A seizure and a seizure disorder are not the same. A seizure is single occurrence of uncontrolled electrical activity in the brain, usually for short time span. It can cause numerous signs and symptoms like convulsions, thought disturbances, loss of consciousness, and/or other symptoms. Usually, doctors consider seizures a symptom of a disease. Epilepsy is a chronic disorder of recurrent unprovoked seizures, and is one type of seizure disorder. In epilepsy, the convulsion is a sudden, violent irregular movement of a limb of the body caused by involuntary contraction of muscles usually associated with epilepsy and/or toxic agents.
A seizure disorder is a medical condition (one of about 40) characterized by episodes of uncontrolled electrical activity in the brain, thus producing symptoms that include two or more seizures. Doctors separate the disorders from each other by their potential causes and their own set of symptoms due to the affected area in the brain.
Which causes are most common depend on when seizures start:
Before age 2: High fevers or temporary metabolic abnormalities, such as abnormal blood levels 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, a birth defect, or a hereditary metabolic abnormality or brain disorder.
2 to 14 years: Often, the cause is unknown (see also Seizures in Children).
Adults: A head injury, stroke, or tumor may damage the brain, causing a seizure. Alcohol withdrawal (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, a low level of oxygen in the blood, or a very low level of sugar in the blood (hypoglycemia)—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 excessive 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.
Nerve cells (neurons) in the brain to create, send and receive electrical impulses, which allow the brain’s nerve cells to communicate. Anything that disrupts these communication pathways can lead to a seizure.
The most common cause of seizures is epilepsy. But not every person who has a seizure has epilepsy. Sometimes seizures happen because of:
- High fever, which can be associated with an infection such as meningitis
- Lack of sleep
- Low blood sodium (hyponatremia), which can happen with diuretic therapy
- Medications, such as certain pain relievers, antidepressants or smoking cessation therapies, that lower the
- seizure threshold
- Head trauma that causes an area of bleeding in the brain
- Brain tumor
- Illegal or recreational drugs, such as amphetamines or cocaine
- Alcohol abuse, during times of withdrawal or extreme intoxication
- Having a seizure at certain times can lead to circumstances that are dangerous for you or others.
- You might be at risk of Falling. If you fall during a seizure, you can injure your head or break a bone
- Drowning. If you have a seizure while swimming or bathing, you’re at risk of accidental drowning.
- Car accidents. A seizure that causes either loss of awareness or control can be dangerous if you’re driving a car or operating other equipment.
- Pregnancy complications. Seizures during pregnancy pose dangers to both mother and baby and certain anti-epileptic medications increase the risk of birth defects. If you have epilepsy and plan to become pregnant, work with your doctor so that he or she can adjust your medications and monitor your pregnancy, as needed.
- Emotional health issues. People with seizures are more likely to have psychological problems, such as depression and anxiety. Problems may be a result of difficulties dealing with the condition itself as well as medication side effects.
An aura (unusual sensations) describes how a person feels before a seizure starts, or it may be part of a focal aware seizure 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 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:
Atonic (involving loss of muscle tone)
Clonic (involving rhythmic jerking of muscles)
Tonic (involving stiffening of muscles)
Myoclonic (involving sudden, lightning-like jerking of muscles)
Epileptic (infantile) spasms and febrile seizures, which occur in children
In focal-onset seizures, the seizures begin in one side of the brain. These 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 if 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.
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 the seizure, 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.
Some people then 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.
Epilepsia partialis continua is rare. Focal seizures occur every few seconds or minutes for days to years at a time. They typically affect an arm, a hand, or one side of the face. These seizures usually result from
In adults: Localized brain damage (such as scarring due to a stroke)
In children: Inflammation of the brain (as occurs in encephalitis and measles)
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)
Myoclonic seizures, including juvenile myoclonic epilepsy
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, 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.
Juvenile myoclonic epilepsy typically begins during adolescence. Typically, seizures begin with quick jerks of both arms. About 90% of these seizures are followed by 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 (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.
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 post-ictal 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 post-ictal 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.
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) 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 (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 or myoclonic seizures
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—see table Some Drugs That Can Cause Problems During Pregnancy). 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). 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.
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: 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 drugs. However, they can usually take lower doses or fewer drugs.
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.
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 (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. 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.