Convulsions happen because of sudden, abnormal electrical activity in the brain.
Febrile convulsions are seizures that occur because of fever, which is a temperature higher than 38°C. High fevers might come with an infection. We don’t know why, but in these cases, the rapid rise in temperature causes an abnormal electrical discharge in the brain.
Febrile convulsions are pretty common, occurring in about 4% of children between the ages of six months and five years. Two-thirds of these children will only ever have one fit. Most will occur while the child is younger than three years old.
Children who have their first febrile convulsion before the age of one year have a higher risk of having recurrent febrile convulsions. This type of convulsion tends to run in families, and affects boys more often than girls.
It can be very frightening to see your child having a febrile convulsion, but children don’t die from them. Febrile convulsions don’t cause long-term consequences or brain damage, either.
Epilepsy is the term given to the condition where your child has more than one seizure, which isn’t triggered by fever, and there’s an abnormal EEG. About 3% of children with febrile convulsions subsequently develop epilepsy (compared to 0.5% of all children). The risk of epilepsy is greater with previous abnormal neurological development, history of epilepsy in first-degree relatives, long febrile convulsions (lasting more than 10 minutes), and multiple convulsions during a single episode of fever.
You can read more in our article on epilepsy.
There are many causes for convulsions other than fever or epilepsy – for example, brain tissue scarring, which might occur after head injury. Convulsions in some children might be triggered by flashing lights – such as a strobe light – or by looking at patterns on a TV or cinema screen.
There’s usually a family tendency towards having convulsions.
There are several different types of convulsions, but they’re usually characterised by:
- your child’s body suddenly stiffening
- your child becoming unconscious
- your child jerking, and his eyes possibly rolling back in his head
- your child usually sleeping deeply for an hour or so afterwards.
Most convulsions don’t last longer than several minutes.
Convulsions can be partial, affecting only one part of the body (and one part of the brain), or generalised, involving the whole body (and spreading throughout the brain).
Some convulsions (petit mal) don’t involve jerking body movements, but simply appear as an ‘absence’ from activities. Your child might stare for a few seconds, then continue with what she was doing as if nothing has happened.
The characteristics of a febrile convulsion are similar to those of a general convulsion. The episode is usually brief, lasting less than five minutes, and your child will make a complete recovery afterwards – but he might be drowsy for an hour or so afterwards. Your child will also have symptoms of the condition that caused the fever, such as a runny nose, earache or cough. Occasionally the febrile seizure will be associated with a more serious condition, such as meningitis, so it’s important to see a doctor in all cases.
When to see your doctor
Go to the doctor if:
- it’s your child’s first convulsion
- your child has several convulsions
- convulsions occur often.
Call an ambulance – phone 000 – if the seizure lasts longer than five minutes.
A child who’s had a febrile seizure probably won’t need tests. Sometimes blood or urine tests, or a chest X-ray, might be performed to work out the condition that caused the fever. Your child might be sent for an EEG if she’s having repeated febrile convulsions, but this won’t usually happen after a single episode.
If your child has a convulsion that isn’t caused by fever, your doctor will suggest sending your child for an EEG, and occasionally a CT scan of the brain.
The long-term treatment of general convulsions will depend on their cause and severity.
A febrile convulsion usually lasts only a few minutes, and almost always stops by itself before any treatment is given.
During the convulsion, place your child on a soft surface, lying on his side or back. Time the convulsion and watch exactly what happens, so you can describe it later. If the seizure goes on for longer than five minutes, call an ambulance or take your child to the doctor or hospital where medication can be given (intravenously or rectally) to stop the seizure.
It’s not usually necessary to hospitalise your child following a febrile seizure, unless your doctor’s concerned about the condition that caused the fever (such as pneumonia or meningitis). Generally, your child will be assessed, the underlying condition will be treated, and your child will be sent home.
There’s no guaranteed method of preventing febrile convulsions. But it’s possible to lower your child’s fever, for her comfort, by using paracetamol and taking off extra clothing. Sometimes the seizure will be the first indication of a fever. There’s no point in giving your child anticonvulsant medication whenever she develops a fever, because it takes several days to build up sufficiently high levels of the drug in the bloodstream.
If your child has recurrent febrile seizures, your doctor might rarely consider prescribing anticonvulsant medications to be taken on a continual basis for several years, to prevent the seizures from occurring. But this treatment should be started and managed only by a paediatrician or paediatric neurologist.
Prevention of non-febrile convulsions will depend on the diagnosed cause.