Definition
The epilepsies are chronic neurological disorders in which clusters of nerve cells, or neurons, in the brain sometimes signal abnormally and cause seizures. Neurons normally generate electrical and chemical signals that act on other neurons, glands, and muscles to produce human thoughts, feelings, and actions.
During a seizure, many neurons fire (signal) at the same time—as many as 500 times per second, much faster than normal. This surge of excessive electrical activity happening at the same time causes involuntary movements, sensations, emotions, and behaviors and the temporary disturbance of normal neuronal activity may cause a loss of awareness.
Epilepsy can be considered a spectrum disorder because of its different causes, different seizure types, its ability to vary in severity and impact from person to person, and its range of co-existing conditions. There also are many different types of epilepsy, resulting from a variety of causes. Recent adoption of the term “the epilepsies” underscores the diversity of types and causes:
- Some people may have convulsions (sudden onset of repetitive general contraction of muscles) and lose consciousness.
- Others may simply stop what they are doing, have a brief lapse of awareness, and stare into space for a short period.
- Some people have seizures very infrequently, while other people may experience hundreds of seizures each day.
About 2.3 million adults and more than 450,000 children and adolescents in the U.S. currently live with epilepsy. Each year, an estimated 150,000 people are diagnosed with epilepsy. In the U.S. alone, the annual costs associated with the epilepsies are estimated to be $15.5 billion in direct medical expenses and lost or reduced earnings and productivity.
Anyone can develop epilepsy. Epilepsy affects both males and females of all races, ethnic backgrounds, and ages. However, Black Americans are more likely to be diagnosed with epilepsy than white Americans due to contributing factors, such as strokes.
According to the U.S. Census Bureau and the Centers for Disease Control and Prevention (CDC), 578,000 Black Americans have epilepsy or a seizure disorder. Over 25,000 Black Americans are diagnosed with seizures or epilepsy each year.
Causes
The epilepsies have many possible causes, but as about half people living with epilepsy do not know the cause. In other cases, the epilepsies are clearly linked to genetic factors, developmental brain abnormalities, infection, traumatic brain injury (TBI), stroke, brain tumors, or other identifiable problems. Anything that disturbs the normal pattern of neuronal activity—from illness to brain damage to abnormal brain development—can lead to seizures.
The epilepsies may develop because of an abnormality in brain wiring, an imbalance of nerve signaling in the brain (in which some cells either over-excite or over-inhibit other brain cells from sending messages), or some combination of these factors. In some pediatric conditions abnormal brain wiring causes other problems such as intellectual impairment.
In other people, the brain’s attempt to repair itself after a head injury, stroke, or other problem may inadvertently generate abnormal nerve connections that lead to epilepsy. Brain malformations and abnormalities in brain wiring that occur during brain development may also disturb neuronal activity and lead to epilepsy.
Genetics
Genetic mutations may play a key role in the development of certain epilepsies. Many types of epilepsy affect multiple blood-related family members, pointing to a strong inherited genetic component. In other cases, gene mutations may occur spontaneously and contribute to development of epilepsy in people with no family history of the disorder (called “de novo” mutations). Overall, researchers estimate that hundreds of genes could play a role.
Several types of epilepsy have been linked to mutations in genes that provide instructions for ion channels, the “gates” that control the flow of ions in and out of cells to help regulate neuronal signaling. For example, most infants with Dravet syndrome, a type of epilepsy associated with seizures that begin before the age of one year, carry a mutation in the SCN1A gene that causes seizures by affecting sodium ion channels.
Genetic mutations have been linked to disorders known as the progressive myoclonic epilepsies, which are characterized by ultra-quick muscle contractions (myoclonus) and seizures over time. For example, Lafora disease, a severe, progressive form of myoclonic epilepsy that begins in childhood, has been linked to a gene that helps to break down carbohydrates in brain cells.
Mutations in genes that control neuronal migration—a critical step in brain development—can lead to areas of misplaced or abnormally formed neurons, called cortical dysplasia, in the brain that can cause neurons to misfire and lead to epilepsy.
Other genetic mutations may not cause epilepsy, but may influence the disorder in other ways. For example, one study showed that many people with certain forms of epilepsy have an abnormally active version of a gene that results in resistance to anti-seizure drugs. Genes also may control a person’s susceptibility to seizures, or seizure threshold, by affecting brain development.
