How can I differentiate between generalized tonic-clonic seizures and other seizure types in a patient with prolonged seizures?

To differentiate generalized tonic-clonic seizures (GTCS) from other seizure types in a patient experiencing prolonged seizures, focus on the clinical features and seizure semiology. GTCS typically present with a sudden loss of consciousness followed by a tonic phase characterized by generalized stiffening of the body, lasting seconds, then evolving into a clonic phase with rhythmic jerking of all limbs. These seizures usually last 1 to 3 minutes but are considered prolonged if lasting 5 minutes or more, requiring emergency treatment ¹.

In contrast, other seizure types such as focal seizures may begin with localized motor or sensory symptoms without immediate loss of consciousness and may or may not evolve into bilateral tonic-clonic seizures. Myoclonic seizures involve brief, shock-like jerks without the tonic stiffening phase, and absence seizures present with brief lapses in awareness without convulsions ¹.

Epilepsia partialis continua, a form of focal motor status epilepticus, manifests as continuous or repetitive focal motor jerks without the generalized tonic-clonic pattern and can be mistaken for prolonged seizures but lacks the bilateral tonic stiffening and clonic jerking phases seen in GTCS (Bien and Elger, 2008).

In prolonged seizures, the presence of generalized tonic stiffening followed by clonic jerking and loss of consciousness strongly supports GTCS. The absence of these features, or the presence of focal onset signs, suggests other seizure types. Prompt recognition is critical as GTCS lasting 5 minutes or more constitute convulsive status epilepticus, necessitating immediate emergency treatment and resuscitation ¹.