Who gets febrile seizures?
Children aged 3 months to 5 or 6 years may have seizures when they have a high fever. These are called febrile seizures (pronounced FEB-rile) and occur in 2% to 5% of all children (2 to 5 out of 100 children). There is a slight tendency for them to run in families. If a child's parents, brothers or sisters, or other close relatives have had febrile seizures, the child is a bit more likely to have them.
Sometimes the seizure comes "out of the blue" before it is recognized that the child is ill. A fever may begin silently in a previously healthy child. A seizure can be the first sign that alerts the family that the child is ill.
What types of febrile seizures are there?
Febrile seizures have been divided two groups, simple or complex.
Febrile seizures are considered “simple” if they meet all of the following criteria:
- Generalized full body convulsions
- Last less than 15 minutes
- No more than one in a 24-hour period
Febrile seizures are considered “complex or complicated” if any of the following features are present:
- Start focally with one body part moving independently of others
- Last more than 15 minutes
- Occur more than once in a 24-hour period
What tests need to be done?
The most important question that needs to be answered in a child with a febrile seizure is, “What is the cause of the fever?” Even if the seizure is over, any young child who has a seizure with fever should be seen by a doctor to make sure they do not have a brain infection, such as meningitis.
- Your doctor will ask questions about any symptoms suggestive of infection and perform a careful physical exam to look for signs of infection.
- Blood tests may be needed.
- A spinal tap may be needed in some cases if your doctor is worried about meningitis. This is done more commonly in children under 12 months of age, but rarely is needed in older children.
- Although an EEG (electroencephalogram) and MRI (magnetic resonance imaging) are not needed most of the time, these may be done when a seizure is very prolonged, if the seizure begins focally, or if there are any concerns on examination.
How are febrile seizures treated?
Febrile seizures cannot be prevented by giving the child lukewarm baths, applying cool cloths to the child's head or body, or using fever-reducing medications such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin). Doing these things may make a feverish child feel better, but they do not prevent febrile seizures.
During a seizure:
- Place the child on his or her side on a protected surface and watch carefully.
- Keep track of the time. If the seizure lasts longer than 5 minutes, call 911 or take the child to an emergency room.
- Learn more seizure first aid
Most children who have febrile seizures do not require daily treatment with seizure medicines. However, children who have a history of prolonged febrile seizures and those who live in more remote areas with poor access to prompt medical care should be given a rescue medication.
- A rescue medicine is designed to stop seizures fast. They are meant to be used in certain situations, not daily.
- For a child with febril seizures, the health care provider may ask that they be given a rescue medicine at the time of another febrile seizure lasting longer than 3-5 minutes.
- Examples of rescue medication include diazepam (Diastat) gel given rectally, midazolam liquid given nasally, or diazapam nasally or orally. (Nasal forms of medicines are being reviewed by the U.S. Food and Drug Administration.)
Giving the child diazepam (Valium) when illness or fever begins can reduce the risk of having another febrile seizure.
- However, to prevent one febrile seizure in this way, 14 other children who were never destined to have another febrile seizure will receive the medicine needlessly!
- 3 out of 10 children treated with diazepam have troublesome side effects, such as sleepiness, irritability, and poor coordination, that may last for several days.
If your child has frequent febrile seizures, talk to your health care team about the best approach to prevent or treat seizures.
What's the outlook?
Among children who have their first febrile seizure before their first birthday, half will have at least one more. Among children who are older than 1 year when the first seizure occurs, about 1 in 4 will have more.
The long-term outlook is excellent, however. The vast majority of children with febrile seizures do not have seizures without fever after age 5.
What are the risks for developing epilepsy later?
- Problems with the child's development before the febrile seizure
- Having complex or complicated febrile seizures that last longer than 15 minutes, more than one seizure in 24 hours, or seizures in which only one side of the body is affected
- Seizures without fever in a parent or a brother or sister
How do those risks factor into the chance my child will develop epilepsy?
- If the child has none of these risk factors, the chances of epilepsy developing later are only 1% to 2% (1 or 2 out of 100). This is very similar to the risk of developing epilepsy in any other child.
- Children with 1 of these risk factors have a 2.5% (1 in 40) chance of later epilepsy.
- For children with 2 or 3 risk factors, their chance of developing epilepsy later ranges from 5% (1 in 20) to over 10% (greater than 1 in 10).
- In rare cases, febrile seizures that last more than 30 minutes may cause scar tissue in the temporal lobe of the brain. In some of these children, chronic epilepsy develops.
If you have concerns about your child's febrile seizures, consider consulting a pediatric neurologist or epileptologist.
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