Fever and febrile convulsions in a child
All children will have feverish illnesses but some may also experience a febrile convulsion. These most commonly occur between the ages of 18 months and three years and about 3 per cent of children have a febrile convulsion before their sixth birthday. This case study from the BNF for Children investigates some of the issues involved
Over the past 24 hours, a 14-month old boy has been crying frequently and has vomited twice. He is not feeding or sleeping as well as he normally does. He appears flushed, his head feels hot, he is coryzal, and his abdomen is tender.
His body temperature, measured with a tympanic thermometer, is 39.5C, his heart rate is 150beats/min and his respiratory rate is 40 breaths/min. He weighs 12kg.
Urine and blood samples are sent to the laboratory for urgent microscopy and culture.
The child’s medical history is otherwise unremarkable and there is no family history of neurological abnormalities. He received his first dose of measles, mumps and rubella vaccine and a booster dose of pneumococcal polysaccharide conjugate vaccine (adsorbed) seven days ago.
During the examination he has a generalised tonic-clonic convulsion lasting two minutes and he is sleepy for some minutes afterwards. On further examination he appears co-ordinated for his age, is able to say “mama”, and is appropriately alert and oriented. He has no rash or neck stiffness.
How should this boy’s febrile convulsion be treated?
The prescribing notes on febrile convulsions in section 4.8.3 of the BNF for Children 2010-2011, advise that brief febrile convulsions need no specific treatment. However, after a first febrile convulsion, it is usual practice to observe the child overnight in hospital. Antipyretic medication (eg, paracetamol) is commonly used to reduce fever and prevent further convulsions, but evidence to support this practice is lacking. However, antipyretic medication can be used to make this child, who is distressed with marked fever, more comfortable.
Diazepam by slow intravenous injection, or preferably rectally in solution, is used if febrile convulsions are prolonged (ie, lasting five minutes or longer) or recurrent. According to the notes on medical emergencies in the community (found in the glossy back pages of the BNFC), midazolam by the buccal route is an alternative. Neither midazolam nor diazepam is indicated in this case.
The child is prescribed paracetamol oral suspension 360mg as a single dose then 240mg every six hours. The parents are concerned that the first dose of paracetamol is much higher than the dose they usually give him at home.
Has he been prescribed an inappropriate dose of paracetamol?
According to the paracetamol monograph in the BNFC 2010-2011, the dose of paracetamol for severe pyrexia in a child of this age is 20-30mg/kg as a single dose then 15-20mg/kg every six to eight hours, to a maximum of 90mg/kg daily in divided doses.
In less severe pyrexia or when paracetamol is given by parents or carers to a child of this age, the standard dose is 120-250mg every four to six hours (maximum of four doses in 24 hours). This child has marked fever with discomfort so he has been prescribed an appropriate dose of paracetamol based on his body-weight.
Does this child require long-term anticonvulsant prophylaxis for febrile convulsions?
According to the prescribing notes on febrile convulsions long-term anticonvulsant prophylaxis is rarely indicated for febrile convulsions. This child does not require long-term prophylaxis because he has had a single, simple febrile convulsion and he has no history of afebrile seizures.
Microscopy of the urine sample shows more than 100 leucocytes/mm3 and the presence of numerous Gram-negative bacilli. The boy is started on intravenous fluids and cefotaxime. He improves within 48 hours of starting the antibiotic and the cefotaxime is switched to cefalexin to complete seven days’ treatment.
Does this child require imaging tests or antibiotic prophylaxis for the urinary-tract infection?
Imaging tests of the urinary tract are not indicated for children of this age with a first-time urinary tract infection that responds to antibiotic treatment within 48 hours.
The prescribing notes on urinary tract infections in (section 5.1.13 BNFC), recommend considering antibiotic prophylaxis for children with recurrent infection, significant urinary tract anomalies or significant kidney damage.
Although antibiotic prophylaxis is not recommended for this child, general advice should be provided on preventing urinary tract infections, such as maintaining an adequate intake of fluid.
Could the MMR vaccine be responsible for this boy’s febrile convulsion?
According to the prescribing notes on MMR vaccine (section 14.4), febrile seizures can occur six to 11 days after MMR vaccination in one in 1,000 children. The incidence is lower than that following measles infection. Adverse reactions are considerably less frequent after the second dose of MMR vaccine than after the first dose.
Although the time at which the febrile convulsion occurred in this child is closely related to the time from when the MMR vaccine was administered, the urinary tract infection is much more likely to be responsible for the fever and febrile convulsion.
Are further vaccinations contraindicated in this child?
According to the prescribing notes on active immunity in the BNFC 2010-2011 (section 14.1), when there is a personal history of febrile convulsions, there is an increased risk of these occurring during fever from any cause, including vaccination. However, this is not a contraindication to vaccination.
In this child, who has had a febrile convulsion without neurological deterioration, further vaccinations can be given at the appropriate age.
Based on a case study from the BNF/BNFC
Citation: The Pharmaceutical Journal URI: 11023424
Recommended from Pharmaceutical Press
Pharmaceutical Press is the publishing division of the Royal Pharmaceutical Society, and is a leading provider of authoritative pharmaceutical information used throughout the world.Visit rpharms.com