Juvenile Absence Epilepsy (JAE)

 

Presentation

Common epilepsy, especially in girls with onset between 8 – 14 years age; but sometimes later.

 

Typical absence make the child suddenly unresponsive, staring in to space for 5 – 15 seconds, sometimes with eyelid flickering, lip smacking or chewing automatisms. There is instant recovery & episodes can come in clusters but less frequent than CAE. More episodes when tired or bored.

 

Atypical absences last longer than 20 seconds (sometimes up to 30 – 40 sec), sometimes with altered behaviour and more automatisms, confusing them with focal seizures. However these also stop abruptly with no post ictal drowsiness

 

Most children with JAE will also have few GTCs (usually after awakening) and rarely few myoclonic jerks (infrequent only, compared to JME where myoclonus predominate).

 

Development and cognition not affected.

 

Investigation

Video evidence of episodes and detailed history helps in making diagnosis.

Hyperventilation for 3 minutes in clinic may unmask absences, so pre-warn.

 

EEG shows 3 to 6Hz generalised spike and slow wave activity, more if tired or sleep-deprived. Few also have photosensitivity.

 

Management

Absences show a good response to Valproate, Lamotrigine or Ethosuximide.

However, GTCs are not controlled with Ethosuxamide & Valproate should be avoided in girls of child-bearing age. Most children become seizure-free on treatment, but JAE is lifelong epilepsy so treatment should not be withdrawn.

Other effective drugs include Clobazam, Topiramate Levetiracetam or Zonisamide.

For resistant seizures, combination of AEDs or Ketogenic diet may be needed under tertiary neurology.