Febrile seizures

Definition

Febrile seizures are convulsions of sudden onset due to abnormal electrical activity in the brain that is caused by fever . Fever is a condition in which body temperature is elevated above normal (generally above 100.4°F [38°C]).

Description

Febrile seizures were first distinguished from epileptic seizures in the twentieth century. The National Institutes of Health defined febrile seizures in 1980 as "an event in infancy or childhood usually occurring between three months and five years of age, associated with fever, but without evidence of intracranial infection or defined cause."

There are three major subtypes of febrile seizures. The simple febrile seizure accounts for 70 to 75 percent of febrile seizures and is one in which the affected child is age six months to five years and has no history or evidence of neurological abnormalities, the seizure is generalized (affects multiple parts of the brain), and lasts less than 15 minutes, and the fever is not caused by brain illness such as meningitis or encephalitis . The complex febrile seizure shares similar characteristics with the exception that the seizure lasts longer than 15 minutes or is local (affects a localized part of the brain), or multiple seizures take place and accounts for about 20 to 25 percent of all febrile seizures. Lastly, about 5 percent of febrile seizures are diagnosed as symptomatic, in cases in which the child has a history or evidence of neurological abnormality.

The seizure activity itself is generally characterized as clonic (consisting of rhythmic jerking movements of the arms and/or legs), or tonic-clonic (commencing with a stiffening of the body followed by a clonic phase).

Demographics

Fever is the most common cause of seizures in children, occurring in 2 to 5 percent of children from six months to five years of age. First onset usually occurs by two years of age, with the risk decreasing after age three; most children stop having febrile seizures by the age of five or six. Male children have been shown to have a higher incidence of febrile seizures. The majority of children who experience a febrile seizure will only have one in their lifetime; approximately 33 percent will go on to have more than one.

Causes and symptoms

Under normal circumstances, information is transmitted in the brain by means of electrical discharges from brain cells. A seizure occurs when the normal electrical patterns of the brain become disrupted. A febrile seizure is caused by fever, most commonly a high fever that has risen quickly. The average fever temperature in which febrile seizures take place is 104°F (40°C). Conversely, a healthy person's body temperature fluctuates between 97°F (36.1°C) and 100°F (37.8°C).

Fevers are caused in most cases by viral or bacterial infections, such as otitis media (ear infection), upper respiratory infection, pharyngitis (throat infection), pneumonia , chickenpox , and urinary tract infection. Other conditions can induce a fever, including allergic reactions, ingestion of toxins, teething, autoimmune disease, trauma, cancer , excessive sun exposure, or certain drugs. In some cases no cause of the fever can be determined.

Febrile seizures generally last between one and ten minutes. A child experiencing a febrile seizure may exhibit some or all of the following behaviors:

• stiff body
• twitching or jerking of the extremities or face
• rolled-back eyes
• unconsciousness
• inability to talk
• problems breathing
• involuntary urination or defecation
• vomiting
• confusion, sleepiness, or irritability after the seizure

Approximately one third of children who have had a febrile seizure will experience recurrent seizures. Several risk factors are associated with recurrent febrile seizures; children who exhibit all four are at a 70 percent chance of developing recurrent seizures, while those who have none of the risk factors have only a 20 percent chance. The risk factors include:

• family history of febrile seizures
• young age of the child (i.e. less than 18 months of age)
• seizure occurs soon after or with onset of fever
• seizure-associated fever is relatively low

When to call the doctor

A healthcare provider should be contacted after a febrile seizure. A visit to the emergency room is warranted if the accompanying fever is greater than 103°F (39.4°C) in a child older than three months or 100.5°F (38°C) in an infant of three months or younger or if the seizure is the child's first. Emergency medical personnel (telephone 911) should be called if a febrile seizure lasts more than five minutes; if the child stops breathing; if the child's skin starts to turn blue; or if the fever is greater than 105.8°F (41°C), a condition called hyperpyrexia.

Diagnosis

A key focus of diagnostic tests will be to determine the underlying cause of the fever. A comprehensive medical history including the fever's duration and course, other symptoms the child is experiencing, prior or current medical conditions, recent vaccinations or exposure to communicable diseases, and the child's current behaviors may point to the fever's origin. A temperature below 100.4°F (38°C) suggests another cause for the seizure. The caregiver who was present with the child while he or she was having the seizure will be asked questions relating to the child's behaviors in an attempt to determine the type of seizure.

Physicians may administer tests to rule out conditions other than fever that could have caused the seizure, such as epilepsy, meningitis, or encephalitis. Children who suffer from recurrent febrile seizures are not diagnosed with epilepsy, a seizure disorder that is not caused by fever. In the case of children under 18 months of age, a lumbar puncture (spinal tap) may be recommended to rule out meningitis because symptoms are often lacking or subtle in children of that age. Because of the benign nature of the simple febrile seizure, tests such as computed tomography (CT) scans, magnetic resonance imaging (MRI), or electroencephalogram (EEG) are not usually recommended.

Treatment

During a seizure parents or caregivers need to remain calm and take steps to make sure the child remains safe. During the period after the seizure the child may be disoriented and/or sleepy (called the postictal state), but quick recovery from this state is normal, and medical treatment is not normally needed.

During a seizure

If a parent or caregiver observes a child having a seizure, there are a number of measures that should be taken to ensure the child's safety . These include:

• staying calm
• laying the child on his or her side or front to prevent vomited matter from being aspirated into the lungs
• loosening any tight clothing or items that could constrict breathing
• marking the start and end time of the seizure
• clearing the surrounding area of unsafe items
• attending to the child for the duration of the seizure
• clearing the child's airway if it becomes obstructed with vomited material or other objects

Parents or caregivers should not attempt to stop the seizure or slap or shake the child in attempt to wake him/her. The child may move around during the seizure, and parents should not try to hold the child down. If the child vomits, a suction bulb can be used to help clear the airway.

