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
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.
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.
Childhood Absence Epilepsy (Epilepsy Foundation)
National organization with local chapters that provides information and support.
Bergqvist, A G Christina.
Idiopathic Pediatric Epilepsy Syndromes.
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