Generalized seizures in adults

Commission for Classification and Terminology of the International League Against Epilepsy (ILAE)​[1]Fisher RS, Cross JH, French JA, et al. Operational classification of seizure types by the International League Against Epilepsy: position paper of the ILAE Commission for Classification and Terminology. Epilepsia. 2017 Apr;58(4):522-30. https://onlinelibrary.wiley.com/doi/full/10.1111/epi.13670 http://www.ncbi.nlm.nih.gov/pubmed/28276060?tool=bestpractice.com [2]Scheffer IE, Berkovic S, Capovilla G, et al. ILAE classification of the epilepsies: position paper of the ILAE Commission for Classification and Terminology. Epilepsia. 2017 Apr;58(4):512-21. https://onlinelibrary.wiley.com/doi/10.1111/epi.13709 http://www.ncbi.nlm.nih.gov/pubmed/28276062?tool=bestpractice.com ​​​​[3]Wirrell EC, Nabbout R, Scheffer IE, et al. Methodology for classification and definition of epilepsy syndromes with list of syndromes: report of the ILAE Task Force on nosology and definitions. Epilepsia. 2022 Jun;63(6):1333-48. https://www.doi.org/10.1111/epi.17237 http://www.ncbi.nlm.nih.gov/pubmed/35503715?tool=bestpractice.com ​​

A generalized tonic-clonic seizure (GTCS) is clinically identified by a discrete and typically self-limited episode involving convulsive activity on both sides of the body with impairment of consciousness, beginning with a tonic phase followed by a clonic phase. An electroencephalogram (EEG) may be utilized to confirm generalized epileptiform activity; however, given the limited time course of a GTCS, this is rarely employed.

A diagnosis of epilepsy is made after two seizures of any type that had no clear provoking factor. Even a single seizure warrants thorough investigation, and a diagnosis of epilepsy can be made after a first seizure if testing suggests the risk of recurrence is similar to that after a second unprovoked seizure (>60%).[54]Fisher RS, Acevedo C, Arzimanoglou A, et al. ILAE official report: a practical clinical definition of epilepsy. Epilepsia. 2014 Apr;55(4):475-82. https://onlinelibrary.wiley.com/doi/full/10.1111/epi.12550 http://www.ncbi.nlm.nih.gov/pubmed/24730690?tool=bestpractice.com Any abnormal study (e.g., EEG or magnetic resonance imaging [MRI]) indicates an increased likelihood of epilepsy, even if a second seizure has not yet occurred.

EEG and MRI are indicated for all patients with a GTCS in order to classify the epilepsy syndrome.[44]Expert Panel on Neurological Imaging, Lee RK, Burns J, et al. ACR Appropriateness Criteria® seizures and epilepsy. J Am Coll Radiol. 2020 May;17(5s):S293-304. https://www.doi.org/10.1016/j.jacr.2020.01.037 http://www.ncbi.nlm.nih.gov/pubmed/32370973?tool=bestpractice.com ​​ An EEG may reveal evidence of lateralizing or localizing epileptiform abnormalities, which would likely suggest focal-onset epilepsy. The EEG can also provide evidence of symmetric, widespread abnormalities that are suggestive of generalized-onset epilepsy. Similarly, MRI of the brain can reveal structural lesions that suggest certain epilepsy syndromes.