Epilepsy 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.
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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.
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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.
Seizure disorders. Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/neurologic-disorders/seizure-disorders/seizure-disorders. Updated June 2016. Accessed February 6, 2017.
What is epilepsy? Epilepsy Foundation website. Available at: http://www.epilepsy.com/learn/epilepsy-101/what-epilepsy. Accessed February 6, 2017.
Last reviewed February 2017 by Rimas Lukas, MD Last Updated: 3/15/2015