Seizure Disorder

Definition

A seizure is a sudden disruption of the brain's normal electrical activity accompanied by altered consciousness and/or other neurological and behavioral manifestations. Epilepsy is a condition characterized by recurrent seizures that may include repetitive muscle jerking called convulsions.

Description

There are more than 20 different seizure disorders. One in ten Americans will have a seizure at some time, and at least 200,000 have at least one seizure a month.

Epilepsy affects 1-2% of the population of the United States. Although epilepsy is as common in adults over 60 as in children under 10, 25% of all cases develop before the age of five. One in every two cases develops before the age of 25. About 125,000 new cases of epilepsy are diagnosed each year, and a significant number of children and adults that have not been diagnosed or treated have epilepsy.

Most seizures are benign, but a seizure that lasts a long time can lead to status epilepticus, a life-threatening condition characterized by continuous seizures, sustained loss of consciousness, and respiratory distress. Non-convulsive epilepsy can impair physical coordination, vision, and other senses. Undiagnosed seizures can lead to conditions that are more serious and more difficult to manage.

Types of seizures

Generalized epileptic seizures occur when electrical abnormalities exist throughout the brain. A partial seizure does not involve the entire brain. A partial seizure begins in an area called an epileptic focus, but may spread to other parts of the brain and cause a generalized seizure. Some people who have epilepsy have more than one type of seizure.

Motor attacks cause parts of the body to jerk repeatedly. A motor attack usually lasts less than an hour and may last only a few minutes. Sensory seizures begin with numbness or tingling in one area. The sensation may move along one side of the body or the back before subsiding.

Visual seizures, which affect the area of the brain that controls sight, cause people to see things that are not there. Auditory seizures affect the part of the brain that controls hearing and cause the patient to imagine voices, music, and other sounds. Other types of seizures can cause confusion, upset stomach, or emotional distress.

GENERALIZED SEIZURES. A generalized tonic-clonic (grand-mal) seizure begins with a loud cry before the person having the seizure loses consciousness and falls to the ground. The muscles become rigid for about 30 seconds during the tonic phase of the seizure and alternately contract and relax during the clonic phase, which lasts 30-60 seconds. The skin sometimes acquires a bluish tint and the person may bite his tongue, lose bowel or bladder control, or have trouble breathing.

A grand mal seizure lasts between two and five minutes, and the person may be confused or have trouble talking when he regains consciousness (postictal state). He may complain of head or muscle aches, or weakness in his arms or legs before falling into a deep sleep.

PRIMARY GENERALIZED SEIZURES. A primary generalized seizure occurs when electrical discharges begin in both halves (hemispheres) of the brain at the same time. Primary generalized seizures are more likely to be major motor attacks than to be absence seizures.

ABSENCE SEIZURES. Absence (petit mal) seizures generally begin at about the age of four and stop by the time the child becomes an adolescent.

Absence seizures usually begin with a brief loss of consciousness and last between one and 10 seconds. A person having a petit mal seizure becomes very quiet and may blink, stare blankly, roll his eyes, or move his lips. A petit mal seizure lasts 15-20 seconds. When it ends, the person who had the seizure resumes whatever he was doing before the seizure began. He will not remember the seizure and may not realize that anything unusual has happened. Untreated, petit mal seizures can recur as many as 100 times a day and may progress to grand mal seizures.

MYOCLONIC SEIZURES. Myoclonic seizures are characterized by brief, involuntary spasms of the tongue or muscles of the face, arms, or legs. Myoclonic seizures are most apt to occur when waking after a night's sleep.

A jacksonian seizure is a partial seizure characterized by tingling, stiffening, or jerking of an arm or leg. Loss of consciousness is rare. The seizure may progress in characteristic fashion along the limb.

Limp posture and a brief period of unconsciousness are features of akinetic seizures, which occur in young children. Akinetic seizures, which cause the child to fall, also are called drop attacks.

PARTIAL SEIZURES. Simple partial seizures do not spread from the focal area where they arise. Symptoms are determined by the part of the brain affected. The patient usually remains conscious during the seizure and can later describe it in detail. In 2003, it was reported that people who experience partial seizures are twice as likely to have sleep disturbances as people their same age and gender.

COMPLEX PARTIAL SEIZURES. A distinctive smell, taste, or other unusual sensation (aura) may signal the start of a complex partial seizure.

Complex partial seizures start as simple partial seizures, but move beyond the focal area and cause loss of consciousness. Complex partial seizures can become major motor seizures. Although a person having a complex partial seizure may not seem to be unconscious, he does not know what is happening and may behave inappropriately. He will not remember the seizure, but may seem confused or intoxicated for a few minutes after it ends.

Causes and symptoms

The origin of 50-70% of all cases of epilepsy is unknown. Epilepsy sometimes is the result of trauma at birth. Such causes include insufficient oxygen to the brain; head injury ; heavy bleeding or incompatibility between a woman's blood and the blood of her newborn baby; and infection immediately before, after, or at the time of birth.

Other causes of epilepsy include:

• head trauma resulting from a car accident, gunshot wound, or other injury.
• alcoholism
• brain abscess or inflammation of membranes covering the brain or spinal cord
• phenylketonuria (PKU, a disease that is present at birth, often is characterized by seizures, and can result in mental retardation ) and other inherited disorders
• infectious diseases like measles, mumps, and diphtheria
• degenerative disease
• lead poisoning, mercury poisoning, carbon monoxide poisoning, or ingestion of some other poisonous substance
• genetic factors

Status epilepticus, a condition in which a person suffers from continuous seizures and may have trouble breathing, can be caused by:

• suddenly discontinuing anti-seizure medication
• hypoxic or metabolic encephalopathy (brain disease resulting from lack of oxygen or malfunctioning of other physical or chemical processes)
• acute head injury
• blood infection caused by inflammation of the brain or the membranes that cover it

Diagnosis

Personal and family medical history, description of seizure activity, and physical and neurological examinations help primary care physicians, neurologists, and epileptologists diagnose this disorder. Doctors rule out conditions that cause symptoms that resemble epilepsy, including small strokes (transient ischemic attacks, or TIAs), fainting, (syncope), pseudoseizures, and sleep attacks (narcolepsy.)

Neuropsychological testing uncovers learning or memory problems. Neuroimaging provides views of brain areas involved in seizure activity.

The electroencephalogram (EEG) is the main test used to diagnose epilepsy. EEGs use electrodes placed on or within the skull to record the brain's electrical activity and pinpoint the exact location of abnormal discharges.

The patient may be asked to remain motionless during a short-term EEG or to go about his normal activities during extended monitoring. Some patients are deprived of sleep or exposed to seizure triggers, such as rapid, deep breathing (hyperventilation) or flashing lights (photic stimulation). In some cases, people may be hospitalized for EEG monitorings that can last as long as two weeks. Video EEGs also document what the patient was doing when the seizure occurred and how the seizure changed his behavior.

Other techniques used to diagnose epilepsy include:

• Magnetic resonance imaging (MRI), which provides clear, detailed images of the brain. Functional MRI (fMRI), performed while the patient does various tasks, can measure shifts in electrical intensity and blood flow and indicate which brain region each activity affects.
• Positron emission tomography (PET ) and single photon emission tomography (SPECT) monitor blood flow and chemical activity in the brain area being tested. PET and SPECT are very effective in locating the brain region where metabolic changes take place between seizures.

Treatment

The goal of epilepsy treatment is to eliminate seizures or make the symptoms less frequent and less severe. Long-term anticonvulsant drug therapy is the most common form of epilepsy treatment.

Medication

A combination of drugs may be needed to control some symptoms, but most patients who have epilepsy take one of the following medications:

• Dilantin (phenytoin)
• Tegretol (carbamazepine)
• Barbita (phenobarbital)
• Mysoline (primidone)
• Depakene (valproic acid, sodium valproate)
• Klonopin (clonazepam)
• Zarontin (ethosuximide).

Dilantin, Tegretol, Barbita, and Mysoline are used to manage or control generalized tonic-clonic and complex partial seizures. Depakene, Klonopin, and Zarontin are prescribed for patients who have absence seizures.

Neurontin (gabapentin), Lamictal (lamotrigine), and topiramate (Topamax) are among the medications more recently approved in the United States to treat adults who have partial seizures or partial and grand mal seizures. Another new medication called Levetiracetam (Keppra) has been approved and shows particularly good results in reducing partial seizures among elderly patients with few side effects. This is important, because elderly patients often have other conditions and must take other medications that might interact with seizure medications. In 2003, Keppra's manufacturer was working on a new antiepilectic drug from the same chemical family as Keppra that should be more potent and effective. Available medications frequently change, and it the physician will determine the best treatment for an individual patient. A 2003 report found that monotherapy, or using just one medication rather than a combination, works better for most patients. The less complicated the treatment, the more likely the patient will comply and better manager the seizure disorder.

