2. ARTICLE
Febrile Seizures
Deborah G. Hirtz, MD*
a similar study in which both febrile
IMPORTANT POINTS and afebrile control children were
1. Most children who have febrile seizures do very well, and the risk of examined, a family history of febrile
epilepsy is low. seizures, neonatal discharge 28 days
2. The earlier the age at which the first febrile convulsion occurs, the or later, parental report of slow
more likely are recurrences. development, and child care atten-
3. Diagnostic laboratory tests never should be routine. Neuroimaging dance were risk factors for febrile
rarely is indicated. seizures (Table 1). Another recent
4. Meningitis always should be ruled out, either clinically or by lumbar study found a correlation between
puncture if indicated.
low serum sodium levels and risk
5. Treatment has not been shown to reduce the risk of later epilepsy and
carries a risk of side effects. for developing febrile convulsions.
RECURRENCE
Definition are used because it has become clear After the first febrile seizure,
Febrile seizures are the most com- through prospective epidemiologic approximately 33% of children will
mon convulsive disorder in young studies that there is not nearly as experience one or more recurrences,
children. As defined in a 1980 great a risk for development of and about 9% of children who have
National Institutes of Health consen- epilepsy or recurrent afebrile febrile seizures will have three or
sus conference, a febrile seizure is: seizures as had been attributed by more. The younger the child when
Livingston to the seizures he called the first febrile seizure occurs, the
“An event in infancy or early child- “epilepsy triggered by fever”. greater the likelihood of recurrence.
hood, usually occurring between More recently, febrile seizures
three months and five years of age,
Most recurrences (75%) happen
have been divided into two sub- within 1 year. A recent study has
associated with fever but without
groups: simple febrile seizures, shown an increased risk of recur-
evidence of intracranial infection
or defined cause. Seizures with fever which last fewer than 15 minutes rence to be associated with a shorter
in children who have suffered a and are generalized, and complex duration of fever before the initial
previous nonfebrile seizure are febrile seizures, which are pro- febrile seizure and a lower tempera-
excluded. Febrile seizures are to longed, multiple within 24 hours, or ture. Family history of febrile
be distinguished from epilepsy, focal. Children in either of these sub- seizures is another reported risk fac-
which is characterized by recurrent groups may have a pre-existing neu- tor for recurrence. A family history
nonfebrile seizures.” rologic abnormality or a family his- of afebrile seizures has been
This definition excludes seizures tory of febrile or afebrile seizures. reported as a risk factor for recur-
that accompany neurologic illnesses, rence in some studies, but not in
such as meningitis, encephalitis, or Epidemiology others. “Complex” febrile convul-
toxic encephalopathy. Seizures in Febrile seizures occur in approxi- sions are not more likely to be fol-
these instances do not carry the mately 2% to 4% of young children lowed by recurrences. Young age of
same prognosis as febrile seizures in the United States, South America, onset and a family history of febrile
because the underlying illness may and Western Europe. They are convulsions are the strongest and
affect the central nervous system. reported to be even more common most consistent predictors of recur-
Febrile seizures have been dis- in Asian countries. Several large rence (Table 2).
cussed in the medical literature since prospective studies have determined
the time of Hippocrates, but it was that in approximately 20% of cases, EPILEPSY
not until the middle of the present the first febrile seizure was complex Although it has been reported that
century that they were recognized as (ie, lasted more than 15 minutes, febrile seizures preceded 15% of
a separate syndrome distinct from was focal, or involved at least two
epilepsy. An early classification pro- seizures within 24 hours). The most
posed by Livingston divided them common age of onset is in the sec-
into “simple febrile seizures” and ond year of life. Febrile seizures are TABLE 1. Risk Factors
“epilepsy triggered by fever.” He slightly more common in males. for a First Febrile Seizure
included in the latter definition
febrile seizures that were prolonged RISK FACTORS FOR A FIRST • Family history of febrile seizures
or focal or that occurred in a child FEBRILE SEIZURE • Neonatal discharge ≥28 days
who has a family history of In studies comparing children who • Delayed development
epilepsy. These definitions no longer have febrile seizures with febrile • Child care attendance
controls, a higher temperature was a • Low serum sodium
*Developmental Neurology Branch, National risk factor for the development of a
• Very high fever
Institute of Neurological Disorders and febrile seizure, as was a history of
Stroke, Bethesda, MD. febrile seizures in a close relative. In
Pediatrics in Review Vol. 18 No. 1 January 1997 5
Downloaded from http://pedsinreview.aappublications.org/ at Dahlgren Medical Library on January 9, 2012
3. NEUROLOGY
Febrile Seizures
tis media. Children of preschool age
TABLE 2. Risk Factors TABLE 3. Risk Factors are subject to frequent infections
for Recurrence of for the Development and accompanying high fevers,
Febrile Seizure of Epilepsy Following which in combination with a rela-
Febrile Seizures tively low seizure threshold, allows
• Young age for the common occurrence of
• Suspect or abnormal development febrile seizures.