After a seizure

A healthcare professional should be called immediately after the seizure in the event that further treatment or tests are required. Hospitalization is not normally required unless the child is suffering from a serious infection or illness or the seizure itself was abnormally long. Parents or caregivers may be instructed to take certain measures at home to reduce the child's fever, such as administering fever-reducing drugs (called antipyretics) such as acetaminophen (Tylenol) or ibuprofen (Advil). There is, however, no evidence that shows fever-reducing therapies reduce the risk of another febrile seizure occurring. If the child is suffering from a bacterial infection that is the cause of the fever, he or she may be placed on antibiotics .

Treating the fever

The treatment of pediatric fever varies according to the age of the child and the fever's cause, if known. Physicians recommend that newborns less than four weeks of age with fever be admitted to the hospital and administered antibiotics until a complete workup can be done to rule out bacterial infection or other serious illness. The same is recommended for infants ages four to 12 weeks if they appear ill. Infants of this age who otherwise appear well can often be managed on an outpatient basis with antipyretics and antibiotics in the case of bacterial infection.

For children ages three months and older, the course of treatment depends on the extent and cause of the fever. Most fevers and associated conditions can be managed on an outpatient basis. Low-grade fevers often do not need to be treated in otherwise healthy children. Antipyretics may be suggested to lower a fever and make the child more comfortable but will not affect the course of an underlying infectious disease. Aspirin should not be given to a child or adolescent with a fever since this drug has been linked to an increased risk of the serious condition called Reye's syndrome . Antibiotics may be administered if the child has a known or suspected bacterial infection.

Alternative treatment

There are some outpatient treatments that parents or caregivers may administer to reduce their febrile child's discomfort, although there is no evidence that indicates such treatments reduce the risk of febrile seizures. These include dressing the child lightly, applying cold washcloths to the face and neck, providing plenty of fluids to avoid dehydration , and giving the child a lukewarm bath or sponging the child in lukewarm water.

Prognosis

The risk of complications associated with febrile seizures is very low. Some of the complications that may occur are:

• biting the tongue
• choking on items that were in the mouth at the start of the seizure
• injury from falling down
• aspirating fluid or vomit into the lungs
• developing recurrent febrile seizures
• developing recurrent seizures unrelated to fever (epilepsy)
• complications related the underlying cause of the fever

Children who have had a febrile seizure are at an increased risk of having another; approximately one third of febrile seizure cases become recurrent. The risk of recurrent seizures decreases with age: infants younger than 12 months have a 50 percent chance of having a second seizure, while children over the age of 12 months have a 30 percent chance. The risk of a child going on to develop epilepsy is slightly increased at approximately 2–5 percent, compared to 1 percent for the general population; such a risk is increased in children who have a history of neurological abnormalities such as cerebral palsy or developmental delays and in children whose seizures recur or are prolonged. Research has shown that febrile seizures do not affect a child's intelligence level or achievement in school.

Prevention

In some cases, a febrile seizure may be the first indication that a child is ill. Prevention is, therefore, not always possible. While the use of anticonvulsants such as Phenobarbital or Valproate has been shown to prevent recurrent febrile seizures, these drugs are associated with significant side effects such as adverse behaviors, allergic reaction, and organ injury, and have not been shown to benefit simple febrile seizures. Only rarely is anticonvulsant therapy recommended for a child with febrile seizures because of the generally benign nature of the seizures and the risk of side effects from the drugs. In some cases oral diazepam (Valium) can be administered at the first sign of fever to reduce the risk of febrile seizures; about two-thirds of children who receive this drug experience side effects such as sleepiness and loss of coordination. The majority of children who have had a febrile seizure do not need drug therapy. Parents may be directed to administer over-the-counter antipyretics at the first sign of fever.

Parental concerns

A febrile seizure can be a frightening experience for both the child and his or her parents. It is important that parents be educated about the low risk of simple febrile seizures and the measures that can be taken to ensure their child's safety during and after a seizure.

Resources

BOOKS

Barkin, Roger M., and D. Demetrios Zukin. "Fever." In Rosen's Emergency Medicine: Concepts and Clinical Practice , 5th ed. Edited by John A. Marx. St. Louis, MO: Mosby, 2002.

Powell, Keith R. "Fever." In Nelson Textbook of Pediatrics , 17th ed. Edited by Richard E. Behrman, Robert M. Kliegman, and Hal B. Jenson. Philadelphia: Saunders, 2004.

PERIODICALS

Jankowiak, J., and B. Malow. "Seizures in Children with Fever: Generally Good Outcome." Neurology 60, no. 2 (January 28, 2003): E1–2.

ORGANIZATIONS

American Academy of Pediatrics. 141 Northwest Point Blvd., Elk Grove Village, IL 60007–1098. Web site: http://www.aap.org.

American College of Emergency Physicians. 1125 Executive Circle, Irving, TX 75038–2522. Web site: http://www.acep.org.

WEB SITES

Baumann, Robert. "Febrile Seizures." eMedicine , March 12, 2001. Available online at http://www.emedicine.com/neuro/topic134.htm (accessed November 28, 2004).

"Febrile Seizure Fact Sheet." National Institute of Neurological Disorders and Stroke , July 1, 2001. Available online at http://www.ninds.nih.gov/health_and_medical/pubs/febrile_seizures.htm (accessed November 28, 2004).

Zempsky, William T. "Pediatrics, Febrile Seizures." eMedicine , October 14, 2004. Available online at http://www.emedicine.com/emerg/topic376.htm (accessed November 28, 2004).

Stephanie Dionne Sherk