Tests
1st tests to order
diagnosis is clinical
Test
Tests may be required to identify the source of fever.
Result
seizures associated with fever
Investigations to avoid
Tests to consider
lumbar puncture
Test
Indicated to rule out meningitis or encephalitis if: presence of suspicious symptoms and signs (e.g., bulging fontanelle, nuchal rigidity) and if age is <12 months; a focal, prolonged, or multiple seizure occurs within 24 hours with prolonged impairment of consciousness; or there is history of persistent irritability or lethargy, or pretreatment with oral antibiotics.
How to perform a diagnostic lumbar puncture in adults. Includes a discussion of patient positioning, choice of needle, and measurement of opening and closing pressure.
Result
normal cells, protein, and glucose
viral studies
Test
Viral studies may be useful in patients with complex febrile seizures and symptoms of encephalitis or encephalopathy.
Result
may be positive
blood culture
Test
Bacteremia is rare, but meningitis should always be considered.
Result
bacteremia may be present
EEG
Test
The role of electroencephalography (EEG) in the workup of febrile seizure remains controversial.[55] Do not routinely use EEG for neurologically healthy children after a simple febrile seizure, because it can increase caregiver and child anxiety without altering the outcome or course of treatment.[1][51]
There is no evidence that an EEG can be used to predict whether a child will develop epilepsy after a simple febrile seizure. Also, development of epilepsy cannot be prevented by knowledge of EEG findings.[66]
However, acute EEG may have a role following status epilepticus. The FEBSTAT study performed baseline EEGs within 72 hours of an episode of febrile status epilepticus. Review of the baseline EEGs showed a focal EEG slowing or attenuation in a substantial proportion of children. The slowing and attenuation are highly associated with MRI evidence of acute hippocampal injury. These findings may be a sensitive and readily obtainable marker of acute injury associated with febrile seizure epilepsy.[56]
Recurrent simple or complex febrile seizures also do not justify an EEG, as it is of no use in identifying a structural abnormality or in predicting recurrent febrile seizure or the development of epilepsy.[67]
EEG should be considered in all children with complex febrile seizures that recur with afebrile convulsions, or in children who have recurrent febrile seizures and also exhibit developmental delays or abnormal neurologic signs and symptoms.[68] One Cochrane review found no evidence to support or refute the use of EEG and its timing after complex febrile seizures among children under the age of 5 years.[57]
Focal EEG slowing or attenuation are present in EEGs obtained within 72 hours following febrile status epilepticus in a substantial proportion of children.[56]
Neurologic consultation is needed.
Result
possible focal EEG slowing or attenuation following febrile status epilepticus
brain MRI
Test
Usually normal; may show hippocampal edema or sclerosis with complex, prolonged, and focal febrile seizure.[56][69][70]
MRI is not indicated in a child with simple febrile seizure because it does not aid diagnosis or treatment and is associated with risk from sedation.[1][50] However, MRI should should be considered in children with complex febrile seizures, an atypical history with abnormal developmental history, or abnormal neurologic exam.
Result
may show acute hippocampal edema or chronic hippocampal sclerosis
serum sodium
Test
Hyponatremia may increase the risk for multiple seizures during the same febrile illness.[71] Despite these and other similar reports, the American Academy of Pediatrics does not recommend routine serum electrolytes after a first simple febrile seizure.[1][49] However, serum electrolytes may be of use in children with complex febrile seizure.
Result
may be low (<130 mEq/L)
CBC
capillary blood glucose
Test
A capillary blood glucose test should be performed on all children who present with a seizure to exclude hypoglycemia.
Result
usually normal
serum glucose
iron studies
Test
Consider testing if clinically indicated or other blood tests are being performed.[72]
Result
may reveal deficiency
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