• Family history of febrile before the first seizure Several recent reports have docu-
seizures
• Family history of afebrile mented the frequent presence of
• Short duration of fever before human herpesvirus 6 (HHSV-6) in
seizures
the initial seizure cases of febrile seizures. HHSV-6 is
• Complex first febrile seizure a recently identified etiologic agent
• Relatively lower fever at the in roseola (exanthem subitum). In
time of the initial seizure one series, the virus was cultured
• Possible family history of from 8 (19%) of 42 patients who had
GENETICS
afebrile seizure a first febrile seizure, and titers rose
Febrile seizures tend to occur in in 9 of the 34 (26%) who returned
families, although the exact mode of for convalescent titers. The virus was
inheritance is not known. Children not detected in 29 cerebrospinal fluid
cases of childhood onset epilepsy, who have febrile seizures tend more (CSF) samples taken. In eight
because febrile seizures are a much often to have a history of febrile patients who had a history of roseola
more common occurrence than convulsions in close relatives. There and multiple febrile convulsions,
childhood epilepsy, fewer than 5% also may be a higher incidence of HHV-6 DNA was detected in the
of children who have febrile afebrile seizures in the families of CSF sampled after a febrile convul-
seizures actually develop epilepsy. children who have febrile seizures, sion; it was not evident in controls,
Rates of epilepsy tend to be but the evidence is not as clear. The and it was documented in only one
higher in populations having febrile relative risk for epilepsy is higher in of seven children who had a single
seizures from selected sources such siblings of children who have febrile febrile seizure. It was postulated that
as hospital admissions or referrals to seizures, but not in other relatives. viral invasion of the brain may
specialists. All types of epilepsy, Parents may ask about the risk of occur sometime during the acute ill-
including absence, generalized tonic- febrile seizures in younger siblings of ness, and during subsequent ill-
clonic, and complex partial, can be children who have febrile convul- nesses, be reactivated by fever.
seen in patients who have a history sions. It is in the range of 10% to
of febrile convulsions. 20%, but will be higher if the parents Clinical Aspects
In the National Institute of Neu- have a history of febrile convulsions.
rologic Disorders and Stroke Febrile seizures usually occur early
(NINDS) Perinatal Collaborative in the course of a febrile illness,
COMPLEX PARTIAL SEIZURES
Project (NCPP), an increased risk often as the first sign. It commonly
Although some authors believe that has been thought that the rate of
for developing one or more afebrile febrile seizures may predispose the
seizures was found among children increase of the fever is an important
child to developing complex partial trigger, but there are no data to sup-
in whom development was suspect seizures (CPS), the evidence is con-
or abnormal prior to the first febrile port the importance of this factor
troversial. Studies of patients who over the height of the fever. The
seizure, whose parent(s) or sibling(s) have CPS and a history of prolonged
had a history of afebrile seizures, seizure may be of any type, but the
febrile convulsions in early child- most common is tonic-clonic. Ini-
and who had a complex first febrile hood show an increase in mesial
seizure (Table 3). Of the 60% of tially there may be a cry, followed by
temporal sclerosis. Although there loss of consciousness and muscular
children who had febrile seizures in may be an association between
the NCPP and none of these risk rigidity. During this tonic phase,
febrile convulsions that are pro- there may be apnea and incontinence.
factors, 2% developed at least one longed or focal and later CPS, a This is followed by the clonic phase
afebrile seizure by age 7 years. Of causal relationship has not been of repetitive, rhythmic jerking move-
the 34% who had one risk factor, proven. Only a very small percent- ments and then by post- ictal lethargy
3% developed one or more afebrile age of children who have febrile or sleep.
