Seizure Disorders

In focal-onset seizures, the seizures begin in one side of the brain.

Focal-onset seizures include the following types:

• Automatisms (coordinated, purposeless, repetitive motor activity)

• Atonic (involving loss of muscle tone)

• Clonic (involving rhythmic jerking of muscles)

• Epileptic spasms (involving bending and straightening the arms and bending the upper body forward) in children

• Hyperkinetic (involving moving the legs as if pedaling a bicycle or thrashing)

• Myoclonic (involving sudden, lightning-like jerking of muscles)

• Tonic (involving stiffening of muscles of one limb or one side of the body)

Some people who have a focal-onset seizure recover fully. In others, the abnormal electrical discharge spreads to adjacent areas and to the other side of the brain, resulting in a generalized seizure. Generalized seizures that result from focal seizures are called focal-to-bilateral seizures. That is, they start in one side of the brain and spread to both sides.

Focal-onset seizures are classified based on whether the person is aware during the seizure:

• Awareness is maintained (called focal aware seizures).

• Awareness is impaired (called focal impaired-awareness seizures).

Awareness refers to knowledge of self and environment. If awareness is impaired during any part of the seizure, the seizure is considered a focal impaired-awareness seizure. Doctors determine whether people remained aware during a seizure by asking them or, if a seizure is occurring, seeing whether they respond when spoken to.

In focal aware seizures, abnormal 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 involuntarily be lifted up and jerk, and the head may turn toward the lifted arm. People are completely conscious and aware of the surroundings. A focal aware seizure may progress to a focal impaired-awareness seizure.

Jacksonian seizures are a type of focal aware seizures. Symptoms start in one hand or foot, then move up the limb as the electrical activity spreads in the brain. People are completely aware of what is occurring during the seizure.

Other focal aware seizures affect the face, then spread to an arm or sometimes a leg.

Epilepsia partialis continua is rare. In this type of seizure, focal seizures occur every few seconds or minutes for days to years at a time. They typically affect an arm, a hand, one side of the face, or one side of the body. People with epilepsia partialis continua remain aware. These seizures usually result from

• In adults: Brain damage (such as scarring due to a stroke) in one area of the brain

• In children: Inflammation of the brain (as occurs in encephalitis and measles)

In focal impaired-awareness seizures, abnormal electrical discharges begin in a small area of the temporal lobe or frontal lobe and quickly spread to other nearby areas. The seizures usually begin with an aura, which lasts 1 to 2 minutes. During the aura, people start to lose touch with the surroundings.

During focal impaired-awareness seizures, awareness becomes impaired, but people do not become unconscious. People may do the following:

• Stare

• Chew or smack the lips involuntarily

• Move the hands, arms, and legs in strange, purposeless ways

• Utter meaningless sounds

• Not understand what other people are saying

• Resist help

Some people can converse, but their conversation lacks spontaneity, and the content is somewhat sparse. They may be confused and disoriented. This state may last for several minutes. Occasionally, people lash out if they are restrained.

In generalized-onset seizures, the seizure begins in both sides of the brain. Most generalized-onset seizures impair awareness. They often cause loss of consciousness and abnormal movements, usually immediately. Loss of consciousness may be brief or last a long time.

Generalized-onset seizures include the following types:

• Tonic-clonic seizures (formerly, called grand mal seizures)

• Clonic seizures (involving sustained rhythmic jerking of muscles after muscles stiffen)

• Tonic seizures (involving stiffening of muscles in all limbs)

• Atonic seizures (involving loss of muscle tone)

• Myoclonic seizures (involving rhythmic jerking of muscles not preceded by stiffening of muscles)

• Myoclonic-tonic-clonic seizures (involving jerking of muscles followed by muscle stiffening and repeated jerking of muscles), including juvenile myoclonic epilepsy

• Myoclonic-atonic seizures (involving jerking of muscles, followed by loss of muscle tone)

• Epileptic (infantile) spasms

• Absence seizures

Most types of generalized seizures (such as tonic-clonic seizures) involve abnormal muscle contractions. Those that do not are called absence seizures.

Generalized-onset seizures begin with abnormal discharges in a deep, central part of the brain and spread simultaneously to both sides of the brain. There is no aura. The seizure typically begins with an outcry. People then become unaware or lose consciousness.

During generalized-onset seizures, particularly generalized tonic-clonic seizures, people may do the following:

• Have severe muscle spasms and jerking throughout the body as muscles rapidly and repeatedly contract and relax

• Fall down

• Clench their teeth

• Bite their tongue (often occurs)

• Drool or froth at the mouth

• Lose control of the bladder and/or bowels

The seizures usually last 1 to 2 minutes. Afterward, some people have a headache, are temporarily confused, and feel extremely tired. These symptoms may last from minutes to hours. Most people do not remember what happened during the seizure.

