A. Clinical Characteristics For Simple FS
- Spiking fever (typically above 38.5°)
- No focality to seizure activity
- Seizure lasting less than 15 minutes
- No persistent deficits
- Otherwise normal neurologic development
- No family history of epilepsy
- Brief postictal period, then patient alert and oriented
- Age range from 6 months to 5 years; 1-3 years most common
B. Clinical Characteristics For Complex FS
- Prolonged more than 15 minutes
- Multiple seizures within 24 hour period
- Focality to seizure activity
- Represents 20% of all febrile seizures
C. Epidemiology
- FS affect 2-5% of all children
- Most common convulsive event in children under 5 years of age
D. Etiology
- Commonly associated with tonsillitis, upper respiratory infections, or otitis media
- HHV-6 (roseola) implicated in some cases
- Shigella gastroenteritis also associated
- Increased incidence following routine vaccinations
- Two days after pertussis vaccine (mainly attenuated pertussis)
- Seven to 10 days after measles immunizations
E. Pathogenesis
- Rapid changes in temperature implicated in seizure activity
- Fever lowers the seizure threshold in all children
- Increasing age makes the brain less responsive to epileptiform activity
- Most brain neurons are myelinated by 5 years old, which provides resistance
- Meningitis and FS
- Retrospective study of children with bacterial meningitis
- Found that <1% of cases presented with features of simple FS
F. Clinical Symptoms
- Initial cry
- Loss of consciousness
- Muscle rigidity
- Followed by clonic phase of repetitive rhythmic jerking movements
- Bowel and bladder incontinence common
- Then postictal lethargy or sleep
G. Laboratory Evaluation
- Complete blood count and culture as indicated for fever evaluation
- Lumbar puncture should be considered in the following scenarios
- Any clinical suggestion of meningitis
- Consider for infants less than18 months (particularly under 12 months) because meningeal signs may be difficult to elicit by physical examination
- Child older than 18 months with meningeal signs
- Partial antibiotic treatment
- Electroencephalogram (EEG)
- May show occipital slowing up to a week after febrile seizure
- Abnormalities not predictive of recurrence of febrile seizures or progression to epilepsy
- No routine clinical indications
- Skull radiographs and neuroimaging not routinely needed
H. Treatment
- Treat underlying illness
- Aggressive fever control with around the clock acetaminophen and ibuprofen antipyretics
- Frequent neurologic checks
- Educate parents about recurrence risks and necessary interventions
- Consider diazepam or phenobarbital to prevent frequently recurrent seizures
I. Recurrences
- One third of all children have recurrences
- Majority occur within one year
- Complex and simple febrile seizes have same risk of recurrence
- Associated risk factors
- Young age
- Family history of febrile seizures
- Short duration of fever before seizure
- Relatively low fever at the time of the seizure
J. True Epilepsy
- Risk of epilepsy with first simple seizure 1% and with repeated seizures 5%
- Associated risk factors
- Abnormal development prior to the first seizure
- Family history of afebrile seizures
- Complex first febrile seizure
References
- Bergman DA, et al. 1996. Pediatrics. 97(5):769
- Fleisher GR and Ludwig S. 1996. Synopsis of Pediatric Emergency Medicine. pp. 240
- Hirtz DG. 1997. Pediatrics in Review. 18(1) 5