What is epilepsy?
Epilepsy is a disorder of the brain characterized by repeated seizures. A seizure is usually defined as a sudden alteration of behavior due to a temporary change in the electrical functioning of the brain. Normally, the brain continuously generates tiny electrical impulses in an orderly pattern. These impulses travel along neurons — the network of nerve cells in the brain — and throughout the whole body via chemical messengers called neurotransmitters.
In epilepsy the brain’s electrical rhythms have a tendency to become imbalanced, resulting in recurrent seizures. In patients with seizures, the normal electrical pattern is disrupted by sudden and synchronized bursts of electrical energy that may briefly affect their consciousness, movements or sensations.
Epilepsy is usually diagnosed after a person has had at least two seizures that were not caused by some known medical condition, such as alcohol withdrawal or extremely low blood sugar.
If seizures arise from a specific area of the brain, then the initial symptoms of the seizure often reflect the functions of that area. The right half of the brain controls the left side of the body, and the left half of the brain controls the right side of the body. For example, if a seizure starts from the right side of the brain in the area that controls movement in the thumb, then the seizure may begin with jerking of the left thumb or hand.
Seizures vary so much that epilepsy specialists frequently re-classify seizure types. Typically, seizures belong in one of two basic categories: primary generalized seizures and partial seizures. The difference between these types is in how they begin. Primary generalized seizures begin with a widespread electrical discharge that involves both sides of the brain at once. Partial seizures begin with an electrical discharge in one limited area of the brain.
Epilepsy in which the seizures begin from both sides of the brain at the same time is called primary generalized epilepsy. Hereditary factors are important in partial generalized epilepsy, which is more likely to involve genetic factors than partial epilepsy — a condition in which the seizures arise from a limited area of the brain.
Some partial seizures are related to head injury, brain infection, stroke or tumor but, in most cases, the cause is unknown. One question that is used to further classify partial seizures is whether consciousness (the ability to respond and remember) is impaired or preserved. The difference may seem obvious, but there are many degrees of consciousness impairment or preservation.
The following factors may increase the risk of seizures in people predisposed to seizures:
- Sleep deprivation or fatigue
- Insufficient food intake
- Alcohol use or drug abuse
- Failure to take prescribed anticonvulsant medications
About half of the people who have one seizure without a clear cause will have another one, usually within six months. A person is twice as likely to have another seizure if there is a known brain injury or other type of brain abnormality. If the patients does have two seizures, there is about an 80 percent chance of having more. If the first seizure occurred at the time of an injury or infection in the brain, it is more likely the patient will develop epilepsy than if the seizure did not happen at the time of injury or infection.
Because epilepsy is caused by abnormal activity in the brain, seizures can affect any process your brain coordinates. Seizure signs and symptoms may include:
- Temporary confusion
- A staring spell
- Uncontrollable jerking movements of the arms and legs
- Loss of consciousness or awareness
- Psychic symptoms such as fear, anxiety or deja vu
Symptoms vary depending on the type of seizure. In most cases, a person with epilepsy will tend to have the same type of seizure each time, so the symptoms will be similar from episode to episode.
Doctors generally classify seizures as either focal or generalized, based on how the abnormal brain activity begins.
When seizures appear to result from abnormal activity in just one area of your brain, they’re called focal (partial) seizures. These seizures fall into two categories:
- Focal seizures without loss of consciousness. Once called simple partial seizures, these seizures don’t cause a loss of consciousness. They may alter emotions or change the way things look, smell, feel, taste or sound. They may also result in involuntary jerking of a body part, such as an arm or leg, and spontaneous sensory symptoms such as tingling, dizziness and flashing lights.
- Focal seizures with impaired awareness. Once called complex partial seizures, these seizures involve a change or loss of consciousness or awareness. During a complex partial seizure, you may stare into space and not respond normally to your environment or perform repetitive movements, such as hand rubbing, chewing, swallowing or walking in circles.
