Status Epilepticus

Basics

Description

  • Status epilepticus (SE) is defined as a continuous seizure lasting >30 minutes or recurrent seizures without return to baseline in between. After 30 minutes, ischemic injury to the brain is more likely to occur. Seizures lasting >5 minutes are unlikely to resolve without anticonvulsant therapy and are likely to progress to SE without intervention.
  • SE presents in several forms:
    • Generalized SE: continuous or repeated generalized convulsion(s) with persistent loss of consciousness and neurologic function
    • Nonconvulsive SE, myoclonic SE, or absence SE: persistent encephalopathy, often with variable subtle motor signs such as myoclonus or nystagmus
    • Repeated partial seizures with alteration of consciousness (focal SE) or preserved consciousness (epilepsia partialis continua)
  • Systemic complications of SE:
    • Hyperthermia, rhabdomyolysis
    • Tachycardia, hypertension early → hypotension late
    • Hypoxia, hypercapnia, aspiration pneumonia
    • Impaired cerebral autoregulation
    • Rare: cardiac arrhythmias, neurogenic pulmonary edema, bone fractures
ALERT
  • Neuromuscular blockers used in intubation may obscure ongoing seizures. EEG monitoring is mandatory for all patients who have had any pharmacologic paralysis during SE.
  • Continued encephalopathy after convulsions have stopped may indicate ongoing electrographic seizures (nonconvulsive SE), found in up to 30% of children after treated SE.
  • Nonepileptic seizures can be mistaken for SE. EEG establishes the diagnosis.

Epidemiology

  • Incidence in pediatric patients is 17 to 23/100,000. In children <1 year old, incidence is 135 to 156/100,000.
  • ~40–70% of children have no history of seizures.

Risk Factors

  • Known epilepsy
  • Remote or acute central nervous system (CNS) insult
  • History of previous SE
  • Low anticonvulsant drug levels
  • Younger age

General Prevention

  • Adherence to the anticonvulsant medication regimen and clinical follow-up in patients with epilepsy
  • Avoid rapid changes in anticonvulsants unless urgently needed.
  • Prompt treatment of convulsive seizures

Pathophysiology

SE may be related to acute or chronic factors or frequently of unknown etiology.

  • Common acute factors:
    • Fever
    • Infectious meningoencephalitis
    • Metabolic: electrolyte abnormalities, hypoglycemia
    • Intoxications
    • Trauma or hemorrhage
    • Ischemic stroke, hypoxic-ischemic injury
    • Medications: low anticonvulsant drug levels or abrupt withdrawal of anticonvulsants, inappropriate anticonvulsants (e.g., absence SE with phenytoin or carbamazepine use in generalized epilepsy or with tiagabine in focal epilepsy)
  • Subacute or chronic factors:
    • Epilepsy of any cause
    • Brain tumors
    • Brain malformations (e.g., lissencephaly, polymicrogyria, hemimegalencephaly, neurocutaneous syndromes)
    • Other structural brain abnormalities such as strokes hypoxic-ischemic encephalopathy (HIE) or periventricular leukomalacia (PVL)
    • Genetic epilepsies: Dravet syndrome (febrile SE), Angelman syndrome (myoclonic SE), progressive myoclonic epilepsy syndromes
    • Inflammatory disorders (e.g., Rasmussen encephalitis, N-methyl-D-aspartate [NMDA] receptor antibody syndrome)
    • Acute malfunction of ventriculoperitoneal (VP) shunt

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