Febrile seizures (or convulsions) are a common benign paediatric condition that are associated with pyrexia. By definition, febrile seizure can only be diagnosed in the absence of CNS infection or acute electrolyte abnormalities. Although febrile seizures are benign, it is essential not to come to a diagnosis of febrile seizure without ruling out an epileptic seizure (possibly induced by pyrexia) or CNS infection.
Febrile seizures occur between 6 months and 6 years of age, though most commonly between 13 months and 3 years, with the peak incidence being in the second year of life. It is unusual for a child to have their first febrile seizure if older than 4, and the seizure normally occurs in the first day of the fever. Febrile seizures occur in up to 4% of all children.
Seizures occur for a number of genetic and environmental reasons. A family history of febrile seizures or epilepsy puts a child at higher risk for having a febrile seizure themselves. Inheritance tends to be polygenic though some families with AD inheritance have been identified. Other associated factors include iron deficiency anaemia.
Febrile seizures may be sub-categorised into simple (typical) febrile seizures or complex (atypical) seizures. They normally occur in the setting of a temperature of > 38 celsius, though afebrile seizures have been noted in association with viral gastroenteritis (these are still classified as febrile seizures). It is often quoted that the seizures occur due to a rapid rise in temperature as opposed to the high temperature itself, though this remains controversial.
Simple seizures present with generalised tonic-clonic activity that lasts under 15 minutes, occurs only once in 24 hours and is associated with fever.
Complex seizures make up ~15% of febrile seizures. A complex seizure is characterised by any one or combination of:
YouTube is a great resource for different types of seizures. You’d be surprised how many parents upload videos of their children seizing!
As with everything in medicine, history and examination are the mainstay of your approach to the patient presenting with a seizure. When approaching the patient you aim to rule out all other possible causes of seizure in a child before coming to a diagnosis of febrile seizure.
History may give details of current febrile illness, history of previous febrile seizures, history of non-febrile seizures such as epilepsy or history of other conditions that may contribute to epilepsy (such as autistic spectrum disorder (ASD), cerebral palsy etc.). A description of the event should be obtained from a first hand witness whenever possible. Often the parent or caregiver will have a video of the event. It is important to rule out meningitis - do ask specifically for symptoms and signs of meningism!
Full physical examination should be performed looking for signs of CNS infection, dysmorphism and skin signs, such as the port wine stain of V1 distribution in Sturge-Weber syndrome (Click here for more medical information regarding SWS published by the Great Ormond Street Hospital for Children; http://www.gosh.nhs.uk/medical-information/search-for-medical-conditions/sturge-weber-syndrome/sturge-weber-syndrome-information/). Examination may reveal signs of underlying febrile illness too.
Investigations for the child presenting with a suspected febrile seizure are mainly to exclude alternative diagnosis. Of note, meningitis is an important differential that should be excluded. The classic triad of meningitis is;
In older children (2+) presenting with the triad and a peticheal rash, treatment for bacterial meningitis should begin accordingly. Those under 12 months may not present with the classic symptoms of meningism so LP should be performed. In particular, those presenting with febrile status epilepticus have an 18% chance of having a bacterial meningitis. Other signs such as lethargy, bulging fontanelle, irritability and changes in central tone (hypo or hypertonic) are indicative of CNS infection.
The acute management of febrile seizures normally begins outside hospital. Advice such as moving the seizing child away from danger, placing them on their side and timing the duration of the seizure are all helpful.
Management of the child in hospital focuses around the febrile illness - anti-pyretics and rehydration are the mainstay of treatment. Venepuncture for bloods such as serum biochemistry are done at discretion of the attending clinician(s), depending on the severity of the child's illness. Further investigations such as lumbar puncture (LP) are indicated if meningitis is suspected. EEG’s generally are not performed as they are unlikely to change management of the child presenting with their first ever seizure. Imaging studies such as MRI brain are not indicated in the absence of neurological abnormality, though it may be considered on a non-urgent basis in patients with recurrent complex febrile seizures.
If the patient is still convulsing (longer than 10 minutes) or drowsy, emergency care should be provided, with an ABC-DEFG approach - maintain airway, breathing and circulation, and Don’t Ever Forget Glucose! Pharmacological and emergency interventions are detailed in the fastbleep article - ‘Suspected Seizure'.
A commonly asked question is whether or not their child has epilepsy. It is to note that 95-98% of children who have febrile seizures do not go on to develop epilepsy, though 35% of children will have a second or more febrile seizure. This is slightly higher than the risk the general population has of developing epilepsy, but is still quite low.
General advice on the management of febrile seizures should be given (as above), both parents and caregivers should be advised to call 999 if the child's seizure is lasting for longer than 5 minutes.
Children presenting with their second or third seizure may be considered for a prescription rectal diazepam or buccal midazolam to take home with them in order to manage future events. Advise the parents that anti-pyretics should be given with any febrile illness, but in general do not change the incidence of febrile seizures. Advice such as tepid bathing of the child and opening windows etc. may act to reassure parents but is unlikely to affect outcomes in the child. A typical febrile seizure is not an indication for taking a child to hospital, but if the underlying febrile illness causing the seizures is prolonged and serious or if the child is dehydrated hospital admission is warranted.
Here's a non-exhaustive list of differential diagnosis for febrile seizure should the examiner asks you after your short case or OSCE.
Reflex anoxic seizures
Other seizure disorders – epilepsy, head injury, encephalitis and electrolyte disturbances.
Febrile seizures are a common benign paediatric condition. The mainstays of management are:
Insuring the correct diagnosis.
Treatment of underlying illness.
Parental education and advice.
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