Introduction
Seizure disorders involve periodic disturbances of the brain's electrical activity, resulting in some degree of temporary brain dysfunction.
Normal brain function requires an orderly, organized, coordinated discharge of electrical impulses. Electrical impulses enable the brain to communicate with the spinal cord, nerves, and muscles as well as within itself. When electrical impulses discharge abnormally, a seizure may occur.
About 2% of adults have a seizure at some time during their lifetime. Two thirds of these people never have another one. Most commonly, seizure disorders begin in early childhood or in late adulthood. The term "seizure disorder" is preferred to "epilepsy" because epilepsy is often incorrectly thought to include some degree of brain damage or a tendency to be violent.
Causes
Seizures starting before age 2 are usually caused by high fevers (see Section 6, Chapter 85) or metabolic disorders, such as abnormal blood levels of sugar (glucose), calcium, magnesium, vitamin B6, or sodium. If the seizures recur, the cause is likely to be a hereditary brain disorder (such as nocturnal frontal lobe epilepsy, which is inherited as an autosomal dominant trait (see Section 1, Chapter 2)). Many seizures that begin between the ages of 2 and 14 years have no known cause. Seizures starting after age 25 may be caused by structural damage to the brain such as from a head injury, stroke, or tumor. However, in about half of people in this age group, the cause is unknown. When no cause can be identified, seizures are called idiopathic.
People with a seizure disorder are more likely to have a seizure when they are under excess physical or emotional stress or deprived of sleep. Strong stimuli that irritate the brain--such as injury, certain drugs, sleep deprivation, infections, fever, low levels of oxygen in the blood, or very low levels of sugar in the blood--can trigger a seizure whether a person has a seizure disorder or not. These seizures are known as "provoked seizures." Avoiding such stimuli can help prevent seizures.
Rarely, seizures are triggered by repetitive sounds, flashing lights, video games, or even touching certain parts of the body. This disorder is called reflex epilepsy.
 See the table Causes of Seizures.
Symptoms
In about 20% of people who have a seizure disorder, seizures are preceded by unusual sensations of smell, taste, or vision or an intense feeling that a seizure is about to begin (aura). Usually, an aura is associated with an unpleasant sensation, such as an odor of burning garbage or decaying flesh.
Almost all seizures are relatively brief, lasting from a few seconds to a few minutes. Most seizures last 2 to 5 minutes. When a seizure stops, the person may have a headache, sore muscles, unusual sensations, confusion, and profound fatigue. These after-effects are called the postictal state. In some people, one side of the body is weak, and the weakness lasts longer than the seizure (a condition called Todd's paralysis). Most people who have a seizure disorder look and behave normally between seizures and can live normal lives.
Symptoms vary depending on which area of the brain is affected by the abnormal electrical discharge (see Section 6, Chapter 76 and Section 6, Chapter 82). For example, if an abnormal electrical discharge occurs in the area that controls smell (located deep within temporal lobe), the person may sense an intensely pleasant or unpleasant smell. If it occurs in another area of the temporal lobe, the person may experience a sense of déjà vu, in which unfamiliar surroundings seem inexplicably familiar. If the abnormal discharge affects the frontal lobe, the person may be unable to speak. If the abnormal discharge affects large areas, it can cause a convulsion (jerking and spasms of muscles, usually throughout the body). Other symptoms include numbness or tingling in a specific body part, brief attacks of altered consciousness (such as drowsiness), loss of consciousness, confusion, and loss of muscle or bladder control.
Symptoms also vary depending on whether the seizure is partial (affecting only one side of the brain) or generalized (affecting large areas on both sides of the brain). Partial seizures may be simple, in which a person is completely conscious and aware of the surroundings, or complex, in which consciousness is impaired but not completely lost. Partial seizures include simple partial seizures, Jacksonian seizures, complex partial seizures, and epilepsia partialis continua. Generalized seizures cause a loss of consciousness and abnormal movements, usually immediately. Loss of consciousness may be brief or prolonged. Generalized seizures include tonic-clonic seizures, primary generalized epilepsy, absence seizures, atonic seizures, myoclonic seizures, and status epilepticus.