Other disorders
Epilepsies may develop as a result of brain damage associated with many types of conditions that disrupt normal brain activity. Seizures may stop once these conditions are treated and resolved. However, the chances of becoming seizure-free after the primary disorder is treated are uncertain and vary depending on the type of disorder, the brain region that is affected, and how much brain damage occurred prior to treatment. Examples of conditions that can lead to epilepsy include:
- Brain tumors, including those associated with neurofibromatosis or tuberous sclerosis complex, two inherited conditions that cause benign tumors called hamartomas to grow in the brain
- Head trauma
- Alcoholism or alcohol withdrawal
- Alzheimer’s disease
- Strokes, heart attacks, and other conditions that deprive the brain of oxygen (a significant portion of new-onset epilepsy in elderly people is due to stroke or other cerebrovascular disease)
- Abnormal blood vessel formation (arteriovenous malformations) or bleeding in the brain (hemorrhage)
- Inflammation of the brain
- Infections such as meningitis, HIV, and viral encephalitis
Cerebral palsy or other developmental neurological abnormalities may also be associated with epilepsy. About 20 percent of seizures in children can be attributed to developmental neurological conditions. Epilepsies often co-occur in people with abnormalities of brain development or other neurodevelopmental disorders. Seizures are more common, for example, among individuals with autism spectrum disorder or intellectual impairment. In one study, a third of children with autism spectrum disorder had treatment-resistant epilepsy.
Seizure triggers
Seizure triggers do not cause epilepsy but can provoke “first seizures” in those who are susceptible or can cause seizures in people with epilepsy who otherwise experience good seizure control with their medication. Seizure triggers include:
- Alcohol consumption or alcohol withdrawal
- Dehydration or missing meals
- Stress
- Hormonal changes associated with the menstrual cycle
In surveys of people with epilepsy, stress is the most commonly reported seizure trigger. Exposure to toxins or poisons such as lead or carbon monoxide, street drugs, or even excessively large doses of antidepressants or other prescribed medications also can trigger seizures.
Sleep deprivation is a powerful trigger of seizures. Sleep disorders are common among people with the epilepsies and appropriate treatment of co-existing sleep disorders can often lead to improved control of seizures. Certain types of seizures tend to occur during sleep, while others are more common during times of wakefulness, suggesting to physicians how to best adjust a person’s medication.
For some people, visual stimulation can trigger seizures in a condition known as photosensitive epilepsy. Stimulation can include such things as flashing lights or moving patterns.
Types of Seizures
Seizures are divided into two major categories: Focal seizures and generalized seizures. However, there are many different types of seizures in each of these categories. In fact, doctors have described more than 30 types.
Focal Seizures
Focal seizures originate in just one part of the brain. About 60 percent of people with epilepsy have focal seizures. These seizures are frequently described by the area of the brain in which they originate. Many people are diagnosed with focal frontal lobe or medial temporal lobe seizures.
In some focal seizures, the person remains conscious but may experience motor, sensory, or psychic feelings (for example, intense dejà vu or memories) or sensations that can take many forms. The person may experience sudden and unexplainable feelings of joy, anger, sadness, or nausea. He or she also may hear, smell, taste, see, or feel things that are not real and may have movements of just one part of the body, for example, just one hand.
In other focal seizures, the person has a change in consciousness, which can produce a dreamlike experience. The person may display strange, repetitious behaviors such as blinks, twitches, mouth movements (often like chewing or swallowing, or even walking in a circle). These repetitious movements are called automatisms. More complicated actions, which may seem purposeful, can also occur involuntarily. Individuals may also continue activities they started before the seizure began, such as washing dishes in a repetitive, unproductive fashion. These seizures usually last just a minute or two.
Some people with focal seizures may experience auras—unusual sensations that warn of an impending seizure. Auras are usually focal seizures without interruption of awareness (e.g., dejà vu or an unusual abdominal sensation) but some people experience a true warning before an actual seizure. An individual’s symptoms, and the progression of those symptoms, tend to be similar every time. Other people with epilepsy report experiencing a prodrome, a feeling that a seizure is imminent lasting hours or days.
The symptoms of focal seizures can easily be confused with other disorders. The strange behavior and sensations caused by focal seizures also can be mistaken for symptoms of narcolepsy, fainting, or even mental illness. Several tests and careful monitoring may be needed to make the distinction between epilepsy and these other disorders.
