A seizure is a paroxysmal event due to disturbed electrical function of the cerebral cortex. It is characterized by uncontrolled neuromuscular movements, convulsions, and/or altered sensorium and typically lasts only seconds or minutes.

Epileptic seizures are recurring events due to an epilepsy syndrome or brain / central nervous system injury. Acute symptomatic seizures occur in close temporal relationship to a central nervous system insult and can be seen with head trauma, alcohol withdrawal, infection, stroke, and metabolic derangements. In some patients, seizures may be triggered or exacerbated by the menstrual cycle (catamenial epilepsy).

Seizures may be classified as focal (in one cerebral hemisphere) or generalized (both cerebral hemispheres). Some seizures may begin as focal seizures but become generalized. Reflex seizures may be precipitated by sensory stimulus such as flashing or bright lights, music or patterns, or by stress, lack of sleep, fatigue, or fever. Other types of seizures include benign neonatal seizures and febrile seizures. A variety of epilepsy syndromes are linked to genetic mutations and may have onset in childhood, adolescence, or adulthood.

Drug-induced seizures can be caused by medications and recreational drugs. A broad range of pharmacological classes are known to induce seizures including alkylating agents, antimalarials, antimicrobials and antivirals, anesthetics and analgesics, dietary supplements, immunomodulatory drugs, psychotropics such as antidepressants and antipsychotics, and radiographic contrast agents. Drugs used recreationally, like amphetamines, cocaine, fentanyl or heroin, marijuana, methylphenidate, phencyclidine, and synthetic cannabinoids, can provoke seizures, while drug withdrawal is also implicated and is associated with alcohol, barbiturates, and benzodiazepines. (See Drug Reaction Data for more information.)

Psychogenic nonepileptic seizures are sudden episodic disturbances that resemble epileptic seizures but are induced by emotional and stress-related events. Also called pseudoseizures, psychogenic seizures, or nonepileptic events, they fall under the category of somatic symptom and related disorders or conversion disorders.

Management of seizures depends on the cause, type, and severity of seizures. Status epilepticus is defined as any seizure lasting more than 5 minutes and is a medical emergency.

Additional related topics:

• Childhood absence epilepsy
• Complex partial seizure
• Simple partial seizure
• Lennox-Gastaut syndrome
• Dravet syndrome
• Juvenile myoclonic epilepsy
• Lafora disease
• Infantile spasms
• Congenital infection, including Zika virus infection