seizures, and if two or more risk seizures develop CPS, and it may be
Other seizure types may occur,
factors were present, the afebrile that the child who is neurologically
such as staring with stiffness or limp-
seizure rate increased to 13%. A at risk is more likely to have both
ness, jerking movements without
prior neurologic abnormality identi- febrile and complex partial seizures.
prior stiffening, or only focal stiffness
fied by examination also was associ-
or jerking. Most seizures last fewer
ated with an increased risk for later Pathophysiology: Etiology than 6 minutes; fewer than 8% last
afebrile seizures, but there was no Most febrile illnesses associated longer than 15 minutes. Thus, the
increased risk from having had mul- with febrile seizures are due to com- child who has a febrile seizure usu-
tiple episodes of febrile seizures. mon infections such as tonsillitis, ally is not brought to medical atten-
upper respiratory infections, and oti- tion until after the seizure has ended.
6 Pediatrics in Review Vol. 18. No. 1 January 1997
Downloaded from http://pedsinreview.aappublications.org/ at Dahlgren Medical Library on January 9, 2012
4. NEUROLOGY
Febrile Seizures
When a child is seen following a nance imaging (MRI) are seldom A written handout is usually help-
febrile convulsion, it is important to helpful and should not be performed ful. The following points should be
identify whether there is an underly- routinely. The electroencephalogram stressed:
ing illness requiring treatment. A (EEG) has not been shown to be 1. Although febrile seizures are
history should include inquiries as to helpful in the evaluation of febrile frightening, they do not cause
symptoms of infectious illness, med- seizures. An EEG obtained up to brain damage, and the likelihood
ication exposure, trauma, develop- 1 week after a febrile seizure may of developing epilepsy or recur-
mental level, and family history of show an abnormality, usually con- rent nonfebrile seizures is very
febrile or afebrile seizures. A com- sisting of occipital slowing. small.
plete description of the seizure Although there is a higher incidence 2. There is, however, a risk of fur-
should be obtained from an eyewit- of EEG abnormalities in children ther febrile seizures during the
ness. In the physical examination, who have febrile seizures, which current or subsequent febrile
the level of consciousness, the increases with age, the EEG does illnesses.
presence of meningismus or a tense not help predict recurrences or risk 3. If another seizure occurs, stay
or bulging fontanelle or of Kernig for later epilepsy. calm, place the child on his or
or Brudzinski sign, and any abnor- her side or abdomen with the
malities or focal differences in face downward; do not force any-
HOSPITALIZATION
muscle strength or tone should be thing between the teeth and
noted carefully and reassessed The decision to admit the child who
observe the child carefully. If the
periodically. has experienced a febrile seizure for
seizure does not stop after
Other causes of seizures associ- overnight observation in the hospital
10 minutes, the child should be
ated with fever must be ruled out, depends on the specific clinical situ-
brought to the nearest medical
especially encephalitis or meningitis. ation and the family circumstances.
facility by car or ambulance.
A lumbar puncture (LP) is indicated The child should be kept in the
if there is any clinical suspicion of
meningitis. The presence of a source Routine laboratory studies are not indicated (for patients
of infection such as otitis media who have febrile seizures) and should be performed only
does not rule out meningitis, and if
the infant has been taking antibi-
as part of the evaluation for a source of fever.
otics, partially treated meningitis
should be suspected and an LP per- emergency department holding area Vigorous control of fever by
formed. or doctor’s office for at least several antipyretics and sponging often is
Typical clinical signs of meningi- hours and re-evaluated. Most chil- advocated but has not been proven
tis may be absent in those younger dren will have improved and be to lower the risk of febrile seizures
than 12 to 18 months of age. In gen- alert, and if the cause of the fever recurring. Often, seizures occur as
eral, the threshold for performing an has been diagnosed and treated the first sign of a febrile illness.