Even a patient whose seizures are well controlled should have regular blood tests to measure levels of anti-seizure medication in his system and to check to see if the medication is causing any changes in his blood or liver. A doctor should be notified if any signs of drug toxicity appear, including uncontrolled eye movements; sluggishness, dizziness, or hyperactivity; inability to see clearly or speak distinctly; nausea or vomiting ; or sleep problems.

Status epilepticus requires emergency treatment, usually with Valium (Ativan), Dilantin, or Barbita. An intravenous dextrose (sugar) solution is given to patients whose condition is due to low blood sugar, and a vitamin B₁ preparation is administered intravenously when status epilepticus results from chronic alcohol withdrawal. Because dextrose and thiamine are essentially harmless and because delay in treatment can be disastrous, these medications are given routinely, as it is usually difficult to obtain an adequate history from a patient suffering from status epilepticus.

Intractable seizures are seizures that cannot be controlled with medication or without sedation or other unacceptable side effects. Surgery may be used to eliminate or control intractable seizures.

Surgery

Surgery can be used to treat patients whose intractable seizures stem from small focal lesions that can be removed without endangering the patient, changing the patient's personality, dulling the patient's senses, or reducing the patient's ability to function.

Each year, as many as 5,000 new patients may become suitable candidates for surgery, which most often is performed at a comprehensive epilepsy center. Potential surgical candidates include patients with:

• partial seizures and secondarily generalized seizures (attacks that begin in one area and spread to both sides of the brain)
• seizures and childhood paralysis on one side of the body (hemiplegia)
• complex partial seizures originating in the temporal lobe (the part of the brain associated with speech, hearing, and smell) or other focal seizures. (However, the risk of surgery involving the speech centers is that the patient will lose speech function.)
• Generalized myoclonic seizures or generalized seizures featuring temporary paralysis (akinetic) or loss of muscle tone (atonal)

A physical examination is conducted to verify that a patient's seizures are caused by epilepsy, and surgery is not used to treat patients with severe psychiatric disturbances or medical problems that raise risk factors to unacceptable levels.

Surgery is never indicated unless:

• the best available anti-seizure medications have failed to control the patient's symptoms satisfactorily
• the origin of the patient's seizures has been precisely located
• there is good reason to believe that surgery will significantly improve the patient's health and quality of life.

Every patient considering epilepsy surgery is carefully evaluated by one or more neurologists, neurosurgeons, neuropsychologists, and/or social workers. A psychiatrist, chaplain, or other spiritual advisor may help the patient and his family cope with the stress that occurs during and after the selection process.

TYPES OF SURGERY. Surgical techniques used to treat intractable epilepsy include:

• Lesionectomy. Removing the lesion (diseased brain tissue) and some surrounding brain tissue is very effective in controlling seizures. Lesionectomy is generally more successful than surgery performed on patients whose seizures are not caused by clearly defined lesions, but removing only part of the lesion lessens the effectiveness of the procedure.
• Temporal resections. Removing part of the temporal lobe and the part of the brain associated with feelings, memory, and emotions (the hippocampus) provides good or excellent seizure control in 75-80% of properly selected patients with appropriate types of temporal lobe epilepsy. Some patients experience post-operative speech and memory problems.
• Extra-temporal resection. This procedure involves removing some or all of the frontal lobe, the part of the brain directly behind the forehead. The frontal lobe helps regulate movement, planning, judgment, and personality, and special care must be taken to prevent post-operative problems with movement and speech. Extra-temporal resection is most successful in patients whose seizures are not widespread.
• Hemispherectomy. This method of removing brain tissue is restricted to patients with severe epilepsy and abnormal discharges that often extend from one side of the brain to the other. Hemispherectomies most often are performed on infants or young children who have had an extensive brain disease or disorder since birth or from a very young age.
• Corpus callosotomy. This procedure, an alternative to hemispherectomy in patients with congenital hemiplegia, removes some or all of the white matter that separates the two halves of the brain. Corpus callosotomy is performed almost exclusively on children who are frequently injured during falls caused by seizures. If removing two-thirds of the corpus callosum doesn't produce lasting improvement in the patient's condition, the remaining one-third will be removed during another operation.
• Multiple subpial transection. This procedure is used to control the spread of seizures that originate in or affect the "eloquent" cortex, the area of the brain responsible for complex thought and reasoning.

Other forms of treatment

KETOGENIC DIET. A special high-fat, low-protein, low-carbohydrate diet sometimes is used to treat patients whose severe seizures have not responded to other treatment. Calculated according to age, height, and weight, the ketogenic diet induces mild starvation and dehydration. This forces the body to create an excessive supply of ketones, natural chemicals with seizure-suppressing properties.

The goal of this controversial approach is to maintain or improve seizure control while reducing medication. The ketogenic diet works best with children between the ages of one and 10. It is introduced over a period of several days, and most children are hospitalized during the early stages of treatment.

If a child following this diet remains seizure-free for at least six months, increased amounts of carbohydrates and protein gradually are added. If the child shows no improvement after three months, the diet is gradually discontinued. A 2003 study of the diet and its effect on growth noted that If used, clinicians should recommend adequate intake of energy and protein and a higher proportion of unsaturated to saturated dietary fats. The report also recommended use of vitamin and mineral supplements with the diet.

Introduced in the 1920s, the ketogenic diet has had limited, short-term success in controlling seizure activity. Its use exposes patients to such potentially harmful side effects as:

• staphylococcal infections
• atunted or delayed growth
• low blood sugar (hypoglycemia )
• excess fat in the blood (hyperlipidemia)
• disease resulting from calcium deposits in the urinary tract (urolithiasis)
• disease of the optic nerve (optic neuropathy)

VAGUS NERVE STIMULATION. The United States Food and Drug Administration (FDA) has approved the use of vagus nerve stimulation (VNS) in patients over the age of 16 who have intractable partial seizures. This non-surgical procedure uses a pacemaker-like device implanted under the skin in the upper left chest, to provide intermittent stimulation to the vagus nerve. Stretching from the side of the neck into the brain, the vagus nerve affects swallowing, speech, breathing, and many other functions, and VNS may prevent or shorten some seizures. A 2003 report said that this treatment has reduced partial seizures by 50% or more in about one-third of patient with no adverse effects.

First aid for seizures

A person having a seizure should not be restrained, but sharp or dangerous objects should be moved out of reach. Anyone having a complex partial seizure can be warned away from danger by someone calling his/her name in a clear, calm voice.

A person having a grand mal seizure should be helped to lie down. Tight clothing should be loosened. A soft, flat object like a towel or the palm of a hand should be placed under the person's head. Forcing a hard object into the mouth of someone having a grand mal seizure could cause injuries or breathing problems. If the person's mouth is open, placing a folded cloth or other soft object between his teeth will protect his tongue. Turning his head to the side will help him breathe. After a grand mal seizure has ended, the person who had the seizure should be told what has happened and reminded of where he is.

Alternative treatment

Stress increases seizure activity in 30% of people who have epilepsy. Relaxation techniques can provide some sense of control over the disorder, but they should never be used instead of anti-seizure medication or used without the approval of the patient's doctor. Yoga, meditation, and favorite pastimes help some people relax and manage stress more successfully. Biofeedback can teach adults and older adolescents how to recognize an aura and what to do to stop its spread. Children under 14 are not usually able to understand and apply principles of biofeedback. Acupuncture treatments (acupuncture needles inserted for a few minutes or left in place for as long as 30 minutes) make some people feel pleasantly relaxed. Acupressure can have the same effect on children or on adults who dislike needles.

Aromatherapy involves mixing aromatic plant oils into water or other oils and massaging them into the skin or using a special burner to waft their fragrance throughout the room. Aromatherapy oils affect the body and the brain, and undiluted oils should never be applied directly to the skin. Ylang ylang, chamomile, or lavender can create a soothing mood. People who have epilepsy should not use rosemary, hyssop, sage or sweet fennel, which seem to make the brain more alert.

Dietary changes that emphasize whole foods and eliminate processed foods may be helpful. Homeopathic therapy also can work for people with seizures, especially constitutional homeopathic treatment that acts at the deepest levels to address the needs of the individual person.

Prognosis

People who have epilepsy have a higher-than-average rate of suicide ; sudden, unexplained death ; and drowning and other accidental fatalities.

Benign focal epilepsy of childhood and some absence seizures may disappear in time, but remission is unlikely if seizures occur several times a day, several times in a 48-hour period, or more frequently than in the past.

