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Wernicke’s encephalopathy

Specialties > Mental health

Background knowledge 🧠

Definition

  • Neurological disorder caused by thiamine (vitamin B1) deficiency.
  • Characterized by a triad of ophthalmoplegia, ataxia, and confusion.
  • Part of Wernicke-Korsakoff syndrome when combined with Korsakoff’s psychosis.

Epidemiology

  • Commonly seen in alcoholics due to poor dietary intake and impaired thiamine absorption.
  • Can also occur in malnourished patients, e.g., those with eating disorders or hyperemesis gravidarum.
  • Incidence in the UK is 1-2% among chronic alcoholics.
  • More common in men and typically presents in the 30-70 age group.

Aetiology and Pathophysiology

  • Caused by thiamine (vitamin B1) deficiency, an essential cofactor for enzymes in carbohydrate metabolism.
  • Thiamine deficiency leads to impaired glucose metabolism and neuronal damage.
  • Damage predominantly affects the thalamus, mammillary bodies, and brainstem.
  • Associated with chronic alcoholism, malnutrition, and conditions leading to poor absorption or increased thiamine demand.

Clinical Features 🌡️

Symptoms

  • Acute confusion or altered mental status.
  • Memory impairment, particularly of recent events.
  • Visual disturbances, including diplopia.
  • Unsteady gait or ataxia.
  • Patients may present with somnolence or stupor.

Signs

  • Ophthalmoplegia (often involving the lateral rectus muscle).
  • Nystagmus.
  • Wide-based, unsteady gait or ataxia.
  • Confusion and disorientation.
  • Peripheral neuropathy may be present.

Investigations 🧪

Tests

  • Clinical diagnosis primarily, based on history and presentation.
  • Blood tests: Thiamine levels may be low but not diagnostic.
  • MRI brain: May show changes in the thalamus, mammillary bodies, and periaqueductal grey matter.
  • LP: Not typically indicated, but may be used to rule out other causes of encephalopathy.
  • Other tests: LFTs, U&Es, FBC to assess for underlying causes.

Management 🥼

Management

  • Immediate parenteral thiamine replacement (e.g., Pabrinex IV).
  • Continue thiamine for several days or until clinical improvement.
  • Correct electrolyte imbalances (e.g., hypomagnesemia).
  • Address underlying causes (e.g., alcohol dependence, malnutrition).
  • Monitor for complications, particularly Korsakoff’s psychosis.

Complications

  • Korsakoff’s psychosis (chronic memory disorder).
  • Permanent neurological deficits if untreated.
  • Increased risk of infections and sepsis.
  • High mortality if left untreated.

Prognosis

  • Good prognosis if treated early with thiamine replacement.
  • Delayed treatment may lead to irreversible damage and chronic cognitive impairment.
  • Mortality rate is high if untreated (up to 20%).
  • Recovery may take weeks to months, with some residual symptoms.

Key Points

  • Wernicke’s encephalopathy is a medical emergency requiring prompt treatment.
  • Thiamine should always be given before glucose in at-risk patients.
  • Early recognition and treatment are critical to prevent permanent damage.
  • Alcoholic patients presenting with confusion should be presumed thiamine deficient until proven otherwise.

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Mental health