Symptoms of focal seizures may be confused with other neurological disorders, such as migraine, narcolepsy or mental illness. A thorough examination and testing are needed to distinguish epilepsy from other disorders.
Seizures that appear to involve all areas of the brain are called generalized seizures. Six types of generalized seizures exist.
- Absence seizures. Absence seizures, previously known as petit mal seizures, often occur in children and are characterized by staring into space or subtle body movements such as eye blinking or lip smacking. These seizures may occur in clusters and cause a brief loss of awareness.
- Tonic seizures. Tonic seizures cause stiffening of your muscles. These seizures usually affect muscles in your back, arms and legs and may cause you to fall to the ground.
- Atonic seizures. Atonic seizures, also known as drop seizures, cause a loss of muscle control, which may cause you to suddenly collapse or fall down.
- Clonic seizures. Clonic seizures are associated with repeated or rhythmic, jerking muscle movements. These seizures usually affect the neck, face and arms.
- Myoclonic seizures. Myoclonic seizures usually appear as sudden brief jerks or twitches of your arms and legs.
- Tonic-clonic seizures. Tonic-clonic seizures, previously known as grand mal seizures, are the most dramatic type of epileptic seizure and can cause an abrupt loss of consciousness, body stiffening and shaking, and sometimes loss of bladder control or biting your tongue.
Epilepsy has no identifiable cause in about half the people with the condition. In the other half, the condition may be traced to various factors, including:
- Genetic influence. Some types of epilepsy, which are categorized by the type of seizure you experience or the part of the brain that is affected, run in families. In these cases, it’s likely that there’s a genetic influence.
Researchers have linked some types of epilepsy to specific genes, but for most people, genes are only part of the cause of epilepsy. Certain genes may make a person more sensitive to environmental conditions that trigger seizures.
- Head trauma. Head trauma as a result of a car accident or other traumatic injury can cause epilepsy.
- Brain conditions. Brain conditions that cause damage to the brain, such as brain tumors or strokes, can cause epilepsy. Stroke is a leading cause of epilepsy in adults older than age 35.
- Infectious diseases. Infectious diseases, such as meningitis, AIDS and viral encephalitis, can cause epilepsy.
- Prenatal injury. Before birth, babies are sensitive to brain damage that could be caused by several factors, such as an infection in the mother, poor nutrition or oxygen deficiencies. This brain damage can result in epilepsy or cerebral palsy.
- Developmental disorders. Epilepsy can sometimes be associated with developmental disorders, such as autism and neurofibromatosis.
A doctor makes his or her epilepsy diagnosis based on symptoms, physical signs and the results of such tests as an electroencephalogram (EEG), computed tomography (CT or CAT scan) or magnetic resonance imaging (MRI).
It is essential that the type of epilepsy and the type of seizures both are diagnosed properly. There are several major classifications of seizures and most are associated with specific forms of the disorder.
Certain factors may increase your risk of epilepsy:
- Age. The onset of epilepsy is most common in children and older adults, but the condition can occur at any age.
- Family history. If you have a family history of epilepsy, you may be at an increased risk of developing a seizure disorder.
- Head injuries. Head injuries are responsible for some cases of epilepsy. You can reduce your risk by wearing a seat belt while riding in a car and by wearing a helmet while bicycling, skiing, riding a motorcycle or engaging in other activities with a high risk of head injury.
- Stroke and other vascular diseases. Stroke and other blood vessel (vascular) diseases can lead to brain damage that may trigger epilepsy. You can take a number of steps to reduce your risk of these diseases, including limiting your intake of alcohol and avoiding cigarettes, eating a healthy diet, and exercising regularly.
- Dementia. Dementia can increase the risk of epilepsy in older adults.
- Brain infections. Infections such as meningitis, which causes inflammation in your brain or spinal cord, can increase your risk.