Seizures that occur repeatedly over time and always involve the same symptoms are called stereotypic seizures. The probability that stereotypic seizures will abate is poor.

About 85% of all seizure disorders can be partially or completely controlled if the patient takes anti-seizure medication according to directions; avoids seizure-inducing sights, sounds, and other triggers; gets enough sleep; and eats regular, balanced meals.

Anyone who has epilepsy should wear a bracelet or necklace identifying his seizure disorder and listing the medication he takes.

Prevention

Eating properly, getting enough sleep, and controlling stress and fevers can help prevent seizures. A person who has epilepsy should be careful not to hyperventilate. A person who experiences an aura should find a safe place to lie down and stay there until the seizure passes. Anticonvulsant medications should not be stopped suddenly and, if other medications are prescribed or discontinued, the doctor treating the seizures should be notified. In some conditions, such as severe head injury, brain surgery, or subarachnoid hemorrhage, anticonvulsant medications may be given to the patient to prevent seizures.

Resources

PERIODICALS

Dilorio, Colleen, et al. "The Epilelpsy Medication and Treatment Complexity Index: Reliability and Validity Testing." Journal of Neuroscience Nursing June 2003: 155-158.

"Epilepsy Surgery and Vagus Nerve Stimulation Are Effective When Drugs Fail." Medical Devices & Surgical Technology Week May 4, 2003: 33.

Finn, Robert. "Partial Seizures Double Risk of Sleep Disturbances (Consider in Diagnosis, Management)." Clinical Psychiatry News June 2003: 36-41.

Liu, Yeou-Mei Christiana, et al. "A Prospetive Study: Growth and Nutritional Status of Children Treated With the Ketogenic Diet." Journal of the American Dietetic Association June 2003: 707.

"New Drug Candidate Shows Promise." Clinical Trials Week April 7, 2003: 26.

ORGANIZATIONS

American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507. (860) 586-7505. 〈http://www.aesnet.org〉.

Epilepsy Concern International Service Group. 1282 Wynnewood Drive, West Palm Beach, FL 33417. (407) 683-0044.

Epilepsy Foundation of America. 4351 Garden City Drive, Landover, MD 20785. (800) 332-1000. 〈http://www.efa.org〉.

Epilepsy Information Service. (800) 642-0500.

KEY TERMS

Acupressure— Needleless acupuncture.

Acupuncture— An ancient Chinese method of relieving pain or treating illness by piercing specific areas of the body with fine needles.

Biofeedback— A learning technique that helps individuals influence automatic body functions.

Epileptologist— A physician who specializes in the treatment of epilepsy.

Seizures

Definition

A seizure is a sudden change in behavior characterized by changes in sensory perception (sense of feeling) or motor activity (movement) due to an abnormal firing of nerve cells in the brain . Epilepsy is a condition characterized by recurrent seizures that may include repetitive muscle jerking called convulsions.

Description

Seizure disorders and their classification date back to the earliest medical literature accounts in history. In 1964, the Commission on Classification and Terminology of the International League Against Epilepsy (ILAE) devised the first official classification of seizures, which was revised again in 1981. This classification is accepted worldwide and is based on electroencephalographic (EEG) studies. Based on this system, seizures can be classified as either focal or generalized. Each of these categories can also be further subdivided.

Focal seizures

A focal (partial) seizure develops when a limited, confined population of nerve cells fire their impulses abnormally on one hemisphere of the brain. (The brain has two portions or cerebral hemispheres—the right and left hemispheres.) Focal seizures are divided into simple or complex based on the level of consciousness (wakefulness) during an attack. Simple partial seizures occur in patients who are conscious, whereas complex partial seizures demonstrate impaired levels of consciousness.

Generalized seizures

A generalized seizure results from initial abnormal firing of brain nerve cells throughout both left and right hemispheres. Generalized seizures can be classified as follows:

• Tonic-clonic seizures: This is the most common type among all age groups and is categorized into several phases beginning with vague symptoms hours or days before an attack. These seizures are sometimes called grand mal seizures.
• Tonic seizures: These are typically characterized by a sustained nonvibratory contraction of muscles in the legs and arms. Consciousness is also impaired during these episodes.
• Atonic seizures (also called "drop attacks"): These are characterized by sudden, limp posture and a brief period of unconsciousness and last for one to two seconds.
• Clonic seizures: These are characterized by a rapid loss of consciousness with loss of muscle tone, tonic spasm, and jerks. The muscles become rigid for about 30 seconds during the tonic phase of the seizure and alternately contract and relax during the clonic phase, which lasts 30–60 seconds.
• Absence seizures: These are subdivided into typical and atypical forms based on duration of attack and level of consciousness. Absence (petit mal) seizures generally begin at about the age of four and stop by the time the child becomes an adolescent. They usually begin with a brief loss of consciousness and last between one and 10 seconds. People having a petit mal seizure become very quiet and may blink, stare blankly, roll their eyes, or move their lips. A petit mal seizure lasts 15–20 seconds. When it ends, the individual resumes whatever he or she was doing before the seizure began, will not remember the seizure, and may not realize that anything unusual happened. Untreated, petit mal seizures can recur as many as 100 times a day and may progress to grand mal seizures.
• Myoclonic seizures: These are characterized by rapid muscular contractions accompanied with jerks in facial and pelvic muscles.

Subcategories are commonly diagnosed based on EEG results. Terminology for classification in infants and newborns is still controversial.

Causes and symptoms

Causes

Simple partial seizures can be caused by congenital abnormalities (abnormalities present at birth), tumor growths, head trauma, stroke , and infections in the brain or nearby structures. Generalized tonic-clonic seizures are associated with drug and alcohol abuse, and low levels of blood glucose (blood sugar) and sodium. Certain psychiatric medications, antihistamines, and even antibiotics can precipitate tonic-clonic seizures. Absence seizures are implicated with an abnormal imbalance of certain chemicals in the brain that modulate nerve cell activity (one of these neurotransmitters is called GABA, which functions as an inhibitor). Myoclonic seizures are commonly diagnosed in newborns and children.

Symptoms

Symptoms for the different types of seizures are specific.

Partial seizures

SIMPLE PARTIAL SEIZURES. Multiple signs and symptoms may be present during a single simple partial seizure. These symptoms include specific muscles tensing and then alternately contracting and relaxing, speech arrest, vocalizations, and involuntary turning of the eyes or head. There could be changes in vision, hearing, balance, taste, and smell. Additionally, patients with simple partial seizures may have a sensation in the abdomen, sweating, paleness, flushing, hair follicles standing up (piloerection), and dilated pupils (the dark center in the eye enlarges). Seizures with psychological symptoms include thinking disturbances and hallucinations , or illusions of memory, sound, sight, time, and self-image.

COMPLEX PARTIAL SEIZURES. Complex partial seizures often begin with a motionless stare or arrest of activity; this is followed by a series of involuntary movements, speech disturbances, and eye movements.

Generalized seizures

Generalized seizures have a more complex set of signs and symptoms.

TONIC-CLONIC SEIZURES. Tonic-clonic seizures usually have vague prodromal (pre-attack) symptoms that can start hours or days before a seizure. These symptoms include anxiety, mood changes, irritability, weakness, dizziness, lightheadedness, and changes in appetite. The tonic phases may be preceded with brief (lasting only a few seconds in duration) muscle contractions on both sides of affected muscle groups. The tonic phase typically begins with a brief flexing of trunk muscles, upward movement of the eyes, and pupil dilation. Patients usually emit a characteristic vocalization. This sound is caused by contraction of trunk muscles that forces air from the lungs across spasmodic (abnormally tensed) throat muscles. This is followed by a very short period (10–15 seconds) of general muscle relaxation. The clonic phase consists of muscular contractions with alternating periods of no movements (muscle atonia) of gradually increasing duration until abnormal muscular contractions stop. Tonic-clonic seizures end in a final generalized spasm. The affected person can lose consciousness during tonic and clonic phases of seizure.

Tonic-clonic seizures can also produce chemical changes in the body. Patients commonly experience lowered carbon dioxide (hypocarbia) due to breathing alterations, increased blood glucose (blood sugar), and elevated level of a hormone called prolactin. Once the affected person regains consciousness, he or she is usually weak, and has headache and muscle pain. Tonic-clonic seizures can cause serious medical problems such as trauma to the head and mouth, fractures in the spinal column, pulmonary edema (water in the lungs), aspiration pneumonia (a pneumonia caused by a foreign body being lodged in the lungs), and sudden death. Attacks are generally one minute in duration.

