Wernicke-Korsakoff syndrome

(Redirected from Wernicke's encephalopathy)

Background

  • Wernicke's Encephalopathy (WE): acute neurologic syndrome caused by thiamine deficiency
  • Korsakoff's Psychosis (KS): chronic neuropsychiatric syndrome caused by thiamine deficiency
  • Wernicke-Korsakoff Syndrome (WKS): presence of Wernicke's Encephalopathy + Korsakoff's Psychosis simultaneously
  • First described by Carl Wernicke in 1881; remains one of the most underdiagnosed and undertreated neurologic emergencies

Epidemiology

  • Autopsy prevalence ~2% in the general population; up to 12.5% in patients with alcohol use disorder[1]
  • Only ~20% of cases are identified before death; failure of diagnosis leads to ~20% mortality and ~75% permanent neurologic damage
  • Classic triad (encephalopathy, oculomotor dysfunction, ataxia) is present in only ~10% of patients[2]
  • ~80% of patients with untreated WE progress to Korsakoff syndrome
  • Not limited to alcoholics — increasingly recognized post-bariatric surgery (~10% prevalence), in hyperemesis gravidarum, cancer, and critically ill patients

Pathophysiology

  • Thiamine (vitamin B1) is a cofactor for enzymes critical to cerebral energy metabolism:
    • Energy production pathways: pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, transketolase (Krebs cycle, pentose phosphate pathway)
      • Deficiency leads to impaired ATP production → lactic acidosis, neuronal/astrocytic injury, and altered brain metabolism
      • Brain regions with high metabolic demand are most vulnerable
    • Lipid metabolism (including myelin sheath formation)
      • Alterations in myelination leads to peripheral neuropathy
  • Thiamine half-life is only ~96 minutes; body stores are depleted within 2-3 weeks without intake
  • Brain lesions/atrophy usually occur in (bilateral, symmetric):
    • Mammillary bodies (nearly all cases — involvement is pathognomonic)
    • Medial thalamus
    • Periaqueductal gray matter
    • 3rd/4th ventricle walls
    • Tectal plate
    • Cerebellum (especially vermis)
    • Frontal lobe (atypical)

Causes

  • Thiamine (vitamin B1) deficiency caused by:
    • Insufficient intake
    • Malabsorption
    • Increased metabolic requirements
      • Malignancy/cancer chemotherapy
      • Thyrotoxicosis
      • Sepsis, critical illness
      • Refeeding syndrome
      • Carbohydrate loading (iatrogenic — can unmask subclinical deficiency)
    • Thiamine losses
    • Miscellaneous: AIDS, chronic liver disease, prolonged ICU admission, magnesium depletion (magnesium is a cofactor for thiamine-dependent enzymes)

Thiamine deficiency types

Clinical Features

Wernicke's Encephalopathy

  • Classic triad: encephalopathy, oculomotor dysfunction, gait ataxia
    • Classic triad present in only ~10% of cases — do NOT rely on complete triad to make diagnosis
  • werNICke mnemonic:
    • Nystagmus/ophthalmoplegia
      • Horizontal nystagmus is the most common ocular finding (not complete ophthalmoplegia)
      • Other ocular findings: bilateral 6th nerve palsy, conjugate gaze palsy, pupillary abnormality, retinal hemorrhage, ptosis
      • May progress to complete ophthalmoplegia
    • Incoordination/ataxia
      • Legs affected more than arms (vestibular + cerebellar dysfunction)
      • Primarily affects gait; arms and speech usually spared
    • Confusion/memory impairment
      • Delirium/encephalopathy is the most consistent clinical feature
      • May present as apathy, inattention, disorientation, or progress to coma
  • Other symptoms:

Korsakoff's Psychosis

  • Usually develops as a consequence of untreated or inadequately treated WE
  • Anterograde > retrograde amnesia (disproportionate to other cognitive functions)
  • Confabulation (often spontaneous)
  • Confusion, disorientation, apathy
  • Lack of insight into deficits
  • Largely irreversible

Differential Diagnosis

Ethanol related disease processes

Vitamin deficiencies

Evaluation

Axial MRI FLAIR image showing hyperintense signal in the mesial dorsal thalami, a common finding in Wernicke encephalopathy

