Wernicke's Encephalopathy

Question 1

Definition

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

Aetiology

Answer 2

• Main cause is CHRONIC ALCOHOL CONSUMPTION which results in thiamine deficiency by causing:
o Inadequate nutritional thiamine intake
o Decreased thiamine absorption
o Impaired thiamine utilisation by cells

• Other conditions that cause thiamine deficiency:
o Chronic subdural haematoma
o AIDS
o Hyperemesis gravidarum
o Thyrotoxicosis

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

Question 3

Epidemiology

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

Presenting symptoms

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

Signs on physical examination (triad)

Answer 5

Wernicke’s is classically defined by a triad of signs:
o Confusion
o Ophthalmoplegia
o Ataxia

Question 6

Signs on 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

Signs on physical examination (korsakoff’s psychosis)

Answer 7

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

Question 8

Investigations

Answer 8

• Diagnosis is mainly based on history and examination

• Possible useful tests:
o FBC (high MCV is a common feature amongst alcoholics)
o U&Es (exclude metabolic imbalances as a cause of confusion)
o LFTs
o Glucose
o ABG (hypercapnia and hypoxia can cause confusion)
o Serum thiamine

• CT head scan may be useful