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Seizures—Febrile, Pediatric

Basics

Description

- Any viral or bacterial infection - Human herpesvirus 6 and 7 - Influenza A

- Vaccines - MMR(V) and DPT - Both increase the risk of febrile seizures but not epilepsy. - Benefits greatly outweigh any risk, and families should be encouraged to vaccinate.

- Obtain detailed description of spell to determine if it was a seizure. - Circumstances in which spell occurred - Duration - Focal features suggest seizure - Postictal weakness suggests seizure

- Ask about new neurologic symptoms such as headache or change in gait that would require further evaluation. - Ask about toxic ingestions. - Identify seizure risk factors from past medical history. - Perinatal complications - Prior brain insult: trauma, meningitis - Developmental delay

- Serum electrolytes, calcium, phosphorus, magnesium, glucose, and complete blood count are not recommended solely for determining the cause of the seizure. - Consider studies to determine fever source. - Lumbar puncture - Perform when symptoms/signs of meningitis or intracranial infection are present - Consider lumbar puncture if - 6 " пїЅ12-month-old infant has deficient or unknown immunization status for Haemophilus influenzae type b or Streptococcus pneumoniae - Pretreated with antibiotics

- Acute symptomatic seizure - Infection - Meningoencephalitis: primary diagnostic consideration; bacterial or viral; consider HSV. - Other infection such as gastroenteritis causing hypernatremic dehydration - Benign convulsions with mild gastroenteritis

- Toxic/metabolic - Stroke - Trauma

- Epilepsy - Nonepileptic spell - Febrile delirium - Chills - Breath-holding spells

- Abortive: consider rectal diazepam (0.5 mg/kg) for febrile seizures ≥5 minutes; may cause drowsiness and ataxia; rarely causes respiratory depression - Preventive - In certain clinical circumstances, for parental anxiety, may use oral diazepam (0.33 mg/kg every 8 hours) to the patient during a febrile illness until afebrile for 24 hours; may cause drowsiness and ataxia - Daily phenobarbital, valproate, or primidone prevents febrile seizures, but risks outweigh benefits.

Febrile seizure: seizure in ≤60-month-old child accompanied by a fever ( ≥100.4 пїЅ пїЅF or 38 пїЅ пїЅC by any method) but without central nervous system infection or prior unprovoked seizure (American Academy of Pediatrics [AAP] guidelines use 6 months as the lower age limit, whereas International League Against Epilepsy uses 1 month) пїЅ пїЅ

2 types: пїЅ пїЅ

  • Simple: febrile seizures that are generalized, last <15 minutes, AND do not recur in 24 hours
  • ComplexFebrile seizures that are focal (including postictal weakness), last ≥15 minutes, OR occur >1 time in 24 hoursFebrile status epilepticus: 1 febrile seizure or series of febrile seizures without full recovery in between lasting ≥30 minutes

Epidemiology

  • AgeMost febrile seizures occur between 6 months and 3 years of age.Peak age is about 18 months.
  • Type65 " пїЅ70% are simple febrile seizures.20 " пїЅ35% are complex febrile seizures. пїЅ пїЅ пїЅ5% are febrile status epilepticus.
  • Timing of seizure пїЅ пїЅ пїЅ20% before or <1 hour of fever onset пїЅ пїЅ пїЅ60% 1 " пїЅ24 hours after fever onset пїЅ пїЅ пїЅ20% >24 hours after fever onset

Prevalence

  • Most common childhood seizure
  • Febrile seizures occur in 2 " пїЅ5% of children in the United States and Western Europe, 9 " пїЅ10% of children in Japan, and 14% of children in Guam.

Risk Factors

Positive family history of febrile seizures пїЅ пїЅ

Genetics

Usually multifactorial or polygenic inheritance пїЅ пїЅ

General Prevention

Antipyretics do not reduce the recurrence risk of simple febrile seizures. пїЅ пїЅ

Pathophysiology

  • Elevated temperatures in developing brain may increase neuronal excitability.
  • Fever increases cytokines that may enhance neuronal excitability.
  • Genetic factors
  • Hyperventilation from fever causes a respiratory alkalosis that may promote seizures.