LP should be low, and it should not appropriately, they may be sent Lowering fevers by appropriate use
be omitted on the sole basis of age, home. However, follow-up care of antipyretics such as aceta-
family history, or previous number must be assured. If the child’s clini- minophen usually will make the
of febrile seizures. If increased cal situation remains unstable, if child more comfortable. However,
intracranial pressure is suspected, there is any question of possible some authors have suggested that
the decision to perform an LP must meningitis, or if parents seem unreli- antipyretics may prolong viral shed-
be made by an experienced physi- able or unable to cope, hospitaliza- ding and impair the body’s ability to
cian who will weigh the risk of tion is advisable. About 16% of chil- respond to viral infection.
delaying a diagnosis of meningitis dren may experience another seizure Questions often arise regarding
against the risk of an LP. within 24 hours, but it is not known continuation of routine childhood
Other causes of seizures associ- how to predict in which cases immunizations. Studies have indi-
ated with fever other than meningitis seizures may recur immediately. cated that seizures following child-
or encephalitis include infections hood immunizations are no different
such as roseola infantum and PARENTAL COUNSELING from other febrile seizures. Seizures
Shigella gastroenteritis; certain tox- Febrile seizures are very frightening may occur most commonly follow-
ins or drug exposures, including events, and it is not uncommon for ing a pertussis or DPT immunization
diphenhydramine, tricyclic antide- parents to state that they believed because the pertussis component
pressants, amphetamines, and that their child was dying during the commonly provokes a fever. In each
cocaine; and dehydration causing seizure. They first must be reassured child, the advantages conferred by
electrolyte imbalances. and then given instructions on the vaccines must be weighed against
Routine laboratory studies are not management of possible recurrences. the risk, and if immunization is
indicated and should be performed Information and counseling should postponed, the situation must be re-
only as part of the evaluation for a be provided after the acute event evaluated at each subsequent visit.
source of fever. Skull radiographs and at a later time, when parents The period of greatest risk for
and neuroimaging such as computed have had a chance to formulate febrile seizure recurrences is up to
tomography (CT) or magnetic reso- questions. 48 hours following a DPT immu-
Pediatrics in Review Vol. 18 No. 1 January 1997 7
Downloaded from http://pedsinreview.aappublications.org/ at Dahlgren Medical Library on January 9, 2012
5. NEUROLOGY
Febrile Seizures
nization and 7 to 10 days after a 1 mg/kg per day when the child is been shown to be both completely
measles immunization. ill or feverish. If side effects of safe and effective. Fortunately, the
lethargy or ataxia occur, the dosage majority of children who have
LONG-TERM MANAGEMENT should be halved, and the physician febrile seizures will require no treat-
The approach to long-term manage- must evaluate whether the lethargy ment other than parental reassurance
ment should focus on decreasing could be masking an underlying ill- and will have a good outcome.
parental anxiety. Whether prophy- ness such as meningitis. Diazepam
laxis with medication is effective is in both oral and rectal forms has
SUGGESTED READING
controversial. Side effects occur, and been used successfully in countries
Berg AT, Shinnar S, Hauser WA, et al. A
antipyretics alone have not been outside of the United States. prospective study of recurrent febrile
shown to be effective in preventing seizures. N Engl J Med. 1992;327:
1122–1127
febrile seizure recurrences. There is Conclusion and Prognosis Farwell JR, Lee YJ, Hirtz DG, et al. Pheno-
no evidence that the treatment to barbital for febrile seizures: effects on intel-
Febrile seizures now are recognized ligence and seizure recurrence. N Engl J
prevent recurrences can prevent the
subsequent development of epilepsy. as a benign syndrome determined Med. 1990;322:364–369
largely by genetic factors, manifested McKinlay I, Newton R. Intention to treat
Diazepam and phenobarbital have febrile convulsions with rectal diazepam,
been used to prevent recurrences of by an age-related susceptibility to valproate, or phenobarbitone. Dev Med
febrile seizures, although not all seizures that eventually is outgrown. Child Neurol. 1989;31:617–625
Although febrile seizures are Nelson KB, Ellenberg JH. Prognosis in chil-
studies have confirmed their effi- dren with febrile seizures. Pediatrics.
cacy. Prescription of prophylaxis extremely frightening to parents, 1978;61:720–727
should be reserved only for the rare children almost always do quite well. Nelson KB, Ellenberg JH, eds. Consensus
Only a small minority will develop Statement on Febrile Seizures: Febrile
cases in which multiple seizures Seizures. New York, NY: Raven Press;
have occurred in a child who still is epilepsy or recurrent nonfebrile 1981:301
very young, there has been focal seizures later. Unless seizures are Offringa M, Patrick M, Bossuyt M, et al.