In generalized tonic-clonic seizures, muscles contract (the tonic part), then rapidly alternate between contracting and relaxing (the clonic part). These seizures may be

• Generalized-onset (starting in both sides of the brain)

• Focal to bilateral (starting in one side of the brain and spreading to both sides)

In both types, consciousness is temporarily lost and a convulsion occurs when the abnormal discharges spread to both sides of the brain.

Focal-to-bilateral tonic-clonic (grand mal) seizures usually begin with an abnormal electrical discharge in a small area of one side of the brain, resulting in a focal aware or focal impaired-awareness seizure. The discharge then quickly spreads to both sides of the brain, causing the entire brain to malfunction. Symptoms are similar to those of generalized-onset seizures.

Atonic seizures occur primarily in children. They are characterized by a brief but complete loss of muscle tone and consciousness. They cause children to fall to the ground, sometimes resulting in injury.

In clonic seizures, the limbs on both sides of the body and often head, neck, face, and trunk jerk rhythmically throughout the seizure. Clonic seizures usually occur in infants. They are much less common than tonic-clonic seizures.

Tonic seizures occur commonly during sleep, usually in children. Muscle tone increases abruptly or gradually, causing muscles to stiffen. The limbs and neck are often affected. Tonic seizures typically last only 10 to 15 seconds but can cause people, if standing, to fall to the ground. Most people do not lose consciousness. If seizures last longer, muscles may jerk a few times as the seizure ends.

Atypical absence seizures (see below), atonic seizures, and tonic seizures usually occur as part of a severe form of epilepsy called Lennox-Gastaut syndrome, which begins before children are 4 years old.

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 and may progress to a tonic-clonic seizure with loss of consciousness.

In myoclonic-atonic seizures, the limbs or trunk jerks briefly, then goes limp (drop attack). Seizures usually begin between the ages of 6 months to 6 years. Before the first myoclonic-atonic seizure, two thirds of children have febrile seizures and generalized-onset convulsive seizures. Development and mental processes are typically normal, but during or after the seizure, development and thinking may be impaired.

Juvenile myoclonic epilepsy typically begins during adolescence. Typically, seizures begin with quick jerks of both arms. About 90% of these seizures are followed by generalized tonic-clonic seizures. Some people also have absence seizures. The seizures often occur when people awaken in the morning, especially if they are sleep-deprived. Drinking alcohol also makes these seizures more likely.

Absence seizures do not involve abnormal muscle contraction. They may be classified as

• Typical (formerly called petit mal)

• Atypical

Typical absence seizures usually begin in childhood, usually between the ages of 5 and 15 years, and do not continue into adulthood. However, adults occasionally have typical absence seizures. Unlike tonic-clonic seizures, absence seizures do not cause convulsions or other dramatic symptoms. People do not fall down, collapse, or move jerkily. Instead, they have episodes of staring with fluttering eyelids and sometimes twitching facial muscles. They typically lose consciousness, becoming completely unaware of their surroundings. These episodes last 10 to 30 seconds. People abruptly stop what they are doing and resume it just as abruptly. They experience no after-effects and do not know that a seizure has occurred. Without treatment, many people have several seizures a day. Seizures often occur when people are sitting quietly. Seizures rarely occur during exercise. Hyperventilation can trigger a seizure.

Atypical absence seizures differ from typical absence seizures as follows:

• They are less common.

• They last longer.

• Jerking and other movements are more pronounced.

• People are more aware of their surroundings.

Most people with atypical absence seizures have neurologic abnormalities or developmental delays. Atypical absence seizures usually continue into adulthood.

Dravet syndrome (severe myoclonic epilepsy of infancy) develops during early childhood. It has focal and generalized characteristics. During the first year of life, focal seizures are typically triggered by fever. At about age 2 years, children tend to have generalized myoclonic seizures. In these seizures, the trunk or one or several limbs jerk. Children with Dravet syndrome may also develop atypical absence, clonic, atonic, or tonic-clonic seizures.

During the second year of life, children no longer develop as expected and may lose the developmental skills they have achieved. Children have difficulty thinking and learning and lack coordination and balance.

In about 70 to 80% of children with Dravet syndrome, the cause is an abnormal gene known to cause seizures.

Convulsive status epilepticus is the most serious seizure disorder and is considered a medical emergency because the seizure does not stop. Electrical discharges occur throughout the brain, causing a generalized tonic-clonic seizure.

