Seizures 101: Common Questions Answered

The causes, risk factors and warning signs of seizure.

ByABC News
February 11, 2009, 9:54 PM

May 17, 2008— -- As U.S. Sen. Edward Kennedy recovers from what his office has identified as a seizure, questions linger about his overall health -- and what these reported seizures may indicate.

Below are some of the more frequently asked questions about seizures.

The National Institutes of Health defines a seizure as a sudden change in behavior due to excessive electrical activity in the brain.

The nature of this change in behavior may vary widely depending on what parts of the brain are affected. While some seizures may lead to loss of consciousness, often accompanied by convulsions, less noticeable seizures may bring about little more than a prolonged staring spell. On occasion, seizures can cause visual disturbances and abnormal sensations.

Doctors classify a seizure in which the sufferer maintains consciousness as a "simple" seizure, while those that result in loss of consciousness are called "complex" seizures.

Seizures can also be categorized in terms of how much of the body is affected; "generalized" seizures affect the entire body, while "focal" seizures affect only one side of the body.

Seizures in general are brought about by an abnormal surge of activity within the brain's cerebral neurons. Some doctors have likened the condition to an "electrical storm" within the brain.

It may be a fitting analogy, since in the same way that electrical storms can overwhelm the circuitry of electronics and household appliances, a seizure can interfere with the brain's sensitive circuitry, albeit temporarily.

There are many possible causes for seizures. While they are most often associated with the neurological condition epilepsy, even those who do not have epilepsy may experience them.

Injury or trauma to the head can lead to an increased risk of seizure -- a fact that may be relevant with regard to Kennedy, who sustained serious injuries in a plane crash in 1964. Seizures are also known to accompany alcohol withdrawal, low blood sugar, certain infections, brain tumors and other medical conditions. Likewise, some seizures are also known to be linked to stroke.