A 3-year-old child presents to the emergency department with continuous seizures lasting 45 minutes. The parents report no prior history of epilepsy. What is the most common cause of status epilepticus in this age group?

Explanation

## Most Common Cause of Status Epilepticus in Children **Key Point:** Febrile seizures (prolonged febrile seizures / febrile status epilepticus) are the **most common cause of status epilepticus** in children aged 1–5 years, accounting for approximately 25–35% of all cases in this age group. ### Epidemiology Multiple large population-based studies (NLSTEPSS, FEBSTAT) consistently identify febrile status epilepticus as the single largest identifiable cause of status epilepticus in young children. In children aged 6 months to 5 years with no prior epilepsy history, a prolonged febrile seizure is the most frequent precipitant. ### Causes of Status Epilepticus in Children — Frequency | Cause | Approximate Frequency | Age Group | Key Feature | |-------|----------------------|-----------|-------------| | **Febrile seizures (febrile SE)** | **25–35%** | 6 months–5 years | Fever, no prior epilepsy, self-limited background | | Acute CNS infection | 15–20% | 1–5 years | Fever + meningeal signs, CSF pleocytosis | | Idiopathic/cryptogenic epilepsy | 20–25% | Any age | Prior seizure history common | | Metabolic derangements | 5–10% | All ages | Specific lab abnormalities | **Clinical Pearl:** Although febrile seizures are classically described as brief (< 15 min), approximately 5% of febrile seizures are prolonged (≥ 5 min) and constitute **febrile status epilepticus**. This is the most common subtype of status epilepticus in previously non-epileptic children under 5 years. (Reference: Nelson Textbook of Pediatrics, 21st ed.; Shinnar et al., Epilepsia 1997) **High-Yield:** Acute CNS infection is an important and dangerous cause that must be excluded in any febrile child with status epilepticus, but epidemiologically, febrile status epilepticus is more common overall. When a child with no prior epilepsy history presents with prolonged seizures in the context of fever, febrile status epilepticus is the leading diagnosis. ### Differential Reasoning - **Febrile seizures** — most common cause of SE in this age group; prolonged febrile seizures = febrile SE. - **Acute CNS infection** — critical to rule out, but accounts for a smaller proportion than febrile SE overall. - **Idiopathic epilepsy** — typically has a prior seizure history; de novo SE is unusual. - **Metabolic derangements** — important but less frequent in this specific age group without prior history. *Reference: Nelson Textbook of Pediatrics, 21st edition; Shinnar S et al., Epilepsia 1997; DeLorenzo RJ et al., Epilepsia 1996.*