Seizure

A seizure is a temporary disruption of brain function caused by abnormal electrical activity. Seizures can alter movement, sensation, awareness, or behavior and usually last seconds to a few minutes. Most resolve without lasting harm, though some require urgent medical attention.

Seizures are categorized by onset. Focal seizures start in a specific brain area and may affect one side of the body or a particular sense. Generalized seizures involve both brain sides and include tonic-clonic, absence, myoclonic, and atonic types. Some events are not caused by epilepsy, occurring instead as non-epileptic events or other medical conditions.

Causes include epilepsy, acute symptomatic seizures from fever, infection, head injury, stroke, tumor, or metabolic disturbance; withdrawal from alcohol or drugs. In many cases no clear cause is found.

Diagnosis combines history, witness description, and tests such as electroencephalography (EEG) and brain imaging (MRI or CT) to determine seizure type and identify underlying conditions. Blood tests may assess metabolic or infectious problems.

Treatment aims to prevent seizures and address causes. Antiseizure medications are the main option for epilepsy; many people achieve control. For refractory cases, options include surgery, neurostimulation (vagus nerve or responsive neurostimulation), and dietary approaches such as the ketogenic diet.

Prognosis varies by type and cause. A single seizure has a different recurrence risk than established epilepsy. Febrile seizures in children typically have good outcomes. Epilepsy affects about 1% of people worldwide, though many achieve long-term control with treatment.

First aid: time the seizure, clear hazards, cushion the head, and turn the person on their side when it ends. Do not place objects in the mouth or restrain movements. Seek emergency help if the seizure lasts more than five minutes, if another seizure follows, or if there is injury or unresponsiveness.