Complex Febrile Seizure

Complex febrile seizure is a febrile seizure with at least one complex feature in a child aged 6 months to 5 years. The complex features are focal onset or focal features (including Todd paresis), duration over 15 minutes, or recurrence within 24 hours (two or more seizures in the same febrile illness, with recovery between).

• Accounts for about 20 to 35 percent of febrile seizures.
• Febrile status epilepticus: febrile seizure lasting 30 minutes or longer (or repeated without recovery); about 5 percent of febrile seizures.
• Risk factors:
  • Family history of febrile seizures or epilepsy, neurodevelopmental abnormality, early onset (under 12 months), and history of a prior complex febrile seizure.
  • Structural brain lesions and mesial temporal sclerosis (long seizures).
  • Genetic syndromes (Dravet syndrome from SCN1A mutation with hemiclonic or prolonged febrile seizures under 1 year, GEFS plus).
  • Meningitis or encephalitis.
• Causes of fever are the usual childhood infections (viral upper respiratory infection, roseola, otitis media, gastroenteritis, urinary tract infection, tonsillitis). However, central nervous system infection (meningitis, herpes simplex or other viral encephalitis, cerebral malaria) must be actively excluded.
• Outcomes: risk of later epilepsy about 4 to 15 percent (higher with multiple complex features, neurodevelopmental abnormality, and family history of epilepsy). Recurrence of febrile seizures about 30 to 50 percent. Prolonged seizures can rarely lead to hippocampal injury.

• Seizure with focal onset (unilateral clonic activity, head or eye deviation), asymmetric tonic posturing, prolonged duration (over 15 minutes), repeated attacks within 24 hours, or incomplete recovery (post-ictal drowsiness beyond 1 hour; Todd paresis).
• Fever may be low grade or recent.
• Examination: temperature, source of infection, meningism, fontanelle, rash, focal deficits, head circumference, developmental milestones, neurocutaneous stigmata, signs of raised intracranial pressure, hydration, perfusion.
• Red flags: persistent drowsiness, focal neurology, meningism, bulging fontanelle, non-blanching rash, hypotension, hypoxia, prolonged seizures requiring multiple doses, developmental regression.
• Further red flags: seizure at first sign of fever with recurrent events, family history of epilepsy, afebrile seizures in the history, age under 12 months, severe vomiting, trauma.

• Admit for observation and investigation.
• Bloods: capillary glucose, full blood count, CRP, blood culture, urea, electrolytes, calcium, magnesium, liver function, ammonia and lactate in prolonged seizures with unexplained encephalopathy, blood gas.
• Malaria rapid test and smear in endemic areas or travel history, HIV test where indicated.
• Urinalysis and culture.
• Lumbar puncture: strongly indicated (after stabilisation and exclusion of contraindications to lumbar puncture) for all children with a complex febrile seizure and signs of meningitis or encephalitis.
• Lumbar puncture is also strongly indicated for those under 12 months, those with persistent altered consciousness, those on antibiotics, or when immunisations are incomplete.
• CSF cell count, protein, glucose, Gram stain, culture, herpes simplex virus PCR, enterovirus PCR.
• Neuroimaging (MRI preferred, CT if urgent) for focal features that persist, prolonged post-ictal deficit, abnormal neurological examination, head trauma, raised intracranial pressure signs, or suspected structural lesion or encephalitis.
• EEG is not helpful in the first days; arrange if recovery is incomplete, seizures recur afebrile, or there is concern for epileptic encephalopathy.
• Genetic testing (SCN1A) if early onset, prolonged hemiclonic seizures, recurrent complex seizures, or developmental slowing.

• Acute management of a prolonged seizure:
  • Airway, breathing, circulation; oxygen; recovery position; check glucose; time the seizure.
  • At 5 minutes: midazolam buccal (6 months to under 1 year 2.5 mg; 1 to under 5 years 5 mg) or intranasal midazolam 0.2 mg/kg, or rectal diazepam 0.5 mg/kg (maximum 10 mg), or intravenous lorazepam 0.1 mg/kg (maximum 4 mg).
  • If seizing 5 to 10 minutes later: repeat the benzodiazepine once in hospital.
  • Second line: levetiracetam 40 mg/kg intravenously over 5 to 10 minutes (maximum 3 g), or phenytoin 20 mg/kg intravenously at no more than 1 mg/kg/min with cardiac monitoring, or phenobarbital 20 mg/kg intravenously over 20 minutes.
  • Refractory (over 30 minutes): intensive care, anaesthetic induction, and continuous infusion (midazolam, thiopentone).
• Empirical treatment if meningitis or encephalitis is possible and lumbar puncture is delayed: ceftriaxone 80 to 100 mg/kg (maximum 4 g) intravenously once daily (or 50 mg/kg every 12 hours).
• Plus aciclovir 10 to 20 mg/kg intravenously every 8 hours (higher dose in children under 12 years).
• Dexamethasone 0.15 mg/kg every 6 hours for 4 days when bacterial meningitis is suspected (start before or with the first antibiotic dose); add vancomycin if resistance risk.
• Intravenous artesunate 2.4 mg/kg at 0, 12 and 24 hours for severe malaria.
• Fever control for comfort with paracetamol 15 mg/kg every 4 to 6 hours (not proven to prevent recurrence).
• Prophylaxis: continuous antiepileptic drugs are not routinely recommended.
• Intermittent oral clobazam 0.5 to 1 mg/kg/day in two divided doses during febrile illness (maximum 20 mg per day) can be considered for frequent or prolonged complex recurrences.
• A buccal midazolam rescue plan for prolonged seizures at home.
• Antiepileptic therapy is started if afebrile seizures occur or an epilepsy syndrome is diagnosed.
• Parent counselling: higher recurrence and epilepsy risk than simple febrile seizures; teach first aid and a rescue plan; emergency instructions; encourage vaccination.
• Follow up: paediatric neurology review in 2 to 4 weeks, developmental assessment, EEG or MRI based on findings. Long term review for children with neurological deficits or recurrent prolonged events.