Wernicke's encephalopathy

Question 1

Define Wernicke’s encephalopathy.

Answer 1

A neurological emergency resulting from thiamine deficiency (vit B1) with varied neurocognitive manifestations, typically involving mental status changes and gait and oculomotor dysfunction.

Question 2

What is the triad of Wernicke’s encephalopathy?

Answer 2

Classical triad (affects 10%):

1. mental status changes/confusion
2. ophthalmoplegia
3. ataxia

Question 3

How common is Wernicke’s encephalopathy?

Answer 3

• Under-diagnosed
• Prevalence highest in alcohol dependence (12.5%), AIDS (10%) and bone marrow transplantation (6%)
• M:F 1.7:1

Question 4

What is the cause of Wernicke’s encephalopathy?

Answer 4

Acute/sub-acute deficiency of thiamine in a susceptible person

• Decreased intake - e.g. poor diet in alcoholism
• Relative deficiency due to increased demand
• Malabsorption from the GI tract - alcohol reduces absorption and storage

Thiamine is a precursor for the Kreb’s cycle and is usually stored in the liver but stores last only 18days.

Deficiency causes neuronal death especially in the medial dorsal thalamic nucleus, mammillary bodies, periaqueductal grey matter and floor of 4th ventricle. If it affects memory circuits then Korsakoff’s results.

Question 5

What are the risk factors for Wernicke’s encephalopathy?

Answer 5

• Alcohol dependence
• Conditions predisposing to malnutrition e.g. AIDS, cancer, prolonged vomiting/ diarrhoea
• Hx of GI surgery
• Genetics - variants in enzymes and transporters involved in thiamine and alcohol metabolism
• BM transplantation
• Infants fed with formula milk deficient in thiamine
• Male

Question 6

Is thiamine fat soluble?

Answer 6

1. 18days worth of thiamine is stored in the liver
2. Thiamine is a water soluble vitamin
3. Korsakoff’s psychosis - memory circuits are affected

Question 7

What are the signs and symptoms of Wernicke’s encephalopathy?

Answer 7

Classical triad (affects 10%): mental status changes, ophthalmoplegia, gait dysfunction

• Nystagmus > ophthalmoplegia
• Gaze palsies - affect a third; CN6 palsies, impaired VOR, miosis
• Irritability, mental slowing, impaired concentration - present in ~80%
• Confusion, delirium, coma, death
• Acute psychosis

Alcohol dependants with WE are more likely to present with cerebellar signs, and less likely to present with ocular signs.

• Seizures
• Hypo/hyperthermia
• Spastic paraparesis
• Tachycardia/hypotension

Question 8

What investigations would you do for Wernicke’s encephalopathy?

Answer 8

Examination: mental, cranial nerve, vestibular and gait function, strength, reflexes, fundoscopy

• 1st line: Therapeutic trial of thiamine (Pabrinex B1)- parenteral, may imporve clinical symptoms
• ECG - can assess effects of treatment
• Glucose
• FBC
• Serum electrolytes - abnormal if not treated or in late-presenting disease (hypotension may cause renal dysfunction)
• Renal function
• LFTs - elevated in chronic alcohol use
• Serum thiamine - low but no ranges for when you should treat are available
• Serum magnesium - may be low
• Blood alcohol level
• Serum ammonia
• Drug screen

Other:

• LP if suspicion of encephalitis/meningitis
• CT/MRI - not reliable in ruling out the diagnosis

Question 9

What are the functions of thiamine in the body?

Answer 9

1. Metabolism of carbohydrates, releasing energy.
2. Production of neurotransmitters including glutamic acid and GABA.
3. Lipid metabolism, necessary for myelin production.
4. Amino acid modification. Probably linked to the production of taurine, of great cardiac importance.

Question 10

What are the differences between Wernicke’s and Korsakoff’s?

Answer 10

Wernicke’s

• Acute
• Confusion
• Cerebellar and eye signs
• Reversible

Korsakoff’s

• Chronic
• Alert
• Amnesia and confabulation (confabulation - making up things to fill gaps in memory; cerebellar signs may remain)
• ?Irreversible

20% roughly will make full recovery following long term treatment with thiamine, but for most Korsakoff’s is irreversible

Question 11

You are called to see a 40 year old man in A&E. You try to take a history but the man in confused and unable to tell you much. On examination he has numerous spider naevi on his chest, an ataxic gait and nystagmus. What is the most likely diagnosis?

• A.Multiple Sclerosis
• B.Motor Neuron Disease
• C.Korsakoff’s syndrome
• D.Wernicke’s Encephalopathy
• E.Head trauma

Answer 11

D

• Patient has classic triad COAT: confusion, ophthalmoplegia, ataxia=thiamine deficiency = Wernicke’s encephalopathy. The spider naevi suggest patient may be alcoholic, which is likely a causative factor.
• If untreated this could progress to Korsakoff’s, which is not the answer as they would not be confused and would be chronic, not acute
• Head trauma can give ataxic gait and confusion, less likely to give eye signs. But probably second most likely on the list
• MND and MS would rarely give confusion.

Question 12

What is the management of Wernicke’s encephalopathy?

Answer 12

Acute presentation to hospital

• ABCDE
• +/- Airway protection
• Thiamine IV 250-500mg/8hrs - until adequate serum levels are achieved
• • Magnesium sulfate 2-4g/day IV - often also low in thiamine deficiency
• • Multivitamin/Folic acid

Chronic risk of thiamine deficiency

• Thiamine 100-200mg OD PO or 100mg IM OD
• • Multivitamin

Question 13

What are the complications of Wernicke’s encephalopathy?

Answer 13

If untreated:

• Ataxia and ophthalmoparesis
• Korsakoff’s psychosis
• Hearing loss
• Seizures
• Spastic paraparesis

Question 14

What is the prognosis with Wernicke’s encephalopathy?

Answer 14

Permanent brain injury if left untreated