TONIC SEIZURES. Tonic and atonic seizures have distinct differences but are often present in the same patient. Tonic seizures are characterized by nonvibratory muscle contractions, usually involving flexing of arms and relaxing or flexing of legs. The seizure usually lasts less than 10 seconds but may be as long as one minute. Tonic seizures are usually abrupt and patients lose consciousness. Tonic seizures commonly occur during nonrapid eye movement (nonREM) sleep and drowsiness. Tonic seizures that occur during wakeful states commonly produce physical injuries due to abrupt, unexpected falls.

ATONIC SEIZURES. Atonic seizures, also called "drop attacks," are abrupt, with loss of muscle tone lasting one to two seconds, but with rapid recovery. Consciousness is usually impaired. The rapid loss of muscular tone could be limited to head and neck muscles, resulting in head drop, or it may be more extensive involving muscles for balance, causing unexpected falls with physical injury.

CLONIC SEIZURES. Generalized clonic seizures are rare and seen typically in children with elevated fever. These seizures are characterized by a rapid loss of consciousness, decreased muscle tone, and generalized spasm that is followed by jerky movements.

ABSENCE SEIZURES. Absence seizures are classified as either typical or atypical. The typical absence seizure is characterized by unresponsiveness and behavioral arrest, abnormal muscular movements of the face and eyelids, and lasts less than 10 seconds. In atypical absence seizures, the affected person is generally more conscious, the seizures begin and end more gradually, and do not exceed 10 seconds in duration.

MYOCLONIC SEIZURES. Myoclonic seizures commonly exhibit rapid muscular contractions. Myoclonic seizures are seen in newborns and children who have either symptomatic or idiopathic (cause is unknown) epilepsy.

Demographics

Approximately 1.5 million persons in the United States suffer from a type of seizure disorder. The annual incidence (number of new cases) for all types of seizures is 1.2 per 1,000 and, for recurrent seizures, is 0.54 per 1,000. Isolated seizures may occur in up to 10% of the general population. Approximately 10–20% of all patients have intractable epilepsy (epilepsy that is difficult to manage or treat). It is estimated that 45 million people in the world are affected by seizures. Seizures affect males and females equally and can occur among all age groups. There seems to be a strong genetic correlation, since seizures are three times more prevalent among close relatives than they are in the general population.

Children delivered in the breech position have increased prevalence (3.8%) of seizures when compared to infants delivered in the normal delivery position (2.2%). Seizures caused by fever have a recurrence rate of 51% if the attack occurred in the first year of life, whereas recurrence rate is decreased to 25% if the seizure took place during the second year. Approximately 88% of children who experience seizures caused by fever in the first two years experience recurrence.

Approximately 45 million people worldwide are affected by epilepsy. The incidence is highest among young children and the elderly. High-risk groups include persons with a previous history of brain injury or lesions.

Diagnosis

Patients seeking help for seizures should first undergo an EEG that records brain-wave patterns emitted between nerve cells. Electrodes are placed on the head, sometimes for 24 hours, to monitor brain-wave activity and detect both normal and abnormal impulses. Imaging studies such as magnetic resonance imaging (MRI) and computed axial tomography (CAT)—that take still "pictures"—are useful in detecting abnormalities in the temporal lobes (parts of the brain associated with hearing) or for helping diagnose tonic-clonic seizures. A complete blood count (CBC) can be helpful in determining whether a seizure is caused by a neurological infection, which is typically accompanied by high fever. If drugs or toxins in the blood are suspected to be the cause of the seizure(s), blood and urine screening tests for these compounds may be necessary.

Antiseizure medication can be altered by many commonly used medications such as sulfa drugs, erythromycin, warfarin, and cimetidine. Pregnancy may also decrease serum concentration of antiseizure medications; therefore, frequent monitoring and dose adjustments are vital to maintain appropriate blood concentrations of the antiseizure medication—known as the therapeutic blood concentration. Diagnosis requires a detailed and accurate history, and a physical examination is important since this may help identify neurological or systemic causes. In cases in which a central nervous system (CNS) infection(i.e., meningitis or encephalitis) is suspected, a lumbar puncture (or spinal tap) can help detect an increase in immune cells (white blood cells) that develop to fight the specific infection. (A lumbar puncture is removing from the spinal chord, by syringe, of a small amount of cerebrospinal fluid—the fluid that bathes and nourishes the brain and spinal cord.)

Treatments

Treatment is targeted primarily to:

• assist the patient in adjusting psychologically to the diagnosis and in maintaining as normal a lifestyle as possible
• reduce or eliminate seizure occurrence
• avoid side effects of long-term drug treatment

Simple and complex partial seizures respond to drugs such as carbamazepine , valproic acid (valproate), phenytoin, gabapentin , tiagabine, lamotrigine , and topiramate. Tonic-clonic seizures tend to respond to valproate, carbamazepine, phenytoin, and lamotrigine. Absence seizures seem to be sensitive to ethosuximide, valproate, and lamotrigine. Myoclonic seizures can be treated with valproate and clonazepam . Tonic seizures seem to respond favorably to valproate, felbamate, and clonazepam.

People treated with a class of medications called barbiturates (Mysoline, Mebral, phenobarbital) have adverse cognitive (thinking) effects. These cognitive effects can include decreased general intelligence, attention, memory, problem solving, motor speed, and visual motor functions. The drug phenytoin (Dilantin) can adversely affect speed of response, memory, and attention. Other medications used for treatment of seizures do not have substantial cognitive impairment.

Surgical treatment may be considered when medications fail. Advances in medical sciences and techniques have improved methods of identifying the parts of the brain that generate abnormal discharge of nerve impulses. Surgical treatment now accounts for about 5,000 procedures annually. The most common type of surgery is the focal cortical resection. In this procedure, a small part of the brain responsible for causing the seizures is removed. Surgical intervention may be considered a feasible treatment option if:

• the site of seizures is identifiable and localized
• surgery can remove the seizure-generating (epileptogenic) area
• surgical procedure will not cause damage to nearby areas

Prognosis

About 30% of patients with severe seizures (starting in early childhood), continue to have attacks and usually never achieve a remission state. In the United States, the prevalence of treatment-resistant seizures is about one to two per 1,000 persons. About 60–70% of persons achieve a five-year remission within 10 years of initial diagnosis. Approximately half of these patients become seizure-free. Usually the prognosis is better if seizures can be controlled by one medication, the frequency of seizures decreases, and there is a normal EEG and neurological examination prior to medication cessation.

People affected by seizure have increased death rates compared with the general population. Patients who have seizures of unknown cause have an increased chance of dying due to accidents (primarily drowning). Other causes of seizure-associated death include abnormal heart rhythms, water in the lungs, or heart attack.

Prevention

There are no gold standard recommendations for prevention, since seizures can be caused by genetic factors, blood abnormalities, many medications, illicit drugs, infection, neurologic conditions, and other systemic diseases. If a person has had a previous attack or has a genetic propensity, care is advised when receiving medical treatment or if diagnosed with an illness correlated with possible seizure development.

See also Computed tomography (CAT); Electroencephalography (EEG); Magnetic resonance imaging (MRI); Substance abuse and related disorders

Resources

BOOKS

Goldman, Lee, and others. Cecil Textbook of Medicine. 21st edition. Philadelphia: W. B. Saunders Company, 2000.

Goroll, Allan H. Primary Care Medicine. 4th edition. Philadelphia: Lippincott Williams and Wilkins, 2000.

Goetz, Christopher G . Textbook of Clinical Neurology. 1st edition. Philadelphia: W. B. Saunders Company, 1999.

PERIODICALS

Dodrill, C. R., C. G. Matthew. "The role of Neuropsychology in the Assessment and Treatment of Persons with Epilepsy." American Psychologist September 1992.

ORGANIZATIONS

Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. Phone: (800) 332-1000. Web site: <http://www.efa.org/>.

Laith Farid Gulli, M.D.

Alfredo Mori, M.D., FACEM

Seizure disorder

Definition

A seizure is a sudden disruption of the brain's normal electrical activity accompanied by altered consciousness and/or other neurological and behavioral manifestations. Epilepsy is a disorder of the brain characterized by recurrent seizures that may include repetitive muscle jerking called convulsions.

Description

There are more than 20 different seizure disorders, although epilepsy is the most familiar. Most seizures are benign, but a seizure that lasts a long time can lead to status epilepticus, a life-threatening condition characterized by continuous seizures, sustained loss of consciousness, and respiratory distress. In addition, non-convulsive epilepsy can impair physical coordination, vision, and other senses. Undiagnosed seizures can lead to conditions that are more serious and more difficult to manage. Ten percent of Americans have a seizure at some time in their lives.

