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# Wernicke encephalopathy (thiamine deficiency)

Wernicke encephalopathy is an emergency caused by lack of vitamin B1 (thiamine): confusion, trouble walking and abnormal eye movements.

Updated 2026-10-31

## Structures involved

Tap one to see what it is and open it in 3D.

- [Thalamus](https://durgical.com/en/anatomy/thalamus/)
- [Hypothalamus](https://durgical.com/en/anatomy/hypothalamus/)
- [Vermis](https://durgical.com/en/anatomy/central-lobule/)
- [Midbrain](https://durgical.com/en/anatomy/midbrain/)
- [Oculomotor nerve (III)](https://durgical.com/en/anatomy/oculomotor-nerve/)
- [Abducens nerve (VI)](https://durgical.com/en/anatomy/abducens-nerve/)
- [Left ventricle](https://durgical.com/en/anatomy/left-ventricle/)

## In biochemistry

- [Krebs cycle: Step 4 · α-Ketoglutarate dehydrogenase](https://durgical.com/en/biochemistry/pathways/krebs-cycle/#paso-4)
- [Pentose phosphate pathway: Step 5 · Transketolase](https://durgical.com/en/biochemistry/pathways/pentose-phosphate-pathway/#paso-5)
- [Pyruvate dehydrogenase complex (PDH)](https://durgical.com/en/biochemistry/enzymes/pyruvate-dehydrogenase-complex/)
- [α-Ketoglutarate dehydrogenase](https://durgical.com/en/biochemistry/enzymes/ketoglutarate-dehydrogenase/)
- [Transketolase](https://durgical.com/en/biochemistry/enzymes/transketolase/)
- [Ethanol](https://durgical.com/en/biochemistry/molecules/ethanol/)
- [Thiamine (vitamin B1)](https://durgical.com/en/biochemistry/molecules/thiamine/)
- [Magnesium](https://durgical.com/en/biochemistry/topics/magnesium/)

## In the clinical exam

- [Mental status: orientation, attention and screening tests](https://durgical.com/en/clinical-exam/mental-status-orientation-attention-and-screening-tests/)
- [Cerebellar tests: finger–nose, heel–shin and rapid alternating movements](https://durgical.com/en/clinical-exam/cerebellar-tests-finger-nose-heel-shin-and-rapid-alternating-movements/)
- [Cerebellar syndrome](https://durgical.com/en/clinical-exam/cerebellar-syndrome/)

## In physiology

- [Vitamins and minerals: a physiological overview](https://durgical.com/en/physiology/vitamins-and-minerals-a-physiological-overview/)
- [Functions of the cerebellum](https://durgical.com/en/physiology/functions-of-the-cerebellum/)
- [Learning and memory](https://durgical.com/en/physiology/learning-and-memory/)

## Why it happens

- [Alcohol: how it injures the liver, brain, heart and fetus](https://durgical.com/en/general-pathology/alcohol-how-it-injures-the-liver-brain-heart-and-fetus/)
- [Vitamin deficiencies: what each one does to tissue](https://durgical.com/en/general-pathology/vitamin-deficiencies-what-each-one-does-to-tissue/)

## What it is

Acute brain injury from thiamine deficiency, the coenzyme of PDH, α-ketoglutarate dehydrogenase and transketolase. Untreated, it can leave Korsakoff syndrome (permanent memory loss).

## Who gets it

It is linked mostly to heavy alcohol use, but also follows bariatric surgery, prolonged vomiting, malnutrition or parenteral nutrition without vitamins. It is underdiagnosed.

## Causes

- Heavy, long-term alcohol use
- Prolonged vomiting (hyperemesis of pregnancy, obstruction)
- Bariatric surgery, malnutrition, anorexia nervosa
- Giving glucose without thiamine to someone with low stores

## Risk factors

- Alcohol use disorder
- Cancer and chemotherapy
- Dialysis

## Pathophysiology

Without thiamine pyrophosphate, PDH and α-ketoglutarate dehydrogenase fail: neurons make less ATP and more lactate, and glutamate builds up. The most energy-hungry areas (medial thalamus, mammillary bodies, around the [third ventricle](https://durgical.com/en/anatomy/third-ventricle/) and aqueduct, [vermis](https://durgical.com/en/anatomy/central-lobule/)) swell and die.

## Classification

- Wernicke encephalopathy (acute)
- Korsakoff syndrome (chronic, amnesia)
- Dry beriberi (neuropathy) and wet beriberi (high-output heart failure)

## Symptoms and signs

- Confusion, disorientation, drowsiness
- Unsteady walking (ataxia)
- Abnormal eye movements: nystagmus, sixth-nerve palsy, double vision
- The full triad appears in only a minority

## Red flags

- Anyone with alcohol use or malnutrition and confusion: treat at once
- Hypothermia, low blood pressure or coma
- Breathlessness with swelling (wet beriberi)

## Diagnosis

**Clinical**
A clinical diagnosis on suspicion: no test is awaited before treating. Caine criteria: malnutrition, eye signs, ataxia and altered mental state (two of four).

**Tests**
Blood thiamine or transketolase activity (before treatment, without delaying thiamine); lactate, glucose, magnesium (its lack stops thiamine from working).

**Imaging**
MRI: symmetric high signal in the medial [thalamus](https://durgical.com/en/anatomy/thalamus/), mammillary bodies and grey matter around the aqueduct.

## Treatment

**Acute**
High-dose intravenous thiamine at once, before or with glucose

**Medical**
Correct magnesium and other deficiencies

**Rehabilitation**
Rehabilitation and support to stop alcohol

## Complications

- Korsakoff syndrome: amnesia with confabulation
- Coma and death without treatment

## Prevention

- Thiamine for everyone at risk who receives intravenous glucose or uses alcohol heavily

## Test yourself

Think of the answer, then tap the question to see it.

## Which enzymes depend on thiamine pyrophosphate?

PDH, α-ketoglutarate dehydrogenase, transketolase and the branched-chain keto acid dehydrogenase.

## What is the classic Wernicke triad?

Confusion, ataxia and ophthalmoplegia (or nystagmus); it is often incomplete.

## Which structures does the MRI show affected?

Medial thalamus, mammillary bodies and periaqueductal grey.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/conditions/wernicke-encephalopathy/)

## Related conditions

- [Lactic acidosis](https://durgical.com/en/conditions/lactic-acidosis/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Wernicke-Korsakoff syndrome: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000771.htm) (MedlinePlus, US National Library of Medicine, 2026); [Beriberi: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000339.htm) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Source: https://durgical.com/en/conditions/wernicke-encephalopathy/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/wernicke-encephalopathy/