[Editor's note: This article is from 2007. Some newer treatments and current statistics are not included here. See further information on BrainWeb]
sections include: types of seizures, diagnosis and treatment, living with epilepsy
A seizure is a sudden, brief attack caused by an abnormal electrical discharge in the brain. People experience it as altered awareness (losing consciousness, for instance), involuntary movements, or convulsions. During a seizure, a person’s brain cells “fire” uncontrollably, temporarily affecting the way he or she behaves, moves, thinks, or feels. This abnormal firing may involve the entire cerebral cortex (primary generalized seizure), or it may begin in one brain area and affect only a limited region (a partial, or focal, seizure).
Many conditions can trigger a seizure, including injury or trauma to the head; brain tumors; infections, especially meningitis and encephalitis; genetic conditions; and structural abnormalities in the brain’s blood vessels. Seizures may also result from high fever (called febrile seizures) or heatstroke, severe sleep deprivation, diabetes (if blood sugar levels become too low or too high), alcohol or drug withdrawal, or a reaction to medications. Some people may have a single unprovoked seizure for no discernible reason. Others will have repeated seizures, again without explanation despite doctors’ best efforts to establish a diagnosis. Although seizures, these examples are not necessarily epilepsy.
Epilepsy is a condition of spontaneously recurring seizures that are typically unprovoked and usually unpredictable. It can arise from a variety of underlying conditions and mechanisms, but the majority of cases in both adults and children have no known cause. Forty-five million people worldwide have epilepsy, and each year 125,000 to 150,000 people are newly diagnosed with the condition in the United States. About 30 percent of these are children.
A person’s lifetime risk of experiencing at least one unprovoked seizure is about 4 percent, and the likelihood of experiencing a seizure of any sort, including those brought on by fever or acute illness, rises to at least 9 percent. The risk that a person will develop epilepsy is about 3 percent. Although genetic diseases account for only 1 percent of epilepsy cases, inheritable factors are important in a much higher percentage, especially in children. As a general rule, however, even children born to a parent with epilepsy have no more than a 10 percent chance of developing the disorder.
Types of Seizures
As mentioned above, there are two major types of seizures: generalized and partial. In generalized seizures, abnormal firing of brain cells begins on both sides of the brain at about the same time. There are four common types of generalized seizures, each producing different symptoms.
Generalized tonic-clonic seizures are also called grand mal seizures. During such an episode, a person abruptly loses consciousness and falls to the ground. All body muscles can contract at once in a sustained fashion (tonic), or they can contract in a series of shorter rhythmic contractions (clonic), or both. Loss of bladder control is common, while loss of bowel control is rare. The seizure episode typically lasts for about 90 seconds and is followed by a brief period of deep stupor, then a longer period of lethargy and confusion. Many people experience headaches, muscle aches, lack of energy, inability to concentrate, and mood changes for up to 24 hours after the seizure.
Absence (petit mal) seizures occur mainly in children. They are characterized by sudden, momentary lapses in awareness, staring, rhythmic blinking, and often a few small jerks of the hands or arms. Most last for less than ten seconds. Because behavior and awareness return immediately to normal, a person usually has no idea that a seizure has occurred. Absence seizures can occur hundreds of times a day.
Myoclonic seizures are characterized by rapid, recurrent, brief muscle jerks. These jerks can range from small movements of the face or hands to massive spasms that can affect the head, arms, legs, and trunk of the body at the same time. The person does not experience a loss of consciousness. Although myoclonic seizures can happen at any time, they are most likely to occur shortly after a person wakes up or while falling asleep.
Atonic seizures, also called drop attacks, are characterized by a sudden loss of muscle tone, which may occur in one part of the body (such as a head drop) or be more generalized, which usually results in the person falling. Sometimes atonic seizures are preceded by a brief myoclonic seizure or a tonic spasm, which can add force to the fall. People experiencing this type of seizure are more apt to injure themselves. In partial or focal seizures, the abnormal firing of brain cells originates in only one region of the brain. This results in seizures that are categorized as either simple or complex. In addition, some partial seizures can evolve to affect the whole brain at once, a condition called secondarily generalized seizures.
Complex partial seizures are the most common type of seizures in adults. A person loses awareness of his or her surroundings, becoming unresponsive or only partially responsive. Some individuals may smack their lips, swallow repeatedly, or engage in other random and inappropriate activity, called automations. After the seizure the person may remain confused and disoriented for several minutes.
In simple partial seizures, the seizure-related discharge remains very localized, sometimes exquisitely so, and the person remains awake and aware. Symptoms vary greatly depending on the specific brain area involved. A person may perceive abnormal smells or a distorted environment, feel ready to throw up, experience feelings of unreality or detachment, have jerking movements in one area of the body, or experience unexplained emotions such as fear and rage. People come to recognize their seizures’ characteristic aura.
Doctors classify types of epilepsy as well. The major divisions depend, first, on whether the seizures are partial or generalized, and second, on their causes. Subtypes are defined by the person’s age and by the anatomic area in which the seizure originates. Other helpful data include the individual’s medical history, findings of neurological examinations, and results of electroencephalograms (EEGs), brain imaging studies, and other tests. Defining seizures within these epileptic syndromes helps doctors evaluate and treat people more specifically.
There are dozens of these epileptic syndromes. Some of the generalized epilepsy syndromes include infantile spasms (West syndrome), childhood absence epilepsy (petit mal), Lennox-Gastaut syndrome, and juvenile myoclonic epilepsy. Localized epilepsy syndromes include benign focal epilepsy of childhood (“rolandic epilepsy”), temporal lobe epilepsy (the most common type in adults), frontal lobe epilepsy, posttraumatic seizures and epilepsia partialis continua (unremitting seizures on one side of the body).
