II. Definition

  1. Febrile Seizure
    1. Seizure with fever (Temperature >100.4 F) in neurologically healthy child without CNS Infection

III. Epidemiology

  1. Ages affected: 6 months to 5 years (peaks at age 2 years)
  2. Most common Seizures of childhood
    1. Occurs in 3-5% of children before age 5 years
  3. Gender: 66% are male
  4. Most common in winter and early spring
    1. Corresponding to increased frequency of respiratory and gastrointestinal infections

IV. Risk Factors: First Febrile Seizure

  1. Low grade fever
    1. High fever also is associated, raising Neuronal excitability and decreasing Seizure threshold
  2. Day care attendance (OR 3.1)
  3. Developmental Delay (OR 4.9)
  4. Neonatal nursery hospitalization >28 days (OR 5.6)
  5. Viral Infections (esp. those associated with high fever)
    1. Primary human herpes 6 Infection (most common association)
      1. Laina (2010) Pediatr Neurol 42(1): 28-31 [PubMed]
    2. Other infections
      1. Influenza Virus
      2. Adenovirus
      3. Parainfluenza Virus
      4. Chung (2007) Arch Dis Child 92(7): 589-93 [PubMed]
  6. Family History
    1. Up to 25-49% of those with Febrile Seizures have a Family History
    2. Febrile Seizure in parent or sibling (10% risk, OR 4.5)
    3. Febrile Seizure in second degree relative (OR 3.6)
  7. Vitamin Deficiency
    1. Iron Deficiency
      1. Hartfield (2009) Clin Pediatr 48(4): 420-6 [PubMed]
    2. Zinc Deficiency
      1. Ganesh (2008) Clin Pediatr 47(2): 164-66 [PubMed]
  8. Vaccinations
    1. Background
      1. Prophylactic antipyretics did not reduce Seizure risk and may reduce immune response to Vaccination
      2. Prymula (2009) Lancet 374(9698): 1339-50 [PubMed]
    2. Influenza Vaccine
      1. 2010 Southern Hemisphere seasonal trivalent Vaccine (Fluvax)
      2. Over the longterm, Influenza Vaccine has not been consistently associated with Febrile Seizures
    3. DTP Vaccine
      1. Limited to within first 24 hours after Immunization
      2. DTaP is not associated with significantly increased risk
    4. MMR Vaccine
      1. Related to fever from Vaccine (not Vaccine itself)
      2. Risk was 1 per 1000 if MMR given at age 16-23 months
        1. However risk drops to 4 in 10,000 (less than half), if Vaccine given at 12-15 months
      3. Increased risk only in the first 2 weeks after Vaccination
      4. Vestergaard (2004) JAMA 292(3): 351-7 [PubMed]

V. Risk Factors: Recurrent Febrile Seizure

  1. Age of onset of first Seizure
    1. First Seizure age 1 to 3 years
      1. Second Febrile Seizure: 30% risk
      2. Third Febrile Seizure: 15% risk
      3. More than 3 Febrile Seizures: <5% risk
    2. First Seizure any other age
      1. Second Febrile Seizure: 50% risk of recurrence
  2. High risk recurrence factors
    1. Complex Febrile Seizure
    2. Febrile Status Epilepticus
      1. Recurrence Febrile Seizure in 43%
      2. Recurrent febrile Status Epilepticus in 10%
  3. Timing of recurrence
    1. When Febrile Seizures recur, they do so in the first year in 75% of cases
  4. Risk Scoring
    1. Criteria: One point for each
      1. Age <18 months
      2. Short interval between fever onset and Seizure (<1 hour)
      3. Lower peak fever (<104 F or 40 C)
      4. First degree relative with Febrile Seizure
    2. Risk of recurrence within 2 years
      1. Recurrence in 14% if 0 risk factors
      2. Recurrence in 24% if 1 risk factors
      3. Recurrence in 32% if 2 risk factors
      4. Recurrence in 63% if 3 risk factors
      5. Recurrence in 75% if 4 risk factors
    3. References
      1. Berg (1997) Arch Pediatr Adolesc Med 151(4): 371-8 [PubMed]

VI. Types: Febrile Seizure

  1. Simple Febrile Seizure (65-90%)
    1. Generalized Seizure
    2. Seizure duration <15 minutes
    3. Occurs once in 24 hour period
    4. No prior neurologic conditions
    5. Normal Neurologic Exam
  2. Complex Febrile Seizure (20-25%)
    1. Focal Seizure (most common reason for classifying as complex Seizure)
    2. Seizure duration >15 minutes
    3. Occurs more than once in a 24 hour period
    4. Known neurologic condition (e.g. Cerebral Palsy)
    5. Postictal neurologic abnormality (Todd's Paralysis)
    6. May also be associated with prolonged postictal state
  3. Febrile Status Epilepticus (5%)
    1. Generalized Febrile Seizure lasting >30 minutes