Etiology

  • Any viral or bacterial infectionHuman herpesvirus 6 and 7Influenza A
  • VaccinesMMR(V) and DPTBoth increase the risk of febrile seizures but not epilepsy.Benefits greatly outweigh any risk, and families should be encouraged to vaccinate.
  • Shigellosis

Commonly Associated Conditions

  • Generalized epilepsy with febrile seizures plus (GEFS+)Febrile seizures beyond 6 years of age or afebrile seizures of varying types ranging from mild to severeMultiple genes identified including SCN1A, SCN2A, SCN1B, GABRG2, GABRD, and PCDH19
  • Febrile infection " пїЅrelated epilepsy syndrome (FIRES)Catastrophic epileptic encephalopathy of unknown etiology that begins with a febrile illness and refractory status epilepticusHas high morbidity and mortality

Diagnosis

History

  • Obtain detailed description of spell to determine if it was a seizure.Circumstances in which spell occurredDurationFocal features suggest seizurePostictal weakness suggests seizure
  • Ask about prior seizures/spells.Prior afebrile seizure suggests epilepsy.Prior febrile seizures supports diagnosis.Prior nonepileptic spells
  • Determine cause of fever/illnessDurationHeight of feverSymptoms: rhinorrhea, diarrhea
  • Ask about new neurologic symptoms such as headache or change in gait that would require further evaluation.
  • Ask about toxic ingestions.
  • Identify seizure risk factors from past medical history.Perinatal complicationsPrior brain insult: trauma, meningitisDevelopmental delay
  • Medications including antibiotics
  • Identify seizure risk factors from family history.

Physical Exam

  • Identify fever source.Vital signs, including temperatureAssess anterior fontanelle, sutures, and head circumference for increased intracranial pressure, which may occur with meningitis or space-occupying lesion.Assess for signs of meningitis such as nuchal rigidity.Examine ears and throat for infection.Examine skin for rashes and other signs of infection.Examine heart and lungs for infection.Assess for trauma.
  • Detailed neurologic examAssess skin for neurocutaneous syndromes.Assess mental status.Assess for subtle signs of seizure such as myoclonus or nystagmus.Examine cranial nerves. Include funduscopic exam for papilledema.Examine gait, motor system, sensation, coordination, and deep tendon reflexes for abnormalities and asymmetries.

Diagnostic Tests & Interpretation

Simple Febrile Seizure

Recommendations from the 2011 AAP Guideline for neurologically healthy infants and children пїЅ пїЅ

Lab

  • Serum electrolytes, calcium, phosphorus, magnesium, glucose, and complete blood count are not recommended solely for determining the cause of the seizure.
  • Consider studies to determine fever source.
  • Lumbar puncturePerform when symptoms/signs of meningitis or intracranial infection are presentConsider lumbar puncture if6 " пїЅ12-month-old infant has deficient or unknown immunization status for Haemophilus influenzae type b or Streptococcus pneumoniaePretreated with antibiotics

Imaging

Not indicated пїЅ пїЅ

Electroencephalogram

  • Not indicated
  • Not predictive of febrile seizure recurrence or development of epilepsy

Complex Febrile Seizures

There is no AAP Guideline. пїЅ пїЅ

Lab

  • Consider studies to identify fever source and as clinically indicated.
  • Indications for lumbar puncture are similar to indications for lumbar puncture for simple febrile seizure but strongly consider for all, especially those with altered mental status.

Imaging

  • Acute brain imaging usually unnecessary, especially if the only complex feature is multiple seizures. Recommend acute MRI (CT acceptable) if with persistently altered mental status, persistent focal neurologic findings, or symptoms/signs of increased intracranial pressure.
  • Recommend routine brain MRI if not done acutely especially for focal seizure, focal exam findings, or focal EEG abnormality.

Electroencephalogram

  • Recommend stat EEG if concerned about nonconvulsive status epilepticus.
  • Recommend routine EEG, especially for abnormal neurologic development or exam. Epileptiform abnormalities or focal slowing may increase risk for developing epilepsy.

Febrile Status Epilepticus

No AAP Guideline. See "Status Epilepticus " пїЅ chapter. пїЅ пїЅ

Lab

  • Recommend studies to treat correctable causes of seizures (e.g., hypoglycemia, hyponatremia) and to identify fever source.
  • Lumbar puncturePerform for any suspicion of meningitis or intracranial infection but strongly consider for all especially if first episode or if mental status is altered.It is important to note that febrile status epilepticus rarely causes a CSF pleocytosis.

