Secondarily generalized tonic-clonic seizures

Robert L Beach MD PhD (Dr. Beach, Director of the Comprehensive Epilepsy Program at SUNY Upstate Medical University, has no relevant financial relationships to disclose.)
Shahram Izadyar MD (Dr. Izadyar of Upstate Medical University in Syracuse has no relevant financial relationships to disclose.)
Jerome Engel Jr MD PhD, editor. (Dr. Engel of the David Geffen School of Medicine at the University of California, Los Angeles, has no relevant financial relationships to disclose.)
Originally released December 16, 2008; last updated December 4, 2018; expires December 4, 2021

This article includes discussion of secondarily generalized tonic-clonic seizures (SGTCS), complex partial seizures with secondary generalization, simple partial seizures with secondary generalization, and focal seizures evolving to a bilateral convulsive seizure. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


Secondarily generalized tonic-clonic seizures involve ictal discharges beginning in a restricted focus and spreading to involve bilateral motor outputs from the brain. Generalized tonic-clonic seizures can occur secondarily in idiopathic or symptomatic focal epilepsies and represent the final common pathway in the ictal progression of most seizure types. In this article, clinical features suggesting lateralization and diagnostic techniques to localize the focus are discussed, and management options are briefly covered.

Key points


• Seizures that clinically appear to be generalized may represent activation of specific pathways, dependent on the location of the focus, and may not be truly generalized.


• Cardiac arrhythmias and SUDEP are associated with intractable, secondarily generalized seizures.


• Novel therapies such as responsive intracranial stimulation hold promise for achieving more optimal seizure control.


• Modulation of inflammatory responses in immune-mediated seizures represents an evolving new avenue of treatment of epilepsy and possibly epileptogenesis.

Historical note and terminology

The earliest descriptions of tonic-clonic seizures appear in Egyptian hieroglyphics prior to 700 BC. Partial-onset seizures in which convulsions were restricted to 1 side of the body were systematically described by Louis François Bravais in his 1827 thesis. In a paper published in 1870, John Hughlings Jackson, unlike Bravais, accepted the fact that convulsions that are initially unilateral could spread to the bilateral muscles of both sides of the body. He also believed that loss of consciousness could occur before the convulsion spread to the contralateral side of the body.

The terminology and classification of seizures and epilepsy by ILAE has undergone several revisions since 1970. In the report of ILAE commission on classification and terminology of seizures and epilepsy in 2010, it was recommended that the phrase “focal seizure evolving to a bilateral convulsive disorder” replace the term “secondarily generalized seizure.”

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