Wernicke's Encephalopathy Flashcards
What is it caused by?
Thiamine deficiency - most commonly seen in alcoholics
What are some rarer causes of wernicke’s encephalopathy?
Persistent vomiting leading to malabsorption Hyperemesis gravidarum Severe diarrhoea Stomach cancer Bariatric surgery Dietary deficiency of thiamine Chemotherapy Brain tumour
What vitamin is thiamine?
Vitamin B1
What classic triad may occur?
Opthalmoplegia /nystagmus
Ataxia - wide based gait
Confusion and agitation (mental state changes) - almost always observed if the patient is not comatose
Other than the classic triad, what other features can occur?
Peripheral sensory neuropathy Memory disturbance Hypotension Tachycardia Hypothermia Ptosis
Where do petichial haemorrhages occur?
Variety of structures in the brain including mammillary bodies and ventricle walls
How is it managed?
Give high does IV/IM thiamine (pabrinex) over 1 weeks then oral supplementation until no longer at risk
Also consider if there are other vitamin deficiencies
If there is coexisting hypoglycaemia, what should you do?
Ensure thiamine given before glucose to prevent Wernicke’s being precipitated by glucose administration
What is B1 essential for?
Glial cells of the nervous system as well as other bodily systems
Thiamine is essential in the metabolism of carbohydrates and lipids, due to its role in the Krebs cycle as a coenzyme. Neural cells rely on glucose metabolism - a deficiency in thiamine and the resultant slowing down of glucose metabolism causes oxidative stress and mitochondrial dysfunction.
Localised areas of low PH due to lactic acidosis further damages neural tissue.
Thiamine deficiency also associated with deranged glutamate transport - results in neural excitotoxicity
If left untreated what can occur?
Death in 20%
Or Korsakoff’s syndrome
What is Korsakoff’s syndrome?
Hypothalamic damage and cerebral atrophy due to thiamine deficiency Antero and retrograde amnesia Confabulation Lack of insight Apathy (In addition to symptoms of Wernicke’s)
Is Korsakoff’s reversible?
1/4 are reversible, but 1/4 will remain in long term institutional care
Even if successful, recovery is slow and incomplete
What is confabulation?
Invented memory to fill in gaps
What is retrograde and anterograde amnesia?
Retrograde = inability to recall past memories Anterograde = inability to create new memories
What differentials are there?
Delirium tremens
- similar population to WE, associated with rapid confusion, tachycardia and shaking (may be confused with ataxia)
- DT associated with hyperthermia rather than hypothermia
- history of significant alcohol reduction in past 5 days
Hepatic encephalopathy
Stroke
Normal pressure hydrocephalus (more gradual onset and typical MRI and CT findings)
Why is precise discrimination between delirium tremens and WE not always required?
High dose parenteral thiamine given to both
What is prognosis dependent on?
The rapidity of giving thiamine
The neurotoxic effects of thiamine deficiency occur in areas of the brain that…
Require highest turnover of glucose
- mamilliary body and areas of brainstem associated with CNs III,IV,VI,VIII, X
Why does alcohol abuse cause WE?
- The high carbohydrate load leads to high thiamine requirement
- Alcohol abuse often associated with a poor, restricted diet, so insufficient thiamine received
Can short term alcohol abuse lead to WE?
Yes - thiamine reserves usually sufficient only for 2 -3 weeks
What colour is Pabrinex and what vitamins does it contain?
A yellow coloured fluid
Contains vitamins B and C
On examination, what tests are usually positive for ataxia?
Romberg’s
Tandem gait
Heel shin
