Neurology

Section 3: Febrile Seizures

Febrile Seizures (FS)

  • Definition: The most common type of seizures in neurologically healthy infants and children, occurring between 6-60 months of age with a temperature ≥ 38°C, not due to CNS infection or metabolic disturbance, and without a history of prior afebrile seizures.

  • Genetics: Several identified genetic mutations contribute to FS, often with a positive family history. Most FS are polygenic, but some are inherited as an autosomal dominant trait.

Types of Febrile Seizures

  • Simple FS:

    • Generalized (usually tonic-clonic) attack associated with fever.

    • Lasts ≤ 15 minutes.

    • Not recurrent within a 24-hour period.

  • Complex FS:

    • Any feature not met by simple FS (e.g., focal onset, duration > 15 minutes, recurrent within 24 hours).

  • Febrile Status Epilepticus:

    • FS lasting > 30 minutes.

Risk Factors for Recurrence

  • Major Criteria:

    • Age < 1 year.

    • Fever 38-39°C.

    • Fever duration < 24 hours.

  • Minor Criteria:

    • Family history of FS or epilepsy.

    • Complex FS.

    • Male gender.

    • Daycare attendance.

    • Hyponatremia.

Risk Factors for Subsequent Epilepsy

  • Simple FS: 1%

  • Recurrent FS: 4%

  • Complex FS: 6%

  • Fever < 1 hour before FS: 11%

  • Family history of epilepsy: 18%

  • Focal complex FS: 29%

  • Neurodevelopmental abnormalities: 33%

Approach to a Patient with Febrile Seizure

  • Assessment:

    • Determine the cause of fever through history, general exam, and relevant investigations (e.g., complete blood count, blood glucose, serum electrolytes).

    • CSF examination by lumbar puncture in infants < 6 months with FS to rule out meningitis.

    • Assess risk factors for recurrence and subsequent epilepsy.

    • EEG and brain imaging (CT or MRI) if risk factors for later epilepsy are present.

Treatment

  • Febrile Status Epilepticus:

    • IV benzodiazepines, phenobarbital, phenytoin, or valproate.

  • General Management:

    • Antiepileptic therapy is not recommended for children with one or more simple FS.

    • Educate parents on handling seizures lasting > 5 minutes with rectal diazepam or buccal/intranasal midazolam.

    • Manage underlying illness and use antipyretics to reduce discomfort (not to prevent FS recurrence).

    • Screen and treat iron deficiency if present.

Prevention

  • Intermittent Prophylaxis:

    • Oral diazepam 0.33 mg/kg or rectal suppository 0.5 mg/kg every 8 hours during febrile illnesses.

  • Chronic Antiepileptic Therapy:

    • Considered for children with a high risk of later epilepsy.

Key Points

  • Febrile seizures are common in children aged 6-60 months with fever.

  • Simple FS are generalized, short, and non-recurrent within 24 hours.

  • Complex FS have features not met by simple FS.

  • Risk factors for recurrence and subsequent epilepsy should be assessed.

  • Treatment includes managing febrile status epilepticus and educating parents.

  • Prevention may involve intermittent or chronic antiepileptic therapy in high-risk cases.

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Flashcards for Febrile Seizures

Definition

  • Febrile Seizures (FS): The most common type of seizures in neurologically healthy infants and children occurring with a temperature ≥ 38°C, not attributed to CNS infection or metabolic disturbance.

Types of Febrile Seizures

  • Simple FS: Generalized tonic-clonic seizure, lasts ≤ 15 minutes, not recurrent in 24 hours.

  • Complex FS: Any feature not met by simple FS (e.g., focal onset, duration > 15 minutes, recurrent within 24 hours).

  • Febrile Status Epilepticus: FS lasting > 30 minutes.

Risk Factors for Recurrence

  • Major Criteria: Age < 1 year, fever 38-39°C, fever duration < 24 hours.

  • Minor Criteria: Family history of FS or epilepsy, complex FS, male gender, daycare attendance, hyponatremia.

Risk Factors for Subsequent Epilepsy

  • Simple FS: 1%, Recurrent FS: 4%, Complex FS: 6%, Fever < 1 hour before FS: 11%, Family history of epilepsy: 18%, Focal complex FS: 29%, Neurodevelopmental abnormalities: 33%.

Assessment Approach

  • Determine cause of fever, perform relevant investigations, and assess risk factors for recurrence and epilepsy. EEG and brain imaging are necessary if risk factors are present.

Treatment

  • Febrile Status Epilepticus: IV benzodiazepines, phenobarbital, phenytoin, or valproate.

  • General Management: Antiepileptic therapy not recommended for single/simple FS, but educate parents on managing long seizures.

Prevention

  • Intermittent Prophylaxis: Oral diazepam or rectal suppository during febrile illnesses.

  • Chronic Antiepileptic Therapy: For children with high risk for later epilepsy.

Key Points

  • FS are common in children aged 6-60 months with fever. Risk factors for recurrence and subsequent epilepsy should be assessed, and treatment focuses on management of febrile status epilepticus.