Febrile Seizures: Evaluation and Treatment

• What is the risk of intracranial pathology in complex febrile seizure?

Patients with complex febrile seizures usually seek medical attention [27]. However, the risk of acute pathology necessitating treatment changes based on neuroimaging was found to be very low and likely not necessary in the evaluation of complex febrile seizures during the acute presentation [27]. Imaging with a high-resolution brain MRI could be considered later on a routine basis for prolonged febrile seizures due to the possible association between prolonged febrile seizures and mesial temporal sclerosis [19,28,29].

Neuroimaging has provided evidence that hippocampal injury can occasionally occur during prolonged and focal febrile seizures in infants who otherwise appear normal. It has been speculated that a pre-existing abnormality increases the propensity to focal prolonged seizures and further hippocampal damage. Hesdorffer and colleagues [30] found definite abnormalities on MRI in 14.8% of children with complex febrile seizures and 11.4 % of simple febrile seizures among 159 children with a first febrile seizure. However, MRI abnormalities were related to a specific subtype of complex seizures: focal and prolonged. The most common abnormalities observed were subcortical focal hyperintensity, an abnormal white matter signal, and focal cortical dysplasia.

• What are important aspects of the clinical evaluation?

The evaluation and management of the child with complex febrile seizures is debated as well. The most important part in the history and examination is to look for the source of the fever and rule out the presence of a CNS infection, since complex febrile seizures are much more frequently associated with meningitis than simple febrile seizures [16]. The American Academy of Pediatrics recommended that a lumbar puncture be strongly considered in infants younger than 12 months after a first febrile seizure and should be considered in children between 12 and 18 months of age, since signs of meningitis may be absent in young children [13]. If the threshold for a lumbar puncture is low in infants with febrile seizures in general, it should be even lower for children with complex febrile episodes for all the factors mentioned above. The guidelines developed in 1990 by the Royal College of Physicians and the British Paediatric Association concluded that indications for performing an lumbar puncture were complex febrile seizure, signs of meningismus, or a child who is unduly drowsy and irritable or systematically ill [21].

Obtaining an EEG within 24 hours of presentation may show generalized background slowing, which could make identifying possible epileptiform abnormalities difficult [22]. Therefore, a routine sleep deprived EEG when the child is back to baseline can be more useful in identifying if epileptiform abnormalities are present. If epileptiform abnormalities are present on a routine sleep deprived EEG, this may suggest the patient is at higher risk for developing future epilepsy and the febrile illness lowered the seizure threshold; however, it is unclear whether clinical management would change as a result [31].

• What treatment options are available?

Complications with prolonged and/or recurrent seizures can occur. Treatments options can be stratified into 3 possible categories: emergency rescue treatment for prolonged or a cluster of febrile seizures, intermittent treatment at the time of illness, and chronic use of medication. Treatment options for complex febrile seizures may include the use of a rescue seizure medication when the febrile seizure is prolonged. Rectal preparations of diazepam gel can be effective in stopping an ongoing seizure and can be provided for home use in patients with known recurrence of febrile status epilepticus [3]. For children and adolescents where a rectal administration is not ideal, intranasal versed can be utilized instead of rectal diazepam. In addition, the use of an intermittent benzodiazepine at the onset of febrile illness can also be considered a treatment option. Using oral diazepam at the time of a febrile illness has been demonstrated in reducing the recurrence of febrile seizures [3]. Other studies have shown similar results when using buccal midazolam [32]. No adequate studies have been performed using second- or third-generation anti-epilepsy medications in the treatment of recurrent of complex febrile seizures [3].