is a chronic condition produced by temporary changes in the electrical function of the brain, causing seizures, which can affect awareness, movement, or sensation.
Seizures occur when clusters of nerve cells in the brain, called neurons, signal or communicate with each other abnormally. During a seizure, the neurons' normal pattern of activity is disturbed. It causes them to fire as many as 500 times per second instead of the normal rate of about 80 times per second. This can cause strange sensations, emotions, and behavior, or convulsions, muscle spasms, and/or loss of consciousness.
A diagnosis of epilepsy is usually not made until a person has a seizure more than once without a preventable cause.
The causes of abnormal brain wiring and imbalance of neurotransmitters are numerous. They can include:
In many cases, the exact cause of epilepsy is not known.
Epilepsy in adults. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed. Updated February 18, 2013. Accessed February 22, 2013.
Epilepsy in children. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed. Updated November 19, 2012. Accessed February 22, 2013.
Lowenstein DH. Seizures and epilepsy. In: Longo DL, Fauci AS, et al, eds.
Harrison's Principles of Internal Medicine.
18th ed. New York, NY: McGraw-Hill; 2012.
NINDS epilepsy information page. National Institute of Neurological Disorders and Stroke website. Available at:
Updated February 21, 2013. Accessed February 22, 2013.
Seizure disorders. Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/neurologic-disorders/seizure-disorders/seizure-disorders. Updated May 2012. Accessed February 22, 2013.
What is epilepsy? Epilepsy Foundation
website. Available at:
http://www.epilepsy.com/learn/epilepsy-101/what-epilepsy. Accessed February 22, 2013.
Last reviewed March 2016 by Rimas Lukas, MD
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