Workup

  • WE is a clinical diagnosis — do NOT delay treatment for workup
  • Labs (to exclude alternative diagnoses and identify co-morbid conditions):
    • BMP— electrolytes, glucose, renal function, hepatic function
    • CBC
    • Magnesium level — critical; hypomagnesemia causes resistance to thiamine therapy
    • Lactate — may be elevated (thiamine is a cofactor for pyruvate dehydrogenase)
    • Blood alcohol level
    • Serum thiamine level (whole blood thiamine preferred over serum/plasma):
      • Draw before administering thiamine if possible, but never delay treatment to obtain
      • Normal range generally 70-180 nmol/L, but sensitivity and specificity are poorly defined
      • A normal thiamine level does NOT exclude WE[3]
    • Other labs as clinically indicated: TSH, ammonia, lipase, toxicology screen, blood cultures
  • Consider lumbar puncture if meningitis/encephalitis suspected — CSF in WKS typically shows normal or mildly elevated protein without pleocytosis

Imaging

  • CT head: sensitivity only ~13% for WE; primary role is to exclude other pathology (hemorrhage, mass, infarct)[4]
  • MRI brain (best imaging modality if obtained):
    • Sensitivity ~53%, specificity ~93%, positive predictive value ~89%
      • MRI is better at confirming the diagnosis than ruling it out
      • A normal MRI does NOT exclude WE — do not withhold treatment based on normal imaging
    • Classic findings: bilateral, symmetric T2/FLAIR hyperintensities in:
      • Mammillary bodies (most distinctive finding; contrast enhancement may be pathognomonic)
      • Periventricular/medial thalamus
      • Periaqueductal gray matter
      • Tectal plate
      • Cerebellar vermis (atypical but recognized)
    • DWI may show restricted diffusion (helps differentiate vasogenic vs cytotoxic edema)
    • Findings may normalize within days of starting thiamine therapy
  • Communicate suspected diagnosis to radiologists so protocols optimized for mammillary bodies, thalami, and periaqueductal region are used

Diagnosis

  • Clinical diagnosis — maintain high index of suspicion
  • Caine criteria (operational diagnostic criteria; ~85% sensitive when ≥2 present)[5]:
    • Nutritional deficiency (any state, not just alcoholism)
    • Ocular findings (ophthalmoplegia, nystagmus)
    • Cerebellar dysfunction (ataxia)
    • Altered mental status or mild memory impairment
  • Per EFNS guidelines, clinical diagnosis of WE in alcoholics requires at least 2 of the following[6]:
    • Dietary deficiencies
    • Ocular findings (ophthalmoplegia, nystagmus)
    • Cerebellar dysfunction (ataxia)
    • Mental status change or mild memory impairment

Management

If you suspect, then treat! Confirming diagnosis is difficult, treatment is low risk and effective, and morbidity/mortality is high if untreated

Acute Treatment

  • Thiamine — IV administration is critical; oral absorption is unreliable in at-risk patients
    • Royal College of Physicians / UK guideline (widely adopted):
      • 500 mg IV over 30 min TID x 2-3 days → then 250 mg IV/IM once daily x 3-5 days → then 100 mg PO daily until patient no longer at risk
    • EFNS guideline:
      • 200 mg IV TID (diluted in 100 mL NS or D5W, infused over 30 min)
    • 100 mg/day (e.g., banana bag dose) is likely insufficient — especially in patients with alcohol use disorder
    • Thiamine has a short half-life (~96 min); multiple daily doses are more effective than once-daily dosing
    • Overall safety of thiamine is very good; anaphylaxis risk with IV thiamine is rare

Key Principles

  • Give thiamine BEFORE glucose in any at-risk patient requiring dextrose
    • Glucose without thiamine can precipitate or worsen WE by driving remaining thiamine intracellularly
    • If both are urgently needed (e.g., symptomatic hypoglycemia), give them simultaneously — do not withhold glucose to wait for thiamine
  • Give magnesium
    • Magnesium is a cofactor for thiamine-dependent enzymes
    • Hypomagnesemia may cause resistance to thiamine therapy
    • Replete magnesium early and aggressively
  • Replete other vitamins/electrolytes as indicated (folate, multivitamin, pyridoxine)
  • Monitor for refeeding syndrome in severely malnourished patients
  • Treatment response can take days to weeks; lack of immediate improvement does not exclude WE