Generalized seizures

A generalized seizure occurs when electrical abnormalities exist throughout the brain. A generalized tonic-clonic (grand-mal) seizure typically begins with a loud cry before the individual having the seizure loses consciousness and falls to the ground. The muscles become rigid for about 30 seconds during the tonic phase of the seizure and alternately contract and relax during the clonic phase, which lasts 30 to 60 seconds. The skin sometimes acquires a bluish tint, and the person may bite the tongue, lose bowel or bladder control, or have trouble breathing.

A grand mal seizure lasts two to five minutes, and the person may be confused or have trouble talking after regaining consciousness (post-ictal state). The individual may complain of head or muscle aches or weakness in the arms or legs before falling into a deep sleep .

Primary generalized seizures

A primary generalized seizure occurs when electrical discharges begin in both halves (hemispheres) of the brain at the same time. Primary generalized seizures are more likely to be major motor attacks than to be absence seizures. Motor attacks cause parts of the body to jerk repeatedly. A motor attack usually lasts less than an hour and may last only a few minutes.

Absence seizures

Absence (petit mal) seizures generally begin at about the age of four and stop by the time the child becomes an adolescent. Absence seizures usually begin with a brief loss of consciousness and last 15 to 20 seconds. An individual having a petit mal seizure becomes very quiet and may blink, stare blankly, roll the eyes, or move the lips. When a petit mal seizure ends, individual resumes whatever he or she was doing before the seizure began and does not remember the seizure. The individual may not realize that anything unusual has happened. Untreated, petit mal seizures can recur as many as 100 times a day and may progress to grand mal seizures.

Myoclonic seizures

Myoclonic seizures are characterized by brief, involuntary spasms of the tongue or muscles of the face, arms, or legs. Myoclonic seizures are most apt to occur when waking after a night's sleep.

A Jacksonian seizure is a partial seizure characterized by tingling, stiffening, or jerking of an arm or leg. Loss of consciousness is rare. The seizure may progress in characteristic fashion along the limb.

Limp posture and a brief period of unconsciousness are features of akinetic seizures. These occur in young children. Akinetic seizures, which cause the child to fall, also are called drop attacks.

Partial seizures

Simple partial seizures do not spread from the focal area of the brain where they arise. Symptoms are determined by the part of the brain affected. The individual usually remains conscious during the seizure and can later describe it in detail. In 2003, it was reported that people who experience partial seizures are twice as likely to have sleep disturbances as people their same age and gender who do not have seizures.

Complex partial seizures

A distinctive smell, taste, or other unusual sensation (aura) may signal the start of a complex partial seizure. Complex partial seizures start as simple partial seizures but move beyond the focal area of the brain and cause loss of consciousness. Complex partial seizures can become major motor seizures. Although individuals having a complex partial seizure may not seem to be unconscious, they do not know what is happening and may behave inappropriately. They will not remember the seizure but may seem confused or intoxicated for a few minutes after it ends.

Demographics

One in ten Americans has a seizure during their lifetime, and at least 200,000 Americans have at least one seizure a month. Epilepsy affects 2.5 million Americans of all ages, and of those, 25 percent of all cases develop before the age of five. Some 181,000 new cases are diagnosed annually and 45,000 of them are children under the age of 15. Though the incidence rate for children is in the early 2000s trending down, epilepsy remains a significant problem for many children.

In all people, the risk of developing epilepsy is approximately 1 percent. However, certain groups are at higher risk. The expectations of the onset of epilepsy in these populations are as follows:

• children with mental retardation : 10%
• children with cerebral palsy : 10%
• children with both cerebral palsy and mental retardation: 50%
• children of mothers with epilepsy: 8.7%
• children of fathers with epilepsy: 2.4%

In addition, males are somewhat more likely to develop epilepsy than females, and African-Americans are more likely to develop it than Caucasians. The incidence of epilepsy is greater in those who are socioeconomically disadvantaged.

Causes and symptoms

The cause of 70 percent of new cases of epilepsy is unknown (idiopathic). Epilepsy sometimes is the result of trauma at birth. Such neonatal causes include insufficient oxygen to the brain, head injury , heavy bleeding, incompatibility between a woman's blood and the blood of her baby, or infection immediately before, after, or at the time of birth.

Other causes of epilepsy include the following:

• head trauma resulting from a car accident, gunshot wound, or other injury
• alcoholism
• brain abscess or inflammation of membranes covering the brain or spinal cord
• phenylketonuria (PKU) or other inherited disorders or genetic factors
• infectious diseases such as measles , mumps , and diphtheria
• degenerative disease
• lead poisoning , mercury poisoning, carbon monoxide poisoning , or ingestion of other poisonous substances

Status epilepticus, a condition in which an individual suffers from continuous seizures and may have trouble breathing, can be caused by the following factors:

• suddenly discontinuing anti-seizure medication
• hypoxic or metabolic encephalopathy (brain disease resulting from lack of oxygen or malfunctioning of other physical or chemical processes)
• acute head injury
• blood infection caused by inflammation of the brain or the membranes that cover it

Symptoms

Different types of seizures have different symptoms. Generalized epileptic seizures occur when electrical abnormalities exist throughout the brain. Partial seizures do not involve the entire brain, although a partial seizure may spread to other parts of the brain and cause a generalized seizure. Some people who have epilepsy have more than one type of seizure.

Motor attacks cause parts of the body to jerk repeatedly. Sensory seizures cause numbness or tingling in one area. The sensation may move along one side of the body or the back before subsiding.

Visual seizures, which affect the area of the brain that controls sight, cause people to see things that are not there. Auditory seizures affect the part of the brain that controls hearing and cause the individual to imagine voices, music, and other sounds. Other types of seizures can cause confusion, upset stomach, or emotional distress.

When to call the doctor

Parents should call the doctor or local emergency number the first time a child has a seizure. For children who have been diagnosed with epilepsy, the doctor should give guidelines about when to call. However, the following situations merit emergency attention:

• a longer seizure than the child usually has or an unusual number of seizures
• seizures that recur repeatedly in the course of a few minutes
• consciousness not regained between seizures
• occurrence of new neurological symptoms
• occurrence of side effects from medication, which could include drowsiness and rash for most anticonvulsants (Specific possible side effects should be reviewed for each medication with the physician and/or pharmacist.)

Diagnosis

Personal and family medical history, description of seizure activity, and physical and neurological examinations help primary care physicians, neurologists, and epileptologists diagnose this disorder. Doctors rule out conditions that cause symptoms that resemble seizure disorders, including small strokes (transient ischemic attacks, or TIAs), fainting (syncope), pseudoseizures, and sleep attacks (narcolepsy ).

Neuropsychological testing uncovers learning or memory problems. Neuroimaging provides views of brain areas involved in seizure activity.

The electroencephalogram (EEG) is the main test used to diagnose epilepsy. EEGs use electrodes placed on or within the skull to record the brain's electrical activity and pinpoint the exact location of abnormal discharges.

Other tests used to diagnose seizure disorders include:

• Magnetic resonance imaging (MRI), which provides clear, detailed images of the brain. Functional MRI (fMRI), performed while the patient does various tasks, can measure shifts in electrical intensity and blood flow and indicate which brain region each activity affects.
• Positron emission tomography (PET) and single photon emission tomography (SPECT) monitor blood flow and chemical activity in the brain area being tested. PET and SPECT are very effective in locating the brain region where metabolic changes take place between seizures.
• Urine and blood lab tests can screen for electrolyte disturbances and possible metabolic disorders.

Treatment

Seizure disorders in children are usually treated with anticonvulsant drugs. Doctors attempt to use a single drug for this purpose, but more than one may be required. Medications are prescribed based on the seizure type. Even when the drugs suppress seizures, they should not be discontinued without a doctor's advice. Most individuals require at least several years of treatment.

If medication is not successful in preventing seizures, surgery, a ketogenic diet, or vagus nerve stimulation (VNS) may be tried. Brain surgery can be useful in certain cases to remove small groups of cells causing the problem.

The ketogenic diet is a high fat, low carbohydrate, limited calorie diet that forces the child's body to burn fat instead of glucose derived from carbohydrates. Burning fat produces chemicals called ketones. One out of three children who begins the diet becomes free or almost free from seizures, while another third improve, and the final third show no improvement. This diet, which is usually begun in the hospital, is extremely rigorous and must be monitored by a doctor and dietician.

The United States Food and Drug Administration (FDA) has approved the use of vagus nerve stimulation (VNS) in patients over the age of 16 who have intractable partial seizures. This non-surgical procedure uses a pacemaker-like device implanted under the skin in the upper left chest, to provide intermittent stimulation to the vagus nerve. Stretching from the side of the neck into the brain, the vagus nerve affects swallowing, speech, breathing.

