Epilepsy is a disorder of the nervous system that causes a person to become unconscious suddenly, often with violent fits of body movements. Epilepsy is a disorder with many possible causes. In epilepsy, the normal pattern of neuronal activity becomes disturbed, causing strange sensations, emotions, and behavior or sometimes convulsions, muscle spasms, and loss of consciousness. Anything that disturbs the normal pattern of neuron activity—from illness to brain damage to abnormal brain development can lead to seizures.

Epilepsy may develop because of an abnormality in brain wiring, an imbalance of nerve signaling chemicals called neurotransmitters, or some combination of these factors. Having a seizure does not necessarily mean that a person has epilepsy, only when a person has had two or more seizures is he considered to have epilepsy. Electroencephlogram and brain scans are common diagnostic tests for epilepsy.