Generalized Seizures
Generalized seizures are a result of abnormal neuronal activity that rapidly emerges on both sides of the brain. These seizures may cause loss of consciousness, falls, or massive muscle contractions. The types of generalized seizures and their effects include:
- Absence seizures may cause the person to appear to be staring into space with or without slight twitching of the muscles
- Tonic seizures cause stiffening of muscles of the body, generally those in the back, legs, and arms
- Clonic seizures cause repeated jerking movements of muscles on both sides of the body
- Myoclonic seizures cause jerks or twitches of the upper body, arms, or legs
- Atonic seizures cause a loss of normal muscle tone, which often leads the affected person to fall down or drop the head involuntarily
- Tonic-clonic seizures cause a combination of symptoms, including stiffening of the body and repeated jerks of the arms and/or legs as well as loss of consciousness
- Secondary generalized seizures
Not all seizures can be easily defined as either focal or generalized. Some people have seizures that begin as focal seizures but then spread to the entire brain. Other people may have both types of seizures but with no clear pattern.
Some people recover immediately after a seizure, while others may take minutes to hours to feel as they did before the seizure. During this time, they may feel tired, sleepy, weak, or confused.
Following focal seizures or seizures that started from a focus, there may be local symptoms related to the function of that focus. Certain characteristics of the post-seizure (or post-ictal) state may help locate the region of the brain where the seizure occurred. A classic example is called Todd’s paralysis, a temporary weakness in the part of the body that was affected depending on where in the brain the focal seizure occurred. If the focus is in the temporal lobe, post-ictal symptoms may include language or behavioral disturbances, even psychosis. After a seizure, some people may experience headache or pain in muscles that contracted.
Types of Epilepsy
Just as there are many different kinds of seizures, there are many different kinds of epilepsy. Hundreds of different epilepsy syndromes—disorders characterized by a specific set of symptoms that include epilepsy as a prominent symptom—have been identified. Some of these syndromes appear to be either hereditary or caused by de novomutations. For other syndromes, the cause is unknown. Epilepsy syndromes are frequently described by their symptoms or by where in the brain they originate.
- Absence epilepsy is characterized by repeated seizures that cause momentary lapses of consciousness. These seizures almost always begin in childhood or adolescence and tend to run in families, suggesting that they may be at least partially due to genetic factors. Individuals may show purposeless movements during their seizures, such as a jerking arm or rapidly blinking eyes, while others may have no noticeable symptoms except for brief times when they appear to be staring off into space. Immediately after a seizure, the person can resume whatever he or she was doing. However, these seizures may occur so frequently (in some cases up to 100 or more a day) that the person cannot concentrate in school or other situations.
- Childhood absence epilepsy usually stops when the child reaches puberty. Although most children with childhood absence epilepsy have a good prognosis, there may be long-lasting negative consequences and some children will continue to have absence seizures into adulthood and/or go on to develop other seizure types.
- Frontal lobe epilepsy is a common epilepsy syndrome that features brief focal seizures that may occur in clusters. It can affect the part of the brain that controls movement and involves seizures that can cause muscle weakness or abnormal, uncontrolled movement such as twisting, waving the arms or legs, eye deviation to one side, or grimacing, and are usually associates with some loss of awareness. Seizures usually occur when the person is asleep but also may occur while awake.
- Temporal lobe epilepsy (TLE) is the most common epilepsy syndrome with focal seizures. These seizures are often associated with auras of nausea, emotions (such as déjà vu or fear), or unusual smell or taste. The seizure itself is a brief period of impaired consciousness which may appear as a staring spell, dream-like state, or repeated automatisms. TLE often begins in childhood or teenage years. Research has shown that repeated temporal lobe seizures are often associated with shrinkage and scarring (sclerosis) of the hippocampus. The hippocampus is important for memory and learning. It is not clear whether localized asymptomatic seizure activity over years causes the hippocampal sclerosis.
- Neocortical epilepsy is characterized by seizures that originate from the brain’s cortex, or outer layer. The seizures can be either focal or generalized. Symptoms may include unusual sensations, visual hallucinations, emotional changes, muscle contractions, convulsions, and a variety of other symptoms, depending on where in the brain the seizures originate.
There are many other types of epilepsy that begin in infancy or childhood. For example:
- Infantile spasms are clusters of seizures that usually begin before the age of 6 months. During these seizures the infant may drop their head, jerk an arm, bend at the waist and/or cry out.
