A tonic-clonic seizure may be generalised from onset or progress from a focal seizure to a bilateral tonic clonic seizure. This term describes the observed semiology of the seizure without specifying whether the onset is focal or generalized. Thus it can be used for coding bilateral tonic-clonic seizures when the onset is not known. This form of seizure was formerly commonly called grand mal seizure.

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.

HP:0007252, HP:0002407, HP:0001306

Bilateral convulsive seizures, Generalised convulsion, Generalized tonic-clonic seizure (without specification of onset), Seizures, tonic-clonic, Tonic-clonic convulsion, Generalized convulsion, Grand mal, Generalised tonic-clonic seizure (without specification of onset), Tonic-clonic convulsions, Grand mal seizures

HP:0002069