Childhood Absence Epilepsy

Childhood absence epilepsy (CAE) is a genetic generalised epilepsy syndrome characterised by frequent typical absence seizures in otherwise neurologically typical children and a characteristic generalised spike-wave EEG pattern.

Absence seizures can be mistaken for daydreaming, inattention or behavioural disengagement. Correct syndrome diagnosis matters because not every staring episode is epileptic and not every epilepsy with absence seizures is childhood absence epilepsy.

Where CAE fits in the ILAE classification

The International League Against Epilepsy includes childhood absence epilepsy among the idiopathic generalised epilepsies and childhood-onset generalised epilepsy syndromes.

The syndrome is diagnosed from the combination of age at onset, seizure semiology and EEG.

Typical age at onset

CAE usually begins in childhood, commonly between about 4 and 10 years of age, with a peak in the early school years.

Onset far outside the expected age range should prompt consideration of another absence epilepsy syndrome or another diagnosis.

What an absence seizure looks like

Typical absences cause a sudden brief interruption of awareness and activity. The child may stop speaking, pause in play, stare and then resume almost immediately.

Subtle eyelid movements, small automatisms or slight changes in facial expression can accompany the impaired awareness.

Why frequency matters

Untreated CAE often causes many absence seizures every day. Individual seizures can be brief, but repeated interruptions can interfere with classroom learning, conversation and safety.

The child may not know that the seizures are occurring and may not remember the interruption.

Absence is not the same as ordinary staring

Normal daydreaming is usually interruptible by touch or voice and tends to begin and end less abruptly.

Epileptic absence seizures are stereotyped, sudden and accompanied by a characteristic EEG discharge. Video and eyewitness description can help, but EEG is central to confirming the syndrome.

Hyperventilation as an activation procedure

Hyperventilation can provoke typical absence seizures and generalised spike-wave discharges in many untreated children with CAE.

When safe and appropriate, supervised hyperventilation during EEG is therefore a useful diagnostic activation procedure. Clinical practice and contraindications should be considered individually.

The EEG pattern

The characteristic EEG shows generalised spike-and-wave activity, typically around 3 Hz, on an otherwise normal background.

The discharges are bilaterally synchronous and generalised, although the first fractions of a second may not look perfectly symmetrical.

MRI

Routine MRI is not required for a straightforward typical presentation of CAE with the expected EEG and normal neurological examination.

MRI may be appropriate if there are atypical features, focal neurological findings, unusual EEG abnormalities or concern for a different diagnosis.

Genetics

CAE is considered genetic, but usually not because of one single high-penetrance gene. The genetic architecture is complex and polygenic in most people.

Routine single-gene testing is therefore not required for every child with classic CAE, although genomic testing may be appropriate when the presentation is atypical or accompanied by developmental or other neurological abnormalities.

First-line treatment evidence

A major randomised controlled trial compared ethosuximide, valproate and lamotrigine in newly diagnosed CAE.

Ethosuximide and valproate were more effective than lamotrigine for initial seizure control. Ethosuximide caused fewer attentional adverse effects than valproate in that study.

Why ethosuximide is often preferred for absence-only CAE

When a child has typical absences without generalised tonic-clonic seizures, ethosuximide is often selected because it is effective against absence seizures and avoids some of the broader adverse-effect burden associated with valproate.

Availability and prescribing practice differ internationally.

When valproate may be considered

If generalised tonic-clonic seizures coexist, ethosuximide is not sufficient for those convulsive seizures. A broad-spectrum medicine may then be required.

Valproate is effective for absence and generalised tonic-clonic seizures but has important adverse effects and major reproductive-safety restrictions in many jurisdictions. Those regulatory rules differ between countries and should not be presented as universally identical.

Lamotrigine

Lamotrigine can treat absence seizures but was less effective than ethosuximide or valproate in the major CAE randomised trial.

It may still be selected in individual situations where other medicines are unsuitable.

Attention and learning

Attention difficulties can occur in CAE even before medication begins. They are not always explained simply by the brief absence seizures themselves.

This matters because apparent seizure control does not automatically mean every learning or attention difficulty will disappear.

School impact

A child having dozens of brief absences each day may miss fragments of teaching without anyone recognising the cause. Teachers may interpret this as poor concentration or deliberate inattention.

School information should explain the child’s individual seizure pattern and what staff should do if a longer or unusual event occurs.

Prognosis

Many children eventually enter remission, but not all do. Some later develop other generalised seizure types or evolve into another idiopathic generalised epilepsy phenotype.

Long-term prognosis should therefore be discussed as a range rather than as a promise that every child will “grow out of it”.

When the diagnosis may be wrong

Red flags include clearly focal seizures, major developmental impairment before seizure onset, persistent focal slowing on EEG, very slow spike-wave, or atypical absence features.

These findings can suggest another generalised epilepsy syndrome, a developmental and epileptic encephalopathy or a focal epilepsy that is producing impaired awareness.

Worldwide access

CAE is often diagnosable with clinical assessment and a routine EEG, making it more accessible to diagnose than syndromes requiring MRI, genomics or prolonged inpatient monitoring.

However, EEG remains unavailable or unaffordable in some regions, and antiseizure medicine availability varies. In such settings, misclassification as behavioural or educational difficulty may persist.

The central point

Childhood absence epilepsy is not simply “staring spells”. It is a defined genetic generalised epilepsy syndrome with frequent typical absences and a characteristic EEG pattern. Correct diagnosis matters because treatment choices and prognosis differ from other causes of staring or impaired awareness.

Sources

Medical note: treatment depends on the exact seizure types, individual risks and local prescribing rules. Medicines should not be started or stopped without clinical advice.

Evidence checked: September 2026.