- Seizures in childhood. High fevers in childhood can sometimes be associated with seizures. Children who have seizures due to high fevers generally won’t develop epilepsy. The risk of epilepsy increases if a child has a long seizure, another nervous system condition or a family history of epilepsy.
Having a seizure at certain times can lead to circumstances that are dangerous to yourself or others.
- Falling. If you fall during a seizure, you can injure your head or break a bone.
- Drowning. If you have epilepsy, you’re 15 to 19 times more likely to drown while swimming or bathing than the rest of the population because of the possibility of having a seizure while in the water.
- 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.
Many states have driver’s license restrictions related to a driver’s ability to control seizures and impose a minimum amount of time that a driver be seizure-free, ranging from months to years, before being allowed to drive.
- 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 you’re considering becoming pregnant, talk to your doctor as you plan your pregnancy.
Most women with epilepsy can become pregnant and have healthy babies. You’ll need to be carefully monitored throughout pregnancy, and medications may need to be adjusted. It’s very important that you work with your doctor to plan your pregnancy.
- Emotional health issues. People with epilepsy are more likely to have psychological problems, especially depression, anxiety and suicidal thoughts and behaviors. Problems may be a result of difficulties dealing with the condition itself as well as medication side effects.
Other life-threatening complications of epilepsy are uncommon, but may happen, such as:
- Status epilepticus. This condition occurs if you’re in a state of continuous seizure activity lasting more than five minutes or if you have frequent recurrent seizures without regaining full consciousness in between them. People with status epilepticus have an increased risk of permanent brain damage and death.
- Sudden unexpected death in epilepsy (SUDEP). People with epilepsy also have a small risk of sudden unexpected death. The cause is unknown, but some research shows it may occur due to heart or respiratory conditions.
People with frequent tonic-clonic seizures or people whose seizures aren’t controlled by medications may be at higher risk of SUDEP. Overall, about 1 percent of people with epilepsy die of SUDEP.
There is currently no cure for most types of epilepsy. However, surgery can stop some kinds of seizure from occurring, and in many cases, the condition can be managed.
If an underlying correctable brain condition is causing the seizures, sometimes surgery can stop them. If epilepsy is diagnosed, the doctor will prescribe seizure-preventing drugs or anti-epileptic drugs.
If drugs do not work, the next option could be surgery, a special diet or VNS (vagus nerve stimulation).
The doctor’s aim is to prevent further seizures from occurring, while at the same time avoiding side effects so that the patient can lead a normal, active, and productive life.
Anti-epileptic drugs (AEDs)
The majority of AEDs are taken orally. The type of seizure the patient is having will decide which drug the doctor may prescribe. Patients do not all react in the same way to drugs, but AEDs appear to help control seizures in 70 percent of cases.
Drugs commonly used to treat epilepsy include:
- sodium valproate
Some drugs may stop seizures in one patient, but not in another. Even when the right drug is found, it can take some time to find the ideal dose.
Epilepsy can affect a person’s life in multiple ways, and the outlook will depend on various factors.
Will seizures continue?
If the cause is clearly identifiable, seizures are more likely to continue.
Other factors affecting the chances of remission include:
- access to treatment
- response to treatment
- age when symptoms started
- other neurological condition the person may have
Can epilepsy lead to brain damage?
A study published in 2005 suggested that people with severe epilepsy who continue to experience seizures were more likelyTrusted Source to have difficulties with cognitive ability and brain function. Longer periods of remission were linked with fewer cognitive problems.
A review published in 2006 concluded that there may be a “mild but measurable” decline in some people in intellectual performance” of adults and children.
However, the researchers point out that there is little reliable research in this area, and that “Due to many confounding variables, the effect of seizures per se is difficult to estimate, but appears limited.”
If there is a risk, say the authors, it appears to be higher among those with generalized symptomatic types of epilepsy, with frequent seizures that started at an early age, and a high level of antiepileptic drug use.
Recent studies have looked at cognitive changes in children as they age, either with or without epilepsy. ResultsTrusted Source suggest that epilepsy is associated with worse cognitive outcomes.
