Febrile Convulsions in Children
What are febrile convulsions?
These are a relatively common form of seizure( fit) where the child will have uncontrolable vigourous muscular shaking.They affect about 4-5% of children under the age of 5.
For the vast majority of these children ,the outcome is excellent ,with no long term consequences
Features and definition:
In order to make a diagnosis of simple benign febrile seizures,the following criteria should be present
- The child should have a documented fever.
- Age between 6 months and 5 years
- The seizure lasts less than 15 minutes
- Only one seizure in a 24 hour period
- They affect the whole body.
- The child is otherwise developing normally
Other related and similar conditions:
Other conditions which may cause confusion include breath-holding attacks,rigors or severe shivering.
It is also important to note that some febrile convulsions are Termed "Complex Febrile Seizures"(about 20%).In these cases,at least one of the following features is present.
- Focal Seizure- this means for example that just one part or the body may be affected- eg shaking arm.This tends to indicate a localised problem in the brain.
- They last longer than 15 minutes
- More than one seizure in 24 hours
Complex febrile convultions slightly increase the risk of seizure recurrence and subsequent risk of epilepsy(see further details)
Why do they happen?
Young children's developing brains have a lower threshold at which a fever will trigger a convulsion, as well as having much more frequent(usually viral) infections.There is also a genetic influence eg where a parent or sibling has a history of febrile convulsions, the child's risk is greatly increased (to between 10-20%)
Diagnosis and Tests needed:
Usually the fit will have stopped by the time the child is seen by a doctor.A thorough examination (and sometimes blood and urine tests)is needed to look for the likely underlying cause of the fever.This is usually a viral respiratory tract infection and no specic treatment is needed,although sometimes antibiotics may be needed for example if an ear or chest or urine infection is shown.
In the past ,many children would have had a lumbar puncture to exclude meningitis,however this is much less frequently done nowdays and usually reserved for cases where meningitis is clinically suspected- eg rash,marked drowsiness or other features.
Usually a child will recover rapidly once fever settles and sometimes a period of close observation will be helpful in deciding which children need further tests .
Brain scans are not needed for simple seizures,although may be required for some cases of complex seizures.(eg focal seizures).Likewise EEGs are not needed or particularly helpful for future prediction of epilepsy.
First Aid and Prevention of Recurrences:
Seeing a first seizure in a child is a frightening experience ,and many parents will have a feeling of panic.
The following may be helpful
- Try stay calm
- Place the child on his/her side,with head slightly down (if they vomit,they are less likely to choke in this position)
- Do not try force anything between the teeth.
- If the seizure does not stop after about 5 minutes,phone an ambulance.
- If the seizure stops on its own, take your child to your doctor.
- taking off cloths(to allow cooling) and giving a dose of paracetemol are helpful
Risk of recurrences and how to reduce this
Once a child has had one seizure,a strategy should be in place to try and reduce the risk of recurrences,this should include
- Control of fevers- in the event of a fever, a full and regular dose of paracetemol should help -make sure you have paracetemol available in the correct dosage. Rectal paracetemol is available and useful for a child who will not take it orally. Despite meticulous attention,not all future seizures will be prevented and they may recur before it is realised the child is feversih.
- See your doctor,so the underlying cause of a fever can be diagnoses and treated as appropriate.
- Wearing less clothing and sponging with luke warm water may help reduce fever(not cold baths).
- Rectal valium(diazepam) is helpful to have available(to administer to stop an actual fit),particularly for parents who may have difficulty accessing medical care.If you do this make sure you have detailed instructions from your doctor on exactly what to do.
How common are recurrences?
The risk is between 30%(if 1 st seizure over 1 year ) to 50% (if first seizure under one year).
Once a child has had a recurrence, the risk of a further one rises to 50%.
Several other factors may also slightly increase the risk or recurrenc,including
- Age under 18 months.
- Complex seizures(see earlier description)
- Family history
- Seizure precipitated by only a low grade fever
Other Long Term concerns
Reassuringly ,many studies show that the long term outlook for children who have simple febrile convultions is excellent.
Mental Development: there is no increased incidence of learning disorders or mental retardation.
Epilepsy: The increased risk of having true long term epilepsy are very small.The rate of epilepsy is around 0,5% to 1 % , in the general population. In children with simple uncomplicated febrile convulsions it is also around 1%.
Several Risk factors(below) may increase the subsequent risk of epilepsy to 2.5%(one risk factor),or 5-10% (2 risk factors)
- Complex seizures
- Pre-existing nervous system problems ,including developmental delay.
- A family history of epilepsy