exceedingly long, there is no evi- Risk factors for seizure recurrence in chil-
paralysis following a seizure, or the dren with febrile seizures: a pooled analysis
parents’ anxiety level remains very dence of risk of brain damage, and of individual patient data from five studies.
high even after reassurance. large studies have documented the J Pediatr. 1994;124:574–584
lack of later intellectual and motor Rantala H, Uhari M. Risk factors for recur-
Diazepam has been administered rences of febrile convulsions. Acta Neurol
orally and rectally to prevent recur- handicap as a result of febrile Scand. 1994;90:207–210
rences only during a febrile illness. seizures. Rosman NP, Colton T, Labazzo J, et al. A
Long-term management of febrile controlled trial of diazepam administered
Phenobarbital 5 mg/kg per day has during febrile illnesses to prevent recur-
been given continuously in a daily seizures should focus on decreasing rence of febrile seizures. N Engl J Med.
or twice-daily dosage. There are parental anxiety. Treatment to pre- 1993;326:79–84
vent recurrences has not been shown Stenklyft PH, Carmona M. Febrile seizures.
significant drawbacks to both treat- Emerg Med Clin North Am. 1994;12:989
ments; diazepam may cause ataxia to prevent the later development of Verity CM, Butler NR, Golding J. Febrile
and lethargy, and phenobarbital epilepsy. Treatment to prevent recur- convulsions in a national cohort followed-
may cause behavior problems and rences should be recommended in up from birth. I. Prevalence and recurrence
in the first five years of life. Br Med J.
affect intellectual performance only a small minority of children 1985;290:1307–1310
adversely. who have febrile seizures. Potential Verity CM, Butler NR, Golding J. Febrile
If treatment is prescribed, oral risks of anticonvulsant therapy convulsions in a national cohort followed-
up from birth. II. Medical history and intel-
diazepam is preferable and may be should be weighed against benefits. lectual ability at 5 years of age. Br Med J.
given in three divided doses to total No currently available treatment has 1985;290:1311–1315
8 Pediatrics in Review Vol. 18. No. 1 January 1997
Downloaded from http://pedsinreview.aappublications.org/ at Dahlgren Medical Library on January 9, 2012
6. NEUROLOGY
Febrile Seizures
PIR QUIZ
1. Which one of the following state- A. A complex first febrile seizure. of the brain.
ments about recurrence of febrile B. A history of febrile seizures in E. Serum electrolyte levels.
seizures is true? the family.
A. A complex first febrile seizure C. Female gender. 4. Which one of the following state-
is more likely to recur than a D. Multiple episodes of febrile ments about the management of a
simple febrile seizure. seizures. child who has had a febrile seizure
B. A first febrile seizure occurring E. Younger age of onset of first is true?
at 6 months of age is more febrile seizure. A. Continuous phenobarbital pro-
likely to recur than one occur- phylaxis will prevent develop-
3. A 6-month-old child who has a ment of epilepsy in subsequent
ring at 3 years of age.
history of fever of 2 days’ duration years.
C. A first febrile seizure with
presents with generalized tonic- B. Immunization with diphtheria-
fever of 104˚F (40˚C) is more
clonic seizures lasting approxi- pertussis-tetanus (DPT) should
likely to recur than one with
mately 10 minutes. Physical be carried out using half the
fever of 101˚F (38.3˚C).
examination reveals a rectal standard dose.
D. Girls are more likely than boys
temperature of 103˚F (39.4˚C), C. Management should be guided
to have recurrence of febrile
slightly bulging fontanelle, bilat- by serial electroencephalo-
seizures.
eral otitis media, and lethargy. graphic studies.
E. Longer duration of fever
The infant is arousable but irrita- D. Parents should be reassured
before the initial febrile seizure
ble. Which one of the following of the benign nature of febrile
is a risk factor for recurrence
is the most appropriate initial seizures and given instructions
compared with shorter duration
diagnostic test? for handling a possible
of fever.
A. Computed tomographic scan recurrence.
2. Which one of the following is the of the head. E. Use of antipyretics at the first
most important risk factor for B. Electroencephalography. sign of fever has been shown
developing epilepsy following C. Lumbar puncture. to decrease the recurrence of
febrile seizures? D. Magnetic resonance imaging febrile seizures.
