Febrile Convulsions

Febrile convulsions are considered the most common type of seizures in children aged 3 months to 5 years. The convulsions are involuntary tremors of the limbs with body toning.

They have been differentiated from other types of seizures since the mid-19th century. At that time, treatment consisted of eliminating the cause of the fever. With the introduction of the thermometer in the late 1880s, it was understood that temperature was the primary factor in causing febrile convulsions.

Febrile convulsions are of two types: simple and complex

“Simple” febrile convulsions are characterized by short, generally generalized crises lasting up to 5 or more minutes, accompanied by high temperature.

The second form of convulsions is the “complex” form: characterized by prolonged convulsions over 15 minutes, focal crises, often with abnormal EEG readings.

The duration of the crisis varies from patient to patient. The crisis can occur at different temperatures several times during a day or a period of temperature elevation.

The peak incidence of febrile convulsions is the age group 9-18 months.

These crises are accompanied by infections, such as: tonsillitis, pharyngitis, otitis, etc.

Epidemiological studies have made a significant contribution regarding the frequency, history of the disease, and prognosis of febrile convulsions.

Almost every article states that “febrile convulsions are the most common type among children's seizures and are found in 2–5% of children.

Using different methodologies, numerous studies have shown that febrile convulsions are encountered in different percentages in children under the age of 5 years. Different incidences are observed in different countries, for example, England 2.4%, Israel 4.7%, Chile 4%, Japan 7%, Mariana Islands 14%.

The reason for this geographical discrepancy remains unexplained, but it may be related to genetic predisposition or environmental factors.

In 28 children, one will have febrile convulsions. Febrile convulsions have 3 critical elements:

• age,
• temperature,
• family predisposition.
• The tendency for febrile convulsions is related to a certain stage of brain maturation. It remains unclear why brain immaturity is susceptible to temperature.

Among risk factors, the most important is the presence of a history of febrile convulsions in the family. The more affected relatives, the higher the risk.

Various studies have also shown other risk factors, such as: smoking during pregnancy or the mother's respiratory infections during the first trimester of pregnancy.

Risk factors for recurrence of febrile convulsions.

Different authors have studied the risk of recurrence of febrile convulsions. About one-third of children who have had a febrile seizure will have at least one recurrence.

Numerous studies have identified the following factors as risks for the recurrence of febrile convulsions.

• A family history of febrile convulsions.
• The first febrile crisis before the age of 18 months
• A not very high level of temperature
• Children with two or more factors have a 30% risk of recurrence within 2 years.
• 50% of the risk for recurrence is realized within the first year immediately after the first febrile seizure. 90% of children who have recurrences, the crisis can reappear within 2 years.
• Age is the most stable determining factor regarding the risk of recurrence.
• As age increases, the risk of recurrence decreases.
• The presence of febrile convulsions in family history is associated with an increase in risk by one to two times. Children who often pass febrile illnesses have a high risk of developing febrile convulsions.
• Up to 50% of children who have recurrences may have more than one recurrence. Other factors such as a family history of epilepsy may also play a role in these children who have already had at least one recurrence. Factors that are often discussed but are still unclear and affect febrile convulsion recurrences include complex signs, neurological abnormalities.

Progression to epilepsy

Data from various epidemiological studies provide figures that from 2 to 10% of children with febrile convulsions develop epilepsy. In most studies, the risk of progression to epilepsy after a single febrile crisis is not significant compared to the normal population. Even in populations with a high incidence of febrile convulsions, such as in Japan, no significant differences from populations with a lower incidence are observed. The risk factors for the progression of febrile convulsions to epilepsy are as follows:

• The presence of neurological abnormalities before the febrile crisis
• Complex febrile convulsions
• Family history of epilepsy

In the case of complex febrile convulsions, the more complex manifestations, the greater the risk. Children with prolonged and focal febrile crises are particularly at high risk for epilepsy.

The more of these factors are encountered, the greater the possibility of progression to epilepsy. Two of the most important risk factors for progression to epilepsy are neurological abnormalities and family history of epilepsy. Whereas family history of febrile convulsions, age at the first febrile crisis, temperature, and gender have not been shown to increase the risk for subsequent epilepsy.

Afebrile convulsions (without fever) can start from a few months after the febrile crisis up to after 30 years, but 85% start after 4 years.

The risk that a child who has experienced febrile convulsions will have afebrile convulsions is:

• 2% at the age of 5 years
• 4.5% at the age of 10 years
• 5.5% at the age of 15 years
• 7% at the age of 25 years.

Febrile convulsions may precede various forms of epilepsy, such as:

• Myoclonic epilepsy
• Rolandic epilepsy
• Panayiotopoulos syndrome
• Dravet syndrome

EEG

Although it is not a reliable method in predicting the prognosis of febrile convulsions, EEG as a non-invasive method remains important in verifying structural changes of the CNS, as well as a conditioned predictor in the prognosis of febrile convulsions and their progression to epilepsy.

Treatment

According to the American Academy of Pediatrics, children with simple febrile convulsions do not require long-term treatment with antiepileptics.

The treatment of complex febrile convulsions with continuous therapy is highly controversial, with opinions divided into two groups.

• The first group supports the idea that febrile convulsions should be treated to prevent progression to epilepsy.
• The second group, based on epidemiological studies, argues that febrile convulsions are generally benign. However, very prolonged febrile convulsions remain a concern.

The presence of febrile convulsions causes panic among parents. Often they are uninformed about this situation and find themselves completely unprepared to act. Feelings of fear and anxiety are created in them whenever their child presents with a fever. Therefore, the doctor should inform the parents with all the necessary information about febrile convulsions, how to prevent the crisis, actions to be taken during the crisis and certainly they should be informed about the prognosis of the disease, which in most cases is benign.