Bilateral tonic-clonic seizure with focal onset

What it means

A bilateral tonic-clonic seizure with focal onset is a focal-onset seizure which progresses into a bilateral tonic-clonic phase.

The ILAE 2017 classification refers to this seizure type as a focal to bilateral tonic-clonic seizure. Previously it has been known as a secondarily generalized tonic-clonic seizure. The focal features of the seizure may be clinically manifest or alternatively, the spread in brain networks may be so rapid that no preceding focal symptom or sign is identified with demonstration of the focal onset resting on investigations. Note that not all instances of a Bilateral tonic-clonic seizure with focal onset will be a Focal motor seizure, some will be a Focal non-motor seizure, thus one can only say that there is a Focal-onset.

Rare diseases that can present with this15

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Focal seizure with secondary generalisation · Focal seizure with secondary generalization · Focal to bilateral tonic-clonic seizure · Generalised tonic-clonic seizure with focal onset · Generalised tonic-clonic seizure with partial onset · Generalised tonic-clonic seizures with focal onset · Generalized tonic-clonic seizure with focal onset · Generalized tonic-clonic seizure with partial onset