Prognosis

Prognosis depends on the type of seizures, the ability to control them with medication, the age of the individual, and the underlying cause of the seizures. Seventy percent of individuals with epilepsy can be expected to go into remission, which is defined as five or more years without seizures while on medication. Three-fourths of those who are seizure free for two to five years while on medication can have the medication reduced or eliminated. However, in 10 percent of new epilepsy cases, the seizures are not controlled by medication.

Prevention

There is no known way to prevent the onset of seizure disorders, but seizures may be controlled and sometimes prevented by the use of medication. Up to 80 percent of those with seizure disorder can have their seizures substantially or completed controlled, allowing them to live normal or close to normal lives.

Parental concerns

Seizure disorders are long-term illnesses, with the added problem of being public. Besides the difficulty of controlling medication and possibly diet, the parents of a child with a seizure disorder must sometimes deal with the public visibility of seizure episode. Parents should be supportive of the child and make sure the child does not consider himself to blame for the seizures.

Siblings are also affected by a child with a seizure disorder. Siblings may feel neglected by parents who focus on care for one child. They may also feel responsible for their brother or sister getting the disease, and they may worry about having seizures themselves. Siblings should be assured that seizure disorders are not contagious. They should be given appropriate information both for themselves and for friends who might be present during seizures.

Some parents worry that stress might bring on a seizure and are therefore unwilling to discipline a child with a seizure disorder and might give in to the usual childish demands. Although stress can be a factor, parents should consult with their doctor on the level of risk and methods of discipline that can be effective for their child.

Teenagers have special concerns. In many states, those who have not been seizure-free for a certain time are not allowed to drive, which affects a teen's mobility and social life. Having seizures in front of friends can be embarrassing. Parents should resist being excessively overprotective of their teenager and should consult with their physician as to which activities are safe for their child to pursue.

Some physicians recommend avoidance of swimming in children with epilepsy. Nearly all practitioners would advise against unaccompanied swimming in persons with seizure disorders. Avoidance of exposure to flashing lights or other triggers might be necessary in some persons with seizure disorders.

KEY TERMS

Epileptologist —A physician who specializes in the treatment of epilepsy.

Glucose —A simple sugar that serves as the body's main source of energy.

Phenylketonuria (PKU) —A rare, inherited, metabolic disorder in which the enzyme necessary to break down and use phenylalanine, an amino acid necessary for normal growth and development, is lacking. As a result, phenylalanine builds up in the body causing mental retardation and other neurological problems.

Resources

BOOKS

Basil, Carl W., et al. Living Well with Epilepsy and Other Seizure Disorders: An Expert Explains What You Really Need to Know. New York: HarperInformation, 2004.

Miles, Daniel K. 100 Questions about Your Child's Epilepsy. Boston, MA: Jones & Bartlett Publishers, 2005.

Stafstrom, Carl E., et al. Epilepsy and the Ketongenic Diet. Totowa, NJ: Humana Press, 2004.

Svoboda, William B. Childhood Epilepsy: Language, Learning, and Behavioral Complications. Cambridge, UK: Cambridge University Press, 2004.

Wallace, Sheila J., et al. Epilepsy in Children. Oxford, UK: Oxford University Press, 2004.

ORGANIZATIONS

Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 2078507223. Web site: <www.epilepsyfoundation.org>.

WEB SITES

Campellone, Joseph V. "Epilepsy." MedLine Plus, July 2, 2004. Available online at <www.nlm.nih.gov/medlineplus/ency/article/000694.htm> (accessed November 14, 2004).

"Epilepsy." Centers for Disease Control. Available online at <www.cdc.gov/nccdphp/epilepsy/index.htm> (accessed November 14, 2004).

Tish Davidson, A.M.

Maureen Haggerty

Teresa G. Odle

Seizures

Definition

A seizure is a sudden change in behavior characterized by changes in sensory perception (sense of feeling) or motor activity (movement) due to an abnormal firing of nerve cells in the brain. Epilepsy is a condition characterized by recurrent seizures that may include repetitive muscle jerking called convulsions.

Description

Seizure disorders and their classification date back to the earliest medical literature accounts in history. In 1964, the Commission on Classification and Terminology of the International League Against Epilepsy (ILAE) devised the first official classification of seizures, which was revised again in 1981. This classification is accepted worldwide and is based on electroencephalographic (EEG) studies. Based on this system, seizures can be classified as either focal or generalized. Each of these categories can also be further subdivided.

Focal seizures

A focal (partial) seizure develops when a limited, confined population of nerve cells fire their impulses abnormally on one hemisphere of the brain. (The brain has two portions or cerebral hemispheres—the right and left hemispheres.) Focal seizures are divided into simple or complex based on the level of consciousness (wakefulness) during an attack. Simple partial seizures occur in patients who are conscious, whereas complex partial seizures demonstrate impaired levels of consciousness.

Generalized seizures

A generalized seizure results from initial abnormal firing of brain nerve cells throughout both left and right hemispheres. Generalized seizures can be classified as follows:

• Tonic-clonic seizures: This is the most common type among all age groups and is categorized into several phases beginning with vague symptoms hours or days before an attack. These seizures are sometimes called grand mal seizures.
• Tonic seizures: These are typically characterized by a sustained nonvibratory contraction of muscles in the legs and arms. Consciousness is also impaired during these episodes.
• Atonic seizures (also called "drop attacks"): These are characterized by sudden, limp posture and a brief period of unconsciousness and last for one to two seconds.
• Clonic seizures: These are characterized by a rapid loss of consciousness with loss of muscle tone, tonic spasm, and jerks. The muscles become rigid for about 30 seconds during the tonic phase of the seizure and alternately contract and relax during the clonic phase, which lasts 30–60 seconds.
• Absence seizures: These are subdivided into typical and atypical forms based on duration of attack and level of consciousness. Absence (petit mal) seizures generally begin at about the age of four and stop by the time the child becomes an adolescent. They usually begin with a brief loss of consciousness and last between one and 10 seconds. People having a petit mal seizure become very quiet and may blink, stare blankly, roll their eyes, or move their lips. A petit mal seizure lasts 15–20 seconds. When it ends, the individual resumes whatever he or she was doing before the seizure began, will not remember the seizure, and may not realize that anything unusual happened. Untreated, petit mal seizures can recur as many as 100 times a day and may progress to grand mal seizures.
• Myoclonic seizures: These are characterized by rapid muscular contractions accompanied with jerks in facial and pelvic muscles.

Subcategories are commonly diagnosed based on EEG results. Terminology for classification in infants and newborns is still controversial.

Causes and symptoms

Simple partial seizures can be caused by congenital abnormalities (abnormalities present at birth), tumor growths, head trauma, stroke , and infections in the brain or nearby structures. Generalized tonic-clonic seizures are associated with drug and alcohol abuse, and low levels of blood glucose (blood sugar) and sodium. Certain psychiatric medications, antihistamines, and even antibiotics can precipitate tonic-clonic seizures. Absence seizures are implicated with an abnormal imbalance of certain chemicals in the brain that modulate nerve cell activity (one of these neurotransmitters is called GABA, which functions as an inhibitor). Myoclonic seizures are commonly diagnosed in newborns and children.

Symptoms for the different types of seizures are specific.

Partial seizures

SIMPLE PARTIAL SEIZURES Multiple signs and symptoms may be present during a single simple partial seizure. These symptoms include specific muscles tensing and then alternately contracting and relaxing, speech arrest, vocalizations, and involuntary turning of the eyes or head. There could be changes in vision, hearing, balance, taste, and smell. Additionally, patients with simple partial seizures may have a sensation in the abdomen, sweating, paleness, flushing, hair follicles standing up (piloerection), and dilated pupils (the dark center in the eye enlarges). Seizures with psychological symptoms include thinking disturbances and hallucinations , or illusions of memory, sound, sight, time, and self-image.

COMPLEX PARTIAL SEIZURES Complex partial seizures often begin with a motionless stare or arrest of activity; this is followed by a series of involuntary movements, speech disturbances, and eye movements.

Generalized seizures

Generalized seizures have a more complex set of signs and symptoms.

