Febrile Seizures

Table of contents
Key points ⚡
Succinct notes to superpower your revision
Febrile seizure\: A seizure occurring in a febrile child (6 months to 5 years) without a CNS infection; most common cause of
seizures in children, a
Aetiology\: Exact cause unknown, likely age-dependent brain response to fever; 80% linked to viral infections (e.g., human
herpesvirus 6, in
Risk factors\: Family history, high fever (>40°C), viral infection, recent immunisation; 50% have no identi
Simple febrile seizures\: \< 15 minutes, generalised, occur once in 24 hours; usually tonic-clonic with limb sti
jerking, possible tongue biting and incontinence, post-ictal phase \< 1 hour.
Complex febrile seizures\: > 15 minutes, focal, prolonged post-ictal state (> 1 hour), more than one seizure in 24 hours; often
in younger children with developmental delays, may indicate febrile status epilepticus if > 30 minutes.
Identify fever source\: Perform clinical examination (ear, nose, throat, respiratory, rashes) to exclude CNS infection or other
sinister causes.
Di
sti
Investigations\: No investigations needed for simple febrile seizures with rapid recovery; exclude hypoglycaemia in actively
seizing child or prolonged recovery.
Management\: Immediate seizure management per acute guidelines; post-seizure focus on identifying fever source,
emergency admission for suspected CNS infection, paediatric team assessment for speci
months, recurrent, complex seizures, etc.).
Parental education\: Explain benign nature, di
help; provide written information, personalised seizure plan, instructions on rescue medication if given.
Complications\: Injury, aspiration, small increased risk of epilepsy, recurrence risk; prognosis is good, seizures usually stop
by age 5-7, one-third may have recurrence.
Article 🔍
A comprehensive topic overview

Introduction

A febrile seizure is a seizure (convulsion) which occurs in a febrile child (between the ages of 6 months and 5 years) and is
not caused by a central nervous system infection.
1
Febrile seizures are the most common cause of seizures in children, with 1 in 20 children having a febrile seizure at some
point.
1

Aetiology

The exact aetiology of febrile seizures is unknown. They are considered an age-dependent response of the immature
brain to fever, with a multifactorial mix of genetic and environmental factors.
1
80% of febrile seizures are caused by viral infections, with human herpesvirus 6 and in
infections.
1Risk factors
Risk factors for febrile seizures include\:
Family history of febrile seizures
High fever (>40°C)
Viral infection (in
Recent immunisation (rare)
Around 50% of children who present with a febrile seizure have no identi
2

Clinical features

Most febrile seizures occur within 24 hours of the child developing a fever. The parents may give a history of a previously
well child who developed a high temperature and started convulsing.
The clinical features will vary depending on the type of febrile seizure.
Simple febrile seizures
80-85% of children will have a simple febrile seizure. Clinical features of a simple febrile seizure include\:
3
Duration of fewer than 15 minutes (most last \<5 minutes)
Generalised seizure (symmetrical and involving the whole body)
Occur only once in 24 hours (i.e. not recurrent seizures)
Simple febrile seizures are usually tonic-clonic in nature, with episodes of limb sti
biting and incontinence during the episode. Parents may also describe abnormal eye movements (e.g. eyes rolling back).
The post-ictal phase for a simple febrile seizure is usually less than one hour. A longer post-ictal state with excessive
drowsiness or confusion should raise suspicion of central nervous system infection or status epilepticus.
Prolonged recovery from a febrile seizure (>1 hour) is more suggestive of a complex febrile seizure.
4
Complex febrile seizures
15-20% of children will have complex febrile seizures. Clinical features of a complex febrile seizure include at least one of
the \:
Duration of longer than 15 minutes
Focal seizure
Prolonged postictal state (more than 1 hour to achieve complete recovery )
More than one seizure in 24 hours
Children with complex seizures tend to be younger and are more likely to have developmental delays.
3
A seizure lasting more than 30 minutes, or multiple seizures without recovery is febrile status epilepticus.
Identifying the source of fever
A thorough clinical examination should be performed to identify the source of the fever. This should include examination
of the ear, nose and throat, respiratory examination, and general inspection for rashes.
It is important to exclude a sinister cause of the seizure (e.g. meningitis).

