Febrile seizures: Viva

Branch 1: Definition and classification

The candidate should confirm the diagnosis by stating the four locked criteria: a convulsion with fever over 38 degrees Celsius in a child aged 6 months to 60 months, without a central nervous system infection and without a prior afebrile seizure. This girl meets all four, so she has had a febrile seizure. A strong candidate then classifies it as complex rather than simple, because it lasted 18 minutes, which is over the 15 minute boundary. The duration alone makes it complex, and the candidate should explain that the simple-versus-complex split drives the workup, the counselling, and the prognosis. [1]

If the examiner presses on the boundaries, the candidate should explain that 15 minutes is the point at which a convulsion is unlikely to self-terminate and active treatment should begin, and that 30 minutes defines febrile status epilepticus. The candidate should note that a convulsion still ongoing at five minutes is heading toward status and should be treated, not observed. The FEBSTAT study linked febrile status epilepticus to acute hippocampal injury and to later temporal lobe epilepsy, which is why duration is a classification feature and not merely a descriptor. [1] [4]

Branch 2: Acute termination of the convulsion

If asked how to manage the convulsion acutely, the candidate should first secure the airway, give oxygen, check a bedside glucose, and obtain intravenous access. The first-line agent is a benzodiazepine. With intravenous access, intravenous lorazepam at 0.1 mg per kg to a maximum of 4 mg, repeated once after five minutes, is standard. Without intravenous access, buccal midazolam at 0.5 mg per kg to a maximum of 10 mg is effective, and the McIntyre randomised trial showed it terminates seizures at least as well as rectal diazepam. Rectal diazepam at 0.5 mg per kg to a maximum of 20 mg remains an option where no other route is available. [3]

A strong candidate then describes escalation. A convulsion persisting despite two benzodiazepine doses is refractory and needs second-line therapy: intravenous levetiracetam at 40 mg per kg, maximum 2.5 g, or intravenous fosphenytoin at 20 mg PE per kg, in a high-dependency or intensive care setting with airway support. The candidate should seek senior paediatric and anaesthetic help early and recognise a convulsion over 30 minutes as febrile status epilepticus. [1]

Branch 3: The lumbar puncture decision

If the examiner moves to when to perform a lumbar puncture, the candidate should state the 2011 American Academy of Pediatrics thresholds clearly. A lumbar puncture is performed in any child with meningeal signs, and is strongly considered in any child aged 6 to 12 months who is incompletely immunised against Haemophilus influenzae type b or Streptococcus pneumoniae, or who has been pre-treated with antibiotics, because both situations can mask meningitis. [1]

The candidate should justify not performing a lumbar puncture on this girl. She is over 12 months, fully immunised, has no meningeal signs, and has recovered to baseline, so a lumbar puncture is not routinely required. The study by Kimia and colleagues supports this, showing that bacterial meningitis is rare among well-appearing children aged 6 to 18 months presenting with a first simple febrile seizure. The candidate should hold a low threshold for lumbar puncture if the conscious state deteriorates, meningeal signs emerge, or the child was pre-treated with antibiotics. [1] [5]

Branch 4: Counselling and the case against prophylaxis

If the examiner asks what to tell the family about preventing recurrence, the candidate should state firmly that routine prophylaxis is not recommended. Continuous phenobarbitone or valproate and intermittent oral diazepam reduce recurrence modestly but their harms (cognitive and behavioural effects, sedation, masked illness) outweigh the benefit, per the 2008 AAP guideline and the 2021 Cochrane review. The candidate should explain that antipyretics are for comfort and do not prevent recurrence. [2]

The candidate should offer the one evidence-supported strategy for a child with prolonged or frequent recurrences: a rescue benzodiazepine, such as buccal midazolam at 0.5 mg per kg, to be given at the onset of a convulsion. The candidate should then counsel on prognosis: about one in three children has another febrile seizure, simple febrile seizures do not cause brain damage, and the subsequent epilepsy risk is low but higher after a complex seizure such as this one. The family leaves with a written rescue plan, a safety-net, and advice on when to call an ambulance. [2] [3]