Febrile seizures

This article was written by Dr. Aursulesei Ruxandra, pediatric neurologist specialist with extensive experience in diagnosing and treating neurological conditions. Pediatric neurology plays an important role in the periodic neurological evaluation of premature infants, as well as of all newborns at risk of developing neurological sequelae, with the goal of early detection and treatment of any impairment of the nervous system.

What are febrile seizures (FS)?

A febrile seizure is defined, according to the International League Against Epilepsy, as an epileptic-type seizure occurring in a child over 1 month of age, in association with fever, but in the absence of any signs of central nervous system infection, in a child without a history of neonatal seizures or other types of prior unprovoked epileptic seizures, and without meeting the criteria for other types of acute symptomatic seizures. ("Pediatric Neurology", Assoc. Prof. Dr. Dana Craiu).

In simple terms, these are seizures triggered by fever that are not caused by infections or other pathologies of the central nervous system (CNS).

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At what age can a child have febrile seizures? 

The age of onset for febrile seizures is between one month and 7 years.

How common are febrile seizures?

Febrile seizures are the most common cause of seizures in childhood.

They affect 2-5% of children under 5 years of age.

What causes febrile seizures? 

The onset of FS is determined by hyperexcitability of the brain, which is favored by the combination of 3 factors:

• Genetic susceptibility. 25-40% of patients with FS have a family history of FS.
• Fever. Alkalosis secondary to fever-induced hyperventilation, together with the regulatory effects of proinflammatory factors, increases neuronal excitability.
• Age. The immature brain is hyperexcitable.

How long does a febrile seizure last? 

Most febrile seizures last less than 5 minutes and resolve spontaneously.

Does the duration or appearance of the seizure matter? 

Duration is an important criterion in defining FS, estimating the prognosis, and establishing the therapeutic approach for an FS. Depending on the clinical appearance of the seizure and its duration, FS are divided into: simple and complex.

• Simple febrile seizures are those FS that have a generalized appearance, last a short time (under 5 minutes), are single occurrences within 24 hours and within the infectious episode. They generally occur in children with no signs of neurological impairment and with normal intellect, being associated with a rapid rise in fever, above 38.5 degrees Celsius, and are not followed by postictal phenomena. They represent the most common type of FS. However, they can also occur in children with pre-existing neurological conditions.
• Complex febrile seizures last longer than 15 minutes, usually have a focal, unilateral appearance, occur multiple times within 24 hours, and can be followed by postictal motor deficit. They can occur in children with prior neurological impairment (premature infants, children with psychomotor development disorders, children with postnatal neurological conditions). ("Pediatric Neurology", Assoc. Prof. Dr. Dana Craiu)

If it's not a febrile seizure, what else could it be? 

• Shivering (the movements are fine oscillations, the state of consciousness is unchanged, and the appearance is bilaterally symmetric)
• Febrile syncope
• Epileptic seizures from CNS infections, acute intoxications
• Seizures of another etiology, such as metabolic imbalances - in a child with a history of vomiting, diarrhea, electrolyte disturbances

What investigations are necessary?

In most children with SFS, extensive investigations are not necessary, with the focus being only on the cause of the infection (upper respiratory tract infection, pneumonia, gastroenteritis, urinary tract infections, etc.)

• lumbar puncture is not performed routinely - only at the treating physician's recommendation
• electroencephalogram (EEG): recommended in complex FS
• routine laboratory tests - may be done in order to identify the cause of the fever.
• other tests such as plain skull X-ray, biological tests (blood glucose, calcium) are not performed routinely - only at the treating physician's recommendation
• brain imaging - is not performed routinely - only at the treating physician's recommendation

Treatment - Intervention during the acute episode 

What should the parent do?

• Position the child on their side (lateral decubitus) with the airway cleared
• Lower the fever below 38.5°C - antipyretics: acetaminophen, ibuprofen, metamizole, lukewarm baths.
• Film the seizure
• Consult the pediatric neurologist

Course and prognosis 

• Is there a risk of developing behavioral disorders or cognitive deficits?

This has not been demonstrated in children with simple FS.

• Is there a risk of developing structural brain changes? 

There is no evidence to support this.

• Is there a risk of the seizure recurring?

Yes.

• What factors does this risk depend on? 
  

The risk of FS recurrence depends on:

- family history of FS in first-degree relatives

- short duration of fever before the FS

- duration of the seizure

- moderate temperature

- focal character of the seizure

- age at the first febrile seizure: < 1 year - 50% risk, > 1 year - 30% risk

- 50-75% of recurrences occur in the first year

- multiple recurrences are 3 times more common in infants

• IS THERE A RISK OF DEVELOPING EPILEPSY?
  

Children with simple FS have the same risk of developing epilepsy by age 7 as the general population (1%).

• WHEN DOES THE RISK OF DEVELOPING EPILEPSY INCREASE?

- When FS begins at a very young age

- When FS occur in large numbers

- Complex FS

- When pre-existing neurological abnormalities are present

- When there is a family history of epilepsy