VII. Differential Diagnosis

  1. See Seizure
  2. Meningitis
  3. Generalized Epilepsy with Febrile Seizure Plus (GEFS+)
    1. Inherited mutation related to Neuronal voltage gated Sodium channel mutations (SCN1A, SCN1B, SCN1B)
  4. Dravet Syndrome
    1. Severe myoclonic Epilepsy
    2. Rare, but severe degenerative neurologic condition

VIII. History

  1. Seizure episode
    1. Duration of Seizure (most Febrile Seizures last <7-8 minutes, typically much less than this)
    2. Characteristics (generalized or focal findings)
    3. Postictal signs and duration
    4. Recurrence
  2. Past medical history
    1. Recent Infections or antibiotic use
    2. Recent head injuries
    3. Prior Seizures
  3. Immunization status
    1. Recent Vaccinations (e.g. MMR)
    2. HaemophilusInfluenzae Type B Vaccine (Hib Vaccine)
    3. Streptococcus PneumoniaeVaccine (Prevnar)
  4. Family History
    1. Febrile Seizures
    2. Seizure Disorder

IX. Exam

  1. Complete Neurologic Exam
    1. Focal neurologic deficit (e.g. Todd Paralysis)
  2. Identify source of fever
    1. Simple Febrile Seizures are not associated with an increased risk of serious infection
      1. Well appearing children are not at higher risk of UTI, Pneumonia or Bacterial Meningitis
    2. Consider Meningitis (for ill appearing children or those with complex Seizures)
      1. However, Meningitis rarely presents as Febrile Seizures (especially not simple Febrile Seizures)
      2. Those with Meningitis and Seizure, had other abnormalities (e.g. ALOC, Nuchal Rigidity, petechial rash)
      3. Green (1993) Pediatrics 92(4): 527-34 [PubMed]
    3. Consider Bacteremia in Children (for ill appearing children or those with complex Seizures)
      1. Streptococcal Bacteremia (Streptococcus Pneumoniae)
      2. Urinary Tract Infection

X. Evaluation: Red Flags

  1. Meningeal Signs
  2. Complex Febrile Seizure
  3. Altered Level of Consciousness
    1. Patient should return to full alertness within one hour
    2. Altered Level of Consciousness is present in 93% of patients with Meningitis
    3. Green (1993) Pediatrics 92(4): 527-34 [PubMed]
  4. Additional risks for serious Bacterial Infection cause
    1. Age <6 months or >60 months with first-time Febrile Seizure
    2. Age <12 months with inadequate or unknown Immunization history
    3. Febrile Status Epilepticus

XI. Labs

  1. Well appearing children with simple Febrile Seizures do not require lab testing
    1. In addition, well appearing children even with complex Febrile Seizures are unlikely to have abnormal labs
  2. Finger stick Blood Sugar (bedside Glucose)
  3. Consider Urinalysis
  4. Consider serum Electrolytes if indicated by history
    1. Example: Diarrhea or Vomiting
    2. However lab testing is not routinely indicated (not recommended by AAP)
    3. Consider basic chemistry panel (Serum Glucose, Serum Sodium, Serum Calcium, Serum Magnesium)

XII. Diagnostics: Criteria for Lumbar Puncture (LP)

  1. No LP if otherwise normal history and exam
    1. Simple Febrile Seizures without other findings are not associated with Meningitis
    2. Kimia (2009) Pediatrics 123(1): 6-12 [PubMed]
    3. Guedj (2015) Acad Emerg Med 22(11): 1290-7 +PMID:26468690 [PubMed]
  2. Atypical Seizure history
    1. Complex Febrile Seizure alone does not mandate Lumbar Puncture
      1. Risk of Bacterial Meningitis as cause of complex Febrile Seizure is <1%
      2. Kimia (2010) Pediatrics 126(1): 62-9 [PubMed]
    2. Focal Seizure
    3. Prolonged Seizure exceeding 15 minutes
    4. Multiple Seizures
  3. Physical exam findings suggestive of intracranial abnormality or findings suggestive of Meningitis
    1. Petechiae
    2. Nuchal Rigidity (or Kernig Sign or Brudzinksi Sign)
    3. Decreased Level of Consciousness or Coma
    4. Hypotension
    5. Focal neurologic deficit
  4. Other possible indications
    1. Pretreatment with antibiotics or
    2. Children 6-12 months of age with unknown or incomplete Vaccination series
      1. HaemophilusInfluenzae type B Vaccine
      2. Streptococcus PneumoniaeVaccine (Prevnar)
    3. Lumbar Puncture is no longer routinely indicated for children under 18 months without other findings

