Febrile seizure

Background

• Defined as seizure accompanied by fever (temperature ≥ 100.4°F by any method)
• Occur in 2-5% of American children before age 5
• High temperatures can alter ion channel function, increasing neuronal excitability
  • However, a high temperature is not necessarily seen in majority of febrile seizures
• Febrile seizures do not increase the risk of serious bacterial illness

Prognosis

• 2-3% chance of developing epilepsy (slightly higher than risk of epilepsy for general population, which is 1%)
• 50% of patients <12 mo will have another simple febrile seizure
• 30% of patients >12 mo will have another simple febrile seizure
• Simple febrile seizures do not increase risk of mortality or developmental delay

Clinical Features

• Seizure + fever

Simple Febrile Seizure

• Age 6mo-5yr, with majority occurring between 12mo-18mo
• Single seizure in 24hr
• Duration <15min
• Generalized with no focal features
• Returns to neurologic baseline and has normal neuro exam after brief post-ictal period
• Febrile seizures cannot be considered simple for any children with known CNS abnormalities, previous neurologic insults, or history of afebrile seizures

Complex Febrile Seizure

• Any exception to above
• May indicate more serious disease process

Differential Diagnosis

Pediatric seizure

• Epileptic seizure
  • First-time seizure
  • Seizure with known seizure disorder
  • Status epilepticus
  • Temporal lobe epilepsy
  • Non-compliance with or "outgrowing" AEDs
• Non-epileptic seizure
  • Febrile seizure
  • Brain inflammation
    • Meningitis
    • Encephalitis
    • CNS abscess
    • Intracranial hemorrhage
    • Neurocysticercosis
  • Increased ICP
    • Seizure with VP shunt
    • Hydrocephalus
    • Intracranial mass
  • Toxicologic
    • Alcohol withdrawal
    • Benzodiazepine withdrawal
    • Toxic ingestion
  • Metabolic abnormalities: hyponatremia, hypernatremia, hypocalcemia, hypomagnesemia, hypoglycemia, hyperglycemia
  • Pyridoxine responsive seizure
  • Eclampsia
  • Posterior reversible encephalopathy syndrome
  • Impact seizure (head trauma)
• Other mimics
  • Psychogenic nonepileptic seizure (pseudoseizure)
  • Syncope (peds)
  • Breath-holding spell
  • Hyperventilation syndrome
  • Migraine headache
  • Movement disorders
  • Narcolepsy/cataplexy
  • Post-hypoxic myoclonus (Status myoclonicus)
  • Infantile Spasms/West Syndrome

Pediatric fever

• Upper respiratory infection (URI)
• UTI
• Sepsis
• Meningitis
• Febrile seizure
• Juvenile rheumatoid arthritis
• Pneumonia
• Acute otitis media
• Whooping cough
• Unclear source
• Kawasaki disease
• Neonatal HSV
• Specific virus
  • COVID-19 (peds)
    • MIS-C

Evaluation

• The key is to distinguish between simple febrile seizure secondary to minor illness vs. seizure from serious central nervous system infection, which may also present with fever and seizure.
• Glucose in all patients

Simple febrile seizure

• Neither labs nor neuroimaging are absolutely necessary
• Normal pediatric fever workup as indicated by presentation

Complex febrile seizure

• Consider CBC, blood culture, UA, urine culture
  • Studies have suggested a link between iron deficiency anemia and rate of febrile seizure
• Consider CMP if suspect hyponatremic from ongoing volume loss
• Consider LP and CSF studies if meningeal signs present
  • Per AAP, consider LP especially if child is between 6-12 months of age and has incomplete immunizations, or if child had recent antibiotic treatment (as meningeal signs can be masked)
• Consider CT if:
  • Persistently abnormal neuro exam (especially with focality)
  • Signs/symptoms of increased ICP
  • Patient has VP shunt
  • History of head trauma
  • Suspected neurocutaneous disorder (ex. NF, tuberous sclerosis) based on exam findings
• Consider ECG if:
  • Family history of long QT, Brugada, sudden death
• Routine EEG not indicated
  • Consider only if developmental delay or for focal symptoms
• Causes amenable to specific treatment
  • Hypoglycemia
  • Hyponatremia (water intoxication, dilution of formula)
  • Hypocalcemia
  • Hypomagnesemia
  • INH ingestion

Algorithm for the differentiation between simple and complex febrile seizures. Guidelines for evaluation of each.

