Kodankandath TV, et al. StatPearls. StatPearls Publishing 2020 Jan– - Review.
A generalized tonic-clonic seizure, formerly known as grand mal seizure, is defined as a seizure that has a tonic phase followed by clonic muscle contractions. Among patients, families, and observers, they are most feared of seizure types. They are usually associated with impaired awareness or complete loss of consciousness. According to the recent classification from the International League Against Epilepsy (ILAE), they are categorized under seizures belonging to generalized in onset. Generalized onset seizures are further categorized into motor and non-motor (absence) seizures. A generalized tonic-clonic seizure is a motor seizure and the most common type seen in patients with epilepsy. Generalized tonic-clonic seizures arise within and rapidly involve bilateral cortical, subcortical, and brainstem networks of the brain. A focal seizure-originating from either left or right hemisphere - can rapidly spread and evolve into a bilateral tonic-clonic seizure (previously known as a secondary generalized seizure), which can be difficult to differentiate from a primary generalized tonic-clonic seizure.