XIII. Imaging: Neuroimaging (MRI or CT) Indications

  1. General
    1. No imaging if otherwise normal history and exam
    2. MRI Head is the preferred modality if imaging is absolutely required (no radiation)
  2. Criteria
    1. Persistent neurologic deficits or Altered Mental Status
    2. Cerebral Abscess risk
    3. Increased Intracranial Pressure signs
    4. Head Trauma
    5. Suspected structural defect (e.g. Microcephaly)
    6. Status Epilepticus
    7. Complex Febrile Seizure
      1. Only obtain imaging if associated with other neurologic findings
      2. Complex Febrile Seizure alone is not associated with intracranial abnormality
      3. Teng (2006) Pediatrics 117(2): 304-8 [PubMed]
  3. References
    1. Offringa (2001) BMJ 323:1111-4 [PubMed]

XIV. Management: Seizure duration >15 minutes (Status Epilepticus)

  1. See Status Epilepticus
  2. Approach
    1. Treated the same regardless of fever presence
    2. Consider initiating Benzodiazepines for Seizure >5 minutes (as these are unlike to stop spontaneously)
    3. ABC Management
    4. Supplemental Oxygen, monitor and airway management
    5. Benzodiazepines (Lorazepam, Diazepam, Midazolam) followed by Fosphenytoin, Levetiracetam or Phenobarbital
  3. Emergency department
    1. Lorazepam
      1. Preferred agent for acute tonic-clonic pediatric Seizures
      2. Dose: 0.1 mg/kg IV up to 4 mg
    2. Diazepam
      1. Consider rectal form (diastat) when no IV Access available
      2. Dose: 0.2 to 0.5 mg/kg IV (or rectally) q15 minutes
      3. Maximum cummulative dose: 5 mg for age <5 years
    3. Midazolam
      1. Consider when no IV Access available (use IM)
      2. Dose: 0.2 mg/kg IM of the IV formulation up to 10 mg
    4. Fosphenytoin (preferred over Phenytoin)
      1. Indicated for Seizure refractory to Benzodiazepine
  4. Home environment (emergency prescription)
    1. Agents
      1. Diazepam gel (buccal Diazepam) - preferred over rectal formulation
      2. Diazepam rectal suppository (Diastat)
    2. Dosing
      1. Diazepam 0.5 mg/kg for single dose (age 2-5 years)
    3. Protocol
      1. Parents would have available at home for prn use
      2. Give for Seizure lasting longer than 15 minutes
      3. Immediate ER evaluation for prolonged Seizure
  5. References
    1. Offringa (2001) BMJ 323:1111-4 [PubMed]

XV. Management: General

  1. Disposition to home criteria
    1. Simple Febrile Seizure
      1. Return to baseline status, tolerating oral fluids, non-toxic in appearance
    2. Complex Febrile Seizure
      1. Return to baseline with no persistent neurologic deficits
  2. Plan follow-up
    1. All children discharged from Emergency Department after Febrile Seizure in 1-2 days in clinic
  3. Lowering Temperature with antipyretics (Tylenol and Ibuprofen)
    1. Some stuides showed no reduced risk of Seizure (although may aid comfort)
      1. Strengell (2009) Arch Pediatr Adolesc Med 163(9): 799-804 [PubMed]
    2. Other studies showed Acetaminophen reduced Seizure recurrence in first 24 hours
      1. Murata (2018) Pediatrics 142(5): e20181009 [PubMed]
  4. Warn parents that recurrence is likely
    1. See recurrence risk factors above
    2. One third of children with febrile seziure will have another (75% within one year)
      1. Berg (1997) Arch Pediatr Adolesc Med 151(4): 371-8 [PubMed]
  5. Discuss with parents general home measures during recurrent Seizure
    1. Place child in safe position in left lateral decubitus position
    2. Ensure unobstructed airway
    3. Give emergency Seizure abortive medication (e.g. rectal Diazepam) if prescribed
    4. Call 911 for prolonged Seizure or at parental discretion
    5. Re-evaluation for new complex Seizure features, Seizure recurrence in 24 hours
  6. Offer reassurance (key)
    1. Children with Febrile Seizures have identical intellectual and behavioral development as with their peers
    2. Simple Febrile Seizures are not associated with increased morbidity or mortality
    3. Complex Febrile Seizures have a very rare mortality, nearly undetectable rate in the first 2 years after Seizure
    4. Verity (1998) N Engl J Med 338(24): 1723-8 [PubMed]
    5. Vestergaard (2008) Lancet 372(9637): 457-63 [PubMed]

