Epilepsy : Overview, Causes, & Risk Factors

Alternate Names : Temporal lobe epilepsy, Seizure disorder

Definition

Epilepsy is a brain disorder involving repeated, spontaneous seizures of any type. 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.

Overview, Causes, & Risk Factors

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)

Pictures & Images

Brain structures

The structures of the brain include: the brainstem, consisting of the spinal cord, the medulla oblongata, the pons and the midbrain; the cerebellum; the cerebrum (one half, or hemisphere shown), and the diencephalon .

Limbic system

The limbic system of the brain is a group of structures which govern emotions and behavior. The limbic system, and in particular the hippocampus and amygdala, is involved in the formation of long-term memory, and is closely associated with the olfactory structures (having to do with the sense of smell).

Treatment of epilepsy

The vagus nerves branch off the brain on either side of the head and travel down the neck, along the esophagus to the intestinal tract. They are the longest nerves in the body, and affect swallowing and speech. The vagus nerves also connect to parts of the brain involved in seizures. In many seizures disorders, electrical stimulation of the vagus nerves may afford relief of symptoms.

Central nervous system and peripheral nervous system

The central nervous system is comprised of the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.

Review Date : 12/21/2009
Reviewed By : Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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Epilepsy : Overview, Causes, & Risk Factors