Wernicke/Korsakoff Flashcards
What is thiamine? Where is it found? How is it metabolised?
Thiamine is vitamin B1 (water-soluble)
Found in diet in yeast, liver, pork, beef, whole grains, legumes, fortified cereals.
Absorbed in the GIT but barely stored.
What is the function of thiamine?
Converted to active form of thiamine pyrophosphate and used to metabolise carbs and AAs by functioning as a coenzyme
How does thiamine deficiency affect the CNS?
CNS uses carbs for energy and all the processes for this (ATP production, myelin production, NT synthesis, axonal conduction and synaptic transmission) need thiamine.
In deficiency: glucose utilisation decreased and ketones increased. Neurons apoptose, focal acidosis in susceptible areas and oxidative stress occurs.
What are the myelin/nerve effects of thiamine deficiency?
Myelin degeneration in PNS and CNS
Polyneuritis with radiating pain along peripheral nerves
Paralysis can occur with fibre tracts severely deteriorating (even without this we get muscle atrophy)
What is Wernicke’s encephalopathy?
Acute and reversible medial emergency that may cause permanent issues. Commonly associated with heavy alcohol use and/or malnutrition.
What is the classic WE triad?
- Ophthalmoplegia (nystagmus and palsies, abnormal caloric test)
- Ataxia (usually truncal, wide-based gait, lower > upper limbs)
- Mental status change (confabulation, anterograde amnesia, delirium 20%)
Incidence of WE, M:F
1-2% in adult autopsies
95% males
Caine’s criteria for WE
2 of the following 4:
- Dietary deficiency
- Oculomotor abnormalities
- Cerebellar dysfunction
- Altered mental state or mild memory impairment.
Is imaging useful in WE?
CT can show areas of reduced density sometimes, MRI shows lesions in thalami and mammillary bodies usually
Acute neuropathology of Wernicke-Korsakoff
Astrocyte swelling
Vascular dilation
Endothelial swelling
Early demyelination
Chronic neuropathology of Wernicke-Korsakoff
Incomplete neuron loss Axon damage Demyelination Loosening or vaculoisation of neuropil Punctuate haemorrhages (cause petechiae)
What is Korsakoff syndrome?
A late manifestation of WE that causes amnesia (long-term usually ok), apathy etc. Little chance of recovery.
What is alcoholic cerebellar degeneration?
Usually with >10yrs of alcohol dependence, with or without WE. Purkinje neurons in the anterior and superior vermis of the cerebellum are lost so we see a slow onset of ataxia in the lower limbs.
What is Beriberi? Including wet/dry distinction
A thiamine deficiency polyneuropathy in normal adults who have bad restrictive diets and used to occur with large rice consumption as we polished it (so no thiamine).
Dry: neuropathic symptoms
Wet: cardiac manifestations predominate
What is alcoholic neuropathy? (cause, presentation, diagnosis)
Most common peripheral neuropathy seen in general practice and common in chronic alcoholism. Deficiency in thiamine and other B vitamins causes cramps, gait difficulty, distal wasting, loss of tendon reflexes, often stocking/glove sensory loss, legs always > arms, sometimes autonomic dysfunction.
Insidious and progressive.
Diagnose with electrodiagnostic studies and EMG showing denervation. Sural nerve biopsy shows loss of nerve fibres and axonal degeneration (regeneration if chronic)
