Many people have unusual sensations just before a seizure starts.
Some seizures cause uncontrollable shaking and loss of consciousness, but sometimes people simply stop moving or become unaware of what is happening.
Doctors suspect the diagnosis based on symptoms, but imaging of the brain, blood tests, and electroencephalography (to record the brain’s electrical activity) are usually needed to identify the cause.
If needed, drugs can usually help prevent seizures.
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. Seizures may result when the brain’s electrical activity is disrupted.
About 2% of adults have a seizure at some time during their life. Two thirds of these people never have another one. Seizure disorders commonly begin in early childhood or in late adulthood.
Types of seizures
Seizures may be described as follows:
Epileptic: These seizures have no apparent trigger (that is, they are unprovoked), and they occur two or more times. One seizure is not considered epilepsy. Epileptic seizures are called a seizure disorder or epilepsy. What causes epileptic seizures is often unknown (called idiopathic epilepsy). But they may be caused by various brain disorders, such as structural abnormalities, strokes Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction) and symptoms that... read more , or tumors Overview of Brain Tumors A brain tumor can be a noncancerous (benign) or cancerous (malignant) growth in the brain. It may originate in the brain or have spread (metastasized) to the brain from another part of the body... read more . In such cases, they are called symptomatic epilepsy. Symptomatic epilepsy is most common among newborns Infantile Spasms In infantile spasms, children suddenly raise and bend their arms, bend their neck and upper body forward, and straighten their legs. The spasms are usually caused by serious brain disorders... read more and older people.
Nonepileptic: These seizures are triggered (provoked) by a reversible disorder or a temporary condition that irritates the brain, such as an infection, a head injury, or a reaction to a drug. In children, a fever can trigger a nonepileptic seizure (called a febrile seizure Febrile Seizures Febrile seizures are seizures triggered by a fever of at least 100.4° F (about 38° C). Most febrile seizures are harmless and caused by fever from a minor infection. Less often, a febrile seizure... read more ).
Certain mental disorders can cause symptoms that resemble seizures, called psychogenic nonepileptic seizures or pseudoseizures.
Causes of Seizure Disorders
Which causes are most common depend on when seizures start:
Before age 2: High fevers or temporary metabolic abnormalities, such as an abnormal blood level of sugar (glucose), calcium, magnesium, vitamin B6, or sodium, can trigger one or more seizures. Seizures do not occur once the fever or abnormality resolves. If the seizures recur without such triggers, the cause is likely to be an injury during birth Birth Injuries in Newborns Birth injury is damage that occurs as a result of physical pressure during the birthing process, usually during transit through the birth canal. Many newborns have minor injuries during birth... read more , a birth defect Overview of Brain and Spinal Cord Birth Defects Birth defects of the brain and spinal cord can occur in early or late fetal development. Typical symptoms include intellectual disability, paralysis, incontinence, or loss of sensation in some... read more , or a hereditary metabolic abnormality Overview of Hereditary Metabolic Disorders Hereditary metabolic disorders are inherited genetic conditions that cause metabolism problems. Heredity is the passing of genes from one generation to the next. Children inherit their parents'... read more or brain disorder.
2 to 14 years: Often, the cause is unknown (see also Seizures in Children Seizures in Children Seizures are a periodic disturbance of the brain’s electrical activity, resulting in some degree of temporary brain dysfunction. When older infants or young children have seizures, they often... read more ).
Adults: A head injury Overview of Head Injuries Head injuries that involve the brain are particularly concerning. Common causes of head injuries include falls, motor vehicle crashes, assaults, and mishaps during sports and recreational activities... read more , stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction) and symptoms that... read more , or tumor Overview of Brain Tumors A brain tumor can be a noncancerous (benign) or cancerous (malignant) growth in the brain. It may originate in the brain or have spread (metastasized) to the brain from another part of the body... read more may damage the brain, causing a seizure. Alcohol withdrawal Withdrawal symptoms Alcohol (ethanol) is a depressant. Consuming large amounts rapidly or regularly can cause health problems, including organ damage, coma, and death. Genetics and personal characteristics may... read more (caused by suddenly stopping drinking) is a common cause of seizures. However, in about half of people in this age group, the cause is unknown.
Older adults: The cause may be a brain tumor or stroke.
Seizures with no identifiable cause are called idiopathic.
