Seizures ("fits," convulsions) are episodes of disturbed brain function that cause changes in attention or behavior. They are caused by abnormally excited electrical signals in the brain.
Sometimes a seizure is related to a temporary condition, such as exposure to drugs, withdrawal from certain drugs, a high fever, or abnormal levels of sodium or glucose in the blood. If the seizure or seizures do not happen again once the underlying problem is corrected, the person does NOT have epilepsy.
In other cases, permanent injury to or changes in brain tissue cause the brain to be abnormally excitable. In these cases, the seizures happen without an immediate cause. This is epilepsy. Epilepsy can affect people of any age.
Epilepsy may be idiopathic, which means the cause cannot be identified. These seizures usually begin between ages 5 and 20, but they can happen at any age. People with this condition have no other neurological problems, but sometimes have a family history of seizures or epilepsy.
Some other more common causes of epilepsy include:
- Stroke or transient ischemic attack (TIA)
- Illnesses that cause the brain to deteriorate
- Dementia, such as Alzheimer's disease
- Traumatic brain injury
- Infections (including brain abscess, meningitis, encephalitis, neurosyphilis, and AIDS)
- Problems that are present from before birth (congenital brain defects)
- Injuries near the time of birth (in this case, seizures usually begin in infancy or early childhood)
- Kidney failure or liver failure
- Metabolic diseases that children may be born with (such as phenylketonuria)
- Tumors or other structural brain lesions (such as hematomas or abnormal blood vessels)