XVI. Management: Prophylaxis

  1. May offer parent some sense of control
  2. Prophylaxis, however, is not recommended
    1. Significant adverse effects (lethargy, irritability)
    2. Does not affect future Seizure risk
    3. Agents taken continuously have adverse effects
    4. Agents taken intermittently (Diazepam) not protective
      1. Typically Seizure presents with fever onset
  3. Intermittent dose for fever >38.5
    1. Not recommended unless high risk of recurrence
    2. Diazepam (adjust dosing per age)
  4. Continuous Dosing (not recommended - adverse effects)
    1. Phenobarbital
      1. Age 2-24 months: 5-8 mg/kg/day
      2. Age >2 years: 3-5 mg/kg/day
    2. Valproic Acid 10-15 mg/kg/day (max 60 mg/kg) divided

XVII. Management: Neurology Consultation Indications

  1. Not recommended in simple Febrile Seizures
  2. Complex Febrile Seizure
  3. Abnormal findings on examination or diagnostics

XVIII. Management: Outpatient EEG

  1. Precautions
    1. AAP does not recommend for simple Febrile Seizures in neurologically healthy children
    2. Electroencephologram (EEG) does not predict future Seizure Disorder
      1. (2011) Pediatrics 127(2):389-94 [PubMed]
  2. Indications
    1. History of neurologic or Developmental Disorders
    2. Family History of Seizure Disorder
    3. More than one feature characterizing Febrile Seizure as complex

XIX. Prognosis: Excellent

  1. Mortality is rare with complex Febrile Seizures and non-existant in simple Febrile Seizures
  2. Normal school progression expected
    1. Verity (1998) N Engl J Med 338(24): 1723-8 [PubMed]
  3. Seizure remission expected
    1. No further Seizures after age 5 years in 98% children

XX. Prognosis: Predictors of continued Epilepsy

  1. Neurodevelopmental disorder
    1. Developmental Delay
    2. Cerebral Palsy
    3. Hydrocephalus
    4. Abnormal Neurologic Exam
  2. Fever duration less than 1 hour before Seizure onset
  3. Age >3 years at time of Febrile Seizure
  4. Multiple Febrile Seizures at age <1 year
  5. Febrile Seizure with Eye Deviation, lip smacking or prolonged motor movement >15 min
  6. Family History of Epilepsy in first degree relative
  7. Complex Febrile Seizure with multiple complex features (see type description above)
    1. Two complex features: 17-22% chance of future Epilepsy
    2. Three complex features: 49% chance of future Epilepsy
  8. References
    1. Shinnar (2002) J Child Neurol 17(suppl 1): S44-S52 [PubMed]

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Related Studies

Ontology: Febrile Convulsions (C0009952)