Treatment Response (Expected Timeline)

  • Oculomotor dysfunction: often begins improving within hours to days
  • Confusion/encephalopathy: may take days to weeks
  • Ataxia: slowest to improve; may be permanent
  • Korsakoff psychosis: largely irreversible once established

Common Pitfalls

Pitfall Correct Approach
Believing WE only affects alcoholics Any nutritionally deficient state can cause WE — consider post-bariatric surgery, cancer, hyperemesis, critical illness
Waiting for the complete classic triad Triad present in only ~10%; any component + risk factor should prompt treatment
Using 100 mg IV thiamine (banana bag) as treatment dose 100 mg is prophylactic, not therapeutic; treatment requires 200-500 mg IV TID
Relying on labs/imaging to confirm before treating Clinical diagnosis; normal thiamine levels and normal MRI do NOT exclude WE
Withholding glucose to wait for thiamine If hypoglycemia is symptomatic, give both simultaneously; do not delay glucose
Forgetting to check/replete magnesium Hypomagnesemia impairs thiamine utilization; always co-replete
Confusing WE with cerebellar stroke Both present with ophthalmoplegia, ataxia, AMS — always consider WE in differential


Medication Dosing

Thiamine 500mg IV over 30min TID x 2-3 days, then 250mg IV/IM daily x 3-5 days, then 100mg PO daily IV — 100mg (banana bag dose) is prophylactic only, NOT therapeutic; treatment requires 200-500mg IV TID

Disposition

  • Admit (inpatient medicine or neurology service)
    • Ensures continued IV thiamine and magnesium administration
    • Observation for development of Korsakoff syndrome
    • Evaluation for cardiovascular beriberi
    • Address underlying cause of thiamine deficiency
  • <25% of patients show full recovery, ~50% show partial recovery, the remainder show no response despite treatment[7]
  • ~80% of patients with untreated WE develop Korsakoff syndrome
  • Refer patients with alcohol use disorder to cessation programs; monitor for alcohol withdrawal

Prevention

  • Give parenteral thiamine to all at-risk patients presenting to the ED — do not wait for symptoms
  • After bariatric surgery: follow thiamine status for at least 6 months; supplement parenterally as needed

Vitamin Prophylaxis for Chronic alcoholics

  • At risk for thiamine deficiency, but no symptoms: thiamine 100mg PO q day
  • Give multivitamin PO; patient at risk for other vitamin deficiencies


Banana bag

The majority of chronic alcoholics do NOT require a banana bag[8][9]

See Also

Ethanol related disease processes

External Links

References

  1. ↑ Donnino MW, Vega J, Miller J, Walsh M. Myths and misconceptions of Wernicke's encephalopathy: what every emergency physician should know. Ann Emerg Med. 2007;50(6):715-21.
  2. ↑ Sinha S, Kataria A, Kolla BP, et al. Wernicke Encephalopathy-Clinical Pearls. Mayo Clin Proc. 2019;94(6):1065-1072.
  3. ↑ Ono K, Hayano S, Kashima M. Wernicke encephalopathy: limitations in a laboratory and radiological diagnosis. BMJ Case Rep. 2023;16(12):e254786.
  4. ↑ Medscape. Wernicke Encephalopathy Workup. Available at: https://emedicine.medscape.com/article/794583-workup
  5. ↑ Caine D, Halliday GM, Kril JJ, Harper CG. Operational criteria for the classification of chronic alcoholics: identification of Wernicke's encephalopathy. J Neurol Neurosurg Psychiatry. 1997;62(1):51-60.
  6. ↑ Galvin R, Bråthen G, Ivashynka A, et al. EFNS guidelines for diagnosis, therapy and prevention of Wernicke encephalopathy. Eur J Neurol. 2010;17(12):1408-18.
  7. ↑ https://www.alz.org/alzheimers-dementia/what-is-dementia/types-of-dementia/korsakoff-syndrome
  8. ↑ Krishel, S, et al. Intravenous Vitamins for Alcoholics in the Emergency Department: A Review. The Journal of Emergency Medicine. 1998; 16(3):419–424.
  9. ↑ Li, SF, et al. Vitamin deficiencies in acutely intoxicated patients in the ED. The American Journal of Emergency Medicine. 2008; 26(7):792–795.
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