Makindo Medical Notes.com

Untreated Wernicke's encephalopathy → Korsakoff's syndrome

About

• Seen most commonly in alcoholics and some cancers
• Also suspect in the malnourished even hyperemesis
• Untreated Wernicke's encephalopathy → Korsakoff's syndrome

Aetiology

• Thiamine Pyrophosphate is the prosthetic group of the enzymes
• 1. Pyruvate dehydrogenase (Pyruvate → Acetyl CoA into Krebs cycle)
• 2. Alpha-ketoglutarate dehydrogenase
• 3. Transketolase (Pentose phosphate pathway)
• Common feature is the transfer of an activated aldehyde unit by thiamine pyrophosphate (TPP). The nervous system is particularly sensitive to thiamine deficiencies as it can only get energy from glucose and so entry to the Krebs cycle is crucial. Lead and Arsenic also cause problems with the Pyruvate dehydrogenase complex.

Clinical

• Wernicke's encephalopathy: Diplopia, nystagmus, confusion, cerebellar ataxia, gaze palsies such as difficulty abducting. Internuclear ophthalmoplegia. Often precipitated by stress such as severe infection, surgery, trauma, or a carbohydrate load
• Korsakoff's syndrome: Confusion, confabulation, psychosis with the main issue being poor memory but otherwise cognition reasonable. Memory impaired to new and recent events.
• Generalised sensory polyneuropathy (Dry) and High output cardiac failure: Wet Beri Beri

Investigations

• ↑ GGT if alcoholic
• ↓ red cell transketolase and ↓ thiamine levels
• ↑ pyruvate levels
• MRI: T2 weighted changes in the thalamus (memory loss) and periaqueductal grey matter (causing eye signs)
• Lumbar puncture is normal
• Post mortem shows necrosis and gliosis in the brainstem, thalamus and hypothalamus

Management

• Response to treatment is both diagnostic and therapeutic. The usual route is to give Pabrinex acutely and then oral thiamine after. Alcohol abstention. A glucose load can precipitate Wernicke's so give pabrinex with or before glucose.
• Those with prolonged Korsakoff's syndrome may have poor recovery