Epilepsy is a disorder of the brain characterized by repeated seizures. A seizure is usually defined as a sudden alteration of behavior due to a temporary change in the electrical functioning of the brain. Normally, the brain continuously generates tiny electrical impulses in an orderly pattern. These impulses travel along neurons—the network of nerve cells in the brain—and throughout the whole body via chemical messengers called neurotransmitters.

In epilepsy the brain's electrical rhythms have a tendency to become imbalanced, resulting in recurrent seizures. In patients with seizures, the normal electrical pattern is disrupted by sudden and synchronized bursts of electrical energy that may briefly affect their consciousness, movements or sensations.

About half of the people who have one seizure without a clear cause will have another one, usually within six months. A person is twice as likely to have another seizure if there is a known brain injury or other type of brain abnormality. If the patients does have two seizures, there is about an 80 percent chance of having more. If the first seizure occurred at the time of an injury or infection in the brain, it is more likely the patient will develop epilepsy than if the seizure did not happen at the time of injury or infection.

Risk Factors for Epilepsy include:


Seizures vary so much that epilepsy specialists frequently classify seizure types. Typically, seizures belong in one of two basic categories. Primary generalized seizures and partial seizures. The difference between these types is in how they begin. Primary generalized seizures begin with a widespread electrical discharge that involves both sides of the brain at once. Partial seizures begin with an electrical discharge in one limited area of the brain.

Family history/heredity is more commonly tied to epilepsy exhibiting generalized seizures, which is more likely to involve genetic factors than partial epilepsy.

If seizures arise from a specific area of the brain, then the initial symptoms of the seizure often reflect the functions of that area. The right half of the brain controls the left side of the body, and the left half of the brain controls the right side of the body. For example, if a seizure starts from the right side of the brain in the area that controls movement in the thumb, then the seizure may begin with jerking of the left thumb or hand.


Epilepsy is usually diagnosed after a person has had at least two seizures that were not caused by some known medical condition, such as alcohol withdrawal or extremely low blood sugar.

Doctors make epilepsy diagnoses based on symptoms, physical signs and the results of such tests as an electroencephalogram (EEG), computed tomography (CT or CAT scan) or magnetic resonance imaging (MRI).

Head injury, brain infection, stroke or tumor can sometimes cause partial seizures but, in most cases, the cause is unknown. One question that is used to further diagnose and classify partial seizures is whether consciousness (the ability to respond and remember) is impaired or preserved. The difference may seem obvious, but there are many degrees of consciousness impairment or preservation.

It is essential that the type of epilepsy and the type of seizures both are diagnosed properly. There are several major classifications of seizures and most are associated with specific forms of the disorder.

In people predisposed to seizures, factors that may increase the risk of seizures include: