Fever seizure

Clinical Notes : Paediatrics

144. Fever Seizure

Definition

Pathophysiology

Classification

Physical signs consistent with diagnosis

Definition

A febrile seizures is a seizure occurring in febrile children between the ages of 6 and 60 months who do not have an intracranial infection, metabolic disturbance, or history of afebrile seizures.(1)

The first occurrence is usually before 3 years of age, but is infrequent in children younger than 6 months.

Febrile seizures have a peak incidence at 18 months of age and are most common between 6 months and 5 years.

Most febrile seizures are simple with approximately 20% to 30% being complex.(2)

Pathophysiology

Viral infections triggering fever are most common, with bacteraemia as an infrequent cause (3)

Febrile seizures are dependent upon a threshold temperature and this seems to vary from one individual to another.(4)

Age plays an important role in the susceptibility of febrile seizures.

the risk of recurrence of seizure declines with growing older (5)

Febrile seizures recur in approximately 30% of children during subsequent febrile illnesses.(6)

Most recurrences occur within 2 years

The most consistently identified risk factor for febrile seizure is the presence of a close family history (within first-degree relatives) of febrile seizure. The more relatives affected, the greater the risk. (7)

Classification

A simple febrile seizure is characterised by generalised tonic-clonic activity without focal features, for less than 10 minutes, without a recurrence in the subsequent 24 hours and resolving spontaneously.(8)

Complex febrile seizures are defined by one or more of the following features: (9)

a focal onset or focal features during the seizure
prolonged duration (greater than 10 to 15 minutes)
recurrent within 24 hours or within same febrile illness

Between 9% and 35% of all first febrile seizures are complex

Physical signs consistent with diagnosis

extracranial infection and fever (e.g., upper respiratory infection, otitis media, gastroenteritis)
rapid recovery of consciousness after seizure (within 30 minutes)
absence of nuchal rigidity and focal neurological abnormalities

Management

During a witnessed seizure, the patient should be protected from physical injury.

Additionally, airway, breathing, and circulatory assessment and support are vital.

A simple febrile seizure will stop spontaneously within a few minutes, and anticonvulsant therapy is not needed.

Body temperature should be reduced to relieve discomfort.

ibuprofen
- children 6 months-12 years of age: 5-10 mg/kg orally every 6-8 hours when required, maximum 40 mg/kg/day
paracetamol
- 10-15 mg/kg orally/rectally every 4-6 hours when required, maximum 75 mg/kg/day

For a complex febrile seizure buccal administration of midazolam may be given in preference to rectal diazepam.

midazolam
- children 1-2 months of age: 300 micrograms/kg (maximum 2.5 mg/dose) buccally as a single dose
  - repeat after 10 minutes if required;
- children 3-11 months of age: 2.5 mg buccally as a single dose
  - repeat after 10 minutes if required;
- children 1-4 years of age: 5 mg buccally as a single dose
  - repeat after 10 minutes if required
- children 5-9 years of age: 7.5 mg buccally as a single dose
  - repeat after 10 minutes if required;
- children 10-17 years of age: 10 mg buccally as a single dose
  - repeat after 10 minutes if required
diazepam
- children <2 years of age: consult specialist for guidance on dose
- children 2-5 years of age: 0.5 mg/kg rectally as a single dose
  - may repeat in 4-12 hours if required;
- children 6-11 years of age: 0.3 mg/kg rectally as a single dose
  - may repeat in 4-12 hours if required

Refer all cases to A+E for evaluation by a pediatrician.

Re-examination of a child with apparent recovery from a febrile seizure is mandatory within 24 hours.

Parent instructions

A first febrile seizure in a child is a frightening experience. Parents' concerns may continue long after the seizure abates.
Child should be protected from injury during the seizure.
Some children have a susceptibility to febrile seizures that resolves before the age of 6.
The risk of non-febrile seizures and epilepsy is small.
Recurrence is likely, usually within the year, but some preventive measures can be successful.
If a seizure develops and lasts longer than 3 to 5 minutes, child should be taken to the nearest hospital emergency department.
Parents should receive CPR training.