Conditions that irritate the brain—such as injuries, certain drugs, sleep deprivation, infections, fever—or that deprive the brain of oxygen or fuel—such as abnormal heart rhythms Overview of Abnormal Heart Rhythms Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more , a low level of oxygen in the blood, or a very low level of sugar in the blood (hypoglycemia Hypoglycemia Hypoglycemia is abnormally low levels of sugar (glucose) in the blood. Hypoglycemia is most often caused by drugs taken to control diabetes. Much less common causes of hypoglycemia include other... read more )—can trigger a single seizure whether a person has a seizure disorder or not. A seizure that results from such a stimulus is called a provoked seizure (and thus is a nonepileptic seizure).
People with a seizure disorder are more likely to have a seizure when the following occur:
They are under excess physical or emotional stress.
They are intoxicated or deprived of sleep.
They have suddenly stopped drinking or using sedatives.
Avoiding these conditions can help prevent seizures.
Rarely, seizures are triggered by repetitive sounds, flashing lights, video games, or even touching certain parts of the body. In such cases, the disorder is called reflex epilepsy.
Symptoms of Seizure Disorders
An aura (unusual sensations) describes how a person feels before a seizure starts. Usually, it is part of a focal aware seizure Focal-onset seizures In seizure disorders, the brain's electrical activity is periodically disturbed, resulting in some degree of temporary brain dysfunction. Many people have unusual sensations just before a seizure... read more that is just starting. An aura may include any of the following:
Abnormal smells or tastes
Butterflies in the stomach
Feeling as if something has been experienced before even though it has not (called déjà vu) or the opposite feeling—something seems unfamiliar even though it is familiar in some way (called jamais vu)
An intense feeling that a seizure is about to begin
Almost all seizures are relatively brief, lasting from a few seconds to a few minutes. Most seizures last 1 to 2 minutes.
Occasionally, seizures recur repeatedly, as occurs in status epilepticus.
Most people who have a seizure disorder look and behave normally between seizures.
Symptoms of seizures vary depending on which area of the brain is affected Brain Dysfunction by Location Because different areas of the brain control specific functions, the location of brain damage determines the type of dysfunction that results. Which side of the brain is affected is also important... read more by the abnormal electrical discharge, as in the following:
An intensely pleasant or unpleasant taste if the part of the cerebrum called the insula is affected
Visual hallucinations (seeing unformed images) if the occipital lobe is affected
Inability to speak if the area that controls speech (located in the frontal lobe) is affected
A convulsion (jerking and spasms of muscles throughout the body) if large areas on both sides of the brain are affected
Seizures may be classified as
Motor: Involving abnormal muscle contractions (such as jerking of a limb or convulsions)
Nonmotor: Not involving abnormal muscle contractions
Other possible symptoms include numbness or tingling in a specific body part, brief episodes of unresponsiveness, loss of consciousness, and confusion. People may vomit if they lose consciousness. People may lose control of their muscles, bladder, or bowels. Some people bite their tongue.
Symptoms also vary depending on whether the seizure is
Focal-onset (the seizure begins in one side of the brain)
Generalized-onset (the seizure begins in both sides of the brain)
There are several types of focal and generalized seizures. Most people have only one type of seizure. Others have two or more types.
Some types of seizures may be focal or generalized.
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)
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 Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction) and symptoms that... read more ) in one area of the brain
In children: Inflammation of the brain (as occurs in encephalitis Encephalitis Encephalitis is inflammation of the brain that occurs when a virus directly infects the brain or when a virus, vaccine, or something else triggers inflammation. The spinal cord may also be involved... read more and measles Measles Measles is a highly contagious viral infection that causes various cold-like symptoms and a characteristic rash. Measles is caused by a virus. Symptoms include fever, runny nose, hacking cough... read more )
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:
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
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)
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
Most types of generalized seizures (such as tonic-clonic seizures) involve abnormal muscle contractions. Those that do not are called absence seizures.
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.
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, people may do the following:
Have severe muscle spasms and jerking throughout the body as muscles rapidly and repeatedly contract and relax
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.
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)
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 drug.
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.
Symptoms after a seizure
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.
Did You Know...
