People with absence epilepsy have repeated absence seizures. Absence epilepsy tends to run in families. The seizures frequently begin in childhood or adolescence. If the seizures begin in childhood, they usually stop at puberty.
Although the seizures don't have a lasting effect on intelligence or other brain functions, children with absence epilepsy frequently have so many seizures that it interferes with school and other normal activities.
Temporal Lobe Epilepsy
Temporal lobe epilepsy (TLE) is the most frequent cause of partial seizures and aura. The temporal lobe is located close to the ear. It is the part of the brain where smell is processed and where the choice is made to express a thought or remain silent.
TLE often begins in childhood. Repeated TLE seizures can damage the hippocampus, a part of the brain that is important for memory and learning. Although the damage progresses very slowly, it is important to treat TLE as early as possible.
Frontal Lobe Epilepsy
The frontal lobes of the brain lie behind the forehead. They are the largest of the five lobes and are thought to be the centers that control personality and higher thought processes, including language and speech.
Frontal lobe epilepsy causes a cluster of short seizures that start and stop suddenly. The symptoms depend upon the part of the frontal lobe affected.
Occipital Lobe Epilepsy
The occipital lobe lies at the back of the skull. Occipital lobe epilepsy is like frontal and temporal lobe epilepsies, except that the seizures usually begin with visual hallucinations, rapid blinking, and other symptoms related to the eyes.
Parietal Lobe Epilepsy
The parietal lobe lies between the frontal and temporal lobes. Parietal lobe epilepsy is similar to other types in part because parietal lobe seizures tend to spread to other areas of the brain.
Different Types Of Seizures
Just as there are many types of epilepsy, there are many types of seizures. Not all seizures are epilepsy. Seizures fall into two major categories:
Partial seizures are often named for the part of the brain in which they happen. For example, a person might be said to have partial frontal lobe seizures if the abnormalities occur in the part of the brain right behind the forehead. About 60% of all people who have epilepsy have this type of seizure.
Recurrent partial seizures are sometimes called psychomotor seizures. The term "psychomotor" refers to the interaction between brain and muscles, and in this case refers to the twitches and hallucinations that characterize the seizures. There are several types of partial seizures:
People who have simple partial seizures stay awake and aware but may hear, see, smell, or taste things that aren't real. They may also suddenly feel afraid, angry, happy or sad for no reason. They may become confused or experience jerking or tingling in an arm or leg.
This type of seizure is sometimes called a focal seizure. It may also be called Jacksonian epilepsy, after Hughlings Jackson, a British doctor who was the first to describe it.
Complex partial seizures.
Complex partial seizures usually begin with a blank stare that indicates a brief loss of consciousness. People who have these seizures may blink, twitch, chew or smack the lips repeatedly. They may seem drunk, express exaggerated anger or fear, and throw things around. They may struggle against restraint. These seizures usually last no more than two minutes.
About 80% of these complex partial seizures take place in the temporal lobe of the brain, which is close to the ear, and they are sometimes called temporal lobe seizures. These seizures may also originate in the frontal lobes.
Some people who have partial seizures experience unusual sensations that warn them that they are about to have a seizure. This premonitory state is called aura.
Auras take several different forms:
Sometimes it is perceived as a sinking feeling in the pit of the stomach or a sense of "deja vu" (already seen).
Sometimes it takes the form of an auditory hallucination, like an advertising jingle.
A person experiencing an aura is having a simple partial seizure without losing consciousness.
Secondarily generalized seizures.
Sometimes people have partial seizures that spread to the whole brain and become generalized seizures. This transition can be so rapid that the partial seizure isn't noticed.
Generalized seizures affect a more widespread area of the brain than the partial seizures do and they have more serious consequences. The types of generalized seizures are:
Absence seizures, also called petit mal (which means "little sickness"), cause a momentary loss of consciousness. These episodes usually last less than 30 seconds and may be so brief that they go unnoticed. People with absence epilepsy can experience as many as 50 to 100 of these seizures a day. They may look as though they are simply staring off into space or they may go rigid or jerk and twitch.
Tonic seizures cause the muscles to stiffen, but no twitching occurs. These seizures usually affect the back, arms, and legs. People who have tonic seizures lose consciousness for about 10 seconds.
Clonic seizures cause muscles to jerk on both sides of the body, but the body does not go rigid as in tonic seizures. This type of seizure is rare and affects mostly young children.
Myoclonic seizures may cause the muscles to jerk and twitch in a part of the body such as an arm or leg, or in the whole body.
Atonic seizures cause a complete loss of muscle tone. These seizures are also called drop attacks because people who have them will suddenly lose consciousness and collapse. After a period as short as 10 seconds, the person regains consciousness and can stand and walk again.
Atonic seizures are sometimes mistaken for fainting. But a faint begins slowly and can be avoided by lying down.
Atonic seizures can also affect a single part of the body such as the jaw and neck. In this case, the jaw will briefly go slack and the head will drop.
Also known as grand mal (which means "big sickness"), tonic-clonic seizures cause a mixture of symptoms:
The seizure may begin with a tonic phase in which the muscles suddenly go rigid.
After about 30 seconds, the seizure may enter the clonic phase in which the muscles go rigid and relax in spasms.
Bladder and bowel control may be lost.
The throat tightens so that breathing makes a high-pitched sound called stridor.
Some people have an aura before a tonic-clonic seizure. These seizures usually last two or three minutes. They are followed by a brief sleep-like state. People feel very tired and confused after tonic-clonic seizures.
Many people have a single seizure at some point in their lives. These seizures may be provoked by something like a reaction to a drug, but sometimes they happen for no obvious reason.
Only if the person has had a serious head injury at some point in their lives, or has a family history of epilepsy, would a solitary seizure be potentially considered epilepsy. Only about a third of the people who have first seizures ever have a second episode.
"Febrile" comes from the Latin word for fever and indicates seizure caused by a high fever. Children sometimes have an episode of convulsions during an illness with high fever, but most children who have a febrile seizure do not develop epilepsy. Only 2% to 3% of children who have febrile seizures continue to have seizures.
Sometimes people have episodes that look like seizures, but their brains show no abnormal activity. These episodes are called pseudoseizures or nonepileptic events. Sometimes pseudoseizures are caused by psychological stresses. They can also be caused by other diseases and conditions.
If a pregnant woman develops a sudden rise in blood pressure and experiences seizures, the condition is called eclampsia. This condition is life-threatening and should be treated as an emergency. Eclampsia is treated in the hospital. The seizures usually disappear once the pregnancy is over.