Simple vs Complex Febrile Seizure

Classification simulator: onset pattern, duration, and recurrence.

Current Stage

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Duration class

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Onset pattern

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Overall classification

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Workup implication

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Seizure duration (minutes)5

Focal features (0=Generalized, 1=Focal)0

Generalized whole-brain activity

Focal localized region activity

Duration timeline / 15-min threshold

Single event (24h clock)

Recurrent event (24h clock)

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Generalized vs Focal Onset Activity

Onset spread across the whole brain versus one localized area.

Whole brain: Generalized onset (Bilateral synchronous activity)
One region: Focal onset (Localized cortical activity)
Symmetric vs local: EEG pattern (Simplified schematic)
Key criterion: Clinical weight (Drives classification)

Onset pattern basics

Generalized onset affects both hemispheres at once; focal onset starts in one area.

Focal features raise suspicion for a complex febrile seizure.

Duration Under vs Over 15 Minutes

The 15-minute mark separates brief from prolonged seizures.

15 min: Threshold (Simple/complex cutoff)
<15 min: Short seizure (Typical simple pattern)
≥15 min: Prolonged seizure (Complex feature)
>30 min: Status epilepticus risk (Emergency threshold)

Why duration matters

Longer seizures carry higher risk and shift classification toward complex.

Duration is timed continuously from seizure onset to end.

Single vs Recurrent Seizures Within 24 Hours

A repeat seizure in the same febrile illness day changes the picture.

1 seizure/24h: Single event (Simple pattern)
≥2 seizures/24h: Recurrent event (Complex feature)
24 hours: Window (Same febrile illness)
Watch interval: Clinical note (Between episodes)

Recurrence window

Multiple seizures in one day during the same illness suggest complexity.

Recurrence is tracked on a simplified 24-hour clock.

Simple Febrile Seizure Criteria

Generalized, brief, and non-recurring defines the simple type.

Generalized: Onset (Whole brain)
<15 min: Duration (Brief)
Single/24h: Recurrence (No repeat)
Favorable: Prognosis (Low risk overall)

Simple pattern summary

All three low-risk criteria together define a simple febrile seizure.

Routine reassurance is usually sufficient for simple cases.

Complex Febrile Seizure Criteria

Any one of focal onset, long duration, or recurrence makes it complex.

Focal (any): Onset (Localized feature)
≥15 min: Duration (Prolonged)
≥2/24h: Recurrence (Repeat episodes)
Often needed: Workup (EEG / imaging considered)

Complex pattern summary

A single complex feature is enough to shift the overall classification.

Complex features prompt more careful clinical evaluation.