Generalized seizures in adults

Generalized seizures are a common seizure type, characterized by loss of consciousness, widespread motor manifestations of tonic contractions followed by clonic jerking movements, and a suppressed level of arousal following the event.

They may reflect an underlying generalized-onset epilepsy or focal to bilateral tonic-clonic seizures.

An electroencephalogram (EEG) and magnetic resonance imaging are essential tests for properly diagnosing an epilepsy syndrome after a generalized tonic-clonic seizure (GTCS). During a GTCS, the EEG will demonstrate bilateral synchrony in the epileptiform activity.

After a GTCS, treatment depends on the type of epilepsy syndrome identified. Generalized-onset epilepsy is treated differently from focal-onset epilepsy. With accurate diagnosis, most seizure disorders respond to treatment, although up to 40% of patients have drug-resistant epilepsy.

The primary treatment complications include lack of efficacy and adverse effects of medication (including dose-dependent and idiosyncratic reactions).

This topic covers generalized seizures in adults. We also have a topic on Generalized seizures in children.

A generalized tonic-clonic seizure is a seizure type as identified by specific clinical and electroencephalographic criteria.[1]Beniczky S, Trinka E, Wirrell E, et al. Updated classification of epileptic seizures: position paper of the International League Against Epilepsy. Epilepsia. 2025 Jun;66(6):1804-23. https://onlinelibrary.wiley.com/doi/10.1111/epi.18338 http://www.ncbi.nlm.nih.gov/pubmed/40264351?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 Clinically, this seizure type classically involves loss of consciousness and a phasic tonic stiffening of the limbs (either symmetrically or asymmetrically), followed by repetitive clonic jerking. The vast majority of these types of seizures are self-limited without intervention. The observed manifestations of the seizure are correlated on the EEG with bisynchronous epileptiform activity in both cerebral hemispheres. These seizures can occur either in a primary fashion (with onset in a widespread or bilateral distribution) or in a secondary fashion (with onset in one hemisphere or region).