A febrile seizure is a convulsion associated with a fever in infants or small children. A typical seizure produces generalized shaking, twitching, or muscle rigidity and is usually associated with loss of consciousness. The seizure typically lasts only a few minutes. Febrile seizures typically occur between the ages of six months and five years. About 30% of children suffer recurrent simple febrile seizures; the long-term risk of developing adult epilepsy is very low (less than 1%).
There are two types of febrile seizures:
- Simple febrile seizures : Convulsions last between a few seconds to 15 minutes and are followed by a period of confusion and sleepiness which slowly resolves.
- Complex febrile seizures: Last longer than 15 minutes, occur more than once within 24 hours, or produce convulsions which affect only part the body.
If you suspect your child is having a febrile seizure, act quickly:
- Protect from physical injury: Place your child on the floor or bed away from any hard or sharp objects.
- Protect airway: Do not place anything in the mouth during the convulsion. Turn the child’s head to the side to allow saliva or vomit to drain from the mouth.
- Watch the time: The length of the convulsive period should be less than five minutes. If convulsions persist for more than five minutes call 911.
Elevated body temperature associated with a fever is believed to trigger the seizure. The common causes of fever include any childhood infection; especially viral infections. Fever often associated with routine immunizations, may also produce a febrile seizure.
Age is the greatest risk factor. Tow to four percent of children have a febrile seizure before age 5. There is some evidence that seizures associated with a high fever can occur if there is a family history of it.
Signs of a febrile seizure include:
- A fever, usually above 102° F
- Convulsion: Jerking or stiffening muscles
- Coarse breath sounds during the convulsion
- Loss of consciousness
- Loss of bladder or bowel control
Following the seizure, there may be a brief period of drowsiness or confusion.
In the case of simple febrile seizures, the diagnosis revolves around determining the source of the fever. This may require blood or urine tests. Rarely, if the doctor suspects meningitis or encephalitis, a lumbar puncture may be necessary to analyze the spinal fluid.
In the case of complex febrile seizures, the source of the fever is important; but additional neurologic evaluation may be needed including a CT or MRI of the brain; electroencephalogram; lumbar puncture; and admission to the hospital for observation.
In most cases the seizure resolves within a few minutes. Treatments are targeted at determining the underlying source of fever which may require antibiotics or antiviral medications. In the rare case of a persistent seizure, call 911 and give antiseizure medication if necessary.
Approximately 30% of children will suffer recurrent febrile seizure with subsequent fevers. This tendency is outgrown and very few will develop epilepsy. Giving your child acetaminophen at the first sign of a fever may help prevent recurrent febrile seizures. Unfortunately, the onset of fever can be rapid and the seizure can be the first sign of a fever. Do not give oral medications during a seizure.
Daily antiseizure medications, such as Phenobarbital and valproic acid, can be used to prevent seizures, but these medication have side effects. Simple febrile seizures, while alarming, do not harm the brain. Given the side effects, daily preventive antiseizure medications are not routinely recommended.