the treatment of absence seizures and may have fewer cognitive effects than valproic acid. Absence seizures may be exacerbated by carbamazepine and gabapentin.

See [Wheless: 2007] for more information regarding treatment options.


The majority (65-70%) of children with CAE remit in adolesence; good prognostic signs are earlier age at onset and absences as the only seizure type (no generalized tonic clonic seizures).


Patient Education

Childhood Absence Epilepsy (Epilepsy Foundation)
National organization with local chapters that provides information and support.


Author: Lynne M Kerr, MD, PhD - 5/2011
Reviewing Author: Denise Morita, MD - 5/2010

Page Bibliography

Bergqvist, A G Christina.
Idiopathic Pediatric Epilepsy Syndromes.
Continuum. 2007;13(4):106-120.
An excellent review article from the life-long learning curriculum of the American Board of Psychiatry and Neurology

Jallon P, Latour P.
Epidemiology of idiopathic generalized epilepsies.
Epilepsia. 2005;46 Suppl 9:10-4. PubMed abstract

Weber YG, Lerche H.
Genetic mechanisms in idiopathic epilepsies.
Dev Med Child Neurol. 2008;50(9):648-54. PubMed abstract

Wheless JW, Clarke DF, Arzimanoglou A, Carpenter D.
Treatment of pediatric epilepsy: European expert opinion, 2007.
Epileptic Disord. 2007;9(4):353-412. PubMed abstract