6th August 2024

Overview of seizures and seizure-like activity

Seizures are defined as transiently occurring events, classically behavioural and/or motor disturbances, secondary to abnormal excessive or synchronised electrical activity within neuronal networks. They may occur at any age and may be secondary to a systemic or brain-specific insult, epilepsy, or have an unknown aetiology.

A single seizure does not constitute a diagnosis of epilepsy – this is only diagnosed when two unprovoked seizures occur less than 24 hours apart, one unprovoked seizure occurs with a high risk of recurrence (e.g. with a focal lesion), or an epilepsy syndrome is diagnosed.

Classification

When assessing patients presenting with seizures or seizure-like activity, an important step to establishing possible causes is to classify the nature of the seizure:

Adapted from Scheffer I, Berkovic S, Capovilla G, Connolly M, French J, Guilhoto L et al. ILAE classification of the epilepsies: Position paper of the ILAE Commission for Classification and Terminology. Epilepsia. 2017;58(4):512-521

Overview of causes of seizures