Febrile convulsion

• Overview:

  • A seizure which occurs in a febrile child
  • Between the ages of 6 months and 5 years
  • Not caused by a central nervous system infection
  • Most common cause of seizures in children - 1 in 20 children will have a febrile seizure
• Aetiology:

  • Exact cause is unknown
  • Considered an age-dependent response of the immature brain to fever - multifactorial mix of genetic and environmental factors
  • 80% of febrile seizures are caused by viral infections - human herpesvirus 6 (roseola) and influenza are most common
• Risk factors:

  • Family history of febrile seizures
  • High fever (>40)
  • Viral infection
  • Recent immunisation (rare)
  • Around half of children who present with a febrile seizure have no identifiable risk factor
• Most febrile seizures occur within 24 hours of the child developing a fever. The parents may give a history of a previously well child who developed a high temperature and started convulsing.
• Simple febrile seizure (most common):

  • Duration <15 minutes (most last <5)
  • Generalised seizure - symmetrical and involving the whole body, may be tongue biting and incontinence
  • Occur only once in 24 hours
  • Post-ictal phase is usually less than 1 hour - longer with excessive drowsiness or confusion should raise suspicion of central nervous system infection of status epilepticus
• Investigations:

  • Children with simple febrile seizures who rapidly recover and are otherwise well, require no investigations following a febrile seizure
  • Important to exclude hypoglycaemia in an actively seizing child or if there is a prolonged recovery period
• Immediate management of seizure:

  • Monitor the duration of the seizure and protect the child from injury
  • If tonic-clonic movements last for more than 5 minutes call an ambulance or give emergency buccal midazolam or rectal diazepam (if advised by specialist for recurrent febrile seizures)
  • Rescue medication can be repeated after 10 minutes
• Clinical assessment following seizure:

  • Focus on finding the source of fever
  • Emergency hospital admission if suspicion of CNS infection or other life-threatening cause of fever
• Generally, assessment by the paediatric team is required for the following situations:

  • First febrile seizure
  • Children under 18 months old
  • Uncertain diagnosis
  • Recent antibiotic use
  • Decreased level of consciousness before the seizure
  • Focal neurological deficits
  • Recurrent or complex seizures
• Children with developmental delay and/or symptoms of neurocutaneous (neurofibromatosis, tuberous sclerosis) or metabolic disorders be referred to a paediatric neurologist
• Parental education:

  • Explain the benign nature of febrile seizures
  • Give information on managing - basic first aid measures and when to call for emergency help
• Complications:

  • Injury while seizing
  • Aspiration
  • Small increased risk of epilepsy as compared to the general population
  • Risk of recurrence
• The prognosis of febrile seizures is good and seizures usually stop by the age of 5 – 7.
• Risk of epilepsy:

  • while the risk is increased compared to a child who has never had a febrile seizure, the risk is still small.
  • The risk also depends on the type of febrile seizure. A child with simple febrile seizures has a 2% risk of developing epilepsy
  • a child with complex febrile seizures has a 5% chance of developing epilepsy
  • a child who has never had a febrile seizure has a 0.5 – 1% chance of developing epilepsy.