Imaging

  • Recommend acute brain imaging (MRI preferred but CT acceptable), especially if first episode with abnormal mental status or focal neurologic findings.
  • Recommend routine brain MRI if not done acutely; may show hippocampal injury that may increase risk for developing epilepsy

Electroencephalogram

  • Recommend stat EEG if concerned about nonconvulsive status epilepticus.
  • Recommend routine EEG; may show temporal slowing or attenuation that correlates with hippocampal abnormality on MRI

Differential Diagnosis

  • Acute symptomatic seizureInfectionMeningoencephalitis: primary diagnostic consideration; bacterial or viral; consider HSV.Other infection such as gastroenteritis causing hypernatremic dehydrationBenign convulsions with mild gastroenteritisToxic/metabolicStrokeTrauma
  • Epilepsy
  • Nonepileptic spellFebrile deliriumChillsBreath-holding spells

Treatment

Medication

  • Abortive: consider rectal diazepam (0.5 mg/kg) for febrile seizures ≥5 minutes; may cause drowsiness and ataxia; rarely causes respiratory depression
  • PreventiveIn certain clinical circumstances, for parental anxiety, may use oral diazepam (0.33 mg/kg every 8 hours) to the patient during a febrile illness until afebrile for 24 hours; may cause drowsiness and ataxiaDaily phenobarbital, valproate, or primidone prevents febrile seizures, but risks outweigh benefits.

Additional Treatment

General Measures

  • See "Status Epilepticus " пїЅ chapter for treating febrile status epilepticus.
  • Treat infection

Ongoing Care

Prognosis

  • Febrile seizure recurrence50% of children <12 months of age at time of first simple febrile seizure have recurrent febrile seizures.30% of children >12 months of age at time of first febrile seizure have a second.Of children with a second febrile seizure, 50% experience a third.
  • Risk for developing epilepsy:6 " пїЅ7% for all febrile seizures2 " пїЅ7.5% for simple febrile seizures10 " пїЅ20% for complex febrile seizures
  • Mortality0.85% for all febrile seizures0% for simple febrile seizures<1.6% for complex febrile seizures with all deaths from febrile status epilepticus
  • No evidence that simple febrile seizures increase risk of neurologic or cognitive deficits.

Additional Reading

  • Chugath пїЅ пїЅM, Shorvon пїЅ пїЅS. The mortality and morbidity of febrile seizures. Nat Clin Pract Neurol. 2008;4(11):610 " пїЅ621. пїЅ пїЅ[View Abstract]
  • Dube пїЅ пїЅCM, Brewster пїЅ пїЅAL, Baram пїЅ пїЅTZ. Febrile seizures: mechanism and relationship to epilepsy. Brain Dev. 2009;31(5):366 " пїЅ371. пїЅ пїЅ[View Abstract]
  • Shinnar пїЅ пїЅS, Glauser пїЅ пїЅTA. Febrile seizures. J Child Neurol. 2002;17(Suppl 1):S44 " пїЅS52. пїЅ пїЅ[View Abstract]
  • Subcommittee on Febrile Seizures. Clinical practice guideline-febrile seizures: guideline for the neurodiagnostic evaluation of the child with a simple febrile seizure. Pediatrics. 2011;127(2):389 " пїЅ394. пїЅ пїЅ[View Abstract]
  • Subcommittee on Febrile Seizures. Febrile seizures: clinical practice guideline for the long-term management of the child with simple febrile seizures. Pediatrics. 2008;121(6):1281 " пїЅ1286. пїЅ пїЅ[View Abstract]

Codes

ICD09

  • 780.31 Febrile convulsions (simple), unspecified
  • 780.32 Complex febrile convulsions

ICD10

  • R56.00 Simple febrile convulsions
  • R56.01 Complex febrile convulsions

SNOMED

  • 434101000124100 Simple febrile seizure, non-refractory (finding)
  • 433681000124102 Complex febrile seizure, non-refractory (finding)
  • 434091000124106 Simple febrile seizure, refractory (finding)
  • 433671000124100 Complex febrile seizure, refractory (finding)
  • 307200007 Recurrent febrile convulsion (finding)
  • 41497008 Febrile convulsion (finding)

FAQ

  • Q: What should parents be told?
  • A: Good neurodevelopmental outcome for simple febrile seizures but relatively high risk for recurrence.
  • Q: Can a child die from a febrile seizure?
  • A: No reported mortality from simple febrile seizures or short complex febrile seizures. Small mortality with febrile status epilepticus.
  • Q: Can a febrile seizure cause brain damage?
  • A: Simple febrile seizures do not. Febrile status epilepticus may.
  • Q: What should the parents do when the child has a seizure?
  • A: Stay calm. Place child in safe place. Turn child on side to keep airway clear. Do not restrain. Do not put anything in mouth. Time seizure. If seizure lasts 5 minutes, call 911 and administer abortive medication such as rectal diazepam if available.
  • Q: What precautions should the parents take?
  • A: Common sense steps such as no unsupervised baths or swimming and no climbing above head height. Always wear helmet when riding bike or doing other activity with wheels. No driving all-terrain vehicles.