Definition (MSH) Seizures that occur during a febrile episode. It is a common condition, affecting 2-5% of children aged 3 months to five years. An autosomal dominant pattern of inheritance has been identified in some families. The majority are simple febrile seizures (generally defined as generalized onset, single seizures with a duration of less than 30 minutes). Complex febrile seizures are characterized by focal onset, duration greater than 30 minutes, and/or more than one seizure in a 24 hour period. The likelihood of developing epilepsy (i.e., a nonfebrile seizure disorder) following simple febrile seizures is low. Complex febrile seizures are associated with a moderately increased incidence of epilepsy. (From Menkes, Textbook of Child Neurology, 5th ed, p784)
Definition (CSP) seizures that occur during a fever; a common condition, affecting 2-5% of children aged 3 months to five years; majority are simple febrile seizures (generally defined as generalized onset, single seizures with a duration of less than 30 minutes); complex febrile seizures are characterized by focal onset, duration greater than 30 minutes, and/or more than one seizure in a 24 hour period.
Concepts Disease or Syndrome (T047)
MSH D003294
ICD9 780.31
ICD10 R56.0 , R56.00
SnomedCT 206733006, 158139003, 323091004, 140804007, 41497008, 269033007
English Convulsion, Febrile, Convulsions, Febrile, Febrile Convulsions, Febrile Seizure, Febrile Seizures, Seizures, Febrile, FEVER CONVULSIONS, Febrile Convulsion, Seizure, Febrile, Febrile convulsions, Convulsions, febrile, Febrile convulsions (simple), unspecified, Febrile seizures NOS, [D]Convulsions, febrile (context-dependent category), [D]Convulsions, febrile, [D]Pyrexial convulsion, Febrile seizures, febrile convulsion (diagnosis), febrile convulsion, Convulsion febrile, Febrile convulsion seizure, Fever convulsions, Febrile fits, Pyrexial fit, Febrile Convulsion Seizure, Febrile Convulsion Seizures, Seizure, Febrile Convulsion, Seizures, Febrile Convulsion, Convulsion, Fever, Convulsions, Fever, Fever Convulsion, Fever Convulsions, Convulsion, Pyrexial, Convulsions, Pyrexial, Pyrexial Convulsion, Pyrexial Convulsions, Febrile Fit, Febrile Fits, Fit, Febrile, Fits, Febrile, Fever Seizure, Fever Seizures, Seizure, Fever, Seizures, Fever, Pyrexial Seizure, Pyrexial Seizures, Seizure, Pyrexial, Seizures, Pyrexial, Febrile convulsions NOS, Febrile seizure NOS, Febrile convulsion NOS, Seizures, Febrile [Disease/Finding], convulsion febrile, fevers seizures, Convulsions;febrile, febrile fit, fever seizure, seizures fever, Seizure;febrile, convulsions febrile seizures, fever convulsion, seizure fever, fever convulsions, fever seizures, febrile seizures, seizure febrile, convulsion fever, [D]Convulsions, febrile (situation), Febrile seizure (from fever), Febrile convulsions (finding), Febrile convulsion, Fever seizure, Febrile seizure, Pyrexial convulsion, Febrile fit, Febrile convulsion (finding), convulsions; febrile, febrile; convulsions, febrile; seizures, seizure; febrile, febrile seizure, febrile convulsions
Portuguese CONVULSOES FEBRIS, Convulsões febris, Crise convulsiva febril, Convulsões Febris, Crises Febris, Ataques Febris, Crises Piréticas, Crise Convulsiva Febril, Crises Convulsivas Febris, Convulsão febril
Spanish CONVULSIONES FEBRILES, Ataques febriles, Crisis febril, Crisis convulsiva febril, Convulsiones febriles, Ataque febril, Ataques Febriles, Convulsiones Febriles, [D]convulsiones febriles (categoría dependiente del contexto), Crisis Febriles, Crisis Piréticas, convulsiones febriles (hallazgo), [D]convulsiones febriles, [D]convulsiones febriles (situación), convulsiones febriles, Crisis Convulsiva Febril, Crisis Convulsivas Febriles, convulsión febril (hallazgo), convulsión febril, convulsión por fiebre, Convulsión febril
German FIEBERKRAEMPFE, Konvulsion, febril, Fieberkonvulsionen, Fieberkonvulsion, Fieberanfall, Fieberanfaelle, Fieberkraempfe, Fieberkrampf, Konvulsionen, febrile, Febrile Krämpfe, Fieberkrämpfe, Krämpfe, Fieber-
Dutch koortsstuipen, febriele convulsie, koortsconvulsie, koortsconvulsies, aanval; febriel, convulsie; febriel, febriel; aanval, febriel; convulsie, koortsstuip, Convulsie, febriele, Febriele aanval, Koortsstuip, Koortsstuipen, Pyrexie-aanval, Stuip, koorts-, Stuipen, koorts-
French Crise fébrile, CONVULSIONS FEBRILES, Accès convulsifs fébriles, Accès convulsif fébrile, Convulsion fébrile, Convulsions fébriles, Crises convulsives fébriles, Crises fébriles
Italian Attacchi di febbre, Attacco febbrile, Crisi convulsiva febbrile, Crisi febbrili, Convulsione febbrile, Convulsioni febbrili
Japanese 熱性痙攣発作, 熱性発作, ネッセイケイレン, ネツセイケイレンホッサ, ネツセイホッサ, ネッセイケイレンホッサ, ネツセイケイレン, 痙攣-熱性, 熱性けいれん, 熱性痙攣, けいれん-熱性, けいれん-発熱性, 発熱性けいれん
Swedish Feberkramper
Czech křeče febrilní, záchvaty febrilní, Febrilní záchvaty, Febrilní záchvat, Horečnatý záchvat, Febrilní křeč, Horečnaté křeče, Febrilní křečovitý záchvat
Finnish Kuumekouristukset
Korean 열성 경련
Polish Drgawki z przegrzania, Drgawki gorączkowe, Drgawki piretyczne
Hungarian Lázgörcs, Lázas convulsiós roham, Lázas rohamok, Lázas görcsroham, Lázas convulsio, Lázgörcsök
Norwegian Feberkramper, Convulsiones febrilis, Feberkonvulsjoner