Neurology: Febrile Convulsions Flashcards
What is a febrile seizure?
A seizure associated with fever in a child between 6 months and 6 years old in the absence of intracranial infection or an identifiable neurological disorder
When does the seizure typically occur?
When body temperature rises rapidly
Early in a viral infection
Describe the typical seizure
A single tonic clonic generalised seizure
Usually brief lasting less than 5 mins
What percentage of children have at least 1 febrile convulsion?
3%
Are febrile seizures the most common cause of seizures in childhood?
Yes
What fraction of children go on the have recurrent febrile seizures?
One third
Recurrence more likely if the first seizure occurs under age of 18 months, the lower the temperature at time of seizure, shorter duration of illness before seizure and if there is a family history
Are febrile seizures classified as epilepsy?
No
The underlying infection causing the fever may be a viral illness or bacterial infection such as…
Otitis media
Tonsillitis
Pneumonia
UTI
What diagnosis is very important to exclude and can present with seizures and fever?
Meningitis
The classical features of neck stiffness and photophobia may not be apparent in children less than 18m, so infection screen may be necessary (blood cultures, urine culture, LP)
What differentials should be considered?
Meningitis Encephalitis CNS lesions Epilepsy Trauma Hypoglycaemia Hypocalcaemia Hypomagnesia
Management includes…
Identify and treat underlying infection - may need additional investigations e.g CXR, bloods, blood culture, urine MSU, LP
Keep patient cool with regular antipyretics and tepid sponging
Termination of prolonged convulsions ie longer than 5-10 mins with rectal diazepam
They occur in 3% of children between what age?
6 months and 6 years
Majority: 12-18 months
Is there a genetic predisposition?
Yes - 10% risk if the child has a first degree relative with febrile seizures
Do simple febrile seizures cause brain damage?
No
There is 1-2% chance of developing epilepsy, similarly to the risk for all children
What are complex febrile seizures?
Focal, prolonged, or repeated in the same illness
These have an increased risk of 4-12% of developing epilepsy
Do antipyretics prevent febrile seizures?
No
Is an EEG indicated?
No - it does not predict seizure recurrence
What possible explanations are there for why a fever can cause seizures?
Fever increases the body’s core temperature which makes neurons more excitable
Fever causes hyperventilation and reduced CO2 in the blood = respiratory alkalosis, which also increases neurons excitability
Cytokines released by WBCs enhancing NMDA receptors
What infection is a common cause?
HHV6 (roseola)
What vaccine has been know to cause febrile seizures?
MMR but it is rare