About 70% of people have only one type of seizure. The rest have two or more types. For example, some children who have juvenile myoclonic epilepsy also have tonic-clonic seizures and absence seizures in addition to the myoclonic seizures, which usually involve the arms.
In simple partial seizures, electrical discharges begin in a small area of the brain and remain confined to that area. Because only a small area of the brain is affected, symptoms are related to the function controlled by that area. For example, if the small area of the brain that controls the right arm's movements (in the left frontal lobe) is affected, the right arm may begin to shake and jerk. A simple partial seizure may progress to a complex partial seizure.
Jacksonian seizures produce symptoms that start in one part of the body, then spread to another. Abnormal movements may occur in the hand or foot, then "march up" the limb as the electrical activity spreads in the brain. The person is completely aware of what is occurring during the seizure. Thus, Jacksonian seizures are simple partial seizures.
Complex partial (psychomotor) seizures usually begin with an aura that lasts 1 to 2 minutes. During the aura, the person starts to lose touch with the surroundings. During or immediately after the aura, some people stare, move the arms and legs in strange and purposeless ways, utter meaningless sounds, do not understand what other people are saying, and resist help. Other people are able to converse, but their conversation lacks spontaneity, and the content is somewhat sparse. This state may last for several minutes. People may then recover fully. Or, the abnormal electrical discharge may spread to adjacent areas and to the other side of the brain. The result is a generalized seizure, which includes jerking of limbs, frothing at the mouth, and loss of consciousness.
Epilepsia partialis continua is a rare type of continuous or frequently recurring partial seizure, usually affecting a hand or the face. Seizures occur every few seconds or minutes for days to years at a time. These seizures usually result from localized damage (such as scarring due to a stroke) in adults or from inflammation of the brain (such as encephalitis and measles) in children.
Tonic-clonic (grand mal) seizures usually begin with an abnormal electrical discharge in a small area of the brain, resulting in a complex partial seizure. However, the discharge quickly spreads to adjoining parts of the brain, causing the entire area to malfunction. Primary generalized epilepsy begins with abnormal discharges in a large area of the brain. The abnormal discharges quickly spread to even more areas. In tonic-clonic seizures and primary generalized epilepsy, abnormal discharges result in a temporary loss of consciousness and a convulsion, with severe muscle spasms and jerking throughout the body. The head may forcefully turn to one side, the teeth may clench, the tongue is often bitten, and bladder control may be lost. The seizures usually last 1 to 2 minutes. Afterward, the person may have a headache, be temporarily confused, and feel extremely tired. Usually, the person does not remember what happened during the seizure.
Absence (petit mal) seizures begin in childhood, usually between the ages of 5 and 15. They do not produce the convulsions and other dramatic symptoms of tonic-clonic seizures. A person does not fall down, collapse, or move jerkily. Instead, the person has episodes of staring with fluttering eyelids and sometimes twitching facial muscles. The person is completely unaware of the surroundings. These episodes last 2 to 3 seconds and, rarely, 10 to 30 seconds. The person abruptly stops activity and resumes it just as abruptly, experiencing no after-effects and not knowing that a seizure has occurred.
Atonic seizures, which occur primarily in children, are characterized by complete loss of muscle tone and consciousness. They are brief, but they cause the child to collapse to the ground, increasing the risk of injury.
Myoclonic seizures are characterized by quick jerks of one or several limbs or the trunk. The seizures are brief and do not cause loss of consciousness, but they may occur repetitively.
In status epilepticus, the most serious seizure disorder and a medical emergency, the seizure does not stop. Electrical discharges occur throughout the brain. The discharges produce a generalized seizure lasting more than 15 minutes or recurring seizures between which the person does not completely regain consciousness. The person has convulsions with intense muscle contractions and cannot breathe adequately. Without rapid treatment, the heart and brain can become overtaxed and permanently damaged, and the person may die.