Convulsive status epilepticus is diagnosed when one or both of the following occur:

• A seizure lasts more than 5 minutes

• People do not completely regain consciousness between two or more seizures

People have convulsions with intense muscle contractions and often cannot breathe adequately. Body temperature increases. Without rapid treatment, the heart and brain can become overtaxed and permanently damaged, sometimes resulting in death.

Generalized convulsive status epilepticus has many causes, including injuring the head and abruptly stopping an antiseizure medication.

Nonconvulsive status epilepticus, another type of status epilepticus, does not cause convulsions. The seizures last 10 minutes or more. During the seizure, mental processes (including awareness) and/or behavior are affected. People may appear confused or spaced out. They may be unable to speak and may behave irrationally. Having nonconvulsive status epilepticus increases the risk of developing convulsive status epilepticus. This type of seizure requires prompt diagnosis and treatment.

When a seizure stops, people 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 after a seizure, and the weakness lasts longer than the seizure (a disorder called Todd paralysis).

Most people do not remember what happened during the seizure (a condition called postictal amnesia).

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. People may have numerous seizures without incurring serious brain damage. However, seizures that recur and cause convulsions may eventually impair intelligence.

If seizures are not well-controlled, people may be unable to get a driver’s license. They may have difficulty keeping a job or getting insurance. They may be socially stigmatized. As a result, their quality of life may be substantially reduced.

If seizures are not completely controlled, people are two to three times more likely to die than those who do not have seizures.

A few people die suddenly for no apparent reason—a complication called sudden unexpected death in epilepsy. This disorder usually occurs at night or during sleep. Risk is highest for people who have frequent seizures, especially generalized tonic-clonic seizures.

An eyewitness report of the episode can be very helpful to doctors. An eyewitness can describe exactly what happened, whereas people who have an episode usually cannot. Doctors need to have an accurate description, including the following:

• How fast the episode started

• Whether it involved abnormal muscle movements (such as spasms of the head, neck, or facial muscles), tongue biting, drooling, loss of bladder or bowel control, or muscle stiffening

• How long it lasted

• How quickly the person recovered

A quick recovery suggests fainting rather than a seizure. Confusion that lasts for many minutes to hours after consciousness is regained suggests a seizure.

Although eyewitnesses may be too frightened during the seizure to remember all details, whatever they can remember can help. If possible, how long a seizure lasts should be timed with a watch or other device. Seizures that last only 1 or 2 minutes can seem to go on forever.

Doctors also need to know what people experienced before the episode: whether they 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.

Doctors ask people about possible causes of seizures, such as the following:

• Whether people have had a disorder that can cause seizures (such as a brain infection) or a head injury

• Which medications or illicit drugs they are using or have recently stopped

• Whether they are consuming alcohol or have recently stopped

• For people who are taking medications to control seizures, whether they are taking the medications as directed

• Whether they are getting enough sleep (not getting enough sleep can make seizures more likely to occur in some people)

• With children, whether they have relatives who also have seizures

A thorough physical examination is done. It may provide clues to the cause of the symptoms.

Once a seizure is diagnosed, more tests are usually needed to identify the cause.

People known to have a seizure disorder may not need tests, except for a blood test to measure the levels of the antiseizure medications they are taking. However, if they have symptoms that suggest a disorder that can be treated (such as a head injury or an infection), more tests are done.

Blood tests are often done to check for possible causes of a seizure or to find out why a seizure may have occurred in someone with a known seizure disorder. These tests include measurement of the levels of substances such as sugar, calcium, sodium, and magnesium and tests to determine whether the liver and kidneys are functioning normally. A sample of urine may be analyzed to check for illicit drugs that may not be reported. Such drugs can trigger a seizure.

Electrocardiography may be done to check for an abnormal heart rhythm. Because an abnormal heart rhythm can greatly reduce blood flow (and therefore oxygen supply) to the brain, it can trigger loss of consciousness and occasionally a seizure or symptoms that resemble a seizure.

Imaging of the brain is usually done promptly to check for bleeding or a stroke. Typically, computed tomography (CT) is done, but magnetic resonance imaging (MRI) may be done. Both tests can identify brain abnormalities that could be causing seizures. MRI provides clearer, more detailed images of the brain tissue, but it is not always readily available.

If doctors suspect a brain infection such as meningitis or encephalitis, a spinal tap (lumbar puncture) is usually done.