- Children with Lennox-Gastaut syndrome have several different types of seizures, including atonic seizures, which cause sudden falls and are also called drop attacks. Seizure onset is usually before age four years. This severe form of epilepsy can be very difficult to treat effectively.
- Rasmussen’s encephalitis is a progressive form of epilepsy in which half the brain shows chronic inflammation.
- Some childhood epilepsy syndromes, such as childhood absence epilepsy, tend to go into remission or stop entirely during adolescence; whereas other syndromes such as juvenile myoclonic epilepsy (which features jerk-like motions upon waking) and Lennox-Gastaut syndrome are usually present for life once they develop.
- Children with Dravet syndrome have seizures that start before age one and later in infancy develop into other seizure types.
- Hypothalamic hamartoma is a rare form of epilepsy that first occurs during childhood and is associated with malformations of the hypothalamus at the base of the brain. People with hypothalamic hamartoma have seizures that resemble laughing or crying. Such seizures frequently go unrecognized and are difficult to diagnose.
While any seizure is cause for concern, having a seizure does not by itself mean a person has epilepsy. First seizures, febrile seizures, nonepileptic events, and eclampsia (a life-threatening condition that can occur in pregnant women) are examples of conditions involving seizures that may not be associated with epilepsy. Regardless of the type of seizure, it’s important to inform your doctor when one occurs.
First seizures
Many people have a single seizure at some point in their lives, and it can be provoked or unprovoked, meaning that they can occur with or without any obvious triggering factor. Unless the person has suffered brain damage or there is a family history of epilepsy or other neurological abnormalities, the majority of single seizures usually are not followed by additional seizures. Medical disorders which can provoke a seizure include low blood sugar, very high blood sugar in diabetics, disturbances in salt levels in the blood (sodium, calcium, magnesium), eclampsia during or after pregnancy, impaired function of the kidneys, or impaired function of the liver. Sleep deprivation, missing meals, or stress may serve as seizure triggers in susceptible people.
Many people with a first seizure will never have a second seizure, and physicians often counsel against starting antiseizure drugs at this point. In some cases where additional epilepsy risk factors are present, drug treatment after the first seizure may help prevent future seizures. Evidence suggests that it may be beneficial to begin antiseizure medication once a person has had a second unprovoked seizure, as the chance of future seizures increases significantly after this occurs. A person with a pre-existing brain problem, for example, a prior stroke or traumatic brain injury, will have a higher risk of experiencing a second seizure. In general, the decision to start antiseizure medication is based on the doctor’s assessment of many factors that influence how likely it is that another seizure will occur in that person.
In one study that followed individuals for an average of eight years, 33 percent of people had a second seizure within four years after an initial seizure. People who did not have a second seizure within that time remained seizure-free for the rest of the study. For people who did have a second seizure, the risk of a third seizure was about 73 percent by the end of four years. Among those with a third unprovoked seizure, the risk of a fourth was 76 percent.
Febrile Seizures
Not infrequently a child will have a seizure during the course of an illness with a high fever. These seizures are called febrile seizures. Antiseizure medications following a febrile seizure are generally not warranted unless certain other conditions are present: a family history of epilepsy, signs of nervous system impairment prior to the seizure, or a relatively prolonged or complicated seizure. The risk of subsequent non-febrile seizures is low unless one of these factors is present.
Results from a study funded by the National Institute of Neurological Disorders and Stroke (NINDS) suggested that certain findings using diagnostic imaging of the hippocampus may help identify which children with prolonged febrile seizures are subsequently at increased risk of developing epilepsy.
Researchers also have identified several different genes that influence the risks associated with febrile seizures in certain families. Studying these genes may lead to new understandings of how febrile seizures occur and perhaps point to ways of preventing them.
Nonepileptic Events
An estimated five to 20 percent of people diagnosed with epilepsy actually have non-epileptic seizures (NES), which can outwardly resemble epileptic seizures, but are not associated with seizure-like electrical discharge in the brain. Non-epileptic events may be referred to as psychogenic non-epileptic seizures (PNES). PNES do not respond to antiseizure drugs; instead, PNES are often treated by cognitive behavioral therapy to decrease stress and improve self-awareness.
A history of traumatic events is among the known risk factors for PNES. People with PNES should be evaluated for underlying psychiatric illness and treated appropriately. Two studies together showed a reduction in seizures and fewer coexisting symptoms following treatment with cognitive behavioral therapy. Some people with epilepsy have psychogenic seizures in addition to their epileptic seizures.
