febrile convulsions

Last edited 01/2022 and last reviewed 01/2022

Febrile convulsions or febrile seizures are benign, generalised convulsions seen in children aged between six months and five years associated with fever in the absence of intra-cranial infection, metabolic disturbance, or history of afebrile seizures.

• these age limits are arbitrary and should only be used as a guide (1,2)
• there is no universal agreement regarding the level of fever required to diagnose febrile seizure,
• consensus guidelines recommends that the axillary temperature should be >37.8°C (3)
• the American Academy of Pediatrics (AAP) defines temperature to be  >= 100.4°F or 38°C by any method (4)
• diagnostically they must occur in a developmentally normal child, last for less than 20 minutes, be generalised with no complex features, and leave no residual abnormality

The International League Against Epilepsy (ILAE) defines a febrile seizure as:

“a seizure occurring in childhood after one month of age associated with a febrile illness not caused by an infection of the central nervous system, without previous neonatal seizures or a previous unprovoked seizure, and not meeting the criteria for other acute symptomatic seizures.” (1)

Febrile seizures occurring in a child older than one month during an episode of fever affect 2-4% of children in Great Britain and the United States and recur in 30%. (5)

• a systematic review found reduced recurrence rates for intermittent diazepam and continuous phenobarbital, with adverse effects in up to 30% of children (5)

Reference:

• (1) Patel N et al. Febrile seizures. BMJ. 2015 ;351:h4240
• (2) Deakin K. Clinical Review – Febrile seizures. GPonline 2011
• (3) Armon K et al. An evidence and consensus based guideline for the management of a child after a seizure. Emerg Med J. 2003;20(1):13-20
• (4) American Academy of Pediatrics. Neurodiagnostic evaluation of the child with a simple febrile seizure. Pediatrics. 2011;127(2):389-94
• (5) Offringa M, Newton R, Nevitt SJ, Vraka K. Prophylactic drug management for febrile seizures in children. Cochrane Database of Systematic Reviews 2021, Issue 6. Art. No.: CD003031. DOI: 10.1002/14651858.CD003031