However, it is unclear whether:
- epilepsy causes the impairment
- a similar structural change causes both the epilepsy and the impairment
- antiepileptic drugs have an effect
This is an area that needs further research
Epilepsy can affect various aspects of a person’s life, including:
- emotions and behavior
- social development and interaction
- ability to study and work
The impact on these areas of life will depend largely on the frequency and severity of seizures.
Life expectancy of people with epilepsy
In 2013, researchers from the University of Oxford and University College London in the U.K. reported that people with epilepsy are 11 times more likely to experience premature death, compared with the rest of the population.
The risk appears to be greater if the person also has a mental illness. Suicides, accidents, and assaults accounted for 15.8 percent of early deaths. Most people affected by these had also been diagnosed with a mental disorder.
Surgical resection (removal of abnormal tissue) for epilepsy may fall into the following broad categories:
A lesion is a generic term for brain abnormalities that show up on imaging. Some types of lesions — such as cavernous malformations (blood vessel abnormality) and tumors — are prone to cause seizures. When the pre-operative testing indicates that these lesions are the cause of the epilepsy, they can be removed surgically.
Each hemisphere, or half, of the brain is divided into four main lobes — the frontal, temporal, parietal and occipital. Seizures may arise within any of the lobes. A lobectomy is an operation to remove a lobe of the brain. Removal of one of the temporal lobes — called a temporal lobectomy — is the most common type of epilepsy surgery performed. Other types of lobectomies may rely on more specialized testing and surgery to prove a lack of vital function (such as speech, memory, vision, motor function).
A multilobar resection involves removal of parts or all of two or more lobes of the brain. It is reserved for more widespread abnormalities causing seizures, providing that no vital functions are in those regions.
The brain is divided into a left and right hemisphere. In rare instances, children may have severe, uncontrollable and devastating seizures that can be associated with weakness on one side of the body. This may occur with a large amount of damage or injury to one of the hemispheres. Surgery to remove or disconnect a hemisphere, a hemispherectomy may be curative. There are many subtypes of this surgery, the two main divisions being anatomic and functional hemispherectomy. Anatomic hemispherectomy involves removing the entire half of the brain that is injured and is generating the debilitating seizures. This includes the four lobes of the hemisphere — frontal, temporal, parietal and occipital. Functional hemispherectomy involves separating the abnormal hemisphere from the normal one by disconnecting fibers that communicate between the two. Often, some portions of the abnormal brain are surgically removed in order to perform this disconnection.
Functional hemispherectomy involves separating the abnormal hemisphere from the normal one by disconnecting fibers that communicate between the two. Often, some portions of the abnormal brain are surgically removed in order to perform this disconnection. This is, very often, surgically curative.
These surgeries involve cutting and dividing fiber bundles that connect portions of the brain. The rationale is to separate the area of the brain generating the seizures from the normal brain.
The corpus callosum is one of the main fiber bundles that connect the two hemispheres. When debilitating generalized seizures or falling-type seizures start on one side of the brain and quickly spread to the other, patients may be candidates for this procedure. A large part of this fiber bundle may be cut. The procedure is palliative, meaning that although seizures may improve, they usually do not disappear.
Multiple subpial transections (MST)
In certain cases of epilepsy, where the seizures are deemed to be arising from an area of the brain that cannot be safely removed, multiple subpial transections can be performed. In this procedure, a small wire is placed into the brain to perform transections at multiple points in a given region which can decrease seizures by disconnecting the cross-communication of neurons.
Stereotactic radiosurgery involves the delivery of a focused beam of radiation to a specific target area. Gamma Knife radiosurgery, one of the most common forms of radiosurgery, uses gamma rays to target the area to be treated. In epilepsy, it is generally reserved for small, deep-seated lesions that are visible on MR imaging.