Earning CME Credit-Completing the PIR Quiz
The American Academy of Pediatrics 1997 PIR will be awarded for up to activities, including AAP Spring
(AAP) is accredited by the Accredita- 2 years. Credits will be posted to the Session or Annual Meeting,
tion Council for Continuing Medical year in which they are submitted. AAP CME courses, ACQIP, Pedi-
Education (ACCME) to sponsor con- Verification of Credit will be atric UPDATE Audiocassette Tape
tinuing medical education for physi- mailed by: April 30, 1998. You will Program, or other AAP-approved
cians. Pediatrics in Review (PIR) was receive a complimentary transcript by courses.
planned and produced in accordance April 30, 1998, containing a sum- Other Organizations Granting
with the ACCME Essentials. mary of CME credits earned in 1997 Credit: PIR has been approved for
The AAP designates this activity through AAP programs. If you credit as follows:
for up to 38 hours in Category 1 of require a transcript at any other time • American Academy of Pediatrics
the Physician’s Recognition Award of of the year, there will be a fee of $25 (AAP): up to 38 hours of credit
the American Medical Association for processing. toward the AAP PREP Education
(3 hours per completed print issue of Mail form to: American Academy Award
PIR and 2 hours per completed com- of Pediatrics - PREP Office, 141 • American Osteopathic Association
pact disc issue of PIR). Northwest Point Boulevard, PO Box (AOA): up to 12 hours, Category
PIR Quiz: A short quiz can be 927, Elk Grove Village, IL 60009- 2-B
found at the end of each article in 0927 • National Association of Pediatric
PIR. Use the PIR Quiz Card (bound PREP Education Award: The Nurse Associates and Practitioners
into the January issue) to record your AAP PREP Education Award recog- (NAPNAP): up to 38 contact
answers. Each question has a single nizes Academy Fellows and Candi- hours.
best answer. The answers to the ques- date Fellows who earn a minimum of • Canadian Paediatric Society has
tions appear on the inside front cover 150 AAP-approved CME credits over approved PREP as one method for
of each issue. 3 consecutive years. The Award will pediatricians to demonstrate main-
1997 Credit Deadline: February be mailed July 1998 to all individuals tenance of competence
28, 1998. If you want to receive who qualify. To qualify for the PREP (MOCOMP)
CME credit in 1997, the PIR Quiz Education Award, an Academy Fel- • PREP has been reviewed and
Card must be received in the PREP low or Candidate Fellow must: accepted by the American Acad-
Office by February 28, 1998. Credit • Earn a minimum of 75 credit emy of Family Physicians (AAFP)
reply material received after February hours through participation in for up to 38 Prescribed hours.
28, 1998, will be applied to the fol- PREP or PREP: The Course, and Term of approval begins January
lowing year. • Earn the remaining credit hours 1997. Enduring materials are
Expiration of Credit: December (75 hours) through other Acade- approved for 1 year with the
31, 1999. Credit for completing the my-sponsored or -approved CME option to request renewal.
Pediatrics in Review Vol. 18 No. 1 January 1997 9
Downloaded from http://pedsinreview.aappublications.org/ at Dahlgren Medical Library on January 9, 2012
7. Febrile Seizures
Deborah G. Hirtz
Pediatrics in Review 1997;18;5
DOI: 10.1542/pir.18-1-5
Updated Information & including high resolution figures, can be found at:
Services http://pedsinreview.aappublications.org/content/18/1/5
References This article cites 8 articles, 1 of which you can access for free
at:
http://pedsinreview.aappublications.org/content/18/1/5#BIBL
Subspecialty Collections This article, along with others on similar topics, appears in the
following collection(s):
Neurologic Disorders
http://pedsinreview.aappublications.org/cgi/collection/neurolo
gic_disorders
Permissions & Licensing Information about reproducing this article in parts (figures,
tables) or in its entirety can be found online at:
/site/misc/Permissions.xhtml
Reprints Information about ordering reprints can be found online:
/site/misc/reprints.xhtml
Downloaded from http://pedsinreview.aappublications.org/ at Dahlgren Medical Library on January 9, 2012