Electroencephalography (EEG) can help confirm the diagnosis. EEG is a painless, safe procedure that records electrical activity in the brain. Doctors examine the recording (electroencephalogram) for evidence of abnormal electrical discharges. Because the recording time is limited, EEG can miss abnormalities, and results may be normal, even in people who have a seizure disorder. EEG is sometimes scheduled after people have been deprived of sleep for 18 to 24 hours because lack of sleep makes abnormal discharges more likely to occur.

Brain Activity During a Seizure

An electroencephalogram (an EEG) is a recording of the brain’s electrical activity. The procedure is simple and painless. About 20 small adhesive electrodes are placed on the scalp, and the brain’s activity is recorded under normal conditions. Then the person is exposed to various stimuli, such as bright or flashing lights, to try to provoke a seizure. During a seizure, electrical activity in the brain accelerates, producing a jagged wave pattern. Such recordings of brain waves help identify a seizure disorder. Different types of seizures have different wave patterns.

EEG may be repeated because when done a second or even a third time, it may detect seizure activity and sometimes help identify the type of seizure. This information may have been missed the first time the test was done.

If the diagnosis is still uncertain, specialized tests, such as video-EEG monitoring, can be done at an epilepsy center.

For video-EEG monitoring, people are admitted to a hospital for 2 to 7 days, and EEG is done while they are video-taped. If people are taking an antiseizure medication, it is often stopped to increase the likelihood of a seizure. If a seizure occurs, doctors compare the EEG recording with the video recording of the seizure. They may then be able to identify the type of seizure and the area of the brain where the seizure began.

Ambulatory EEG enables doctors to record brain activity for days at a time—while people are at home. It may be useful if seizures recur in people who cannot be admitted to the hospital for a long time.

Exercise is usually recommended and social activities are encouraged. However, people who have a seizure disorder may have to make some adjustments. For example, they may be advised to do the following:

• Eliminate or limit their consumption of alcoholic beverages

• Not use illicit drugs

• Refrain from activities in which a sudden loss of consciousness could result in serious injury, such as bathing in a bathtub, climbing, swimming, or operating power tools

After seizures are controlled (typically for at least 6 months), they can do these activities if adequate precautions are taken. For example, they should swim only when lifeguards are present.

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 and coworkers 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. 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. However, helpers should do the following during a seizure:

• Protect the person from falling

• Loosen clothing around the neck

• Place a pillow under the head

• Roll the person over to one side

If a pillow is unavailable, helpers can put their foot or place an item of clothing under the person’s head.

People who lose consciousness should be rolled onto one side to ease breathing and help prevent them from inhaling vomit or saliva. Inhaling vomit or saliva can lead to aspiration pneumonia (a lung infection caused by inhaling saliva, stomach contents, or both).

People who have had a seizure should not be left alone until they have awakened completely, are no longer confused, and can move about normally. Usually, their doctor should be notified.

Antiseizure medications (also called anticonvulsants or antiepileptic medications) reduce the risk of having another seizure. Usually, they are prescribed only if people have had more than one seizure and if reversible causes, such as low blood sugar, have been ruled out or completely corrected. Antiseizure medications are usually not prescribed when people have had only one generalized seizure.

Most antiseizure medications are taken by mouth.

Antiseizure medications can completely stop seizures in about one third of people who have them and greatly reduce the frequency of seizures in another third. Almost two thirds of people who respond to antiseizure medications can eventually stop taking them without having a relapse. However, if antiseizure medications are ineffective, people are referred to a seizure center and evaluated for surgery.

There are many different types of antiseizure medications. Which one is effective depends on the type of seizure and other factors. For most people, taking one antiseizure medication, usually the first or second one tried, controls seizures. If seizures recur, different antiseizure medications are tried. In such cases, determining which medication is effective may take several months. Some people have to take several medications, which increases the risk of side effects. Some antiseizure medications are not used alone but only with other antiseizure medications.

Doctors take care to determine the appropriate dose for each person. The best dose is the smallest dose that stops all seizures while having the fewest side effects. Doctors ask people about side effects, then adjust the dose if needed. Sometimes doctors also measure the level of antiseizure medication in the blood.

Antiseizure medications should be taken just as prescribed. People who take medications to control seizures should see a doctor regularly for dose adjustment and should always wear a medical alert bracelet inscribed with the type of seizure disorder and the medication being taken.

Antiseizure medications can interfere with the effectiveness of other medications, and vice versa. Consequently, people should make sure their doctor knows all the medications, supplements, and illicit drugs they are taking before they start taking antiseizure medications. They should also talk to their doctor and possibly their pharmacist before they start taking any other medications, including over-the-counter medications.

