Exam Master Neuro Practice Exam 2026 - Free Neuro Practice Questions and Study Guide

Tonic-clonic seizures, also known as grand mal seizures, are characterized by two main phases: the tonic phase and the clonic phase. The tonic phase involves a sudden loss of consciousness along with sustained muscle contraction. This is followed by the clonic phase, where the person experiences rhythmic jerking movements of the extremities.

The key symptom that indicates a tonic-clonic seizure is the combination of loss of consciousness together with convulsions. This distinct presentation helps differentiate tonic-clonic seizures from other seizure types, such as absence seizures, where there is a brief loss of awareness without convulsions, or other forms of seizure that may not involve the characteristic muscle contractions accompanying a loss of consciousness. The presence of convulsions or jerking movements alongside a loss of consciousness is particularly indicative of this type of seizure, making it a critical symptom in the diagnosis.