Can Febrile Seizures Present Like Absence Seizures?
No, febrile seizures do not present as absence seizures in a 2.5-year-old girl. Febrile seizures are defined as generalized tonic-clonic seizures accompanied by fever (≥100.4°F/38°C) in children aged 6 months to 5 years, and they do not manifest with the staring spells and brief lapses of consciousness characteristic of absence seizures 1, 2, 3.
Key Clinical Distinctions
Febrile Seizure Characteristics
- Febrile seizures are generalized tonic-clonic events lasting seconds to 15 minutes (for simple febrile seizures), followed by postictal drowsiness 1, 4, 5.
- They occur exclusively in the presence of fever without central nervous system infection 1, 2, 3.
- The typical presentation involves rhythmic jerking movements of all extremities, loss of consciousness, and a clear postictal period 4, 5.
Absence Seizure Characteristics
- Absence seizures present as brief episodes of staring with impaired consciousness, typically lasting 5-10 seconds, with no postictal confusion 6.
- They are not associated with fever and represent a distinct epilepsy syndrome 6.
- Onset is typically between 4-8 years of age (51% of cases), with only 12% occurring before age 4 years 6.
Critical Diagnostic Pitfall
If a child presents with staring spells during a febrile illness, this represents an afebrile seizure occurring coincidentally with fever, not a febrile seizure. This distinction is crucial because:
- By definition, febrile seizures exclude children who have had prior afebrile seizures 7.
- Absence-like episodes with fever should prompt evaluation for underlying epilepsy or central nervous system infection rather than being dismissed as simple febrile seizures 1, 2.
- Such presentations warrant EEG evaluation to identify the characteristic 2.5-4 Hz spike-wave discharges of absence epilepsy 6.
Clinical Approach
- Document the exact seizure semiology: generalized tonic-clonic movements versus staring/behavioral arrest 2, 3.
- Assess for postictal state: present in febrile seizures, absent in typical absence seizures 4, 6.
- Consider lumbar puncture in children under 12 months with fever and seizure, as meningeal signs may be absent in up to one-third of meningitis cases 2.
- Do not perform routine neuroimaging or EEG for simple febrile seizures, but these are indicated if the clinical presentation suggests absence epilepsy or other afebrile seizure types 1, 2, 3.
Historical Context Note
While 16% of children with absence epilepsy have a past history of febrile convulsions 6, this does not mean febrile seizures can present as absence seizures—these are distinct events occurring at different times in a child's life.