Other nonepileptic events may be caused by:
- Narcolepsy (sudden attacks of sleep)
- Tourette syndrome (repetitive involuntary movements called tics)
- Cardiac arrhythmia (irregular heartbeat)
- Other medical conditions with symptoms that resemble seizures
Because symptoms of these disorders can look very much like epileptic seizures, they are often mistaken for epilepsy.
Although most people with epilepsy lead full, active lives, there is an increased risk of death or serious disability associated with epilepsy. There may be an increased risk of suicidal thoughts or actions related to some antiseizure medications that are also used to treat mania and bipolar disorder. Two life-threatening conditions associated with the epilepsies are status epilepticus and sudden unexpected death in epilepsy (SUDEP).
- Status epilepticus is a potentially life-threatening condition in which a person either has an abnormally prolonged seizure or does not fully regain consciousness between recurring seizures. Status epilepticus can be convulsive (in which outward signs of a seizure are observed) or nonconvulsive (no outward signs and is diagnosed by an abnormal EEG). Nonconvulsive status epilepticus may appear as a sustained episode of confusion, agitation, loss of consciousness, or even coma.
Any seizure lasting longer than five minutes should be treated as though it was status epilepticus. There is some evidence that five minutes is sufficient to damage neurons and that seizures are unlikely to end on their own, making it necessary to seek medical care immediately. One study showed that 80 percent of people in status epilepticus who received medication within 30 minutes of seizure onset eventually stopped having seizures, whereas only 40 percent recovered if two hours had passed before they received medication. The mortality rate can be as high as 20 percent if treatment is not initiated immediately.
Researchers are trying to shorten the time it takes for antiseizure medications to be administered. A key challenge has been establishing an intravenous (IV) line to deliver injectable antiseizure drugs in a person having convulsions. A NINDS-funded study on status epilepticus found that when paramedics delivered the medication midazolam to the muscles using an autoinjector, similar to the EpiPen drug delivery system used to treat serious allergic reactions, seizures could be stopped significantly earlier compared to when paramedics took the time to give lorazepam intravenously. In addition, drug delivery by autoinjector was associated with a lower rate of hospitalization compared with IV delivery. - For reasons that are poorly understood, people with epilepsy have an increased risk of dying suddenly for no discernible reason. Some studies suggest that approximately one case of Sudden Unexplained Death in Epilepsy (SUDEP) occurs for every 1,000 people with the epilepsies each year. This risk can be higher, depending on several factors. For instance, people with more difficult to control seizures tend to have a higher incidence of SUDEP.
Researchers are still unsure why SUDEP occurs, although some research points to abnormal heart and respiratory function due to gene abnormalities (ones which cause epilepsy and also affect heart function). SUDEP can occur at any age. People with epilepsy may be able to reduce the risk of SUDEP by carefully taking all antiseizure medication as prescribed. Not taking the prescribed dosage of medication on a regular basis may increase the risk of SUDEP in individuals with epilepsy, especially those who are taking more than one medication for their epilepsy.
Diagnosis
A number of tests are used to determine whether a person has a form of epilepsy and, if so, what kind of seizures the person has.
Imaging and Monitoring
An electroencephalogram (EEG) can assess whether there are any detectable abnormalities in the person’s brain waves and may help to determine if antiseizure drugs would be of benefit. Video monitoring may be used in conjunction with EEG to determine the nature of a person’s seizures and to rule out other disorders such as psychogenic non-epileptic seizures, cardiac arrhythmia, or narcolepsy that may look like epilepsy.
A magnetoencephalogram (MEG) detects the magnetic signals generated by neurons to help detect surface abnormalities in brain activity. MEG can be used in planning a surgical strategy to remove focal areas involved in seizures while minimizing interference with brain function.
The most commonly used brain scans include:
- CT (computed tomography)
- MRI (magnetic resonance imaging)
- PET (positron emission tomography)
CT and MRI scans reveal structural abnormalities of the brain such as tumors and cysts, which may cause seizures. A type of MRI called functional MRI (fMRI) can be used to localize normal brain activity and detect abnormalities in functioning. Single photon emission computed tomography (SPECT) is sometimes used to locate seizure foci in the brain.
A modification of SPECT, called ictal SPECT, can be very helpful in localizing the brain area generating seizures. In a person admitted to the hospital for epilepsy monitoring, the SPECT blood flow tracer is injected within 30 seconds of a seizure, then the images of brain blood flow at the time of the seizure are compared with blood flow images taken in between seizures. The seizure onset area shows a high blood flow region on the scan.
