A. Clinical Characteristics For Simple FS

1. Spiking fever (typically above 38.5°)
2. No focality to seizure activity
3. Seizure lasting less than 15 minutes
4. No persistent deficits
5. Otherwise normal neurologic development
6. No family history of epilepsy
7. Brief postictal period, then patient alert and oriented
8. Age range from 6 months to 5 years; 1-3 years most common

B. Clinical Characteristics For Complex FS

1. Prolonged more than 15 minutes
2. Multiple seizures within 24 hour period
3. Focality to seizure activity
4. Represents 20% of all febrile seizures

C. Epidemiology

1. FS affect 2-5% of all children
2. Most common convulsive event in children under 5 years of age

D. Etiology

1. Commonly associated with tonsillitis, upper respiratory infections, or otitis media
2. HHV-6 (roseola) implicated in some cases
3. Shigella gastroenteritis also associated
4. Increased incidence following routine vaccinations
   1. Two days after pertussis vaccine (mainly attenuated pertussis)
   2. Seven to 10 days after measles immunizations

E. Pathogenesis

1. Rapid changes in temperature implicated in seizure activity
2. Fever lowers the seizure threshold in all children
   1. Increasing age makes the brain less responsive to epileptiform activity
   2. Most brain neurons are myelinated by 5 years old, which provides resistance
3. Meningitis and FS
   1. Retrospective study of children with bacterial meningitis
   2. Found that <1% of cases presented with features of simple FS

F. Clinical Symptoms

1. Initial cry
2. Loss of consciousness
3. Muscle rigidity
4. Followed by clonic phase of repetitive rhythmic jerking movements
5. Bowel and bladder incontinence common
6. Then postictal lethargy or sleep

G. Laboratory Evaluation

1. Complete blood count and culture as indicated for fever evaluation
2. Lumbar puncture should be considered in the following scenarios
   1. Any clinical suggestion of meningitis
   2. Consider for infants less than18 months (particularly under 12 months) because meningeal signs may be difficult to elicit by physical examination
   3. Child older than 18 months with meningeal signs
   4. Partial antibiotic treatment
3. Electroencephalogram (EEG)
   1. May show occipital slowing up to a week after febrile seizure
   2. Abnormalities not predictive of recurrence of febrile seizures or progression to epilepsy
   3. No routine clinical indications
4. Skull radiographs and neuroimaging not routinely needed

H. Treatment

1. Treat underlying illness
2. Aggressive fever control with around the clock acetaminophen and ibuprofen antipyretics
3. Frequent neurologic checks
4. Educate parents about recurrence risks and necessary interventions
5. Consider diazepam or phenobarbital to prevent frequently recurrent seizures

I. Recurrences

1. One third of all children have recurrences
2. Majority occur within one year
3. Complex and simple febrile seizes have same risk of recurrence
4. Associated risk factors
   1. Young age
   2. Family history of febrile seizures
   3. Short duration of fever before seizure
   4. Relatively low fever at the time of the seizure

J. True Epilepsy

1. Risk of epilepsy with first simple seizure 1% and with repeated seizures 5%
2. Associated risk factors
   1. Abnormal development prior to the first seizure
   2. Family history of afebrile seizures
   3. Complex first febrile seizure

References

1. Bergman DA, et al. 1996. Pediatrics. 97(5):769
2. Fleisher GR and Ludwig S. 1996. Synopsis of Pediatric Emergency Medicine. pp. 240
3. Hirtz DG. 1997. Pediatrics in Review. 18(1) 5