Medicine:Childhood absence epilepsy
Childhood absence epilepsy (CAE), formerly known as pyknolepsy, is an idiopathic generalized epilepsy which occurs in otherwise normal children. The age of onset is between 4–10 years with peak age between 5–7 years. Children have absence seizures which although brief (~4–20 seconds), they occur frequently, sometimes in the hundreds per day. The absence seizures of CAE involve abrupt and severe impairment of consciousness. Mild automatisms are frequent, but major motor involvement early in the course excludes this diagnosis. The EEG demonstrates characteristic "typical 3Hz spike-wave" discharges. The presence of any other seizure type at time of diagnosis rules out the diagnose of CAE.[1] Prognosis is usually good in well-defined cases of CAE with most patients "growing out" of their epilepsy.[2]
Signs and symptoms
In CAE, there is only one seizure type observed at time of diagnosis: typical absence seizure.[1] Typical absence seizure is a generalized onset seizure characterized by an abrupt arrest of the activity associated with an awareness impairment. A typical absences seizure usually last between 10 and 30 seconds.[3] Mild automatisms could be seen during the course of the absence and stop with the end of the absence seizure. When an EEG is recorded during the typical absence seizure, a 3 Hz spike-and-wave discharges is recorded starting with the start of the arrest of the activity. At the end of the discharge, the patient resumes its activity.
Causes
CAE is a complex polygenic disorder. Particularly in the Han Chinese population there is association between mutations in CACNA1H and CAE. These mutations cause increased channel activity and associated increased neuronal excitability. Seizures are believed to originate in the thalamus, where there is an abundance of T-type calcium channels such as those encoded by CACNA1H.
Pathophysiology
The pathophysiology of absence seizures has been linked to oscillatory thalamic-cortical potentials, calcium currents, and the interaction of GABAergic neurons. It seems clear that the pathophysiology of absence seizures differs from other epilepsies which may, in part, explain the unique efficacy of ethosuximide in this syndrome. Multiple genetic regions have been associated with CAE and no diagnostic clinical genetic tests have yet been developed for this disorder.
Diagnosis
Diagnosis is made upon history of absence seizures during early childhood and the observation of ~3 Hz spike-and-wave discharges on an EEG. The new classification of the epilepsy syndrome provides mandatory and exclusionary criteria, as well as some points that signs that should be considered as alerts [4]
Management
There are evidenced based data for the treatment of CAE. A randomized controlled trial including 453 children showed that valproate and ethosuximide had similar absence-free rate after 16 weeks of treatment. In addition, ethosuximide did not increase attentional deficit while valproate increased the incidence of attention deficit.[5] In addition, a prospective cohort of CAE found that ethosuximide was associated with a better rate of complete remission (hazard ratio 2.5 (CI95:1.1-6.0) in a multivariate analysis . Based on these 2 studies, the use of ethosuximide as a first-line treatment for CAE should be recommended. Valproate would be proposed if ethosuximide does not provide full absence control.
Epidemiology
The prevalence of this childhood epilepsy syndrome is 10% or less.[citation needed]. Very few of these people will likely have mutations in CACNA1H or GABRG2[citation needed].
See also
- Generalized epilepsy with febrile seizures plus
- Calcium channel
- Spike and Wave
References
- Perez-Reyes E (2006). "Molecular characterization of T-type calcium channels". Cell Calcium 40 (2): 89–96. doi:10.1016/j.ceca.2006.04.012. PMID 16759699.
Footnotes
- ↑ 1.0 1.1 Hirsch, Edouard; French, Jacqueline; Scheffer, Ingrid E.; Bogacz, Alicia; Alsaadi, Taoufik; Sperling, Michael R.; Abdulla, Fatema; Zuberi, Sameer M. et al. (June 2022). "ILAE definition of the Idiopathic Generalized Epilepsy Syndromes: Position statement by the ILAE Task Force on Nosology and Definitions". Epilepsia 63 (6): 1475–1499. doi:10.1111/epi.17236. ISSN 1528-1167. PMID 35503716. https://pubmed.ncbi.nlm.nih.gov/35503716/.
- ↑ "Childhood and absence epilepsies.". Epilepsy: A Comprehensive Textbook: 2397–2411. 2007.
- ↑ Fisher, Robert S.; Cross, J. Helen; French, Jacqueline A.; Higurashi, Norimichi; Hirsch, Edouard; Jansen, Floor E.; Lagae, Lieven; Moshé, Solomon L. et al. (April 2017). "Operational classification of seizure types by the International League Against Epilepsy: Position Paper of the ILAE Commission for Classification and Terminology". Epilepsia 58 (4): 522–530. doi:10.1111/epi.13670. ISSN 1528-1167. PMID 28276060.
- ↑ Hirsch, Edouard; French, Jacqueline; Scheffer, Ingrid E.; Bogacz, Alicia; Alsaadi, Taoufik; Sperling, Michael R.; Abdulla, Fatema; Zuberi, Sameer M. et al. (June 2022). "ILAE definition of the Idiopathic Generalized Epilepsy Syndromes: Position statement by the ILAE Task Force on Nosology and Definitions" (in en). Epilepsia 63 (6): 1475–1499. doi:10.1111/epi.17236. ISSN 0013-9580. PMID 35503716. https://onlinelibrary.wiley.com/doi/10.1111/epi.17236.
- ↑ Glauser, Tracy A.; Cnaan, Avital; Shinnar, Shlomo; Hirtz, Deborah G.; Dlugos, Dennis; Masur, David; Clark, Peggy O.; Capparelli, Edmund V. et al. (2010-03-04). "Ethosuximide, valproic acid, and lamotrigine in childhood absence epilepsy". The New England Journal of Medicine 362 (9): 790–799. doi:10.1056/NEJMoa0902014. ISSN 1533-4406. PMID 20200383.
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