Di

Table 1. Di
DiCentral nervous system (CNS)
infections (meningitis,
meningoencephalitis, and
encephalitis)
Red
1
neck sti
photosensitivity
high-grade fever
non-blanching rash
irritability
bulging fontanelle
decreased level of consciousness
and focal neurological de
more than 1 hour after the seizure
Post-ictal fever
Rigors
Syncope
A
lumbar puncture
should be performed if there is clinical
suspicion of a CNS infection, or if the
child has been treated with antibiotics
(as antimicrobials may mask signs of
meningeal involvement)
Some children can develop a fever in
the post-ictal phase following a non-
febrile seizure.
A rigor is an episode of
shaking/shivering accompanied by a
rapid rise in temperature.
Myoclonic jerks following a syncopal
episode can mimic a seizure. Syncope
does not cause a post-ictal period and
children rapidly recover. It is important
to establish a clear history of what
happened before, during and after the
event. Syncopal events may have a
trigger (e.g. pain, the sight of blood).
A seizure following a head injury is a
red
brain imaging (
CT head
).
Head injury
It is important to ask about trauma in
the history and consider
non-accidental injury
in a non-mobile child with any injuries.

Investigations

Children with simple febrile seizures, who rapidly recover and are otherwise well, require no investigations following a
febrile seizure.
1
It is important to exclude hypoglycaemia in an actively seizing child or if there is a prolonged recovery period.

Management

Immediate management of a seizureMost febrile seizures will have resolved at the time of presentation to healthcare services.For more information on the immediate management of seizures, see the Geeky Medics guide to the acute management
of seizures.
Management following the seizure
The clinical assessment following a simple febrile seizure should focus on
If there is suspicion of a central nervous system infection or other life-threatening cause of a fever, arrange an emergency
hospital admission.
Generally, assessment by the paediatric team is required for the following situations\:
First febrile seizure
Children under 18 months old
Uncertain diagnosis
Recent antibiotic use
Decreased level of consciousness before the seizure
Focal neurological de
Recurrent or complex seizures
Children with developmental delay and/or symptoms of neurocutaneous or metabolic disorders be referred to a
paediatric neurologist.
1
Parental education
Parents can be very distressed after witnessing a febrile seizure.
It is important to explain the benign nature of febrile seizures, the di
chance of a child having another febrile seizure and the natural history of febrile seizures.
Parents and caregivers should be given information on managing seizures, including basic
recovery position) and when to call for emergency help.
Written information including patient information lea
given to parents. If they have been given rescue medication (e.g. buccal midazolam) by a specialist, they should be shown
how and when to administer it.
2

Complications

Complications of febrile seizures include\:
Injury while seizing
Aspiration while seizing
Small increased risk of epilepsy as compared to the general population
Risk of recurrence
The prognosis of febrile seizures is good and seizures usually stop by the age of 5 - 7.
One-third of children will have a recurrence of a febrile seizure. Risk factors for recurrence include a family history of
febrile seizures, onset aged \<18 months, lower temperature, or shorter duration of fever at the onset.
Risk of epilepsy
Parents may be worried about the future risk of epilepsy. It is important to advise them that while the risk is
increased compared to a child who has never had a febrile seizure, the risk is still small.
The risk also depends on the type of febrile seizure. A child with simple febrile seizures has a 2% risk of developing
epilepsy, a child with complex febrile seizures has a 5% chance of developing epilepsy. In contrast, a child who has
never had a febrile seizure has a 0.5 - 1% chance of developing epilepsy.
4References
NICE Clinical Knowledge Summary. Febrile Seizures. Available from\: [LINK]
StatPearls. Febrile Seizure. Available from\: [LINK]
BMJ Best Practice. Febrile Seizures. Available from\: [LINK]
NHS Choices. Febrile Seizures. Available from\: [LINK]
Patient.info Febrile Convulsions. What Causes Febrile Convulsions. Available from\: [LINK]

Reviewer

Dr Sanjay Gupta
Consultant Paediatrician

Related notes

Attention De
Autism Spectrum Disorder (ASD)
Biliary Atresia
Bronchiolitis
Cerebral Palsy

Test yourself

Contents

Introduction
Aetiology
Risk factors
Clinical features
Di
Investigations
M t
Source\: geekymedics.com