Epilepsy : Types of Seizures

by Food and Drug Administration (FDA)

(Page 2 of 3)

With epilepsy, people experience different types of seizures. Some people have just one type, while others have more than one. The kind of seizure a person has depends on which part and how much of the brain is affected by the electrical disturbance that produces seizures.

Seizures are currently classified by their clinical symptoms, such as how a person acts during a seizure, or how he or she reports the experience. The classification most widely used today is based on a system introduced by the International League Against Epilepsy in 1969 that divides more than 30 types of seizures into two major categories: partial, also called focal, and generalized.

Partial seizures, the most common type experienced by people with epilepsy, occur when abnormal electrical activity involves only one area of the brain. There also are two kinds of partial seizures: simple, in which the person remains conscious; and complex, in which consciousness is lost or altered. Although the person remains aware of the environment and remembers the experience, he or she may be limited in how to interact while it is in process. Speech, for example, may be lost.

The Epilepsy Foundation says that partial seizures may progress through several stages that reflect the spread of abnormal neuronal firing to different areas of the brain. When this happens, for example, a seizure that begins in a motor area may cause twitching of the hand or face.

Generalized seizures affect both sides of the brain and cause loss or alteration of consciousness either briefly or for a longer period of time. These seizures are subcategorized into several major types including:

• tonic-clonic, formerly called grand mal
• myoclonic
• absence, formerly called petit mal
• atonic, also called drop attacks.

Generalized tonic-clonic seizures begin with stiffening limbs, the tonic phase, followed by jerking of the limbs and face, the clonic phase. During the tonic phase, breathing may decrease or cease altogether, producing blue lips, nail beds, and face. Breathing typically returns during the clonic phase, but it may be irregular. Some people experience only the tonic phase of the seizure, while others exhibit only the clonic phase, or jerking movements. Still others may have a tonic-clonic-tonic pattern.

Doctors believe that most of Mike's seizures began as complex partial and developed into generalized tonic-clonic seizures, the same type that Scribner has had. Both say that their seizures typically occur during sleep, and each is aware that he's had one because he feels bad physically afterward. "I've never had a seizure when I was fully awake," says Scribner, whose wife has witnessed his nighttime episodes.

Myoclonic seizures are rapid, brief contractions of bodily muscles, which usually occur at the same time on both sides of the body. People usually think of them as sudden jerks or clumsiness.

Absence seizures are lapses of awareness, sometimes with staring, that begin and end abruptly, lasting only a few seconds. There is no warning and no aftereffect from this type of seizure. According to the Epilepsy Foundation, absence seizures are frequently so brief that they escape anyone's notice.

Atonic seizures produce an abrupt loss of muscle tone. They cause head drop, loss of posture, or sudden collapse. This type of seizure tends to be resistant to drug therapy, according to the Epilepsy Foundation.

Most epileptic seizures last only a minute or two and are not life-threatening. The person, however, who experiences repeated seizures (status epilepticus) and does not regain awareness between seizures needs immediate attention. And someone with prolonged seizures, those lasting at least 30 minutes, also needs immediate attention.

Contrary to popular belief, nothing should be placed in the mouth of a person experiencing a seizure. Experts say that at no time is it possible to swallow the tongue.

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