The Child With a 'Simple' Febrile Seizure

Abstract

\s=b\ Febrile seizures are a common pediatric problem, yet there is a great deal of disagreement about the appropriate diagnostic evaluation of a child with this disorder. We reviewed the routine diagnostic tests performed on 100 consecutive children admitted with their first "simple" febrile seizure. The studies performed included lumbar puncture, measurement of blood glucose, serum calcium, serum electrolytes, and BUN levels, blood cell count, urinalysis, skull roentgenograms, and EEG. Though resulting in a significant expense, these routine investigations proved to be of little diagnostic value. Based on this experience and a review of the current literature, we concluded that diagnostic procedures should be performed only when specifically called for by the patient's condition or medical history. (Am J Dis Child 1981;135:431-433) Approximately 3% to 5% of all chil-11 dren will have experienced at least one febrile seizure by the time they enter school.'1 More than 80% of these febrile seizures may be classi¬ fied as "simple": a single, isolated seizure that occurs in a febrile child between 1 month and 7 years of age with no sign of acute neurological disease, lasting 15 minutes or less, and without focal features.' As shown by a recent nationwide survey of pediatricians, there is a great deal of disagreement about the appropriate diagnostic evaluation of children with first febrile seizures.4 Some have recommended that lumbar punctures be performed routinely, along with determinations of blood glucose, serum calcium and phospho¬ rous, electrolyte, and BUN levels. Additionally, blood cell count, urinalysis, skull roentgenograms, and EEG are often routinely performed/'" Re¬ cently, however, the value of these investigations has been seriously questioned.7 * Much of this confusion is attributable to the lack of informa¬ tion on the yield of commonly per¬ formed diagnostic procedures, and perhaps to the failure to distinguish between simple and complex febrile seizures. Lumbar punctures are often per¬ formed on children with febrile sei¬ zures to exclude meningitis as the cause of the seizure. Thirteen percent to 18% of the children with meningitis may initially appear with a febrile seizure, and approximately 40% of these children may have no clinical signs of meningeal irritation." "' The majority of these children without clinical evidence of meningitis were, however, younger than 2 years of age, and a careful differentiation of simple and complex febrile seizures was not attempted by the authors of these reports. Many believe that a history of previous febrile seizures or the iden¬ tification of a potential source of fe¬ ver outside of the CNS preclude the necessity for a lumbar puncture in a child with a febrile seizure. However, a significant number of children with febrile seizures who are diagnosed as having meningitis have a history of previous febrile seizures or a potential source of fever outside of the CNS.!M" Wolf et al reviewed 308 lumbar punctures performed on children with their first febrile...

Seizures associated with fever: clinical data as predictors for normal biochemical blood levels

“…The indications they found were multiple-type seizures, status epilepticus, history of metabolic or gastro-intestinal disease and young age [3,7,10,11,12,15,17]. These indications, which imply an increased risk of abnormal test results, have been con®rmed quantitatively by our analysis.…”

“…All other abnormalities of sodium and calcium levels were mild and all glucose levels were within the normal range. Earlier studies showed that sodium, calcium and glucose blood tests in children with seizures associated with fever resulted in a very low number of abnormal results, in particular in children with`simple' (non-complex) seizures [6,7,11,12,16,17,20]. However, some authors state that a glucose and calcium test should be done because these are treatable conditions and the tests are relatively inexpensive [21].…”

“…If prediction of normal test results would be possible, the number of unnecessary tests may be reduced; only patients with a low probability of normal test results will need to be tested. Previous studies have shown that performing all standard biochemical tests as a routine is useless [6,7,11,12,16,17,20].…”

“…An association between biochemical abnormalities and complex seizure characteristics has been found [ 10± 12, 15], implying that children with complex seizure characteristics should be tested [7]. Other patient characteristics studied include age and history of metabolic or gastro-intestinal disease [3,11,12].…”

Assessment of febrile seizures in children

“…In a recent evidence-based guideline, Baumer [12] suggests that a urine sample should be checked for infection in a child with simple FS, but that no other investigation is routinely indicated. Other researchers suggest a broader laboratory investigation of infections, but do not recommend routine analysis of serum electrolytes, calcium, phosphorus, complete blood count, and blood glucose, unless they are indicated by a suspicious history or physical findings [6,33,41,47,75].…”