Wernicke's Encephalopathy

Question 1

What is the definition of Wernicke’s Encephalopathy?

Answer 1

The presence of neurological symptoms caused by biochemical lesions of the central nervous system following exhaustion of vitamin B (particularly thiamine) reserves.

Question 2

What is the aetiology of Wenicke’s encephalopathy?

Answer 2

Main cause is CHRONIC ALCOHOL CONSUMPTION which results in thiamine deficiency by causing:

• Inadequate nutritional thiamine intake
• Decreased thiamine absorption
• Impaired thiamine utilisation by cells

Other conditions that cause thiamine deficiency:

• Chronic subdural haematoma
• AIDS
• Hyperemesis gravidarum
• Thyrotoxicosis

Thiamine deficiency results in abnormal cellular function in the cerebral cortex, hypothalamus and cerebellum

Question 3

What is the epidemiology of Wenicke’s encephalopathy?

Answer 3

Alcohol-related brain damage accounts for 10-24% of all dementia

Prevalence rates are higher in areas of socio-economic deprivation

Higher prevalence in 50-60 year olds

Question 4

What are the presenting symptoms of Wernicke’s encephalopathy?

Answer 4

• Vision changes: diplopia, eye movement abnormalities, ptosis
• Loss of muscle coordination: unsteady gait
• Loss of memory
• Inability to form new memories
• Hallucinations

Question 5

What is the triad of signs present in Wernicke’s encephalopathy?

Answer 5

Confusion

Opthalmoplegia (+ Nystagmus)

Ataxia

Question 6

What signs are present in Wernicke’s encephalopathy upon physical examination?

Answer 6

The patient is usually mentally alert with vocabulary, comprehension, motor skills, social habits and naming ability maintained

Some show signs suggestive of polyneuropathy

Reflexes may be decreased

Abnormal gait and coordination

Eye abnormalities on movement: nystagmus, bilateral lateral rectus palsy, conjugate gaze palsy

Low temperature

Rapid pulse

Some may be cachectic

Question 7

What is Korsakoff’s Psychosis?

Answer 7

Korsakoff’s Psychosis occurs when the condition deteriorates further, leading to the additional symptoms of:

• Amnesia
• Confabulation (Made up stories fill gaps in memories)

Question 8

What investigations are appropriate when suspecting Wernicke’s encephalopathy?

Answer 8

Diagnosis is mainly based on history and examination

Possible useful tests may include:

• FBC (high MCV is a common feature amongst alcoholics)
• U&Es (exclude metabolic imbalances as a cause of confusion)
• LFTs
• Glucose
• ABG (hypercapnia and hypoxia can cause confusion)
• Serum thiamine
• CT head scan may also be useful