TONIC-CLONIC SEIZURES Tonic-clonic seizures usually have vague prodromal (pre-attack) symptoms that can start hours or days before a seizure. These symptoms include anxiety, mood changes, irritability, weakness, dizziness , lightheadedness, and changes in appetite. The tonic phases may be preceded with brief (lasting only a few seconds in duration) muscle contractions on both sides of affected muscle groups. The tonic phase typically begins with a brief flexing of trunk muscles, upward movement of the eyes, and pupil dilation. Patients usually emit a characteristic vocalization. This sound is caused by contraction of trunk muscles that forces air from the lungs across spasmodic (abnormally tensed) throat muscles. This is followed by a very short period (10–15 seconds) of general muscle relaxation. The clonic phase consists of muscular contractions with alternating periods of no movements (muscle atonia) of gradually increasing duration until abnormal muscular contractions stop. Tonic-clonic seizures end in a final generalized spasm. The affected person can lose consciousness during tonic and clonic phases of seizure.

Tonic-clonic seizures can also produce chemical changes in the body. Patients commonly experience lowered carbon dioxide (hypocarbia) due to breathing alterations, increased blood glucose (blood sugar), and elevated level of a hormone called prolactin. Once the affected person regains consciousness, he or she is usually weak, and has a headache and muscle pain . Tonic-clonic seizures can cause serious medical problems such as trauma to the head and mouth, fractures in the spinal column, pulmonary edema (water in the lungs), aspiration pneumonia (a pneumonia caused by a foreign body being lodged in the lungs), and sudden death. Attacks are generally one minute in duration.

TONIC SEIZURES Tonic and atonic seizures have distinct differences but are often present in the same patient. Tonic seizures are characterized by nonvibratory muscle contractions, usually involving flexing of arms and relaxing or flexing of legs. The seizure usually lasts less than 10 seconds but may be as long as one minute. Tonic seizures are usually abrupt and patients lose consciousness. Tonic seizures commonly occur during non-rapid eye movement (non-REM) sleep and drowsiness. Tonic seizures that occur during wakeful states commonly produce physical injuries due to abrupt, unexpected falls.

ATONIC SEIZURES Atonic seizures, also called "drop attacks," are abrupt, with loss of muscle tone lasting one to two seconds, but with rapid recovery. Consciousness is usually impaired. The rapid loss of muscular tone could be limited to head and neck muscles, resulting in head drop, or it may be more extensive, involving muscles for balance and causing unexpected falls with physical injury.

CLONIC SEIZURES Generalized clonic seizures are rare and seen typically in children with elevated fever. These seizures are characterized by a rapid loss of consciousness, decreased muscle tone, and generalized spasm that is followed by jerky movements.

ABSENCE SEIZURES Absence seizures are classified as either typical or atypical. The typical absence seizure is characterized by unresponsiveness and behavioral arrest, abnormal muscular movements of the face and eyelids, and lasts less than 10 seconds. In atypical absence seizures, the affected person is generally more conscious, the seizures begin and end more gradually, and do not exceed 10 seconds in duration.

MYOCLONIC SEIZURES Myoclonic seizures commonly exhibit rapid muscular contractions. Myoclonic seizures are seen in newborns and children who have either symptomatic or idiopathic (cause is unknown) epilepsy.

Demographics

Approximately 1.5 million persons in the United States suffer from a type of seizure disorder. The annual incidence (number of new cases) for all types of seizures is 1.2 per 1,000 and, for recurrent seizures, is 0.54 per 1,000. Isolated seizures may occur in up to 10% of the general population. Approximately 10–20% of all patients have intractable epilepsy (epilepsy that is difficult to manage or treat). It is estimated that 45 million people in the world are affected by seizures. Seizures affect males and females equally and can occur among all age groups. There seems to be a strong genetic correlation, since seizures are three times more prevalent among close relatives than they are in the general population.

Children delivered in the breech position have increased prevalence (3.8%) of seizures when compared to infants delivered in the normal delivery position (2.2%). Seizures caused by fever have a recurrence rate of 51% if the attack occurred in the first year of life, whereas recurrence rate is decreased to 25% if the seizure took place during the second year. Approximately 88% of children who experience seizures caused by fever in the first two years experience recurrence.

Approximately 45 million people worldwide are affected by epilepsy. The incidence is highest among young children and the elderly. High-risk groups include persons with a previous history of brain injury or lesions.

Diagnosis

Patients seeking help for seizures should first undergo an EEG that records brain-wave patterns emitted between nerve cells. Electrodes are placed on the head, sometimes for 24 hours, to monitor brain-wave activity and detect both normal and abnormal impulses. Imaging studies such as magnetic resonance imaging (MRI ) and computed axial tomography (CT )—that take still "pictures"—are useful in detecting abnormalities in the temporal lobes (parts of the brain associated with hearing) or for helping diagnose tonic-clonic seizures. A complete blood count (CBC) can be helpful in determining whether a seizure is caused by a neurological infection, which is typically accompanied by high fever. If drugs or toxins in the blood are suspected to be the cause of the seizure(s), blood and urine screening tests for these compounds may be necessary.

Antiseizure medication can be altered by many commonly used medications such as sulfa drugs, erythromycin, warfarin, and cimetidine. Pregnancy may also decrease serum concentration of antiseizure medications; therefore, frequent monitoring and dose adjustments are vital to maintain appropriate blood concentrations of the antiseizure medication—known as the therapeutic blood concentration. Diagnosis requires a detailed and accurate history, and a physical examination is important since this may help identify neurological or systemic causes. In cases in which a central nervous system (CNS) infection (i.e., meningitis or encephalitis) is suspected, a lumbar puncture (or spinal tap) can help detect an increase in immune cells (white blood cells) that develop to fight the specific infection.

Treatments

Treatment is targeted primarily to:

• assist the patient in adjusting psychologically to the diagnosis and in maintaining as normal a lifestyle as possible
• reduce or eliminate seizure occurrence
• avoid side effects of long-term drug treatment

Simple and complex partial seizures respond to drugs such as carbamazepine , valproic acid (valproate), phenytoin, gabapentin , tiagabine , lamotrigine , and topiramate . Tonic-clonic seizures tend to respond to valproate, carbamazepine, phenytoin, and lamotrigine. Absence seizures seem to be sensitive to ethosuximide, valproate, and lamotrigine. Myoclonic seizures can be treated with valproate and clonazepam. Tonic seizures seem to respond favorably to valproate, felbamate , and clonazepam.

People treated with a class of medications called barbiturates (Mysoline, Mebral, phenobarbital ) have adverse cognitive (thinking) effects. These cognitive effects can include decreased general intelligence, attention, memory, problem solving, motor speed, and visual motor functions. The drug phenytoin (Dilantin) can adversely affect speed of response, memory, and attention. Other medications used for treatment of seizures do not have substantial cognitive impairment.

Surgical treatment may be considered when medications fail. Advances in medical sciences and techniques have improved methods of identifying the parts of the brain that generate abnormal discharge of nerve impulses. Surgical treatment now accounts for about 5,000 procedures annually. The most common type of surgery is the focal cortical resection. In this procedure, a small part of the brain responsible for causing the seizures is removed. Surgical intervention may be considered a feasible treatment option if:

• the site of seizures is identifiable and localized
• surgery can remove the seizure-generating (epileptogenic) area
• surgical procedure will not cause damage to nearby areas

Prognosis

About 30% of patients with severe seizures (starting in early childhood), continue to have attacks and usually never achieve a remission state. In the United States, the prevalence of treatment-resistant seizures is about one to two per 1,000 persons. About 60–70% of persons achieve a five-year remission within 10 years of initial diagnosis. Approximately half of these patients become seizure-free. Usually the prognosis is better if seizures can be controlled by one medication, the frequency of seizures decreases, and there is a normal EEG and neurological examination prior to medication cessation.

People affected by seizure have increased death rates compared with the general population. Patients who have seizures of unknown cause have an increased chance of dying due to accidents (primarily drowning). Other causes of seizure-associated death include abnormal heart rhythms, water in the lungs, or heart attack.

Prevention

There are no gold standard recommendations for prevention, since seizures can be caused by genetic factors, blood abnormalities, many medications, illicit drugs, infection, neurologic conditions, and other systemic diseases. If a person has had a previous attack or has a genetic propensity, care is advised when receiving medical treatment or if diagnosed with an illness correlated with possible seizure development.

Resources

BOOKS

Goetz, Christopher G. Textbook of Clinical Neurology. 1st edition. Philadelphia: W. B. Saunders Company, 1999.

Goldman, Lee, and others. Cecil Textbook of Medicine. 21st edition. Philadelphia: W. B. Saunders Company, 2000.

Goroll, Allan H. Primary Care Medicine. 4th edition. Philadelphia: Lippincott Williams and Wilkins, 2000.

PERIODICALS

Dodrill, C. R., C. G. Matthew. "The role of Neuropsychology in the Assessment and Treatment of Persons with Epilepsy." American Psychologist (September 1992).

ORGANIZATIONS

Epilepsy Foundation. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. <http://www.efa.org>.

