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KeywordsSeizure Type Epileptiform Activity Focal Seizure Absence Seizure Complex Partial Seizure
An absence (usually pronounced with a French accent as “ab-SAWNS”) seizure is a type of generalized seizure caused by a large burst of electrical discharges that begins in broad, bilaterally distributed networks simultaneously as opposed to a complex partial seizure (focal seizure with altered awareness/responsiveness).1 During an absence seizure, the patient will lose interaction with the environment, stare blankly (“zone out”), and perhaps blink the eyes (eyelid myoclonia) or have sudden jerks (myoclonic absence). There is no true loss of consciousness or motor functions. The seizure is typically short in duration (only several seconds), and patients often resume their ongoing activity without realizing even that they had a seizure (but will be amnestic for anything occurring during the episode). There are no postictal problems after the end of the seizure. Although no first aid is required, the patient should be protected from doing anything dangerous during the episode (e.g., cooking, crossing the street), but the episodes are often so brief that intervention is difficult.
The cause of absence seizures is unknown. Patients with typical absence seizures have no positive neuroimaging findings but usually have bursts of 3-per-second bilaterally synchronous spike/wave epileptiform activity on a routine EEG (even when not having a seizure). Atypical absence seizures can have a slightly different frequency or pattern. Absence seizures can be differentiated clinically from complex partial seizures (focal seizures with altered awareness/responsiveness), in which there is a similar disruption of consciousness and “zoning out,” by the duration of the episode. Absence seizures last only a few seconds, while complex partial seizures usually last 1–1.5 min. Absence seizures typically begin in childhood, respond well to medication, and often remit spontaneously by adulthood. Common medications for absence seizures include divalproex/valproate sodium (Depakote), ethosuximide (Zarontin), and lamotrigine (Lamictal). Although the frequency of absence seizures can approach dozens per day, only mild (at worst) neuropsychological deficits are typically shown if the absence episodes occur without other seizure types. They do not have a dramatic impact on academic performance. However, absence seizures may occur with other seizure types in serious disorders such as Lennox-Gastaut syndrome, in which case there is considerable cognitive dysfunction and a worse prognosis.
References and Readings
- Berg, A. T., Berkovic, S. F., Brodie, M. J., Buchhalter, J., Cross, J. H., van Emde, B. W., Engel, J., French, J., Glauser, T. A., Mathern, G. W., Moshe, S. L., Nordli, D., Plouin, P., & Scheffer, I. E. (2010). Revised terminology and concepts for organization of seizures and epilepsies: Report of the ILAE Commission on Classification and Terminology, 2005–2009. Epilepsia, 51(4), 676–685.CrossRefPubMedGoogle Scholar
- Wyllie, E. (Ed.). (2015). Wyllie’s treatment of epilepsy: Principles and practice (6th ed.). New York: Lippincott Williams & Wilkins.Google Scholar