A seizure is a sudden change in behavior, movement or consciousness due to abnormal electrical activity in the brain.

[3][8] If a seizure lasts longer than 5 minutes, it is a medical emergency (status epilepticus) and needs immediate treatment.

[3][8] A period of confusion typically follows the seizure that lasts from seconds to hours before a person returns to normal.

[15] Other symptoms during this period include drowsiness, headache, difficulty speaking, psychosis, and weakness.

[21] Those with epilepsy may have certain triggers that they know cause seizures to occur, including emotional stress, sleep deprivation, and flickering lights.

[3] In people with brain tumours, the frequency of epilepsy depends on the location of the tumor in the cortical region.

[3] In babies and children, congenital brain abnormalities, such as lissencephaly or polymicrogyria, will also result in epilepsy.

If the first seizure occurs more than 7 days following a stroke, there is a higher chance of the person developing epilepsy.

[29] Infections of newborns that occur while before or during birth, such as herpes simplex virus, rubella, and cytomegalovirus, all carry a risk of causing epilepsy.

[37][38][36] γ-aminobutyric acid (GABA) and Glutamate are chemicals called neurotransmitters that work by opening or closing ion channels on neurons to cause inhibition or excitability.

[42] Prolonged and recurrent seizures, such as status epilepticus, typically cause brain damage.

[43] Diagnosis of seizures involve gathering history, doing a physical exam, and ordering tests.

[5] In babies and children, information about developmental milestones, birth history, and previous illnesses are important as potential epilepsy risk factors.

[15] A bite mark on the side of the tongue or bleeding from the mouth strongly indicates a seizure happened.

[8][44] A lumbar puncture is mainly done if there is reason to believe infection or inflammation of the nervous system is occurring.

[5][44] Brain imaging by CT scan and MRI is recommended after a first seizure, especially if no provoking factors are discovered.

[5] MRI is generally the better imaging test, but CT scan is preferred when intracranial bleeding is suspected.

[55] Potentially sharp or dangerous objects should be moved from the area around a person experiencing a seizure so that the individual is not hurt.

[55] After the seizure, if the person is not fully conscious and alert, they should be turned to their side to prevent choking.

[3] Rectal and intranasal forms also exist if a child has had seizures previously and was prescribed the rescue medication.

[5][59] Anti-seizure medications may be slowly stopped after a period of time if a person has just experienced one seizure and has not had any more.

[5] The decision to stop anti-seizure medications should be discussed between the doctor and patient, weighing the benefits and risks.

In severe cases where seizures are uncontrolled by at least two anti-seizure medications, brain surgery can be a treatment option.

The term "epilepsy" itself is a Greek word, which is derived from the verb "epilambanein", meaning "to seize, possess, or afflict".

[72] Early surgical treatment of epilepsy was primitive in Ancient Greek, Roman and Egyptian medicine.

[73] The 19th century saw the rise of targeted surgery for the treatment of epileptic seizures, beginning in 1886 with localized resections performed by Sir Victor Horsley, a neurosurgeon in London.

[72] Another advancement was that of the development by the Montreal procedure by Canadian neurosurgeon Wilder Penfield, which involved use of electrical stimulation among conscious patients to more accurately identify and resect the epileptic areas in the brain.

[72] Seizures result in direct economic costs of about one billion dollars in the United States.

[78] Gene therapy for epilepsy consists of employing vectors to deliver pieces of genetic material to areas of the brain involved in seizure onset.

[76][78] Computational neuroscience has been able to bring a new point of view on the seizures by considering the dynamical aspects.