Clinical features of febrile convulsions

The usual presentation is of a child who is unwell with high temperature and then has a major seizure lasting a few minutes.

• febrile seizures usually occur in the first 24 hours of illness (1,2).
• fever
  • may be present at any time (at times after seizures)
    • seizures which occur 3 or more days after the onset of fever is unlikely to be febrile seizures (2)
  • if the fever is less than 380 C, consider an alternative diagnosis (3)
• seizures
  • they are predominantly brief, generalised tonic-clonic seizures. There may be cyanosis or incontinence
    • duration of the febrile seizure is less than 10 minutes in majority of cases
  • after the fit the child may sleep for some time
  • it is important to establish that there are no features of a complex seizure - ie that there were no focal features, there are no residual deficits(1,3)
  • febrile myoclonic seizures have also been reported in some cases (3)
  • presence of post-ictal symptoms (except for drowsiness) should raise suspicion of another diagnosis or a more serious cause (4)

Reference:

• (1) Patel N et al. Febrile seizures. BMJ. 2015 ;351:h4240
• (2) Patterson JL et al. Febrile seizures. Pediatr Ann. 2013;42(12):249-54
• (3) Sadleir LG, Scheffer IE. Febrile seizures. BMJ. 2007; 334(7588): 307–311.
• (4) Deakin K. Clinical Review – Febrile seizures. GPonline 2011