What occurs during tonic-clonic seizures?

Tonic-clonic seizures, also known as grand mal seizures, are characterized by a two-phase progression. The first phase, known as the tonic phase, involves a sudden stiffening of the body and loss of consciousness. During this phase, the muscles tense up, causing the person to fall if they are standing. The second phase, the clonic phase, follows, which consists of rhythmic jerking movements of the limbs and face as the body relaxes intermittently. This distinctive pattern of stiffening followed by jerking is what defines tonic-clonic seizures, making the choice that describes it the correct one.

The other options do not accurately describe the nature of tonic-clonic seizures. A total loss of muscle function pertains more closely to other seizure types or conditions, leading to confusion with atonic seizures, which result in sudden muscle weakness. Gradual onset of muscle weakness does not apply as tonic-clonic seizures manifest suddenly and intensely, not gradually. Similarly, prolonged temporary paralysis of limbs can relate to a postictal state after a seizure but does not define what happens during the seizure itself. Thus, the description of the sudden stiffening followed by jerking movements is the correct representation of tonic-clonic seizures.