Causes of Seizures

Genetic and Neurometabolic Causes. There are many genetic and neurometabolic causes that lead to seizures, typically beginning in childhood. Genetic disorders include disorders such as severe myoclonic epilepsy of childhood, tuberous sclerosis, Rett syndrome, Angelman syndrome, and fragile X. Neurometabolic disorders, which may also have a genetic cause, result in disturbances of metabolism and can lead to seizures. Disorders such as urea cycle defects, pyridoxine dependency, biotinidase deficiency, and glucose transporter deficiencies can cause severe seizures.

Structural Causes. The most common types of brain lesions causing seizures are tumors, vascular lesions, head trauma, infectious diseases, congenital malformation of the brain, and biochemical or degenerative disease processes affecting the brain.

Brain tumor is an important cause of seizures, particularly in the adult patient, becoming an increasingly likely cause after the second decade of life and one of the main causes in the fourth and fifth decades. A brain tumor should be suspected in any person who has onset of seizures, especially focal seizures, after age 20 years.

Head trauma is a major cause of seizures, which may occur shortly after the head injury or, more often, several months to several years later. Factors that increase the chance of development of post-traumatic seizures are a penetrating head injury, severe damage to the brain, prolonged periods of unconsciousness, post-traumatic amnesia, complications of wound healing, and a persistent neurologic deficit.

Vascular disease is one of the most common causes of seizures in older persons, particularly after age 50 years. Seizures can occur transiently after an acute stroke (thrombotic, embolic, or hemorrhagic) or may develop later as a sequela of cerebrovascular disease. Although uncommon, arteriovenous malformations are frequently associated with seizures. Other vascular causes include subdural hematomas, venous thrombosis, and hypertensive encephalopathy.

Seizures may occur with any acute infection of the nervous system or as a complication of damage to the nervous system by the inflammatory process. Patients with cerebral abscesses have a high incidence of seizures, and encephalitis and meningoencephalitis may be associated with either focal or generalized seizures.

Congenital brain malformations are a common cause of childhood seizures. With improved neuroimaging, many patients who were thought to have idiopathic epilepsy have now been found to have brain malformations. The severity of the seizures is related to the type and extent of the malformation.

Systemic Causes. Disease processes or disorders that can cause seizures include various types of metabolic, electrolyte, and biochemical disturbances; hypoxia; hypoglycemia; toxic processes; drugs; or abrupt withdrawal from drugs or alcohol. Various conditions, such as fever, fatigue, sleep deprivation, flashing lights, sound, or emotional factors may also precipitate seizures in susceptible individuals. In young children, fever is a common cause of seizures.

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