About 50 percent to 70 percent of people who develop epilepsy are eventually able to keep the disorder under control to their satisfaction. On the other hand, severe seizures that resist treatment, especially those that appear in early childhood, are associated with a shortened life span, risk of intellectual impairment, and a sharply reduced quality of life.
Diagnosis and Treatment
When doctors treat a person who has had a seizure, they have three goals:
- determining whether the person has epilepsy, or whether the seizure has some other cause that requires treatment
- classifying the seizure and type of epilepsy
- identifying, if possible, the underlying cause
A doctor first takes a medical history, which should include a detailed description of the person’s seizure. The doctor will also ask about relevant risk factors for epilepsy, such as a family history of seizures, severe head trauma, encephalitis, meningitis, or recent infection with fever. Most people with epilepsy have normal results on a physical examination, but in some the examination may uncover underlying neurological or systemic problems, of which the seizures are a symptom.
An EEG is usually the most important diagnostic test for epilepsy. An EEG can show specific types of brain wave patterns, helping physicians determine the precise type of seizure. Sometimes doctors need to do multiple tests to actually record a seizure while it happens.
In addition to the EEG, brain imaging studies, especially magnetic resonance imaging (MRI), can aid in the diagnosis. Some people may benefit from the other types of brain scans as well, including computed tomography (CT), positronemission tomography (PET), or single-photonemission computed tomography (SPECT). Other basic laboratory tests may include blood tests, a lumbar puncture (spinal tap) if physicians suspect meningitis or encephalitis, and toxicological screens for possible drug use or poisoning.
Treatment depends on the cause of the seizure. For those with a known cause (such as an infection, a blood vessel malformation in the brain, a brain tumor, or a severe chemical imbalance in the blood), the condition can often be corrected with medication or surgery.
Treating unprovoked seizures can be a bit trickier. About 25 percent of people with unprovoked seizures come to a doctor after a single attack, nearly always a generalized tonic-clonic seizure. Only about a quarter of these people later develop epilepsy. Providing medications to head off future seizures carries a risk of adverse effects, which approaches 30 percent after the initial treatment. Treating children with antiepileptic drugs raises additional issues because we do not know their long-term effects on brain development, learning, and behavior. Therefore, physicians do not treat many people after a first seizure. After a second seizure, however, a person’s risk of further seizures rises to 80 percent, and drug treatment is usually recommended.
There is no treatment currently available that can cure epilepsy. The treatment of epilepsy therefore has three main objectives:
- eliminating seizures, or reducing them as much as possible
- avoiding drug-related side effects
- helping the person restore or maintain a normal lifestyle
Of people with epilepsy, 60 percent to 70 percent achieve satisfactory control of their seizures with antiepileptic drugs, but fewer than 50 percent of adults achieve complete control without drug side effects.
Drugs used to suppress partial and secondarily generalized seizures include carbamazepine (Tegretol), phonation (Dilantin), and new medications such as oxcarbazepine (Trileptal), levetiracetam (Keppra), lamotrigine (Lamictal), topiramate (Topamax), and zonisamide (Zonegran). Valproate has been the drug of first choice for generalized-onset seizures, but many patients now have the option of taking lamotrigine or levetiracetam as well. All of these drugs can produce side effects, the most common of which are dose related and typically occur when the drug is first given or when the dose is increased. These side effects include nausea, sleepiness, mood changes, mental dulling, and dizziness. Other side effects indicating too high a dose include blurred or double vision, dizziness, slurred speech, and incoordination. Individuals and their doctors should be alert to these possible problems when starting a new dosage. All of these effects go away when the dosage is lowered. Side effects unrelated to the dosage, such as allergic reactions, can be severe but are rare.
Some people continue to have seizures despite drug treatment. When medication fails to control a person’s seizures, surgery is an option— but not a risk-free one. The decision to perform surgery depends on many factors, including the frequency and severity of seizures, the risk of brain damage or bodily injury from frequent seizures, the likelihood that the operation will control seizure episodes, the seizures’ effect on quality of life, and the person’s overall health. The most common type of epilepsy surgery is focal cortical resection: removing the small part of the brain in which the seizures originate so that the remaining portions can operate without disruption. People with focal seizures whose attacks cannot be controlled with drugs may benefit from this. Another surgical approach involves cutting the corpus callosum, thus disconnecting the brain’s two hemispheres; this does not cure a person of seizures but limits how the seizures can affect the whole brain and thus lead to injury.
Living with Epilepsy
Many people who take medication for epilepsy never experience another seizure. In fact, 60 percent to 70 percent of people with epilepsy will not have a seizure for five straight years at some point within ten years of being diagnosed. About half of these individuals eventually become seizure-free. A seizure-free period of three or four years may indicate that it is possible to reduce an individual’s medications. Some people may be able to eliminate them altogether. For others, however, seizures cannot be eliminated. The risk of continued seizures is higher for those who have partial seizures, an abnormal EEG, or associated mental retardation or cerebral palsy.
The episodic nature of the disease—periods of wellness punctuated by unpredictable attacks— can make epilepsy difficult to live with. Infrequent seizures may not severely restrict people’s lifestyle; you do not necessarily need to restrict work, school, and recreational activities. However, serious injury may result if a seizure occurs while a person is driving or operating dangerous equipment, so people with poorly controlled seizure disorders should not perform these activities. Accidental death, especially by drowning, is also more likely in people with epilepsy. Avoid factors that increase the likelihood of a seizure’s occurring, such as lack of sleep, use of alcohol and other drugs, and stress.
Despite dramatic scientific advances, we have many unanswered questions about seizures: why they begin, how trauma can produce them years later, how genetic factors influence seizures, and what factors make brain cells susceptible. Research to provide answers to these questions is under way and may lead eventually to the cure.
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