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  • Updated 03.11.2024
  • Released 12.16.2008
  • Expires For CME 03.11.2027

Focal to bilateral tonic-clonic seizures



Focal to bilateral tonic-clonic seizures are seizures that begin as ictal discharges in a restricted focus of the brain and subsequently propagate to involve bilateral motor outputs from the brain. 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 sudden unexpected death in epilepsy are associated with intractable focal to bilateral seizures.

• Intracranial neurostimulation (responsive neurostimulation and deep brain stimulation) can be used as an adjunct therapy in patients with medically refractory epilepsy.

• 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 ancient Babylonian tablets around 600 to 700 BC. Focal-onset seizures in which convulsions were restricted to one side of the body were systematically described by Louis François Bravais in his 1827 thesis and were referred to as hemiplegic epilepsy. In a paper published in 1870, John Hughlings Jackson, unlike Bravais, accepted the fact that convulsions that are initially unilateral could spread to involve both sides of the body. He also believed that loss of consciousness could occur before the spread of convulsion to the contralateral side of the body.

The terminology and classification of seizures and epilepsy by ILAE has undergone several revisions since 1970. In 2017, the revised ILAE operational classification of seizure types suggested that the term “secondarily generalized” be replaced by “focal to bilateral tonic-clonic” seizures (16).

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