Todd's paralysis

ABSTRACT

A febrile seizure Is a benign convulsion that occurs in Infants or small children and Is brought on by fever without evidence of meningitis or encephalitis. Little is known about the etiology; however, it Is associated with disease processes outside the central nervous system. In most children, the primary causative factors appear to be the height and rapidity of temperature el vation, which usually exceeds 101.8 deg F (38.8 deg C). Seizures occur most often during the temperature rise Itself rather than after a prolonged elevation. Variation persists in Interpretation, evaluation, and treatment of chin dren with febrile seizures, rendering the diagnosis one of exclusion. Pharmacologic treatment for febrile seizures should be easy to administer, have virtually no adverse effects, and be remarkably efficacious. Along with Invasive intervention and pharmacologic management, the clinician must also provide counseling during this stressful event.

The brief, generalized clonic attacks of a febrile seizure are frightening for parents or other caregivers to witness. The caregivers' fright may be amplified by the erroneous belief that the child is likely to choke to death, have brain damage, develop a learning disability, or acquire a chronic seizure disorder. However, the vast majority of children who experience these brief electrical storms develop no sequelae. The seizures are related to the fever, and prospective studies have shown a low incidence of acquired motor or intellectual abnormalities following a febrile seizure.1

The febrile seizure is usually a benign event that can occur in a feverish child in the absence of evidence of meningitis or encephalitis. Febrile seizures are the most common type of seizure encountered in infants and young children.

Although usually self-limiting and benign, febrile seizures frequently recur and can be a precursor to epilepsy in some children.2 This article reviews primary care of the child with febrile seizures by tracing the etiology and pathophysiology of these seizures and presenting a rational management approach.

Epidemiology

Approximately 2 % to 4% of all children will experience at least one febrile seizure.3 The episode will most likely occur between the ages of 3 months and 5 years and will be associated with fever without evidence of intracranial infection.

The majority of cases occur in children between ages 6 months and 3 years, with a peak incidence between 18 and 24 months. A family history of afebrile or febrile seizures is present in 25 % of patients.2

Characteristics that put a child at absolute risk for febrile seizures were identified in one study (see Table 1 If a child has two or more of these factors, the risk of having a first febrile seizure is 30%.4 Targeting anticipatory guidance in this small, at-risk group helps alleviate the child's fears as well as those of caregivers.

Additionally, one-third of children who experience febrile seizures will have a recurrent episode, with 15% having more than one recurrence. A shorter duration of fever and a lower temperature (less than 104 deg F [40 deg C]) before the initial febrile seizure were associated with an increased risk of recurrence, presumably because of a lower threshold for seizures with fever.2,5

Some 50% of children under age 1 experience recurrences compared with only 20% of children whose first febrile seizure occurred at age 3 or older. Children are also at greater risk if they have neurologic impairment or a family history of febrile or afebrile seizures.

Pathogenesis

The etiology of febrile seizures is still uncertain, but they are associated with disease processes outside the central nervous system (CNS). Upper respiratory tract infections, especially otitis media, as well as gastrointestinal infections, roseola, and other viral illnesses are usually the illnesses accompanying febrile seizures. A careful history and physical assessment usually rule out CNS disease.

In most children, primary causative factors of febrile seizures seem to be the height and rapidity of the temperature elevation. The temperature usually exceeds 101.8 deg F (38.8 deg C), and the seizures usually occur during the temperature rise rather than after a prolonged elevations.5

A high rate of febrile seizures exists with shigellosis and salmonellosis, possibly related to their effects on the CNS or to a neurotoxin they produce. Febrile seizures occur in young children at a time in their developmental process when their seizure threshold is low. They are more susceptible to frequent infections and respond with comparably higher temperatures.6,7

Clinical Features

Seizures typically follow fever onset and occur early within a febrile illness. Although there is increased risk of a seizure with higher fevers, half of all episodes occur at temperatures below 104 deg F (40 deg C). The actual seizure itself may be any type including tonic, clonic, and focal. Table 2 compares simple and complex febrile seizures.7,8

The simple febrile seizure may be mild, with the child showing only a slight slumping and the eyes rolling back. More noticeably, there may be momentary stiffening of the arms and legs followed by jerking movements.