There are currently two FDA-approved devices that modulate the nervous system with the goal of improved seizure control. This includes vagus nerve stimulation and responsive neurostimulation. Both devices are considered palliative in that the goal is improved seizure control, and rarely do patients become seizure free.
Vagus nerve stimulation
The vagus nerve stimulator (VNS) is an FDA-approved device for the treatment of epilepsy that is not controlled with antiepileptic medications. It involves the surgical placement of electrodes around the vagus nerve in the neck and a generator placed below the collar bone in the upper chest region. It requires two separate incisions, but is an outpatient procedure. Subsequently, a programmer can be used by the epileptologist (from outside the skin) to change the intensity, duration and frequency of stimulation to optimize seizure control. VNS decreases seizure frequency by at least half in 40 to 50 percent of patients, but rarely eliminates all seizures. It is an option for those who are not candidates for other types of surgery.
Responsive neurostimulation (RNS)
The NeuroPace responsive neurostimulation (RNS) device was approved by the FDA in 2014 as a treatment for adults with partial-onset seizures with one or two seizure onset-zones, whose seizures have not been controlled with two or more antiepileptic drugs. Surgery involves placing a neurostimulator in the skull and connecting to two electrodes that are placed either on the surface or into the brain, in or around the area which is deemed to be the likely onset region for the seizure. The device records brain waves (EEG), and is trained by the epileptologist to detect the electrical signature of the seizure onset and then deliver an impulse which can stop the seizure. Data collected by the neurostimulator can by uploaded by the patient with the use of a hand-held wand to a secure web-based application which can be accessed by the epileptologist. This surgery is generally reserved for patients who are not a candidate for surgical resection, since the RNS improves seizure control but rarely stops seizures from occurring.
Improved technology and testing has made it possible to identify more accurately where seizures originate in the brain (epileptogenic regions), and advances in surgery have made operative management safer for all forms of surgery for epilepsy. Of the surgeries presented, surgical resection offers the best chance of rendering a patient seizure-free. However, the benefits of surgery should always be weighed carefully against its potential risks.
People with epilepsy are at risk for two life-threatening conditions: tonic-clonic status epilepticus and sudden unexplained death in epilepsy (SUDEP). Tonic-clonic status epilepticus is a long-lasting seizure that’s considered a medical emergency. If not stopped within about 30 minutes, it may cause permanent injury or death.
SUDEP is a rare condition in which young or middle-aged people with epilepsy die without a clear cause. It accounts for less than two percent of deaths among people with epilepsy. The risk is about one in 3,000 per year for all people with epilepsy. However, it can be as high as one in 300 for those who have frequent, uncontrollable seizures and take high doses of seizure medicines. Researchers are uncertain why SUDEP causes death. Some believe that a seizure causes an irregular heart rhythm. More recent studies have suggested that the person may suffocate from impaired breathing, fluid in the lungs and lying face down on bedding.
Although the risk is low, people with epilepsy also can die from inhaling vomit during or just after a seizure.
Most women with epilepsy can become pregnant, but they should discuss their epilepsy and the medications they are taking with their doctors before getting pregnant. Many patients with epilepsy take high doses of medication that may lead to potentially harmful drug exposure to unborn babies. In some cases, medications may be reduced before pregnancy, particularly if seizures are well-controlled. While seizure medications can produce birth defects, severe birth defects are rare in infants of women who receive regular prenatal care and whose seizures are carefully managed. Women with epilepsy have a 90 percent or better chance of having a normal, healthy baby.
Epilepsy is a chronic condition that affects people in different ways. Many people with epilepsy lead normal, active lives. Between 70 and 80 percent of people with epilepsy can successfully control their seizures through medication or surgical techniques.
Some people find that they rarely have to think about epilepsy, except when taking their medications or going to see the doctor. No matter how epilepsy affects a person, it is important to remember that being well-informed about the condition and keeping a positive attitude are important. Working closely with ahealthcare team and adhering to prescribed medications are essential to helping control seizures so that the patient can lead a full, balanced life.
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