Childhood Absence Epilepsy (CAE)

 

Presentation

Common form, absences start in early school (4 – 8y) age, more common in girls.

Cause unclear, but regarded as ‘Idiopathic or Genetic’. Absences are noticed more when child is unwell, tired or bored.

 

Typical episodes makes the child unresponsive, suddenly stop activities and stare ahead in to space for 5 – 15 seconds with sudden recovery. Sometimes associated with eyelid flickering, lip smacking or finger automatisms.

 

Common to find 20 – 50 (up to 100) absences daily if untreated. Child can ‘miss’ information e.g. during a story or lesson causing confusion and affecting learning.

 

Atypical absences last longer than 20 seconds, and have more automatisms.

 

If episodes are not daily or have post-ictal drowsiness, consider alternative diagnosis e.g. TLE.

 

Other seizure types may emerge especially around puberty if underlying disorder was JAE or JME, as absences are also noticed in other epilepsy syndromes, so re-classification may be necessary if not CAE.

 

Investigation

Hyperventilation in clinic for 3 minutes will often precipitate absences, so families should be pre-warned about it.

 

EEG shows generalized spike and wave discharges at 3 Hz (accept 2.5 to 3.5 Hz).

Abnormalities on EEG enhanced by sleep deprivation, hyperventilation or photic stimulation.

 

Consider MRI Brain or genetic studies if atypical or poorly controlled absences.

 

Management

Good response to Valproate, Ethosuximide or Lamotrigine, or their combination.

Most children with CAE respond well to medications and go in to remission by puberty.

Resistant absences may require tertiary neurology input to re-classify epilepsy or consider newer AEDs or ketogenic diet.