The seizure usually lasts less than 5 minutes, although frightened parents often report it to be much longer. The postictal period may consist of paralysis of one limb or a gaze palsy (Todd's paralysis). Following the incident, the child may sleep a short while, awakening later without sequelae or memory of the event.9

The complex febrile seizure is focal, prolonged (15 minutes), and recurs within the first 24 hours of the initial seizure. The complex seizure involves one side of the body, affecting an arm, a leg, or the face, and sometimes causing an eye deviation toward one side. Complex febrile seizures may also be associated with a higher risk of developing epilepsy.

Predictors for the possible recurrence of febrile seizures have been identified.4 The higher the temperature at the time of the first febrile seizure, the lower the risk of a recurrent seizure. Children who had a fever for less than 1 hour before onset of the first seizure have a remarkably increased risk of recurrence. Researchers found the following to be significant, independent predictors of recurrent febrile seizures: age less than 18 months at the time of the first seizure; fever of less than 104deg F (40deg C); less than 1 hour between onset of fever and occurrence of the seizure; and a history of febrile seizures in a first-degree relative.

Diagnostic Evaluation

Despite recent advances in the understanding of febrile seizures and the development of consensus statements about their diagnostic evaluation and management, a review of practice patterns for pediatricians indicates that interpretation, evaluation, and treatment of febrile seizures varies.' The goal of the initial evaluation should be to exclude serious conditions that may present with seizures and a fever so that appropriate referrals may be made. A careful, thorough history is the keystone of this process.

Developing a differential diagnosis of febrile seizures will guide the clinician in distinguishing among the various disorders likely to be confused with generalized febrile seizures: meningitis, epilepsy, breath-holding spells, psychological problems, cardiac disease, and pseudoseizures. The distinction between the various illnesses relies significantly on the history and an eyewitness account of the seizure.

Once the distinction is made, a thorough physical examination can define the infection source and rule out meningitis, because 20% to 30% of children with meningitis have seizures.6 A developmentally appropriate neurologic examination is also an important part of the investigation; the clinician should look for focal signs, irritability, impaired level of consciousness, nuchal rigidity, bulging fontanelle, and Kernig's or Brudzinski's signs.

A search should be made for depigmented macules and sha een skin (indicating tuberous sclerosis), cafeau-lait spots (indicating neurofibromatosis), and portwine stains (identified with Sturge-Weber syndrome). Any subtle abnormalities may require more detailed neurologic testing, such as a lumbar puncture (LP), and a referral to a pediatrician." After determining whether the seizure was an isolated problem or a sign of an ongoing seizure disorder, the clinician must determine the cause of the fever.

Practice Parameters

In 1996, the American Academy of Pediatrics and the Provisional Committee on Quality Improvement developed practice parameters for the neurodiagnostic evaluation of a child with a first simple febrile seizure. These guidelines were designed to ensure that underlying diseases such as meningitis are detected, that injuries are reduced, and that parents are reassured. The statement also stressed that the cause of the fever, not the seizure, should be evaluated.5

Blood studies. Complete blood count (CBC), serum electrolytes, calcium, phosphorus, magnesium, or blood glucose studies should not be performed routinely in the evaluation of a child with a first febrile seizure. However, a CBC may be valuable in the evaluation of fever, particularly in children younger than age 2, because the incidence of bacteremia with or without febrile seizures is the same.5

Although some children are initially dehydrated and have abnormal serum electrolyte values, their conditions should be identifiable by obtaining appropriate histories and performing careful physical examinations. Blood glucose may be obtained if the child has a prolonged period of postictal obtundation. Laboratory testing should be aimed at identifying the source of the fever rather than evaluating the seizure.