PET scans can be used to identify brain regions with lower-than-normal metabolism, a feature of the epileptic focus after the seizure has sped.
Medical History
Taking a detailed medical history, including symptoms and duration of the seizures, is still one of the best methods available to determine what kind of seizures a person has had and to determine any form of epilepsy. The medical history should include details about any past illnesses or other symptoms a person may have had, as well as any family history of seizures.
Since people who have suffered a seizure often do not remember what happened, caregiver or other accounts of seizures are vital to this evaluation. The person who experienced the seizure is asked about any warning experiences. The observers will be asked to provide a detailed description of events in the timeline they occurred.
Blood Tests
Blood samples may be taken to screen for metabolic or genetic disorders that may be associated with the seizures. They also may be used to check for underlying health conditions such as infections, lead poisoning, anemia, and diabetes that may be causing or triggering the seizures. In the emergency department, it is standard procedure to screen for exposure to recreational drugs in anyone with a first seizure.
Developmental, Neurological, and Behavioral Tests
Tests devised to measure motor abilities, behavior, and intellectual ability are often used as a way to determine how epilepsy is affecting an individual. These tests also can provide clues about what kind of epilepsy the person has.
Treatment
Accurate diagnosis of the type of epilepsy a person has is crucial for finding an effective treatment. There are many different ways to successfully control seizures. Doctors who treat the epilepsies come from many different fields of medicine and include neurologists, pediatricians, pediatric neurologists, internists, and family physicians, and neurosurgeons. An epileptologist is someone who has completed advanced training and specializes in treating the epilepsies.
Once epilepsy is diagnosed, it is important to begin treatment as soon as possible. Research suggests that medication and other treatments may be less successful once seizures and their consequences become established. There are several treatment approaches that can be used depending on the individual and the type of epilepsy. If seizures are not controlled quickly, referral to an epileptologist at a specialized epilepsy center should be considered, so that careful consideration of treatment options, including dietary approaches, medication, devices, and surgery, can be performed in order to gain optimal seizure treatment.
Medications
The most common approach to treating the epilepsies is to prescribe antiseizure drugs. More than 20 different antiseizure medications are available today, all with different benefits and side effects. Most seizures can be controlled with one drug (monotherapy). Deciding on which drug to prescribe, and at what dosage, depends on many different factors, including seizure type, lifestyle and age, seizure frequency, drug side effects, medicines for other conditions, and, for a woman, whether she is pregnant or will become pregnant. It may take several months to determine the best drug and dosage. If one treatment is unsuccessful, another may work better.
Diet
Dietary approaches and other treatments may be more appropriate depending on the age of the individual and the type of epilepsy. A high-fat, very low carbohydrate ketogenic diet is often used to treat medication-resistant epilepsies. The diet induces a state known as ketosis, which means that the body shifts to breaking down fats instead of carbohydrates to survive. A ketogenic diet effectively reduces seizures for some people, especially children with certain forms of epilepsy. Studies have shown that more than 50 percent of people who try the ketogenic diet have a greater than 50 percent improvement in seizure control and 10 percent experience seizure freedom. Some children are able to discontinue the ketogenic diet after several years and remain seizure-free, but this is done with strict supervision and monitoring by a physician.
The ketogenic diet is not easy to maintain, as it requires strict adherence to a limited range of foods. Possible side effects include impaired growth due to nutritional deficiency and a buildup of uric acid in the blood, which can lead to kidney stones.
Researchers are looking at modified versions of and alternatives to the ketogenic diet. For example, studies show promising results for a modified Atkins diet and for a low-glycemic-index treatment, both of which are less restrictive and easier to follow than the ketogenic diet, but well-controlled randomized controlled trials have yet to assess these approaches.
Surgery
Evaluation for surgery is generally recommended only after focal seizures persist despite the person having tried at least two appropriately chosen and well-tolerated medications, or if there is an identifiable brain lesion believed to cause the seizures. When someone is considered to be a good candidate for surgery, experts generally agree that it should be performed as early as possible.
Surgical evaluation takes into account the:
- Seizure type
- Brain region involved
- Importance of the area of the brain where seizures originate (the focus) for everyday behavior
Prior to surgery, individuals with epilepsy are monitored intensively in order to pinpoint the exact location in the brain where seizures begin. Implanted electrodes may be used to record activity from the surface of the brain, which yields more detailed information than an external scalp EEG. Surgeons usually avoid operating in areas of the brain that are necessary for speech, movement, sensation, memory and thinking, or other important abilities. fMRI can be used to locate such “eloquent” brain areas involved in an individual.
