Wernicke's Encephalopathy + Korsakoff syndrome

Question 1

Wernicke’s encephalopathy

Answer 1

Reversible, acute neurological emergency that arises due to severe deficiency of thiamine (Vit B1

Question 2

Korsakoff’s syndrome

Answer 2

Chronic and irreversible neurological damage

Question 3

Risk factors

Answer 3

Alcohol dependence
Previous GI surgery
AIDS
Cancer
Prolonged vomiting or diarrhoea
Poor oral intake

Question 4

Pathophysiology

Answer 4

Thiamine is a co-factor required for glucose metabolism (Kreb’s cycle and pentose phosphate pathway). In chronic alcohol abuse, levels are reduced due to poor nutrition, absorption and hepatic storage of thiamine
Thiamine deficiency leads to impaired glucose metabolism resulting in depleted ATP and subsequent cardiac dysfunction, failure of neurotransmission and neuronal death. Given these widespread effects, thiamine deficiency is broadly divided into:
- wet beriberi: cardiac manifestations e.g. dilated cardiomyopathy + cardiac failure
- dry beriberi: sensorimotor peripheral neuropathy
Wernicke’s encephalopathy is an extreme example of dry beriberi. It is associated with neuronal death in the mammillary bodies and thalamus.

Question 5

Wernickes encephalopathy TRIAD

Answer 5

Confusion
Ataxia: inability to coordinate voluntary movement
Ophthalmoplegia and nystagmus

Question 6

Other symptoms

Answer 6

Slow pupillary response
Anisocoria
Ptosis
Autonomic dysfunction e.g. hypotension, tachycardia

Question 7

Primary investigations

Answer 7

Evidence of long term alcohol abuse: macrocytic anaemia, deranged LFTs and clotting
MRI = low sensitivity but show mamillary bodies, thalamus, and third and fourth ventricles

Question 8

Treatment

Answer 8

FIRST LINE = Parenteral thiamine
IV magnesium = chronic alcohol abuse often leads to magnesium def, which in turn impairs the therapeutic effect of thiamine

Question 9

Complications

Answer 9

Korsakoff’s syndrome: a neuropsychiatric disorder caused by severe thiamine deficiency and characterised by disproportionate memory loss in relation to other cognitive features. In rare cases, individuals may fill the gaps in their memory with made-up events (confabulation). It is estimated that 80-90% of patients with Wernicke’s encephalopathy will develop Korsakoff’s syndrome