FEBRILE SEIZURES


I. Clinical features:

  1. No other identifiable cause for seizures
  2. 6mo-6y of age
  3. <30min duration
  4. Generalized tonic-clonic
  5. No neurol. abnormalities before or after seizures
  6. Family hx contributes to suspicion
  7. Temp of at least 38'C (100.4'F)-Duration of fever is usually <24h prior to seizures; typically rapid rise

II. Course:

  1. May occur mult. times during an illness
  2. Pathogenesis involves rate of rise of fever more than absolute temp
  3. About 30% of children with one febrile seizure will have another

III. Workup for initial febrile seizure

  1. Lumbar puncture w/ CSF analysis (cell count, protein, glucose, culture); blood culture, serum glucose (to detect hypoglycorrhachia which is characteristic of bacterial meningitis) 
  2. AAP practice guidelines for "simple" febrile seizures (seizure accompanied by fever but no CNS infection from 6-60mos old, lasting < 15min and not recurring within 24h) (Peds. 127:389, 2011-JW):

    1. Do LP if fever and signs of meningitis are present (e.g. neck stiffness or Kernig or Brudzinski signs) or history or exam otherwise suggests CNS infection

    2. LP is an "option" if 6-12mos old if immunization status is unknown or insuficiently immunized for H. influenzae or S. pneumoniae because of the potential for meningitis to present without typical "meningeal" signs in this age group

    3. LP is an "option" if pt has recently received antibiotics (can mask the signs and symptoms of meningitis).

    4. EEG should not be performed if neurologically healthy

    5. Should not routinely perform neuroimaging

    6. CBC and serum electrolytes rarely helpful

IV. Treatment approach

  1. Treatment with anticonvulsants after febrile seizures not shown to reduce risk of subsequent afebrile seizures (Peds 103:1307, 1999--AFP-- a practice guideline)
  2. Can treat the seizures with phenobarbital, valproic acid, or diazepam; but not carbamazepine or phenytoin, may reduce risk of subsequent febrile seizures (ibid.)
  3. AAP says no special precautions are necessary after a single febrile seizure, though one option would be to use oral diazepam at the onset of fever in a pt with h/o febrile seizures (ibid.)
  4. Antipyretics for secondary prevention
    1. In a study in 231 children 4mo-4yo with a history of one febrile seizure randomized to (diclofenac 1.5mg/kg PR then acetaminophen or ibuprofen) vs. placebo with any fever 38'C or higher, over 2y f/u, there was no sig. diff. in incidence of recurrent febrile seizures among any of the treatment groups (Arch. pediat. Adol. Med. 163:799, 2009-JW)

V. Long-term outcome:

  1. Recurrence occurs in 30-50% of pts
  2. In a series of 381 kids with febrile convulsions c/w 13,000 controls, no sig. differences in academic achievement, behavior, development, or intelligence at 10yo were seen (NEJM 338:1723, 1998--JW)
  3. Risk of subsequent non-fever-associated seizures is only slightly higher than that of the general population and is greatest in kids who had first febrile seizures < 12mo or kids with h/o multiple febrile seizures

(Sources include: Practice parameter: the neurodiagnostic evaluation of the child with a first simple febrile seizure. Pediatrics 97:769, 1996)