Conditions InDepth: Epilepsy
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, 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
A diagnosis of epilepsy is usually not made until a person experiences a seizure more than once without a known cause. According to the Epilepsy Foundation, about three million Americans 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 (eg, 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)
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Exposure to:
- Lead
- Carbon monoxide
- Other environmental toxins
- Chemical warfare agents
- Certain illegal drugs (eg, cocaine, amphetamines, phencylidine)
- Overdose of antidepressants and other medicines
- Withdrawal from alcohol, sedatives, and hypnotics
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Certain medicines can lower the seizure threshold and thus increase the risk of seizures, such as:
- Tricyclics
- Theophylline
- Penicillin
- Phenothiazine
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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.
References:
Berkow R. The Merck Manual of Medical Information. 17th ed. New York, NY: Simon and Schuster; 2000.
Epilepsy and seizure statistics. Epilepsy Foundation website. Available at: http://www.epilepsyfoundation.org/. Accessed February 17, 2010.
National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/.
Last reviewed Feburary 2010 by Rimas Lukas, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.