Diagnosis of Seizure Disorders
A doctor's evaluation
If the person has never had a seizure before, blood and other tests, imaging of the brain, and usually electroencephalography
If a seizure disorder has already been diagnosed, usually blood tests to measure levels of antiseizure drugs
The diagnosis of a seizure is based on symptoms and the observations of eyewitnesses. Symptoms that suggest a seizure include loss of consciousness, muscle spasms that shake the body, a bitten tongue, loss of bladder control, sudden confusion, and inability to pay attention. Doctors diagnose a seizure disorder (epilepsy) when people have at least two unprovoked seizures that occur at different times.
People who lose consciousness, sometimes even when they lose muscle tone and muscles jerk, may not be having a seizure. A brief loss of consciousness is more likely to be fainting Fainting Light-headedness (near syncope) is a sense that one is about to faint. Fainting (syncope) is a sudden, brief loss of consciousness during which the person falls to the ground or slumps in a... read more (syncope) than a seizure.
People are usually evaluated in an emergency department. If a seizure disorder has already been diagnosed and people have completely recovered, they may be evaluated in a doctor’s office.
History and physical examination
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 Overview of Brain Infections Infections of the brain can be caused by viruses, bacteria, fungi, or, occasionally, protozoa or parasites. Another group of brain disorders, called spongiform encephalopathies, are caused by... read more ) or a head injury Overview of Head Injuries Head injuries that involve the brain are particularly concerning. Common causes of head injuries include falls, motor vehicle crashes, assaults, and mishaps during sports and recreational activities... read more
Which drugs (including alcohol) they are taking or have recently stopped
For people who are taking drugs to control seizures, whether they are taking the drugs 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 drugs 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 recreational drugs that may not be reported. Such drugs can trigger a seizure.
Electrocardiography Electrocardiography Electrocardiography (ECG) is a quick, simple, painless procedure in which the heart’s electrical impulses are amplified and recorded. This record, the electrocardiogram (also known as an ECG)... read more may be done to check for an abnormal heart rhythm Overview of Abnormal Heart Rhythms Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more . 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 Intracerebral Hemorrhage An intracerebral hemorrhage is bleeding within the brain. Intracerebral hemorrhage usually results from chronic high blood pressure. The first symptom is often a severe headache. Diagnosis is... read more or a stroke Ischemic Stroke An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery. Ischemic stroke... read more . 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 Spinal Tap Spinal fluid is a liquid that surrounds your brain and spinal cord. Spinal fluid helps cushion your brain if you hit your head or fall. Spinal fluid moves freely around your brain and spinal... read more (lumbar puncture) is usually done.
Electroencephalography Electroencephalography Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography (EEG) is a simple, painless procedure in which... read more (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 drug, 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.
Prognosis of Seizure Disorders
With treatment, one third of people with epilepsy are free from seizures, and most become seizure-free shortly after starting treatment. In another third, seizures recur less than half as often as they did before treatment. If seizures are well-controlled with drugs, about 60 to 70% of people can eventually stop taking antiseizure drugs and remain seizure-free.
Epileptic seizures are considered resolved when people have been seizure-free for 10 years and have not taken antiseizure drugs for the last 5 years of that time period.
Treatment of Seizure Disorders
Elimination of the cause if possible
Drugs to control seizures
Sometimes surgery or other procedures if drugs are ineffective
If the cause of the seizures can be identified and eliminated, no additional treatment is necessary. For example, if a low blood sugar (glucose) level (hypoglycemia Hypoglycemia Hypoglycemia is abnormally low levels of sugar (glucose) in the blood. Hypoglycemia is most often caused by drugs taken to control diabetes. Much less common causes of hypoglycemia include other... read more ) caused the seizure, glucose is given, and the disorder causing the low level is treated. Other treatable causes include an infection, certain tumors, and an abnormal sodium level.
If the cause cannot be eliminated, general measures plus drugs are usually sufficient to treat seizure disorders. If drugs are ineffective, surgery may be recommended.
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 recreational 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 Aspiration Pneumonia and Chemical Pneumonitis Aspiration pneumonia is lung infection caused by inhaling mouth secretions, stomach contents, or both. Chemical pneumonitis is lung irritation caused by inhalation of substances irritating or... read more (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 drugs (also called anticonvulsants or antiepileptic drugs) 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 drugs are usually not prescribed when people have had only one generalized seizure.
Most antiseizure drugs are taken by mouth.
Antiseizure drugs 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 drugs can eventually stop taking them without having a relapse. However, if antiseizure drugs are ineffective, people are referred to a seizure center and evaluated for surgery.