While surgery can significantly reduce or even halt seizures for many people, any kind of surgery involves some level of risk. Surgery for epilepsy does not always successfully reduce seizures and it can result in cognitive or personality changes as well as physical disability, even in people who are excellent candidates for it. Nonetheless, when medications fail, several studies have shown that surgery is much more likely to make someone seizure-free compared to attempts to use other medications. Anyone thinking about surgery for epilepsy should be assessed at an epilepsy center experienced in surgical techniques and should discuss with the epilepsy specialists the balance between the risks of surgery and desire to become seizure-free.
Even when surgery completely ends a person’s seizures, it is important to continue taking antiseizure medication for some time. Doctors generally recommend continuing medication for at least two years after a successful operation to avoid recurrence of seizures.
Surgical procedures for treating epilepsy disorders include:
- Surgery to remove a seizure focus involves removing the defined area of the brain where seizures originate. It is the most common type of surgery for epilepsy, which doctors may refer to as a lobectomy or lesionectomy, and is appropriate only for focal seizures that originate in just one area of the brain. The most common type of lobectomy is a temporal lobe resection, which is performed for people with medial temporal lobe epilepsy. In such individuals one hippocampus (there are two, one on each side of the brain) is seen to be shrunken and scarred on an MRI scan.
- Multiple subpial transection may be performed when seizures originate in part of the brain that cannot be removed. It involves making a series of cuts that are designed to prevent seizures from spreading into other parts of the brain while leaving the person’s normal abilities intact.
- Corpus callosotomy, or severing the network of neural connections between the right and left halves (hemispheres) of the brain, is done primarily in children with severe seizures that start in one half of the brain and spread to the other side. Corpus callosotomy can end drop attacks and other generalized seizures. However, the procedure does not stop seizures in the side of the brain where they originate, and these focal seizures may get worse after surgery.
- Hemispherectomy and hemispherotomy involve removing half of the brain’s cortex, or outer layer. These procedures are used predominantly in children who have seizures that do not respond to medication because of damage that involves only half the brain, as in Rasmussen’s encephalitis. While this type of surgery is excessive and performed only when other therapies have failed, with intense rehabilitation, children can recover many abilities.
- Thermal ablation for epilepsy, also known as laser interstitial thermal therapy, directs a set amount of energy to a specific, targeted brain region causing the seizures (the seizure focus). The energy, which is changed to thermal energy, destroys the brain cells causing the seizures. Laser ablation is less invasive than open brain surgery for treating epilepsy.
Devices
Electrical stimulation of the brain remains a therapeutic strategy of interest for people with medication-resistant forms of epilepsy who are not candidates for surgery. The FDA-approved vagus nerve stimulator is surgically implanted under the skin of the chest and is attached to the vagus nerve in the lower neck. The device delivers short bursts of electrical energy to the brain via the vagus nerve. On average, this stimulation reduces seizures by about 20 to 40 percent. Individuals usually cannot stop taking epilepsy medication because of the stimulator, but they often experience fewer seizures and they may be able to reduce the dosage of their medication.
Responsive stimulation involves the use of an implanted device that analyzes brain activity patterns to detect a forthcoming seizure. Once detected, the device administers an intervention, such as electrical stimulation or a fast-acting drug to prevent the seizure from occurring. These devices are also known as closed-loop systems. NeuroPace, one of the first responsive stimulation, closed-loop devices, is available for adults with refractory epilepsy (hard to treat epilepsy that does not respond well to trials of at least two medicines).
Prevention
At this time there are no medications or other therapies that have been shown to prevent epilepsy. In some cases, the risk factors that lead to epilepsy can addressed. For example:
- Good prenatal care, including treatment of high blood pressure and infections during pregnancy, may prevent brain injury in the developing fetus that may lead to epilepsy and other neurological problems later.
- Treating cardiovascular disease, high blood pressure, and other disorders that can affect the brain during adulthood and aging also may prevent some cases of epilepsy.
- Prevention or early treatment of infections such as meningitis in high-risk populations may also prevent cases of epilepsy.
- Wearing seatbelts and bicycle helmets, and correctly securing children in car seats, may avert some cases of epilepsy associated with head trauma.