Febrile Seizures

febrile seizures

A 20 Month-Old Male

It is a busy Wednesday afternoon in your pediatric emergency department. You work at a tertiary center, so you are used to receiving transfers from other hospitals for further evaluation and management. You see a new patient on the board. It is a 20 month-old male who came in as a hospital transfer for evaluation of first-time seizure. You go to bedside to start your evaluation. Parents tell you that he had three episodes of seizures in the past 6 hours. All of them lasted for less than 15 minutes, did not require medication for cessation, one of them was described as partial-focal and two were described as generalized tonic-clonic seizures, and the patient had complete return to baseline behavior a few minutes after each episode. Mom says that the patient had his axillary temperature taken by her at home and by the staff at the outside hospital and he had no fever on these measurements. However, she did notice some runny nose in the past 24 hours. As soon as the mom tells you that information, the nurse looks at you and says that the patient’s rectal temperature is 40.1 C.

Febrile Seizures

The first-step in the management of febrile seizures is to understand its definitions. Following that, we need to appropriately classify the patient’s presentation within one of the two types of febrile seizure.

Definition

  • Age greater than six-months-old and lower than five-years-old
  • Seizure in a patient with a temperature higher than 38 C
  • No inflammation or infection of the central nervous system
  • No metabolic abnormality that may cause seizures
  • No history of afebrile seizures

Two Types of Febrile Seizures

Class Age Number of seizures in 24h Duration Type of seizure Resolution Return to baseline
Simple
6 mo to 5 yo
1
< 15 min
No focal features
No meds required
Yes
Complex
6 mo to 5 yo
> 1
> 15 min
Focal features
Med required
No return to baseline in a reasonable time

You must note that you will be able to easily identify those patients who fit the criteria for simple febrile seizures and those who fit the criteria for complex febrile seizures. However, there will be a group of patients that fill one or two criteria for complex febrile seizure, but are extremely well-appearing. We will talk more about that later on during the discussion.

Workup

Simple Febrile Seizures

The evaluation of a child with a simple febrile seizure should focus on the underlying febrile illness. In the vast majority of the cases the cause for the fever will be a viral infection that does not require further evaluation and treatment other than some acetaminophen (paracetamol), ibuprofen, and oral hydration.

However, as part of your job, you need to think outside of the box and have a broad differential diagnosis for your patient’s presentation. Make sure to rule out signs of CNS infection (altered mental status, nuchal rigidity, petechial rashes, and prolonged, focal or multiple seizures); risk factors, symptoms, and signs of systemic conditions that could be causing a seizure; and, history of afebrile seizures. Special factors that increase the risk for CNS infections and that you should consider in your evaluation are age 6 -12 months with incomplete immunization status (Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae) and pre-treatment with antibiotics for another disorder (which could mask meningitis).

Complex Febrile Seizure in Ill-Appearing Child

The workup in this situation is simple. The patient has meningitis until proven otherwise. You should consider starting antibiotics immediately and obtaining a full sepsis workup including complete blood cell count, urinalysis, urine culture, blood cultures, chest x-ray, and lumbar puncture for cerebrospinal fluid analysis. In addition to the infectious work-up, the differential also includes epileptic seizures, toxic ingestion, metabolic disorders, head trauma, and intracranial hypertension.

Complex Febrile Seizure in Well-Appearing Child

Now we reached the tricky part of the discussion. There are no consensus guidelines for the workup of patients with complex febrile seizures in the well-appearing child. As stated in the simple febrile seizure section, you should consider further workup if any concerns for CNS infection, systemic conditions causing seizures, or history of afebrile seizures. You should decide which workup to perform on a case by case basis. In a perfect scenario, these cases should be evaluated in conjunction with specialist consultation (e.g. with pediatric neurology) for guidance with work-up and treatment.

Case Resolution

After you finish your assessment, you make the diagnosis of complex febrile seizure because the patient had multiple seizures in less than 24 hours and had one episode with focal features. The patient is well-appearing, is fully vaccinated, has not used antibiotics recently, returns to baseline completely soon after an episode, and has no findings concerning for CNS infection on his exam. Therefore, you think that a CNS infection is less likely. Since you are facing a case of complex febrile seizure in a well-appearing child, you consult pediatric neurology for guidance with the workup and treatment. They agree with the low likelihood of CNS infection and recommend symptomatic treatment for the patient’s likely upper respiratory infection with observation during six hours in the ED. The patient has no problems during the period of observation. You re-discuss the case with pediatric neurology and they recommend discharge home with close follow-up on their clinic for further workup of other causes of seizure. A couple days later, you check the patient’s records and find that he had a spot EEG done, which was negative for epileptiform waves, and a brain MRI performed, which was unremarkable. Patient was diagnosed with complex febrile seizure and recommended to keep follow-up with his primary care physician with no need for further follow-up with pediatric neurology.

Take-Home Points

  • Always obtain a temperature from a core source, in the ED the most feasible source is a rectal temperature
  • The differential diagnosis for febrile seizures includes CNS infections, epileptic seizures, toxic ingestion, metabolic disorders, head trauma, and intracranial hypertension
  • There is no consensus about the workup and treatment of the well-appearing patient with a complex febrile seizure

References and Further Reading

  1. Festekjian A. Seizures and Status Epilepticus in Children. In: Cydulka RK, Fitch MT, Joing SA, Wang VJ, Cline DM, Ma O. eds. Tintinalli’s Emergency Medicine Manual, 8e New York, NY: McGraw-Hill; . http://accessemergencymedicine.mhmedical.com/content.aspx?bookid=2158§ionid=162271372. Accessed May 12, 2019.

  2. https://www.emrap.org/episode/kiddos/febrileseizures

  3. https://www.emrap.org/episode/c3seizuresin/seizuresin 

  4. John J Millichap. Clinical features and evaluation of febrile seizures. Mar 25, 2019. https://www.uptodate.com/contents/clinical-features-and-evaluation-of-febrile-seizures?source=history_widget

Cite this article as: Henrique Puls, "Febrile Seizures," in International Emergency Medicine Education Project, September 9, 2019, https://iem-student.org/2019/09/09/febrile-seizures/, date accessed: November 12, 2019

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