Epilepsy is a chronic medical condition produced by temporary changes in the electrical function of the brain, causing seizures, which 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, causing them to fire as many as 500 times per second (normal rate is about 80 times per second). This can cause strange sensations, emotions, and behavior, or convulsions, muscle spasms, and/or loss of consciousness.

Neurons in Nerve Tissue

© 2008 Nucleus Medical Art, Inc.

A diagnosis of epilepsy is usually not made until a person experiences a seizure more than once without a known cause. It is estimated that approximately 2 million people in the United States have epilepsy.

The causes of abnormal brain wiring and imbalance of neurotransmitters are numerous. They can include:

  • Head injury
  • Stroke
  • Brain abnormalities inherited at birth
  • Gene abnormalities inherited at birth
  • Brain injury at birth
  • Hypoxia at birth (mesial temporal sclerosis)
  • Brain tumors
  • Alcoholism
  • Metabolic conditions, such as very low blood sugar , very high blood sugar, low calcium, high or low sodium, or low magnesium
  • Alzheimer's disease
  • Heart failure
  • Liver failure
  • Kidney failure
  • Sickle cell anemia
  • Vasculitis (for example, systemic lupus erythematous )
  • Any condition that deprives the brain of oxygen (eg, near drowning)
  • Infectious diseases, such as:
  • Hydrocephalus (excess fluid in the brain)
  • Celiac disease (intolerance to wheat gluten)
  • Exposure to:
  • Certain illegal drugs such as cocaine, amphetamines, phencylidine
  • Overdose of antidepressants and other medications
  • Withdrawal from alcohol, sedatives, and hypnotics
  • Certain medications can lower the seizure threshold and thus increase the risk of seizures
    • Tricyclics
    • Theophylline
    • Penicillin
    • Phenothiazine
  • In children:
    • High fever
    • Maternal infections
    • Poor nutrition
    • Lead poisoning
    • B6 deficiency in neonates, infants
    • Hereditary (genetic syndromes, metabolic disorders)

In many cases, the exact cause of epilepsy is not known. When a cause is not known, the disease is idiopathic .