Wernicke's Encepalopathy

Question 1

Define Wernickes encepalopathy

Answer 1

the presence of neurological symptoms

caused by biochemical lesions of the CNS

following exhaustion of vitamin B (particularly thiamine) reserves.

Question 2

Explain the aetiology/risk factors of Wernicke’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

Summarise the epidemiology of Wernicke’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

Recognise the presenting symptoms of Wernicke’s encephalopathy

Answer 4

Vision changes: (opthalmoplegia) diplopia, eye movement abnormalities, ptosis

Loss of muscle coordination: unsteady gait (ataxia)

Loss of memory
Inability to form new memories

Hallucinations

Question 5

Recognise the signs of Wernicke’s encephalopathy on physical examination

Answer 5

Wernicke’s is classically defined by a triad of signs:

Confusion
Ophthalmoplegia
Ataxia

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

Mammillary bodies on CT head these atrophy in korsakoffs

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

Question 6

Identify appropriate investigations for Wernicke’s encephalopathy

Answer 6

Diagnosis is mainly based on history and examination

Possible useful tests:

FBC (high MCV is a common feature amongst alcoholics)

U&Es (exclude metabolic imbalances as a cause of confusion)

LFTs

Glucose (low thiamine = lowglucose hence tiredness)

ABG (hypercapnia and hypoxia can cause confusion)

Serum thiamine

CT head scan may be useful