Overview
Definition:
A febrile seizure is a convulsion in a child associated with an illness that causes fever, but without any central nervous system infection or metabolic abnormality
It occurs in children aged 6 months to 5 years
Simple febrile seizures are generalized, last less than 15 minutes, and do not recur within 24 hours
Complex febrile seizures have one or more of the following characteristics: focal onset, duration longer than 15 minutes, or recurrence within 24 hours.
Epidemiology:
Febrile seizures affect approximately 2-5% of children aged 6 months to 5 years
They are most common between 12 and 18 months of age
There is a slight male preponderance
Family history of febrile seizures is a significant risk factor, with a recurrence risk of 30-50% in siblings.
Clinical Significance:
While generally benign and self-limiting, differentiating simple from complex febrile seizures is crucial as complex seizures may be associated with an increased risk of developing epilepsy
Understanding imaging indications helps avoid unnecessary investigations and identifies potential underlying serious conditions
This topic is frequently tested in DNB and NEET SS examinations, requiring a thorough understanding of diagnostic criteria and management.
Clinical Presentation
Symptoms:
Fever, often high grade (typically >38°C or 100.4°F)
Sudden onset of seizure activity
Child may lose consciousness
Jerking movements of the limbs
Possible postictal lethargy or confusion
May be associated with an acute illness like viral exanthem, otitis media, or upper respiratory tract infection
Absence of focal neurological deficits before or after the seizure (for simple seizures).
Signs:
Fever on examination
Generalized tonic-clonic movements (simple)
Focal clonic or tonic movements, or asymmetric tonic activity (complex)
Duration of seizure
Neurological examination findings
may be normal or show transient focal deficits (Todd's paralysis) after the seizure
Absence of meningeal signs, focal neurological deficits, or signs of metabolic derangement during the interictal period.
Diagnostic Criteria:
A febrile seizure is diagnosed in children aged 6 months to 5 years who have a seizure with fever (temperature ≥ 38°C/100.4°F) without evidence of central nervous system infection or other serious pathology
Simple febrile seizure: Generalized tonic-clonic
Duration < 15 minutes
No recurrence within 24 hours
No focal neurological deficit or developmental delay before the seizure
Complex febrile seizure: Focal onset, or duration ≥ 15 minutes, or recurrence within 24 hours
Children with complex febrile seizures may have focal neurological deficits, developmental delay, or abnormalities on EEG.
Diagnostic Approach
History Taking:
Detailed history of the current illness and fever
Duration, character, and type of seizure (generalized vs
focal)
Any recurrence within 24 hours
Child's developmental milestones and past medical history
Family history of seizures, epilepsy, or febrile seizures
Medications taken by the child
Red flags: prolonged seizure, focal neurological signs, developmental delay, suspicion of CNS infection (meningitis, encephalitis).
Physical Examination:
Vital signs including temperature
Comprehensive neurological examination: assess for cranial nerve palsies, motor deficits, sensory deficits, and reflexes
Thorough examination for signs of infection (e.g., otitis media, pharyngitis, pneumonia, skin rash)
Evaluate for signs of meningitis (nuchal rigidity, Kernig's sign, Brudzinski's sign)
Assess hydration status.
Investigations:
Routine laboratory investigations are generally NOT recommended for simple febrile seizures in otherwise healthy children
Blood glucose, electrolytes, calcium, and magnesium may be considered if the seizure is prolonged, recurrent, or if there are concerns about metabolic derangement
Lumbar puncture (LP) is indicated if meningitis is suspected (fever + seizure + signs of meningeal irritation or prolonged seizure)
EEG is generally NOT indicated for simple febrile seizures
It may be considered for complex febrile seizures, especially if there are focal neurological deficits, developmental delay, or suspicion of underlying epilepsy
Neuroimaging (CT or MRI brain) is NOT routinely indicated for simple febrile seizures
It is considered for complex febrile seizures, recurrent febrile seizures, focal seizures, or if there are focal neurological deficits on examination, to rule out structural brain lesions, tumors, or infections.
Differential Diagnosis:
Epilepsy with febrile precipitates (seizures occurring with fever in children with epilepsy)
Meningitis
Encephalitis
Metabolic disorders (hypoglycemia, electrolyte imbalances)
Intracranial hemorrhage
Toxic ingestions.
