Wernicke Encephalopathy

Definition: Encephalopathy that occurs secondary to thiamine (vitamin B1) deficiency. While Wernicke encephalopathy is reversible with treatment, it can progress to the irreversible Korsakoff’s syndrome if left untreated.

Pathophysiology

• Thiamine is a cofactor for the enzyme pyruvate dehydrogenase
• This enzyme converts pyruvate to acetyl-CoA
• Acetyl-CoA enters the Krebs cycle and ATP is produced
• Without thiamine, the Krebs cycle breaks down leading to ATP depletion affecting the brain and heart

At Risk Populations

• US incidence of 0.2 – 2% (Hoffman 2015)
• Affects people with malnutrition or malabsorption
• Specific groups
  • Chronic alcoholics
  • Bariatric surgery patients
  • AIDS patients
  • Active malignancy
  • Hyperemesis gravidarum
  • Eating disorder patients
  • Bone marrow transplant recipients
  • CHF on furosemide (furosemide enhances renal elimination of thiamine)

History and Physical Examination

• Patients will have a history of malnutrition or malabsorption
• Classic Triad
  • Ataxia
  • Ophthalmoplegia (classically nystagmus and lateral rectus palsy)
  • Altered Mental Status/Confusion
  • All three features present in < 10% of patients (Donnino 2007)
• Hypotension and hypothermia may be seen
• Elevated lactate levels are common due to interruption of the Krebs cycle (Donnino 2007)
• Clinical Assessment Tool
  • Dietary deficiencies
  • Oculomotor abnormalities
  • Cerebellar dysfunction
  • Altered mental status or mild memory impairment
  • > 2 of above components is diagnostic

Management

• Preventive care: Thiamine 100 mg IV/IM
  • Parenteral route recommended as many of these patients have abnormal GI absorption
  • IV better than IM as many patents have diminished muscle mass making absorption less predictable
  • Should be provided to all groups at risk of thiamine deficiency (see above)
  • Unclear how long this provides protection for. Best estimates are about 1-2 weeks (Hoffman 2015)
• Treatment of Wernicke’s Encephalopathy
  • Basics
    • Check glucose and supplement as needed
    • Check electrolytes as concomitant electrolyte deficiencies (magnesium, potassium etc) are common
  • Thiamine 500 mg IV Q8 X 3 days
  • Follow with thiamine 250 mg IV Q24 X 3-5 days
  • Ophthalmoplegia can improve in hours while altered mental status and ataxia are frequently more delayed in improvement if they improve at all

Take Home Points

• Wernicke encephalopathy is characterized by ataxia, altered mental status and ophthalmoplegia but patients are unlikely to have all these components
• Suspect Wernicke encephalopathy in any patient that is at risk of malnutrition or malabsorption and has any one of the classic symptoms
• Prophylactic administration of thiamine 100 mg IV/IM to at risk patients can prevent development of the disease
• Once Wernicke encephalopathy has developed, it must be treated with high-dose, IV thiamine

Read More

• ER Cast: What You Don’t Know About Wernicke’s Encephalopathy
• LITFL: Thiamine Deficiency
• EMRAP: Remember to Take Your Vitamins
• ALiEM: Mythbusting the Banana Bag

References

1. Hoffman RS. Antidotes in Depth. In: Hoffman RS, Howland M, Lewin NA, Nelson LS, Goldfrank LR. eds. Goldfrank’s Toxicologic Emergencies, 10e New York, NY: McGraw-Hill; 2015. [Access Emergency Medicine]
2. Donnino MW et al. Myths and Misconceptions of Wernicke’s Encephalopathy: What Every Emergency Physician Should Know. Ann Emerg Med 2007; 50: 715-21. PMID: 17681641

Post Peer Reviewed By: Salim R. Rezaie, MD (Twitter: @srrezaie)

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