There are many different types of antiseizure drugs. Which one is effective depends on the type of seizure and other factors. For most people, taking one antiseizure drug, usually the first or second one tried, controls seizures. If seizures recur, different antiseizure drugs are tried. In such cases, determining which drug is effective may take several months. Some people have to take several drugs, which increases the risk of side effects. Some antiseizure drugs are not used alone but only with other antiseizure drugs.
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 drug in the blood.
Antiseizure drugs should be taken just as prescribed. People who take drugs 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 drug being taken.
Antiseizure drugs can interfere with the effectiveness of other drugs, and vice versa. Consequently, people should make sure their doctor knows all the drugs they are taking before they start taking antiseizure drugs. They should also talk to their doctor and possibly their pharmacist before they start taking any other drugs, including over-the-counter drugs.
After seizures are controlled, people take the antiseizure drug until they have been seizure-free for at least 2 years. Then, the dose of the drug may be decreased gradually, and the drug eventually stopped. If a seizure recurs after the antiseizure drug is stopped, people may have to take an antiseizure drug 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 drug to be seizure-free
Seizures while taking an antiseizure drug
Focal seizures Focal-onset seizures In seizure disorders, the brain's electrical activity is periodically disturbed, resulting in some degree of temporary brain dysfunction. Many people have unusual sensations just before a seizure... read more or myoclonic seizures Generalized-onset seizures In seizure disorders, the brain's electrical activity is periodically disturbed, resulting in some degree of temporary brain dysfunction. Many people have unusual sensations just before a seizure... read more
Abnormal EEG results within the previous year
Structural damage to the brain—for example, by a stroke or tumor
Antiseizure drugs, although very effective, may have side effects. Many cause drowsiness, but some may make children hyperactive. For many antiseizure drugs, blood tests are done periodically to determine whether the drug is impairing kidney or liver function or reducing the number of blood cells. People taking antiseizure drugs 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 drug increases the risk of miscarrying or of having a baby with a birth defect of the spinal cord, spine, or brain (neural tube defect Neural Tube Defects and Spina Bifida Neural tube defects are a certain type of birth defect of the brain, spine, and/or spinal cord. Neural tube defects can result in nerve damage, learning disabilities, paralysis, and death. The... read more —see table Some Drugs That Can Cause Problems During Pregnancy Some Drugs That Can Cause Problems During Pregnancy* More than 50% of pregnant women take prescription or nonprescription (over-the-counter) drugs or use social drugs (such as tobacco and alcohol) or illicit drugs at some time during pregnancy... read more ). However, stopping the antiseizure drug 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 drug is usually recommended (see Seizure Disorders During Pregnancy Seizure Disorders During Pregnancy Most women who have a seizure disorder that is well-controlled by antiseizure drugs are able to safely give birth to a healthy baby. If these women get enough sleep and take antiseizure drugs... read more ). All women who are of childbearing age and taking an antiseizure drug should take folate supplements to reduce the risk of having a baby with a birth defect.
Did You Know...
Emergency treatment to stop the seizures is required for
Seizures that last more than 5 minutes
Large doses of one or more antiseizure drugs (often starting with a benzodiazepine, such as lorazepam) are given intravenously as quickly as possible to stop the seizure. The sooner antiseizure drugs are started, the better and the more easily seizures are controlled.
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 drugs or if they cannot tolerate side effects of the drugs, 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 Functional MRI In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more : To determine which areas in the brain are causing seizures (called seizure foci)
Single-photon emission CT Single-photon emission computed tomography (SPECT) In radionuclide scanning, radionuclides are used to produce images. A radionuclide is a radioactive form of an element, which means it is an unstable atom that becomes more stable by releasing... read more (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 drugs. However, they can usually take lower doses or fewer drugs.
Before and after surgery, a psychologic and neurologic evaluation Neurologic Examination When a neurologic disorder is suspected, doctors usually evaluate all of the body systems during the physical examination, but they focus on the nervous system. Examination of the nervous system—the... read more 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.
Stimulation of the vagus nerve
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 drugs 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 Keeping the Beat: Artificial Pacemakers Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more (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 drugs.
Side effects of vagal nerve stimulation include hoarseness, cough, and deepening of the voice when the nerve is stimulated.
Stimulation of the brain
The responsive neurostimulation system is a device that looks like a heart pacemaker Keeping the Beat: Artificial Pacemakers Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more . 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 drugs. It is used when adults have focal-onset seizures that are not controlled by drugs. 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.