Generalized seizures begin in one area of the brain and rapidly spread throughout both hemispheres of the brain. Patients who have a generalized seizure usually experience a loss of consciousness resulting from this massive electrical activity throughout the brain.
Generalized seizures are further classified into the following five types:
- Tonic–clonic seizures involve dramatic tonic–clonic muscle contractions (involuntary muscle contraction followed by relaxation appearing as an aggressive spasm), loss of consciousness, and a recovery period characterized by confusion and exhaustion.
- Absence seizures involve abrupt, brief (3- to 5-second) periods of loss of consciousness. Absence seizures occur commonly in children, starting at about 3 years of age, and frequently disappear by puberty. Absence seizures do not usually involve muscle contractions.
- Myoclonic seizures involve short, sporadic periods of muscle contractions that last for several minutes. They are relatively rare and are often secondary seizures.
- Febrile seizures are related to very high fevers and usually involve tonic–clonic seizures. Febrile seizures most frequently occur in children; they are usually self-limited and do not reappear.
- Jacksonian seizures are seizures that begin in one area of the brain and involve one part of the body, and then progressively spread to other parts of the body; they can develop into generalized tonic–clonic seizures.
- Psychomotor seizures are complex seizures that involve sensory, motor, and psychic components. They usually begin with a loss of consciousness, and patients have no memory of the event. Patients may exhibit automatic movements, emotional outbursts, and motor or psychological disturbances.
- Status epilepticus, potentially the most dangerous of seizure conditions, is a state in which seizures rapidly recur again and again with no recovery between seizures.