Management

Initial management of pediatric status epilepticus

Timeline	General Considerations	Seizure Treatment
0-5 minutes	Supportive care ABC's Maintain airway; suction, jaw thrust Provide O2 via positive pressure ventilation with BVM/Mapleson Likely apneic/hypoventilating/hypercapneic Only apply CPAP or a non-rebreather if patient stops seizing and has adequate chest rise Establish IV/IO access Check blood glucose If fever, acetaminophen 15 mg/kg rectally	Benzodiazepine: first dose IV/IO access established Lorazepam 0.1 mg/kg IV (max 4 mg) if IV/IO access, OR Diazepam 0.2 mg/kg IM (max 10 mg) if no access IV or IO access not achieved within 3 minutes: Buccal midazolam 0.2 mg/kg (max 10 mg), OR IM midazolam 0.2 mg/kg (max 10 mg), OR Rectal diazepam (Diastat gel or injection solution given rectally) 0.5 mg/kg (max 20 mg)
5-10 minutes	Give antibiotics if concern for sepsis or meningitis POC electrolytes, if available	Benzodiazepine: second dose
10-15 minutes	All equally efficacious for status epilepticus Levetiracetam is preferred given quick administration, favorable side effect profile, and less drug interactions Do not combine Phenytoin and Fosphenytoin	Antiepileptic: first therapy Levetiracetam 60 mg/kg IV/IO (max 4500mg) over 5 min, OR Fosphenytoin^ 20 mg PE/kg IV/IO (max 1500mg) over 10 min, OR Valproate 40 mg/kg IV/IO (max 3000mg) over 10 min, OR Phenobarbital 20 mg/kg IV/IO, (max 1 g) over 20 min, (expect respiratory depression with apnea)¥
15-30 minutes	Consider intubation, if not already performed Consider NG tube to decompress stomach prior to intubation Pediatric neurology consultation	Antiepileptic: second therapy (if medication not already given) Fosphenytoin^ 20 mg PE/kg IV/IO (max 1500mg) over 10 min, OR Valproate 40 mg/kg IV/IO (max 3000mg) over 10 min, OR Phenobarbital 20 mg/kg IV/IO (max 1 g) over 20 min 10 mg/kg if phenobarbital already given, OR Levetiracetam 60 mg/kg IV/IO (max 4500mg) over 5 min If isoniazid toxicity suspected, pyridoxine Infants (<1 year): 100 mg IV or IO in Otherwise 70 mg/kg IV or IO (max = 5 g)
>30 minutes	Intubate patient, if not already performed Consult referral site / PICU for admission and continuous EEG	Antiepileptic: third therapy Midazolam 0.2mg/kg IV bolus (max 10mg), followed by 0.2mg/kg/hr (max 10mg/hr) infusion drip Increase infusion rate by 0.2mg/kg/hr (max 10mg/hr) every 10 minutes until burst suppression or max dose of 2mg/kg/hr (max 100mg/hr)

^May be ineffective for toxin-induced seizures and contraindicated in cocaine toxicity

Seizure Stopped

• Treat underlying infection if indicated
  • See pediatric fever of uncertain source

Disposition

Discharge

• Simple febrile seizure if patient at baseline
  • Follow-up in 1-2d
  • Around-the-clock acetaminophen may prevent seizure recurrence in the same febrile episode
  • Anticipatory guidance that emphasizes benign nature of simple febrile seizures while educating return precautions
• Complex febrile seizure if patient well-appearing, work-up normal
  • Follow-up in 24hr

Admit

• Ill-appearing
• Lethargy beyond postictal period

See Also

• Seizure (peds)
• Fever (Peds)