Seizures may have serious consequences. Intense, rapid muscle contractions can cause injuries, including broken bones. Sudden loss of consciousness can cause serious injury due to falls and accidents. The turbulent electrical activity of convulsive seizures that recur without recovery between them can cause brain damage. Most people who have a seizure disorder experience dozens or more seizures in their lives without serious brain damage. A single seizure does not impair intelligence, but recurring convulsive seizures may eventually do so.
Diagnosis
People who have at least two unprovoked seizures that occur at different times have a seizure disorder. A diagnosis is made based on the person's history and the observations of eyewitnesses. Seizures may be suspected if symptoms such as loss of consciousness, muscle spasms that shake the body, loss of bladder control, sudden confusion, and an inability to pay attention occur. However, true seizures are much less common than most people think; most episodes of brief unconsciousness are more likely to be fainting (syncope (see Section 3, Chapter 23)).
An eyewitness report of the episode can be very helpful to doctors. An eyewitness can describe exactly what happened, whereas the person who had the episode usually cannot. An accurate description of the circumstances is needed: how fast the episode started; whether it involved abnormal muscle movements (such as spasms of the head, neck, or facial muscles), tongue biting, or loss of bladder control; how long it lasted; and how quickly the person recovered. Doctors also need to know what the person experienced before the episode: whether the person had a premonition or warning that something unusual was about to happen and whether anything, such as certain sounds or flashing lights, seemed to trigger the episode.
To help diagnose a seizure disorder, doctors use electroencephalography (EEG), a painless, safe procedure that records electrical activity in the brain (see Section 6, Chapter 77). Doctors examine the recording (electroencephalogram) for evidence of abnormal electrical discharges. Because abnormal discharges are more likely to occur after too little sleep, EEG is sometimes scheduled after a person has been deprived of sleep for 18 to 24 hours. Even if a seizure did not occur during EEG, abnormalities may be present. Because of the limited recording time, EEG can miss abnormalities and the electroencephalogram may appear normal, even in people who have a seizure disorder.
 See the figure Brain Activity During a Seizure.
Once a seizure disorder is diagnosed, more tests are usually needed to identify the cause. Routine blood tests are performed to measure the levels of sugar, calcium, and sodium in the blood and to determine whether the liver and kidneys are functioning properly. A complete blood count is performed to determine how many white and red blood cells are present. A high white blood cell count may indicate an infection. A low red blood cell count (anemia) may indicate an inadequate supply of oxygen to the brain. Often, electrocardiography (ECG) (see Section 3, Chapter 21) is performed to rule out an abnormal heart rhythm as a possible cause of symptoms. Because an abnormal heart rhythm can reduce blood flow (and therefore the oxygen supply) to the brain, it can trigger seizures and cause loss of consciousness.
Computed tomography (CT) or magnetic resonance imaging (MRI) of the head is usually performed to check for structural damage to brain tissue (for example, by a stroke). Sometimes a spinal tap (lumbar puncture (see Section 6, Chapter 77)) is needed to determine whether the person has an infection of the layers of tissue covering the brain (meningitis) or of the brain (encephalitis).
Treatment
If the cause can be identified and eliminated, no additional treatment is necessary. For example, if low sugar (glucose) levels in the blood (hypoglycemia (see Section 13, Chapter 166)) caused the seizure, glucose is given to increase the levels and the disorder causing the low levels is treated. Other treatable causes include a tumor, an infection, and abnormal sodium levels.
Anticonvulsants may be needed to reduce the risk of having another seizure. Anticonvulsants are not usually prescribed for people who have had only one generalized seizure for which no cause can be found. But they are necessary for people who have had more than one, unless the cause has been identified and completely eliminated.
Anticonvulsants can completely prevent convulsive seizures in more than half of the people who have them and greatly reduce the frequency of seizures in another third. These drugs are only slightly less effective for absence seizures. Half of the people who respond to anticonvulsants can eventually discontinue them without having a relapse. However, for about 10 to 20% of people with a seizure disorder, anticonvulsants do not adequately prevent seizures.
