Wernicke's encephalopathy Flashcards
what is the general presentation of Wernicke’s encephalopathy?
Acute presentation of confusion, opthalmoplegia (e.g. nystagmus), and ataxia –> korsakoff: alert (no longer confused), cerebellar signs remain but now have amnesia and confabulation
what are the differences between hepatic ecephalopathy and wernicke’s encephalopathy?
hepatic encephalopathy is due to liver disease and/ or shunting of blood around liver-> results in altered metabolism of nitrogenous substances
wernicke’s encephalopathy is due to thiamine deficiency
Define Wernicke’s encephalopathy?
presence of neurological symptoms caused by biochemical lesions of the central nervous system following exhaustion of vitamin B (particularly thiamine/B1) reserves
what is the main cause of Wernicke’s encephalopathy?
CHRONIC ALCOHOL CONSUMPTION-> results in THIAMINE DEFICIENCY by causing
- inadequate nutritional thiamine intake
- low content of vitamins in alcohol
- low storage capacity in liver
- decreased intestinal absorption
- impaired conversion of thiamine to its active form ( thiamine pyrophosphate)
- increased demand to metabolise carbohydrates in alcohol
what are the other causes of thiamine deficiency?
malnutrition + eating disorders
history of GI surgery
prolonged vomiting eg with chemotherapy
GI malignancy
chronic subdural haematoma
AIDS
Hyperemesis gravidarum
Thyrotoxicosis
what are the effects of thiamine deficiency?
thiamine needed to produce a cofactor in the Krebs cycle -> leads to neuronal death in neuronal populations with high metabolic requirements and high thiamine turnover
-> leads to abnormal cellular function in CEREBRAL CORTEX, HYPOTHALAMUS, CEREBELLUM
Outline the epidemiology of Wernicke’s encephalopathy?
- Alcohol-related brain damage accounts for 10-24% of all dementia
- Prevalence rates are higher in areas of socio-economic deprivation
- Higher prevalence in 50-60 year olds
what are the presenting symptoms of Wernicke’s encephalopathy?
- Vision changes: diplopia, eye movement abnormalities, ptosis
- Loss of muscle coordination: unsteady gait
- Loss of memory
- Mental slowing and impaired concentration
- Inability to form new memories
- Hallucinations
what are the signs of Wernicke’s enephalopathy on physical examination?
- Wernicke’s triad of signs
- patient is usually mentally alert with vocabulary, comprehension, motor skills, social habits and naming ability maintained
- Some show signs suggestive of polyneuropathy
- Reflexes may be decreased
- Abnormal gait and coordination
- Eye abnormalities on movement: nystagmus, bilateral lateral rectus palsy, conjugate gaze palsy
- Low temperature
- Rapid pulse
- Some may be cachectic
- Korsakoff’s psychosis
what is wernicke’s triad of signs?
- Confusion
- Ophthalmoplegia (nystagmus, lateral rectus or conjugate gaze palsies)
- Ataxia (wide based gait)
what is korsakoff’s physchosis?
occurs when condition deteriorates further leading to additional symptoms
- amnesia
- Confabulation- memory error defined as the production of fabricated, distorted, or misinterpreted memories about oneself or the world, without the conscious intention to deceive.
- IRREVERSIBLE?
what are the appopriate investigations for Wernicke’s encepahlopathy?
- FBC (high MCV is a common feature amongst alcoholics; an infection may trigger acute decomp of thiamine deficiency and elevated WBC)
- U&Es (exclude metabolic imbalances as a cause of confusion; magnesium deficiency is also common in people who misuse alcohol)
- LFTs (chronic alcohol use => elevated LFTs)
- Blood alcohol level
- Glucose
- ABG (hypercapnia and hypoxia can cause confusion)
- Serum ammonia - A metabolic encephalopathy due to hyperammonaemia can easily mimic or be confused with Wernicke’s encephalopathy.
- Serum thiamine
- Red cell transketolase activity is decreased – rarely done
- Therapeutic trial of PE thiamine-> see If there is clinical response to treatment