Management
Initial Management:
For a child experiencing a febrile seizure, the immediate goal is to ensure airway patency and safety
Place the child on their side to prevent aspiration
Do not restrain the child
If the seizure is prolonged (>5 minutes) or recurrent, administer benzodiazepines
Lorazepam 0.1 mg/kg IV/IM/PR (max 4 mg) or Diazepam 0.2-0.5 mg/kg IV/PR (max 10 mg)
Phenobarbital may be used as a second-line agent.
Medical Management:
Long-term anticonvulsant prophylaxis is generally NOT recommended for simple febrile seizures due to low risk of recurrence and potential side effects
Anticonvulsant therapy is considered for recurrent complex febrile seizures or when there is an underlying epilepsy
Options include valproate, levetiracetam, or phenobarbital
Antipyretics (acetaminophen or ibuprofen) should be used to manage fever, but they do not prevent recurrence of febrile seizures
Continuous rectal diazepam or intranasal midazolam may be prescribed for home use in children with a history of prolonged or recurrent seizures to be administered by parents.
Surgical Management:
Surgical management is not applicable for typical febrile seizures
It may be considered in rare cases where a focal structural lesion (identified on imaging) is the cause of recurrent complex seizures, and the lesion is amenable to surgical resection.
Supportive Care:
Reassurance for parents is paramount
Educate parents about the benign nature of simple febrile seizures and when to seek medical attention
Monitor vital signs and neurological status
Ensure adequate hydration and nutrition
Advise on appropriate clothing to prevent overheating.
Complications
Early Complications:
Status epilepticus (prolonged seizure)
Hypoxia
Injury from the seizure itself
Respiratory distress
Todd's paralysis (temporary focal neurological deficit).
Late Complications:
Development of epilepsy: The risk of developing epilepsy after a febrile seizure is approximately 1-2%, which is only slightly higher than the general population
This risk is increased in children with risk factors such as a family history of epilepsy, focal seizures, prolonged seizures, or underlying neurological abnormalities
Intellectual disability or developmental delay: This is primarily associated with underlying neurological conditions that predispose to seizures, rather than the febrile seizure itself.
Prevention Strategies:
Prevention focuses on prompt and effective management of fever with antipyretics, although this does not prevent seizure occurrence
Early recognition and management of underlying infections is crucial
For children at high risk of prolonged or recurrent seizures, home administration of benzodiazepines may be considered under strict medical supervision.
Prognosis
Factors Affecting Prognosis:
The prognosis for simple febrile seizures is excellent, with no long-term adverse effects on cognitive function or development
Prognosis is influenced by the presence of risk factors for epilepsy development, such as a family history of epilepsy, abnormal neurological status before the seizure, or complex features of the seizure
Recurrence is common, with about one-third of children experiencing a repeat febrile seizure.
Outcomes:
Most children with simple febrile seizures have a normal neurodevelopmental outcome
The risk of developing epilepsy is low, and most children who do develop epilepsy eventually achieve seizure control
The vast majority of febrile seizures do not lead to brain damage or long-term neurological deficits.
Follow Up:
Follow-up is primarily for parental reassurance and education regarding simple febrile seizures
For complex febrile seizures, follow-up should focus on assessing for developmental progress, neurological status, and any further seizure activity
Consider referral to a pediatric neurologist if there are concerns about epilepsy or underlying neurological issues
Regular review may be required if anticonvulsant medication is initiated.
Key Points
Exam Focus:
Distinguishing between simple and complex febrile seizures is critical for management and risk assessment
Understand the indications for lumbar puncture and neuroimaging
Recognize the low risk of developing epilepsy from simple febrile seizures and the factors that increase this risk
Antipyretics treat fever, not prevent seizures.
Clinical Pearls:
Always confirm the temperature before labeling a seizure as febrile
When in doubt, perform an LP if meningitis is suspected
Neuroimaging is reserved for complex cases or when a structural lesion is suspected
Reassure parents
most febrile seizures are harmless.
Common Mistakes:
Over-investigating simple febrile seizures with unnecessary EEGs or neuroimaging
Underestimating the risk of meningitis in infants with fever and seizure
Prescribing long-term anticonvulsants for simple febrile seizures
Failing to consider underlying neurological conditions in children with recurrent complex febrile seizures.