Lumbar puncture (LP). In infants younger than age 12 months who experience first seizures with fever, performance of an LP should be considered because of the minimal or absent clinical signs and symptoms associated with meningitis in this age-group. In children ages 12 months to 18 months, an LP should be considered because the clinical signs and symptoms of meningitis may be subtle. In a child older than 18 months, an LP is not routinely warranted but is recommended if the child shows any meningeal signs and symptoms.

Additionally, an LP is recommended in children whose history or examination suggests the presence of intracranial infection. In infants and children who have received prior antibiotic treatment, clinicians should be aware that treatment may mask the signs and symptoms of meningitis. An LP should be strongly considered in this case.

Electroencephalogram (EEG). An EEG should not be performed in the evaluation of a neurologically healthy child with a first simple seizure. Although the incidence of abnormal EEGs increases over time after a simple febrile seizure, evidence does not support the suggestion that abnormal EEGs after the first febrile seizure are predictive for either the risk of febrile seizure recurrence or epilepsy development.8

Neuroimaging. Neuroimaging is not recommended in the routine evaluation of simple febrile seizures.5 Data have not been published supporting or negating the use of computed tomography or magnetic resonance imaging in febrile seizure evaluation. Data from the literature in the use of computed tomography in children with epilepsy indicate that clinically important intracranial structure abnormalities in this patient population are scarce.

Management

The long-term prognosis for the child with a first febrile seizure is excellent. The child's caregivers should be counseled regarding care during a seizure and the use of antipyretics. The clinician must decide whether to treat recurrent febrile seizures by balancing the risk of recurrence against the potential adverse effects of antiepileptic medication!

In most cases, the clinician will see the child after the febrile seizure has occurred. Consequently, the clinician must decide whether an underlying illness may be present and whether to consult a pediatrician to perform an LP. The ideal pharmacologic treatment for febrile seizures should be easy to administer, have virtually no adverse effects, and be efficacious. If the proposed treatment does not meet these criteria, it should be questioned.11

Antipyretics. Because the fever is an essential element in the emergence of a febrile seizure, the clinician may assume that aggressive use of antipyretic agents (acetaminophen 15 mg/kg orally every 3 to 4 hours or ibuprofen 10 mg/kg every 6 hours) for children older than age 6 months will prevent seizure.11

A Dutch study suggested that ibuprofen might have a more marked effect on the temperatures of those children with previous febrile seizures. Ibuprofen use reduced body temperature more swiftly and to greater degree than acetaminophen.11 Sponging has also been used as an antipyretic measure but is generally ineffective in reducing temperature.13

Diazepam. Using aggressive measures to prevent recurrences of febrile seizures is controversial. Although a number of children experience recurrences, the majority do not. Therefore, no prophylactic antiseizure treatment is advocated after the first febrile seizure if the child has no risk factors for recurrence. 14 Anticonvulsant prophylaxis may be considered in selected conditions: the presence of abnormal neurologic development; if the seizure is greater than 15 minutes in duration or is focal; if the seizure is followed by transient or persistent neurologic abnormalities; and if there is a history of afebrile seizures of genetic origin in a parent or sibling. 14

If the child with complex or frequent recurrent febrile seizures must be treated pharmacologically, diazepam may be used. The decision to treat must balance the risk of recurrent seizures against the potential adverse effects of antiepileptic drugs.2

Diazepam may be administered in two ways to treat febrile seizures. It may be given rectally in doses of 0.2 to 0.5 mg/kg every 8 hours for the first 2 days of a fever (children ages 2 to 5, 0.5 mg/kg; children ages 6 to 11, 0.3 mg/kg). Diazepam may also be given orally, 0.3 3 mg/kg every 8 hours for the first 2 days at the start of a febrile episode, reaching levels protective against seizures within 1 hour.2,15

