A febrile seizure is a convulsion in a child triggered by a fever. Such convulsions occur without any underlying brain or spinal cord infection or other neurologic cause.
Causes, incidence, and risk factors
About 3-5% of otherwise healthy children between the ages of 9 months and 5 years will have a seizure caused by a fever. Toddlers are most commonly affected. There is a tendency for febrile seizures to run in families. Most febrile seizures are triggered by a rapid rise of body temperature over 102.2°F. Most occur well within the first 24 hours of an illness, not necessarily when the fever is highest. The seizure is often the first sign of a fever.
The first febrile seizure is one of life’s most frightening moments for parents. Most parents are afraid that their child will die or have brain damage. Thankfully, simple febrile seizures are harmless. There is no evidence that simple febrile seizures cause death, brain damage, epilepsy, mental retardation, a decrease in IQ, or learning difficulties.
Most febrile seizures are triggered by fevers from viral upper respiratory infections, ear infections, or roseola. Meningitis causes less than 0.1% of febrile seizures but should ALWAYS be considered, especially in children less than one year old or those who still look ill when the fever comes down.
A simple febrile seizure stops by itself within a few seconds to 10 minutes, usually followed by a brief period of drowsiness or confusion. Anticonvulsant medicines are generally not needed.
A complex febrile seizure is one that lasts longer than 15 minutes, occurs in an isolated part of the body, or recurs during the same illness.
About a third of children who have had a febrile seizure will have another one with a subsequent fever. Of those who do, about half will have a third seizure. Few children have more than three febrile seizures in their lifetime.
If there is a family history, if the first seizure happened before 12 months of age, or if the seizure happened with a fever below 102, a child is more likely to fall in the group that has more than one febrile seizure.
A febrile seizure may be as mild as the child’s eyes rolling or limbs stiffening. Quite often a fever triggers a full-blown convulsion that involves the whole body.
Febrile seizures may begin with the sudden sustained contraction of muscles on both sides of a child’s body - usually the muscles of the face, trunk, arms, and legs. A haunting, involuntary cry or moan often emerges from the child, from the force of the muscle contraction. The contraction continues for seemingly endless seconds, or tens of seconds. The child will fall, if standing, and may pass urine. He may vomit. He may bite his tongue. The child will not be breathing, and may begin to turn blue. Finally, the sustained contraction is broken by repeated brief moments of relaxation - the child’s body begins to jerk rhythmically. The child is unresponsive to the parent’s screams.
Signs and tests
A febrile seizure may be diagnosed by the health care provider when a grand mal seizure occurs in a child with a fever and no prior history of seizure disorders (epilepsy). In infants and young children, it is important to rule out other causes for a first-time seizure, especially meningitis.
In a typical febrile seizure, the examination usually shows no abnormalities other than the illness causing the fever. Typically, a full seizure workup including an EEG, head CT, and lumbar puncture (spinal tap) is not warranted.
However, the child’s condition must meet strict medical criteria if these tests are to be avoided:
- The child must be developmentally normal
- The seizure must be generalized (not focal), meaning more than one part of the body is involved.
- The seizure may not last longer than 15 minutes.
- The child cannot have had more than one febrile seizure in 24 hours.
- The child’s neurologic exam performed by a physician must be normal to be called a simple febrile seizure.
If all of these criteria are met, no further studies are likely to be required.
During the seizure, leave your child on the floor. You may want to slide a blanket under him if the floor is hard. Move him only if he is in a dangerous location. Remove objects that may injure him. Loosen any tight clothing, especially around the neck. If possible, open or remove clothes from the waist up. If he vomits, or if saliva and mucus build up in the mouth, turn him on his side or stomach. This is also important if it looks like the tongue is getting in the way of breathing.
DO NOT try to force anything into his mouth to prevent him from biting the tongue, as this increases the risk of injury. DO NOT try to restrain your child or try to stop the seizure movements.
Focus your attention on bringing the fever down. Inserting rectal acetaminophen is a great first step - if you happen to have some. DO NOT try to give anything by mouth. Apply cool washcloths to the forehead and neck. Sponge the rest of the body with lukewarm (not cold) water. Cold water or alcohol may make the fever worse. After the seizure is over and your child is awake, give the normal dose of ibuprofen or acetaminophen.
After the seizure, the most important step is to identify the cause of the fever.
Most children outgrow febrile seizures by age 5.
A small number of children who have had a febrile seizure go on to develop epilepsy, but not because of the febrile seizures. Children who would develop epilepsy anyway will sometimes have their first seizures during fevers. These are usually prolonged, complex seizures. Previous neurologic problems and a family history of epilepsy also make future epilepsy more common. The number of febrile seizures has no correlation with future epilepsy.
- An injury from falling down or bumping into objects
- Biting oneself
- Breathing fluid into the lungs, pneumonia
- Injury from prolonged or complicated seizures
- Side effects of medications used to treat and prevent seizures (if prescribed)
- Complications if a serious infection, such as meningitis, caused the fever
- Seizures unrelated to fever
Calling your health care provider
- Children should see a doctor as soon as possible after their first febrile seizure.
- If the seizure is lasting several minutes, call 911 to have an ambulance bring your child to the hospital.
- If the seizure ends quickly, drive the child to an emergency room when it is over.
- A child should also see a doctor if repeated seizures occur during the same illness, or if this looks like a new type of seizure for your child.
- Call or go in if any other symptoms occur before or after the seizure, such as nausea, vomiting, rash, tremors, abnormal movements, problems with coordination, drowsiness, restlessness, confusion, or sedation. It is normal for children to sleep or be briefly drowsy or confused immediately following a seizure.
To prevent future febrile seizures, give acetaminophen or ibuprofen at the first sign of a fever. (You may want to keep acetaminophen suppositories on hand). Then sponge your child with lukewarm water. Give him cool liquids to drink - both to lower the temperature and keep him well hydrated.
Because febrile seizures can occur as the first sign of illness, prevention is often not possible. Neither an initial nor recurrent febrile seizure suggests that your child is not being properly cared for.
Occasionally, a physician will prescribe diazepam to prevent or treat recurrent febrile seizures.
by Harutyun Medina, M.D.