A bilateral tonic-clonic seizure is a seizure defined by a tonic (bilateral increased tone, lasting seconds to minutes) and then a clonic (bilateral sustained rhythmic jerking) phase. The phenotype is Bilateral tonic-clonic seizure (HP_0002069, a Human Phenotype Ontology id). Also known as: Bilateral convulsive seizures, Generalised convulsion, Generalised tonic-clonic seizure (without specification of onset), Generalized convulsion, Generalized tonic-clonic seizure (without specification of onset), Grand mal, Grand mal seizures, Seizures, tonic-clonic.