Febrile Seizure : Clinical approach

A) General consideration:

Febrile seizures are seizures during fever occuring between 6 months and 5 years of age in absence of:

  • CNS infections
  • Abnormal neurologic findings

Types of febrile seizure:

  1. Simple febrile seizure:
    • Solitary
    • Brief (< 15 minutes)
    • Within 24 hours of onset of fever
    • Generalized Tonic Clonic Seizure (GTCS)
  2. Atypical/Complex febrile seizure:
    • Lasting more than 15 minutes
    • Multiple occurence in a day
    • Focal seizures

Risk of recurrence:

Risk of reccurence increases in following conditions:

  1. Age < 18 months
  2. Family history of febrile seizure
  3. Low peak temperature
  4. Shorter duration of fever

HISTORY FOR FEBRILE SEIZURE

1. Seizure:

  • Generalized or focal at onset?
    • Incontinece of urine and tongue biting confirms generalized nature of seizure
    • Unilateral postictal weakness (todd paresis) or speech difficulty indicates focal onset of seizure
  • Length of seziure:
    • Simple or typical vs Complex or atypical febrile seizure
    • Status epilepticus (>30 minutes)
  • Differentiate between seizure itself and postictal state
  • Prior history of seizures with or without fever?
  • If more than 1 seizure occured in 24 hours?

2. Nature of illness and relation to seizure:

  • How long was the temperature elevated before onset of seizure?
  • Rule out possible CNS infections?
    • Altered mental state
    • Severe headache
    • Focal signs before seizure
  • Evidence of acute rise in ICP?
  • Any treatment or drugs received?

3. Family history: Epilepsy ?

4. Rule out differential diagnoses:

Febrile seizure differential

  • School aged child, partial seizure in sleep: Benign epilepsy of childhood with centrotemporal spikes (Benign rolandic epilepsy)
  • Early morning tonic-clonic seizure: Juvenile myoclonic epilepsy
  • Possible precipitants: Toxins or drugs
  • Pre-existing developmental/neurologic disorders
  • Immunization: Pertussis
  • Post-infection: Varicella, Measles
  • Non-epileptic paroxysmal events:
    • Breath holding attacks
    • Benign nocturnal myoclonus
    • Shuddering or shivering attack
    • Tics/Tourette
    • Night terrors
    • Migraine
    • Conversion disorder
    • Staring spells
    • Benign Positional Paroxysmal Vertigo (BPPV)

PHYSICAL EXAMINATION FOR FEBRILE SEIZURE

1. Source of infection or fever?

  • Acute Gastroenteritis (AGE)
  • Sepsis
  • Otitis Media
  • Urinary tract infection
  • Penumonia
  • Upper respiratory tract infection

2. Features of meningitis: Meningismus is absent in 1/3rd infants

3. Features of raised ICP:

  • Abnormal eye movement (setting sun sign)
  • Excessive vomiting
  • Cushing’s triad: Raised blood pressure, Irregular respiration and Bradycardia
  • Papilledema

4. Examine scalp for head trauma

5. Complete neurologic examination to rule out focus

6. Examination of skin:

  • Neurofibromatosis: Cafe-au-lait spots
  • Tuberous sclerosis:Ash-leaf lesions (hypopigmented lesions with pointed tip)
  • Sturge-Weber syndrome: Facial hemangioma

INVESTIGATIONS FOR FEBRILE SEIZURE

Consider following investigations according to the history and examination:

  1. CBC, differential counts and C-reactive protein (CRP)
  2. Cultures (blood and urine)
  3. Lumbar puncture
  4. Urinalysis
  5. Electrolytes
  6. Random blood glucose
  7. BUN and creatinine
  8. Calcium and Magnesium levels
  9. Toxicology screen
  10. Metabolic tests (In infants and mental retardation)
  11. Stool culture (If shigellosis is suspected)
  12. CT or MRI (MRI is preferred):
    • Rarely required in:
      • Febrile seizures
      • Absence seizure
      • Benign rolandic epilepsy
      • Nonfebrile Generalized seizure with normal examination findings
    • Required in:
      • Features suggestive of raised ICP
      • Intracranial hemorrhage
      • Space Occupying Lesions
      • Difficulty controlling seizure
      • Prolonged unresponsiveness
      • Progressive neurologic findings
  13. EEG:
    • To document ongoing seizure
    • To identify underlying cerebral structural process
    • Identify risk of recurrence
    • Diagnosing epilepsy syndromes
    • May be part of evaluation of 1st unprovoked seizure (controversy – very low reccurence risk) or 2nd

MANAGEMENT OF FEBRILE SEIZURE

1. Hospitalization: Indications of hospitalization are –

  • Number of seizures: 2 or more spontaneous seizures within 24-48 hours
  • Duration of seziures: Prolonged seizures that resolved spontaneously
  • Prolonged altered mental state or focal signs
  • Initiation of anticonvulsant therapy (Observation)
  • Severe febrile seizure:
    • Serious bacterial infections
    • Bacteremia
    • Meningitis
    • Pneumonia
    • UTI/pyelonephritis
    • Bacterial enteritis
  • Very severe febrile seizure:
    • Status epilepticus
    • Shock
    • Coma
    • Respiratory failure
    • Hypoxia

2. Antipyretics

3. Benzodiazepines if needed

4. Education and reassurance

Febrile seizure anticonvulsants

PROPHYLAXIS OF FEBRILE SEIZURE

1. Intermittent prophylaxis:

Indications:

  • 3 or more episodes in 6 months
  • 6 or more episodes in 1 year
  • Lasting more than 15 minutes

Regimen:

  • 2 doses of oral diazepam 0.3-0.5 mg/kg given 8 hours apart at the time of fever (or rectal diazepam or clobazam for 3 days)
  • Antipyretics
  • Hydrotherapy

2. Continuous prophylaxis:

Indications:

  • Failed intermittent prophylaxis
  • Recurrent atypical febrile seizure
  • Parents unable to recognize onset of fever

Regimen:

  • Valproate or Phenobarbitone X 1-2 years or untile 5 years of age

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