Laith Farid Gulli, MD

Alfredo Mori, MD, FACEM

Seizures

Two Stories

What Is a Seizure?

How Do Seizures Differ?

What Causes A Seizure?

Resources

Seizures (SEE-zhers) occur when the electrical patterns of the brain are interrupted by powerful, rapid bursts of electrical energy. A seizure may cause a person to lose consciousness, to fall down, to jerk or convulse, or simply to blank out for a few seconds. Infection, injury or medical problems can cause a seizure. Epilepsy is a disease of the nervous system characterized by recurring seizures.

KEYWORDS

for searching the Internet and other reference sources

Brain Function

Epilepsy

Neurology

Two Stories

Eric’s Story

As part of his sixth grade study of self-awareness, Eric was assigned to draw the frames of a film that would show the world as he saw it. Teachers were puzzled by what Eric drew. One frame showed him pouring milk, the next frame was completely black, and the next frame showed spilled milk. In another sequence, Eric drew a teacher calling on him to answer a math problem, followed by another black frame, and then a picture of the teacher complaining that Eric was not paying attention. The teachers realized that Eric’s project did show the world as he saw it. The mysterious black frames were blackouts. Doctors determined that Eric had absence seizures, a type of seizure that causes a brief loss of consciousness. Medication successfully controlled Eric’s seizures.

Carol’s Story

All the students in Carol’s art class were preparing work for an art show when Carol stood up and began walking around the room. Looking like she was in a trance, Carol smacked her lips and tugged at the sleeve of her dress. About two minutes later, Carol became aware of her surroundings, only to discover that her classmates were laughing at her strange behavior. Embarrassed, she ran from the room. Carol had experienced a complex partial seizure.

What Is a Seizure?

Whether a person is sleeping or awake, millions of tiny electrical charges pass between neurons* in the brain and to all parts of body. These cells “fire,” or transmit electrical impulses, in an orderly and controlled manner. Seizures occur when overactive nerve cells send out powerful, rapid electrical charges that disrupt the brain’s normal function. The disruption can temporarily affect how a person behaves, moves, thinks, or feels.

* neurons

are nerve cells. Most neurons have extensions called axons and dendrites through which they send and receive signals from other neurons.

Symptoms of a seizure can include combinations of the following:

• twitching and tingling in part of the body (for example, fingers and toes)
• muscle spasms spreading to arms and legs
• hallucinations
• intense feeling of fear or of familiarity (sometimes called déjà vu)
• a peculiar sensation, sometimes called an aura, immediately before the seizure (for example, seeing a flashing light or sensing strange odors)
• loss of consciousness.

How Do Seizures Differ?

There are two kinds of seizure disorders: an isolated seizure that occurs only once, and epilepsy (EP-i-lep-see). Epileptic seizures occur more than once, and they occur over a period of time. In both epilepsy and isolated seizures, the seizure may have different symptoms or characteristics depending on where it begins in the brain and how the electrical discharge spreads across the brain. Seizures can be generalized or partial.

Generalized seizures

Generalized seizures affect nerve cells throughout the cerebral cortex (the cauliflower-like outer portion of the brain), or all of the brain. Generalized seizures often are hereditary, which means they run in families. They may also be caused by imbalances in a person’s kidney or liver function, or in their blood sugar.

The most common generalized seizures are:

• Generalized tonic-clonic seizure (formerly called grand mal seizure): In the tonic phase of this seizure, people often lose consciousness, drop to the ground, and emit a loud cry as air is forced over their vocal cords. In the clonic phase, body muscles contract all at once or in a series of shorter rhythmic contractions, causing thrashing motions. Usually, this kind of seizure lasts for about one or two minutes and is followed by a period of relaxation, sleepiness, and possibly a headache.
• Absence seizure (formerly called petit mal seizure): Loss of consciousness in this seizure is often so brief (usually 10 to 30 seconds) that a person does not even change positions. The person may display a blank stare, rapid blinking, or chewing movements. Facial or eyelid muscles may jerk rhythmically. Absence seizures may be inherited and usually are seen for the first time in children between the ages of 6 and 12.
• Infantile spasms: This type of seizure occurs before age 4 and may cause a child to suddenly flex the arms, thrust the trunk forward, and extend the legs. The seizure lasts only a few seconds, but can recur several times a day.
• Atonic seizures: Also seen primarily in children, these seizures cause a complete loss of muscle tone and consciousness, which means they pose a serious risk of injury due to falling.
• Myoclonic seizures: Brief seizures characterized by quick jerking movements of one limb or several limbs. The person experiencing the seizure does not lose consciousness.
• Febrile seizures: These seizures occur in infancy or childhood and cause a child to lose consciousness and convulse. The seizures are accompanied by a high fever and they are described as either simple or complex. Simple febrile seizures account for about 85 percent of febrile seizures. They occur once in 24 hours and last less than 15 minutes. Complex febrile seizures last more than 15 minutes or occur more than twice in 24 hours.

Partial seizures

Partial seizures affect nerve cells contained within one region of the cerebral cortex. Types of partial seizures include:

• Simple partial: The seizure-related brain messages remain very localized, and the patient is awake and alert. Symptoms vary depending on what area of the brain is involved. They may include jerking movements in one part of the body, emotional symptoms such as unexplained fear, an experience of peculiar smells, or nausea.
• Complex partial: A person loses awareness of surroundings and is unresponsive or only partially responsive. There may be a blank stare, chewing movements, repeated swallowing, or other random activity. After the seizure, the person has no memory of the experience. In some cases, the person may become confused, begin to fumble, to wander, or to repeat inappropriate words or phrases.

What Causes A Seizure?

A seizure generally is easy to recognize, but finding the cause can be extremely difficult. Doctors begin with a thorough physical examination. They try to determine if the person has experienced other seizures or has a family history of seizures. Physicians also want to know if the patient has experienced an aura*, because that can help establish the location in the brain of the seizure. They also will note the persons age and the nature of the movements the person made during the seizure.

* aura

is a warning sensation that precedes α seizure or other neurologic disorder.

An electroencephalogram (e-LEK-tro-en-SEF-a-lo-gram), commonly known as an EEG, records electric currents in the brain and can track abnormal electrical activity. Doctors may also look for structural brain abnormalities using other types of scans, including computerized tomography (CT) and magnetic resonance imaging (MRI). In some research centers, positron emission tomography (PET) is used to identify areas of the brain that are producing seizures.

A lumbar puncture, sometimes called a spinal tap, can detect infection. The procedure requires that a physician carefully insert a thin needle between two vertebrae (bones) in the patient’s spine and draw out a small amount of cerebrospinal fluid (CSF). The fluid is analyzed for the presence of bacterial or viral infections, tumors, or blood disorders that might provide a clue to the cause of the seizure.

Seizures are associated with the following diseases and conditions:

• Epilepsy a disorder of the nervous system characterized by seizures that occur more than once and over a period of time.
• Head trauma that damages the brain.
• Loss of oxygen caused by birth trauma, carbon monoxide poisoning, or near drowning.
• Brain infections, such as meningitis or encephalitis.
• Brain tumor.
• Stroke.

• Toxic (poisonous) agents, including drug abuse or ingestion of poisons such as lead, alcohol, or strychnine.
• Withdrawal from alcohol and drugs.
• Metabolic imbalances such as hypoglycemia (very low blood sugar), uremia (kidney failure), or liver problems.
• Eclampsia or toxemia, which may occur during pregnancy and is characterized by high blood pressure, protein in the urine, and fluid retention.

It is important to remain calm and not to panic when someone has a seizure. An adult usually will ask if the person has epilepsy. If the person is unable to communicate, an adult will check for a medical identification bracelet or tag that carries information about the underlying cause of the seizure.

See also

Brain Tumor

Diabetes

Encephalitis

Fever

Hypoglycemia

Incontinence

Infection

Kidney Disease

Lead Poisoning

Lupus

Meningitis

Stroke

Substance Abuse

Resources

Books

Orrin, Devinsky, M.D. A Guide to Understanding and Living With Epilepsy. Philadelphia: F.A. Davis, 1994. An easy-to-read guide with a glossary of terms and antiepileptic drugs.

Wilner, Andrew N. Epilepsy: 199 Answers. A Doctor Responds to His Patients’ Questions. New York: Demos Vermande, 1996.

Organization

The Epilepsy Foundation, 4351 Garden Drive, Landover, MD 20785. Formerly the Epilepsy Foundation of America, this national organization offers information on seizures and epilepsy. The website provides general information on diagnosis and treatment, plus web links and a chat room for teenagers.
Telephone 800-332-1000 http://www.efa.org