Lennox-Gastaut Syndrome (LGS) was first characterized by  Dr. William G. Lennox as a form of epilepsy known as a "Petit mal variant." In 1966, the Marseille School in France provided a more detailed description of the syndrome. Dr. Henri Gastaut and his colleagues introduced the term "Lennox syndrome" to refer to a type of epilepsy that begins in childhood and is characterized by recurrent tonic and absence seizures. In 1989, the International League Against Epilepsy (ILAE) issued a more precise diagnosis of Lennox-Gastaut Syndrome (LGS). The illness is categorized as an epileptic encephalopathy, which means that the epileptic activity has a role in causing cognitive and behavioral abnormalities.