Are febrile seizures in adults considered a type of acute symptomatic seizure?

Febrile Seizures in Adults and Acute Symptomatic Seizures

Febrile seizures do not occur in adults by definition—they are exclusively a pediatric phenomenon occurring between 6 months and 5 years of age. 1, 2 However, if an adult presents with a seizure in the context of fever, this would be classified as an acute symptomatic (provoked) seizure, not a febrile seizure. 3

Key Definitional Framework

Febrile Seizures Are Age-Restricted

• Febrile seizures are defined as seizures accompanied by fever (≥38.0°C/100.4°F) occurring specifically in children between 6 months and 60 months of age, in the absence of CNS infection or metabolic derangement. 1, 2
• This age restriction is fundamental to the diagnosis—the term "febrile seizure" cannot be applied to adults. 2

Adult Seizures with Fever Are Acute Symptomatic Seizures

• When adults present with seizures and fever, these are classified as acute symptomatic (provoked) seizures. 3
• The American College of Emergency Physicians defines acute symptomatic seizures as those occurring at the time of or within 7 days of an acute neurologic, systemic, metabolic, or toxic insult. 3
• Examples include seizures from hyponatremia, electrolyte abnormalities, withdrawal, toxic ingestions, encephalitis, or CNS mass lesions. 3

Clinical Approach to Adults with Seizures and Fever

Immediate Diagnostic Priorities

• Suspect CNS infection (encephalitis, meningitis) first when an adult presents with fever, altered consciousness, and new seizures. 3
• The constellation of fever with altered behavior, personality changes, or new focal neurological signs should trigger immediate investigation for encephalitis or other CNS infection. 3
• Metabolic, toxic, autoimmune, and non-CNS sources of sepsis must be considered early, especially if there are symmetrical neurological findings, myoclonus, asterixis, or lack of fever despite encephalopathy. 3

Treatment Strategy

• Identify and treat the underlying cause rather than initiating long-term antiseizure medications. 4
• For active seizures not self-limiting within 5 minutes, first-line treatment is appropriate dosing of benzodiazepines. 4
• The primary approach is to correct the underlying acute insult (infection, metabolic abnormality, toxin) with temporary seizure control using short-acting medications if necessary. 4

Critical Distinction: Provoked vs. Unprovoked Seizures

Provoked (Acute Symptomatic) Seizures

• Occur within 7 days of an identifiable acute insult. 3
• Include metabolic causes (hyponatremia, hypocalcemia, hyperglycemia, uremia), infections, withdrawal, and toxic ingestions. 3, 4
• Do not typically require long-term antiepileptic therapy—treatment focuses on the underlying cause. 4

Unprovoked Seizures

• Occur without acute precipitating factors. 3
• Include idiopathic seizures, epilepsy (if recurrent), or remote symptomatic seizures from events >7 days in the past (stroke, traumatic brain injury). 3
• May warrant long-term antiseizure medication consideration. 5

Common Pitfall to Avoid

Do not confuse adult seizures occurring with fever as "febrile seizures"—this pediatric diagnosis does not apply to adults and will lead to incorrect classification and potentially inappropriate management. 1, 2 In adults, always investigate for serious underlying causes such as CNS infection, metabolic derangements, or structural brain lesions when seizures occur with fever. 3, 6