What is characteristic of a tonic-clonic seizure?

A tonic-clonic seizure, formerly known as a grand mal seizure, is characterized by alternating stiffness and movement, which is indicative of the seizure's two phases. The tonic phase involves a sudden onset of muscle stiffness, causing the person to lose consciousness and become rigid. This is followed by the clonic phase, where rapid and uncontrollable muscle contractions occur, leading to jerking movements. This pattern of alternating stiffness and movement is a hallmark of this type of seizure, distinguishing it from other types of seizures which may have different manifestations.

The other choices describe characteristics that are not associated with tonic-clonic seizures. Brief lapses of consciousness are more typical of absence seizures. Limited to one part of the brain refers to focal seizures, which do not encompass the full-body involvement seen in tonic-clonic seizures. Seizures occurring only at night do not specifically define tonic-clonic seizures, as they can happen at any time and are not restricted to nighttime episodes.