Define Febrile Seizures. Describe its aetiology, classification, clinical features and investigations.

Definition

• A febrile seizure is a seizure occurring with fever (temperature ≥ 38 °C) in a child aged 6 months to 5 years, in the absence of central nervous system infection, metabolic disturbance or a history of afebrile seizures.
• It is the commonest seizure disorder of childhood.

Etiology & Risk Factors

• Usually triggered by a viral infection (upper respiratory infection, roseola, otitis media).
• A rapid rise in temperature (rather than the absolute peak) is important.
• Strong genetic predisposition — a positive family history is common.
• Peak age is around 12–18 months.

Classification

Clinical Features

• A brief generalised tonic-clonic seizure during a febrile illness, followed by post-ictal drowsiness.
• The child is neurologically normal before and after (in simple febrile seizures).
• Complex features (focal, prolonged, recurrent) warrant closer evaluation.

Investigations

• Investigations are directed at finding the source of fever, not the seizure itself.
• Lumbar puncture — if meningitis is suspected; consider strongly in infants < 12–18 months (in whom meningeal signs may be subtle) or if the child is not recovering.
• EEG and neuroimaging are not routinely indicated for simple febrile seizures; considered for complex/atypical cases.
• Blood glucose, electrolytes and calcium if clinically indicated.

Acute Management of the Seizure

• Protect the airway — place the child in the recovery position, do not restrain or put anything in the mouth.
• Most seizures are brief and self-terminating; if it lasts > 5 minutes, give a benzodiazepine — rectal diazepam or buccal/intranasal midazolam.
• Antipyretics (paracetamol) for comfort; treat the underlying infection.
• Ensure it is not meningitis/encephalitis before attributing it to a simple febrile seizure.

Prevention of Recurrence

• Regular prophylactic antiepileptics are not recommended (risks outweigh benefits).
• Antipyretics reduce discomfort but do not reliably prevent recurrence.
• For prolonged/recurrent seizures, parents can be given intermittent/rescue benzodiazepine to use at home.

Prognosis

• Excellent — simple febrile seizures do not cause brain damage or affect development/intelligence.
• Recurrence occurs in ~30% (higher if young age, low peak temperature, short fever-to-seizure interval, family history).
• The risk of later epilepsy is only slightly raised (higher after complex febrile seizures).

Epidemiology

• Affects 2–5% of children; the commonest seizure type of childhood.
• Peak incidence 12–18 months; a positive family history is frequent.

Febrile Status Epilepticus

A febrile seizure lasting > 30 minutes (or recurrent without recovery) is febrile status epilepticus — it is managed as status epilepticus and warrants closer evaluation for an underlying CNS infection.

Differential Diagnosis

• CNS infection — meningitis/encephalitis (the crucial one to exclude).
• Rigors/shivering with fever; a first afebrile seizure that coincidentally occurs with fever; metabolic disturbance.

When to Admit / Evaluate Further

• Complex features, a first complex seizure, or a child who is not fully recovering.
• Age < 12–18 months, signs suggesting meningitis, or a toxic/unwell child.
• Diagnostic uncertainty or significant parental anxiety needing observation.

Parent Education (a Key Part of Management)

• Explain the benign nature and excellent prognosis; teach first-aid and seizure timing.
• Advise antipyretics for comfort (not as guaranteed prevention) and when to seek help.

Risk Factors for Recurrence

• Young age at first seizure (< 18 months); a lower peak temperature at the time of the seizure.
• A short interval between fever onset and the seizure; a family history of febrile seizures.
• The more risk factors present, the higher the recurrence rate.

Risk of Subsequent Epilepsy

The risk of later epilepsy after a simple febrile seizure is only marginally above the background population risk; it is higher after complex febrile seizures, or with a family history of epilepsy or pre-existing neurodevelopmental abnormality.

Vaccination & Febrile Seizures

Some vaccines (e.g. MMR, DTP) can cause fever and, occasionally, an associated febrile seizure; this is not a contraindication to immunisation, and parents should be reassured and advised on antipyretics and first-aid.