Unfortunately, several studies have found that the prophylactic use of diazepam in children may cause lethargy or ataxia, a concern for the clinician when differentiating between febrile seizures and meningitis." Therefore, the intermittent or prophylactic administration of diazepam at the onset of fever is not recommended.16

Phenobarbital. In the past, phenobarbital was used for the prevention of recurrent febrile seizures. It is effestive even before a fever is recognized; however, continuous use is needed even if the child is not sick. Oral doses of 4 mg/kg to 8 mg/kg are needed per day, and adverse effects are both behavioral and cognitive. Even in small doses, drowsiness, sleep disturbances, and intellectual impairment are clinically observed. Consequently, this intervention is reserved for children with prolonged or recurrent febrile seizures when diazepam has been ineffective.'

Controlled studies have produced mixed results on the prophylactic use of phenobarbital. A placebocontrolled study" and a study funded by the National Institutes of Health found no statistical reduction in recurrence rate.I Results in both studies concluded that the evidence provides little justification for the use of phenobarbital for a benign condition such as a simple febrile seizure.

Valproic acid. In oral doses of 20 mg/kg to 40 mg/kg daily, valproic acid is effective in the prevention of recurrent febrile seizures, and it is associated with fewer intellectual and behavioral adverse effects. However, the potential for valproic acid to induce hepatic toxicity must be considered,'9 and several randomized studies have found valproic acid to be ineffective.

A meta-analysis review of studies using valproic acid for prophylaxis of recurrent febrile seizures showed the risk of recurrence in children receiving valproate to be low compared with placebo.10 However, because of its known adverse effects, prophylactic use was not recommended.

Counseling. Counseling an anxious caregiver may be the most important acute management consideration (see Patient Education). Caregivers should be educated about proper care of a child during a febrile seizure. For example, parents should be counseled to place the child in a side-lying position during the seizure and to remove any nearby objects that may cause injury. Caregivers should also be cautioned not to place anything into the child's mouth during the seizure or to try to restrain the child.

Caregivers should be advised to call emergency transport if the seizure does not end within 15 minutes. If the seizure ends within 15 minutes and the child seems to be breathing normally and is awake and alert, parents should contact the child's regular health care provider. Caregivers should also be cautioned to take the child to the emergency department if the child is extremely irritable or has a stiff neck immediately after the seizure ends."

The clinician should educate the caregivers about the possible recurrence of febrile seizures and how to manage a fever. Sometimes, children who have febrile seizures are treated by their caregivers as frail and vulnerable; however, these children should not be restrained from their normal activities, and the seizures should not be allowed to disrupt family life.

If the child is younger than age 12 months, if the family is especially frightened, or if serious concerns such as preexisting neurologic impairments are present, continuous follow-up and hospitalization may be advisable. I The clinician should contact the caregivers within 24 hours after a seizure has been reported to offer support, to relieve fears, and to correct any erroneous beliefs they may have.

Febrile Seizures in Practice

Further research on the use of long-term prophylaxis and the predictors and outcomes of febrile seizures in children is needed. Until more information is available, optimal treatment includes educating the caregivers on the child's prognosis and evaluating the need for pharmacologic therapy. The clinician plays an instrumental role in counseling families whose child has experienced a febrile seizure by providing information and reassurance about the consequences of febrile seizures.

ACKNOWLEDGMENT

The authors thank Mary Muscari, RN, CRNP PhD, Associate Professor, Department of Nursing, University of Scranton, Scranton, Pa., for her guidance and critical review of this manuscript.

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ABOUT THE AUTHORS

Catherine Champs, CRNP, ACRN, MSN, is a family nurse practitioner in nephrology with Henry Yeager, M.D., in Scranton, Pa. Patricia A. Gaffney-Yocum, CRNP, MSN, is a family nurse practitioner with Planned Parenthood of North East Pennsylvania in Wilkes-Barre and Scranton, Pa.

Copyright Springhouse Corporation Oct 1999
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