Seizure - Classification

Classification

Clinicians organize different types of seizure according to whether the source of the seizure within the brain is localized (partial- or focal-onset seizures) or distributed (generalized seizures). Partial seizures are further divided on the extent to which consciousness is affected (simple partial seizures and complex partial seizures). Simple partial seizures do not cause a loss in consciousness, but can cause a change in consciousness. A complex partial seizure causes loss of consciousness. Partial seizures have a specific focus, which is the source of the irritation. This is commonly a scarred area of the brain, often scarred due to events such as a brain injury or a blood vessel. A partial seizure may spread within the brain, a process known as secondary generalization. Generalized seizures are divided according to the effect on the body, but all involve loss of consciousness. These include absence, myoclonic, clonic, tonic, tonic–clonic, and atonic seizures. Generalized seizures are more widespread than partial seizures. Unlike partial seizures, generalized seizures do not always have a focal point. In those cases the point of origin is unknown. A mixed seizure is defined as the existence of both generalized and partial seizures in the same patient.

Following standardization proposals devised by Henri Gastaut and published in 1970, terms such as "petit mal", "grand mal", "Jacksonian", "psychomotor", and "temporal-lobe seizure" have fallen into disuse.