Absence Seizure

The seizure lasts for a few to 20 seconds and ends suddenly with resumption of the pre-absence activity, as if had not been interrupted, Absence seizures have a significant impact on quality of life.

Blink, blank, mind takes pause
Cortico-thalamic cause
3hz spike and wave
Pulsing pushes thoughts aside
First line ethosuximide Link to author

About

• Part of the generalized seizure spectrum
• Rare in adults starts age 4-8 and Girls > Boys
• Previously called petit mal epilepsy
• Classified as typical, atypical, and absence with special features.

Aetiology

• The cause of childhood absence epilepsy is presumed to be genetic.

Features

• May be a family history
• History of brain injury

Clinical

• May have been a recent decline in performance at school
• Transient LOC often with open blinking eyes "daydreaming"
• May have twitching mouth movements
• Duration less than 30 seconds
• Some people have hundreds of absences a day.
• They may be induced by hyperventilation

Investigations

• EEG: The ictal electroencephalogram (EEG) reveals generalized spike-and-wave discharges, usually at 3 Hz, though the interictal EEG is usually normal
• MRI may be needed
• Testing for metabolic disorders

EEG showing generalized spike-and-wave discharges at 3 Hz

Management

• In childhood absence epilepsy, in which typical absence seizures are the only type of seizures suffered by the child, seizures generally cease spontaneously by 12 years of age or sooner. Less than 10% of children develop infrequent generalised tonic clonic seizures, and it is rare for them to continue having absence seizures.
• Affected children need to take precautions to prevent injury during absences, and should refrain from activities that would put them at risk if seizures occurred (e.g. climbing heights, swimming unsupervised, or cycling on busy roads)
• Ethosuximide or Lamotrigine or valproate are the preferred treatment in individuals who have absence seizures
• Lamotrigine increases the likelihood of being seizure free compared with placebo, but it can cause serious skin reactions.
• Ethosuximide is associated with aplastic anaemia, skin reactions, and renal and hepatic impairment.
• Valproate is associated with behavioral and cognitive abnormalities, liver necrosis, and pancreatitis

References

• Absence seizures in children