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.

This patients brain is exposed during surgery in order for surgeons to remove the mass responsible for epileptic seizures. (Custom Medical Stock Photo Inc.)
This patient's brain is exposed during surgery in order for surgeons to remove the mass responsible for epileptic seizures.
(Custom Medical Stock Photo Inc.)

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: http://www.epilepsyfoundation.org.

WEB SITES

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

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

Tish Davidson, A.M.

Maureen Haggerty

Teresa G. Odle



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