Pediatric febrile seizure: When do I need to do a lumbar puncture?

You are in the ED when a 7 month old is brought in by EMS after a witnessed generalized seizure. The grandmother reports that the child has had URI symptoms for a couple of days and then developed a fever today. Shortly after giving ibuprofen, the child began to seize with arms and legs twitching. The episode lasted approximately 8 minutes and when EMS arrived, the child was sleepy, but arousable. The glucose was 92 mg/dL en route. On exam in the ED, child is awake and staring at you to make the next move…

Vitals: Temp 39C, P 136, RR 28, Sat 100%

Clinical Question

Which children with a febrile seizure require a lumbar puncture to evaluate for bacterial meningitis?

Definitions

What is a Pediatric Febrile Seizure?

• A convulsion associated with an elevated temperature > 38^oC
• Age: 6 months – 5 years
• Occurs in 2-5% of all children

Two types of febrile seizures:

1. Simple Febrile Seizure
   • Generalized
   • Short duration (< 15 minutes)
     
   • Only one seizure within 24 hours

2. Complex Febrile Seizure
   • Focal
   • Longer duration (≥ 15 minutes)
   • More than one seizure within 24 hours

The Data on Managing Febrile Seizures

1. Simple Febrile Seizures

The revised American Academy of Pediatrics clinical practice guideline (2011) for simple febrile seizure state ¹ :

• The decision to test should be directed toward identifying the source of the fever, and NOT the seizure.
  • Viral infections cause the majority of fevers in this age group
  • Don’t forget UTI’s in young females and uncircumcised males
  • The following should NOT be routinely performed:
    • Blood tests, electrolytes, and blood cultures
    • Neuroimaging or EEG
• Consider a lumbar puncture if:
  
  • There are signs or symptoms of meningitis after the seizure
  • If the child is not fully immunized or immunization status is unknown
    • H. influenza type b or S. pneumonaie
  • If the patient has been pretreated with antibiotics, because this may mask signs and symptoms of meningitis
• This guideline is not intended for patients with:
  • Complex febrile seizures
  • Children with previous neurologic insults
  • Known CNS abnormalities
  • History of afebrile seizures

2. Complex Febrile Seizures

Children with complex febrile seizures are traditionally worked up with a lumbar puncture because of the association between seizures and CNS infection. Because complex febrile seizures are so heterogeneous (i.e. prolonged, focal, or recurrent), there are no consensus guidelines on which children require a lumbar puncture.

In 2010, a retrospective cohort study assessed the rate of acute bacterial meningitis among children 6-60 months, who presented with their first complex febrile seizure between 1995 and 2008. ²

• Total 526 patients with first complex febrile seizure
  • 83% had no previous seizure
  • 340 of 526 (64%) underwent a lumbar puncture
    • 14 of 340 (2.7%) had CSF pleocytosis
    • 3 of 340 (0.9%) were diagnosed with acute bacterial meningitis
      • 2 of the 3 had a positive CSF culture for S. pneumonia
        • Both were ill appearing (non-responsive, bulging fontanelle, apnea)
      • 3rd patient had a failed lumbar puncture but grew S. pneumonia in the blood and was treated for a suspected diagnosis of bacterial meningitis

• Author conclusions: Few children with a complex febrile seizure have acute bacterial meningitis in the absence of other signs or symptoms.

Take Home Points

1. A simple febrile seizure does not require further diagnostic evaluation (beyond simply working up the fever) or an LP.

“Current data no longer support routine lumbar puncture in well appearing, fully immunized children who present with a simple febrile seizure.” ¹

2. There are no consensus guidelines at this time for the work up of complex febrile seizures, although…

• Bacterial meningitis is rare in patients who present with complex febrile seizures, who are otherwise well appearing and have no other signs or symptoms on physical exam.

Author information

Steven Bin, MD

Associate Clinical Professor of Pediatrics and Emergency Medicine

Division of Pediatric Emergency Medicine
University of California, San Francisco

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