No one drug can control all types of seizures. For most people, seizures can be controlled with a single drug. If seizures recur, different anticonvulsants are tried. Determining which anticonvulsant is effective may take several months. Some people have to take several drugs.
For women who have a seizure disorder and are pregnant, taking an anticonvulsant increases the risk of miscarrying or of having a baby with a birth defect (see Section 22, Chapter 259). However, stopping the anticonvulsant may be more harmful to the woman and the baby.
Because status epilepticus is an emergency, large intravenous doses of one or more anticonvulsants are given as quickly as possible. Measures to prevent injuries are taken during the prolonged seizure.
Anticonvulsants, though very effective, may have side effects. Many cause drowsiness but, paradoxically, sometimes cause hyperactivity in children. Blood tests are performed periodically to determine whether an anticonvulsant is affecting the kidneys, liver, or blood cells. People taking anticonvulsants should be aware of possible side effects and should consult their doctor at the first sign of side effects.
The dose of an anticonvulsant is critical: The best dose of an anticonvulsant is the smallest dose that stops all seizures while causing the fewest side effects. Doctors ask the person about side effects, then adjust the dose if needed. Sometimes doctors also measure the level of anticonvulsant in the blood. Anticonvulsants should be taken just as prescribed. No other drugs should be taken at the same time without the doctor's or pharmacist's authorization because many drugs alter the level of anticonvulsant in the blood. People who take anticonvulsants should see a doctor regularly for dose adjustment and should always wear a Medic Alert bracelet inscribed with the type of seizure disorder and the drug being taken.
Exercise is recommended and social activities are encouraged. However, people who have a seizure disorder may have to make some adjustments. For example, they should not drink alcoholic beverages. They should not engage in activities where a sudden loss of consciousness could result in serious injury: They should not swim alone or operate power tools. In most states, laws prohibit people with a seizure disorder from driving until they have been free of seizures for at least 6 months to 1 year.
A family member or close friend should be trained to help if a seizure occurs. Attempting to put an object (such as a spoon) in the person's mouth to protect the person's tongue should not be tried, because such efforts can do more harm than good. The teeth may be damaged, or the person may bite the helper unintentionally as the jaw muscles contract. The important steps are protecting the person from falling, loosening clothing around the neck, and placing a pillow under the head. People who lose consciousness should be rolled onto one side to ease breathing. People who have had a seizure should not be left alone until they have awakened completely and can move about normally. Usually, their doctor should be notified.
If all drugs are ineffective in controlling seizures or if side effects of the drug cannot be tolerated, brain surgery is a possibility. If a defect in the brain (such as a scar) can be identified as the cause and is confined to a small area, surgically removing that area may eliminate the seizures or reduce their severity and frequency. Surgically cutting the nerve fibers that connect the two sides of the brain (corpus callosum) may help people who have seizures that originate in several areas of the brain or that spread to all parts of the brain very quickly. This procedure usually has no appreciable side effects. After surgery, many people need to continue to take anticonvulsants.
Electrical stimulation of the vagus nerve (cranial nerve X) can reduce the number of partial seizures by one third. The vagus nerve is thought to have indirect connections to areas of the brain often involved in producing seizures. A device that looks like a heart pacemaker is implanted under the left collarbone and is connected to the vagus nerve in the neck with a wire that runs under the skin. The device causes a small bulge under the skin. The operation is performed on an outpatient basis and takes about 1 to 2 hours. When people who have such a device sense that a seizure is about to begin, they turn the device on with a magnet. Or, the device may be left on all the time. For some people, vagus nerve stimulation prevents seizures or reduces their frequency and severity. Vagus nerve stimulation is used in addition to anticonvulsants. Side effects include hoarseness, cough, and deepening of the voice.
 See the drug table Drugs Used to Treat Seizures.
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