Juvenile Absence Epilepsy (JAE)

Overview

  • Juvenile Absence Epilepsy (JAE) is one of the commonest forms of epilepsy in adolescence.
  • The seizures can typically include absences, infrequent generalised tonic clonic seizures (GTCS) and myoclonic seizures. Absence seizures are the predominant seizure type.
  • The EEG has generalized spike or polyspike slow-wave complexes.
  • JAE is a lifelong disorder, although seizures can be controlled in 70% to 80% of patients.
  • Treatment is with sodium valproate (see serious concerns with teratogenicity of child bearing age), lamotrigine, clobazam, or ethosuximide. Ethosuximide does not control GTCS.

According to the NICE Guideline: The Epilepsies:

  • The seizure type(s) and epilepsy syndrome, aetiology, and co-morbidity, should be determined.
  • If there is diagnostic uncertainty, individuals should be referred to tertiary services soon (within 4 weeks) for further assessment.

Demographics

Prevalence

  • ~2% to 3% of all epilepsies – more common in young adults.

Age at onset

  • Peak at 9 to 13 years (70% of the patients).

Genetics

  • Genetically determined.

Signs | Symptoms

Seizure Semiology

  • JAE manifests with severe typical absence seizures; many patients (~80%) also suffer from infrequent GTCS and ~1/5 have sporadic myoclonic jerks.
  • The absences occur less frequently than in Childhood Absence Epilepsy (approximately ≤ 5 per day). Duration can be prolonged, varying from 4 to 30 sec (~16 sec).
  • GTCS can occur, usually infrequently, and are usually controlled with medication.
  • Myoclonic jerks are infrequent, mild and of random distribution.

Neurological and mental state

  • Normal

Seizure-precipitating factors

  • Typical absence seizures can be provoked by hyperventilation in the untreated or poorly-controlled patient.
  • Sleep deprivation is the major precipitant of GTCS.

Differential diagnosis

  • Mainly from other IGEs such as CAE or Juvenile Myoclonic Epilepsy (JME).
  • At onset, both JAE and JME may present with GTCS. JME has prominent early morning myoclonic seizures (may occur at other times) in addition to GTCS and absence seizures.
  • CAE generally occurs in a younger child but age is not an absolute discriminant. In CAE, there are many daily absences.

Investigations

EEG

  • Normal background. Generalized 3-4 Hz spike or polyspike slow-wave complexes.

Neuro Imaging

  • Not usually required.

Prognosis

  • JAE is thought to be a lifelong disorder, although seizures can be well controlled in ~70% to 80% of patients. A significant cohort however, do require long-term medications, sometimes > one drug. 

Management

  • Sodium valproate is often very effective. However, for women of child bearing age there are serious concerns of teratogenicity. Other alternatives are lamotrigine, clobazam or ethosuximide, sometimes in combination (ethosuximide does not control GTCS).
  • Sodium valproate has been associated with significant concerns of teratogenicity (i.e. malformations, cognitive impairment, and Autistic Spectrum Disorder). This is particularly true at higher dosages. The risk of teratogenicity increases with increasing dosage. It is important clinicians and women of child bearing age are aware of this risk. Ideally, pregnancies in women with epilepsy should be planned and managed by a neurologist. Medication choices should be selected and discussed keeping in mind the safety of mother and foetus. Click here for further information on pregnancy and teratogenicity.
  • Patients should be warned with regard to precipitating factors of GTCS - sleep deprivation, fatigue, and alcohol.

 
Discussion with family

References

  • Panayiotopoulos CP. The epilepsies: Seizures, syndromes and management: Based on the ILAE classifications and practice parameter guidelines. Chipping Norton, Oxfordshire: Bladen Medical Publishing; 2005.
  • Roger J, Bureau M, Dravet C, Genton P, Tassinari CA, Wolf P, editors. Epileptic syndromes in infancy, childhood and adolescence (4th ed).  Montrouge, France: John Libbey Eurotext Ltd ; 2005.