Which of the following criteria must be met for a seizure to be classified as a febrile seizure?

Choice A rationale A febrile seizure, by definition, is precipitated by a fever, which must be above the normal body temperature threshold. The current clinical standard requires the temperature to be ≥ 38°C (≥ 100.4°F), thus a temperature less than 38°C would exclude a diagnosis of a febrile seizure, irrespective of other factors. Choice B rationale The core criteria for a simple febrile seizure include an associated fever of ≥ 38°C, occurring in a child typically between the ages of 6 months and 5 years, without a history of a central nervous system infection or a previous afebrile seizure. This age range reflects the peak neuronal excitability combined with the frequent occurrence of common childhood viral illnesses that trigger fever. Choice C rationale Febrile seizures rarely occur in children older than 6 years because the central nervous system (CNS) has generally matured sufficiently, making the developing brain less susceptible to the effects of fever-induced hyperexcitability. Seizures occurring after this age, even with a fever, warrant a thorough workup for other underlying causes, as they are atypical for a simple febrile seizure. Choice D rationale A seizure occurring in the context of a central nervous system infection (e.g., meningitis, encephalitis) is classified as a seizure secondary to infection or symptomatic seizure, not a simple febrile seizure. The defining characteristic of a simple febrile seizure is the absence of an underlying CNS structural abnormality or infection as the cause of the seizure.