After seizures are controlled, people take the antiseizure medication until they have been seizure-free for at least 2 years. Then, the dose of the medication may be decreased gradually, and the medication eventually stopped. If a seizure recurs after the antiseizure medication is stopped, people may have to take an antiseizure medication indefinitely. Seizures usually recur within 2 years if they are going to.

Seizures are more likely to recur in people who have had any of the following:

• A seizure disorder since childhood

• The need to take more than one antiseizure medication to be seizure-free

• Seizures while taking an antiseizure medication

• Focal seizures or myoclonic seizures

• Abnormal EEG results within the previous year

• Structural damage to the brain—for example, by a stroke or tumor

Antiseizure medications, although very effective, may have side effects. Many cause drowsiness, but some may make children hyperactive. For many antiseizure medications, blood tests are done periodically to determine whether the medication is impairing kidney or liver function or reducing the number of blood cells.

osteoporosis.

People taking antiseizure medications should be aware of possible side effects and should consult their doctor at the first sign of side effects.

For women who have a seizure disorder and are pregnant, taking an antiseizure medication increases the risk of miscarrying or of having a baby with a birth defect of the spinal cord, spine, or brain (neural tube defect—see table Some Medications That Can Cause Problems During Pregnancy). However, stopping the antiseizure medication may be more harmful to the woman and the baby. Having a generalized seizure during pregnancy can injure or kill the fetus. Consequently, continuing to take an antiseizure medication is usually recommended (see Seizure Disorders During Pregnancy). All women who are of childbearing age and taking an antiseizure medication should take folate supplements to reduce the risk of having a baby with a birth defect.

Emergency treatment to stop the seizures is required for

• Status epilepticus (seizures that last more than 5 minutes)

Measures to prevent injuries are taken during the prolonged seizure. People are monitored closely to make sure breathing is adequate. If it is not, a tube is inserted to help with breathing—a procedure called intubation.

If seizures persist, a general anesthetic is given to stop them.

If people continue to have seizures while taking two or more antiseizure medications or if they cannot tolerate side effects of the medications, brain surgery may be done. These people are tested at specialized epilepsy centers to determine whether surgery can help. Testing may include MRI of the brain, video-EEG monitoring, and the following:

• Functional MRI: To determine which areas in the brain are causing seizures (called seizure foci)

• Single-photon emission CT (SPECT): To check for areas with increased blood flow around the time of a seizure, which may indicate which areas in the brain are causing seizures

• EEG combined with magnets used for imaging (magnetic source imaging): Also to help determine which areas in the brain are causing seizures

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 can eliminate seizures in up to 60% of people, or surgery may reduce the severity and frequency of seizures.

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. However, even if surgery reduces the frequency and severity of seizures, many people need to continue to take antiseizure medications. However, they can usually take lower doses or fewer medications.

Before and after surgery, a psychologic and neurologic evaluation may be done to determine how well the brain is functioning.

If people cannot undergo these surgical procedures, other procedures, such as stimulation of the vagus nerve or brain, may be done.

Electrical stimulation of the 10th cranial nerve (vagus nerve) can reduce the number of focal-onset seizures by more than one half in about 40% of people who have focal-onset seizures. This treatment is used when seizures continue despite use of antiseizure medications and when surgery is not a possibility.

The vagus nerve is thought to have indirect connections to areas of the brain often involved in causing seizures.

For this procedure, a device that looks like a heart pacemaker (vagus nerve stimulator) 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 done on an outpatient basis and takes about 1 to 2 hours.

The device is programmed to periodically stimulate the vagus nerve. Also, people are given a magnet, which they can use to stimulate the vagus nerve when they sense that a seizure is about to begin. Vagus nerve stimulation is used in addition to antiseizure medications.

Side effects of vagal nerve stimulation include hoarseness, cough, and deepening of the voice when the nerve is stimulated.

The responsive neurostimulation system is a device that looks like a heart pacemaker. It is implanted within the skull. The device is connected by wires to one or two areas in the brain that are causing the seizures. This system monitors the brain's electrical activity. When it detects unusual electrical activity, it stimulates the areas of the brain that are causing the seizures. The aim is to restore normal electrical activity in the brain before a seizure can occur.

The responsive neurostimulation system is used in addition to antiseizure medications. It is used when adults have focal-onset seizures that are not controlled by medications. It can reduce the frequency of seizures in these people.

Surgery to implant the system requires general anesthesia and typically takes 2 to 4 hours. Many people can go home the next day. Some need to stay in the hospital for up to 3 days. Many people can return to their daily activities within a few days and return to work in 2 to 4 weeks.

People cannot feel the device or the stimulation, and the device can be removed if needed.