Epilepsy is a brain disorder in which clusters of nerve cells, or neurons, in the brain sometimes signal abnormally. Neurons normally generate electrochemical impulses that act on other neurons, glands, and muscles to produce human thoughts, feelings, and actions.
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 known as epileptic
seizures. The condition is, therefore, sometimes referred to as a
seizure disorder. It affects people in all nations and of all races.
During a
seizure, neurons may fire as many as 500 times a second, much faster than the normal rate of about 80 times a second. In some people, this happens only occasionally; for others, it may happen up to hundreds of times a day.
Epilepsy was one of the first brain disorders to be described. It was mentioned in ancient Babylon more than 3,000 years ago. The strange behavior caused by some seizures has contributed through the ages to many superstitions and prejudices. The word epilepsy is derived from the Greek word for "attack." People once thought that those with epilepsy were being visited by demons or gods. However, in 400 B.C., the early physician Hippocrates suggested that it was a disorder of the brain -- and we now know that he was right.
Epilepsy is a disorder with many possible causes. Anything that disturbs the normal pattern of neuron activity -- such as illness, brain damage, or abnormal brain development -- can lead to seizures. It may develop because of an abnormality in brain wiring, an imbalance of nerve signaling chemicals called neurotransmitters, or some combination of these factors.
It is not contagious, and is not caused by mental illness or mental retardation.
Having a
seizure does not necessarily mean that a person has it. Only when a person has had two or more
seizures is he or she considered to have epilepsy. Electroencephalograms (EEGs) and brain scans are common tests used to diagnose the disorder.
Once epilepsy is diagnosed, it is important to begin treatment as soon as possible. For about 80 percent of those diagnosed with epilepsy, seizures can be controlled with modern medicines and surgical techniques. In 1997, the Food and Drug Administration (FDA) approved the
vagus nerve stimulator for use in people with seizures that are not well-controlled by medication.
While epilepsy cannot currently be cured, for some people it does eventually go away. One study found that children with idiopathic epilepsy, or epilepsy with an unknown cause, had a 68 to 92 percent chance of becoming seizure-free by 20 years after their diagnosis.
The odds of becoming seizure-free are not as good for adults or for children with severe epilepsy syndromes, but it is nonetheless possible that seizures may decrease or even stop over time. This is more likely if the epilepsy has been well-controlled by medication or if the person has had
epilepsy surgery.
Most seizures do not cause brain damage. It is not uncommon for people with epilepsy, especially children, to develop behavioral and emotional problems, sometimes the consequence of embarrassment and frustration or bullying, teasing, or avoidance in school and other social settings.
For many people with this condition, the risk of seizures restricts their independence (some states refuse driver's licenses to people with epilepsy) and recreational activities.
People with epilepsy are at special risk for two life-threatening conditions:
status epilepticus and sudden unexplained death.
Most women with epilepsy can become pregnant, but they should discuss their epilepsy and the medications they are taking with their doctors. Women with epilepsy have a 90 percent or better chance of having a normal, healthy baby.
Scientists are studying potential antiepileptic drugs with goal of enhancing treatment for epilepsy.
Scientists continue to study how neurotransmitters interact with brain cells to control nerve firing and how non-neuronal cells in the brain contribute to
seizures. One of the most-studied neurotransmitters is
GABA, or
gamma-aminobutyric acid.
Researchers are working to identify genes that may influence the disorder. This information may allow doctors to prevent it or to predict which treatments will be most beneficial.
Doctors are now experimenting with several new types of therapies for epilepsy, including:
- Transplanting fetal pig neurons into the brains of patients to learn whether cell transplants can help control seizures
- Transplanting stem cells
- Using a device that could predict seizures up to three minutes before they begin.
More than two million people in the United States -- about 1 in 150 -- have experienced an unprovoked seizure or been diagnosed with epilepsy. For about 80 percent of those diagnosed, seizures can be controlled with modern medicines and surgical techniques.
However, about 20 percent of people with epilepsy will continue to experience seizures even with the best available treatment. Doctors call this situation intractable epilepsy. Having a seizure does not necessarily mean that a person has epilepsy. Only when a person has had two or more seizures is he or she considered to have epilepsy.
Many people with epilepsy lead productive and outwardly normal lives. Medical and research advances in the past two decades have led to a better understanding of epilepsy and seizures than ever before. Advanced brain scans and other techniques allow greater accuracy in diagnosing it and determining when a patient may be helped by surgery.
Research on the underlying causes of epilepsy, including identification of genes for some forms of epilepsy and
febrile seizures, has led to a greatly improved understanding of the condition that may lead to more effective treatments or even new ways of
preventing epilepsy in the future.
