Wernicke–Korsakoff syndrome
| Wernicke–Korsakoff syndrome | |
|---|---|
| Classification and external resources | |
 Thiamine |
|
| ICD-10 | E51.2, F10.6 |
| ICD-9 | 294.0 |
| OMIM | 277730 |
| MedlinePlus | 000771 |
| eMedicine | med/2405 |
| MeSH | D020915 |
Wernicke–Korsakoff syndrome (also called wet brain, Korsakoff's psychosis, alcoholic encephalopathy, Wernicke's disease, and encephalopathy - alcoholic)[1] is a manifestation of thiamine (vitamin B1) deficiency, or beriberi. This is usually secondary to alcohol abuse. It mainly causes vision changes, ataxia and impaired memory.[2]
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[edit] Korsakoff's syndrome and Wernicke's encephalopathy
The syndrome is a combined manifestation of two eponymous disorders, Korsakoff's syndrome and Wernicke's encephalopathy, named after Sergei Korsakoff and Carl Wernicke.
Wernicke's encephalopathy is characterized by:
- confusion
- nystagmus (involuntary eye movement)
- ophthalmoplegia (impaired eye movement)
- anisocoria (unequal size of pupils)
- ataxia (lack of muscle coordination)
- sluggish pupillary reflexes
- coma and death if untreated
Korsakoff's psychosis is characterized by:
- anterograde amnesia (inability to form new memories)
- retrograde amnesia (loss of existing memories)
- confabulation (false perceptions or memories)
- hallucinations[2]
[edit] Causes
Wernicke-Korsakoff syndrome is usually found in chronic alcoholics. Wernicke-Korsakoff syndrome results from thiamine deficiency. It is generally agreed that Wernicke's encephalopathy results from severe acute deficiency of thiamine (vitamin B1), whilst Korsakoff's psychosis is a chronic neurologic sequela after Wernicke's encephalopathy. The metabolically active form of thiamine is thiamine diphosphate which plays a major role as a cofactor or coenzyme in glucose metabolism. The enzymes which are dependent on thiamine diphosphate are associated with the citric acid cycle (also known as the Kreb's cycle), and catalyze the oxidation of pyruvate, alphaketoglutarate and branched chain amino acids. Thus, anything that encourages glucose metabolism will exacerbate an existing clinical or sub-clinical thiamine deficiency.
As stated above, Wernicke-Korsakoff syndrome in the United States is usually found in malnourished chronic alcoholics, though it is also found in patients who undergo prolonged intravenous (IV) therapy without vitamin B1 supplementation, gastric stapling, intensive care unit (ICU) stays or hunger strikes. In some regions, physicians have observed thiamine deficiency brought about by severe malnutrition, particularly in diets consisting mainly of polished rice, which is thiamine-deficient. The resulting nervous system ailment is called beriberi. In individuals with sub-clinical thiamine deficiency, a large dose of glucose (either as sweet food, etc. or glucose infusion), can precipitate the onset of overt encephalopathy.[3][4][5]
Wernicke-Korsakoff syndrome in alcoholics particularly is associated with atrophy/infarction of specific regions of the brain, especially the mamillary bodies. Other regions include the anterior region of the thalamus (accounting for amnesic symptoms), the medial dorsal thalamus, the basal forebrain, and median and dorsal raphe nuclei.[6]
One as-yet-unreplicated study has associated susceptibility to this syndrome with a hereditary deficiency of transketolase, an enzyme that requires thiamine as a coenzyme.[7]
[edit] Diagnosis and findings
Diagnosis of Wernicke-Korsakoff syndrome is by clinical impression and can sometimes be confirmed with formal neuropsychological assessment. Wernicke's encephalopathy typically presents with ataxia and nystagmus, and Korsakoff's psychosis with anterograde and retrograde amnesia and confabulation upon relevant lines of questioning.
Frequently, for unknown reasons, patients with Korsakoff's psychosis will exhibit marked degeneration of the mamillary bodies. Sufferers may also exhibit a dislike for sunlight and so may wish to stay indoors with the lights off. The mechanism of this degeneration is unknown, but it supports current neurological theory that the mamillary bodies play a role in various "memory circuits" within the brain. An example of a memory circuit is the Papez circuit.
[edit] Treatment
Treatment consists of reversing the thiamine deficiency by giving supplemental thiamine, usually beginning with an initial intravenous or intramuscular dose, followed by supplemental oral doses. Some people think that it is important to start the thiamine treatment before giving any glucose, as the encephalopathy will be worsened by the glucose; however, this is based only on case reports. (Glucose administration promotes decarboxylation of pyruvate, a biochemical reaction which requires thiamine.) By the time amnesia and psychosis have occurred, complete recovery is extremely unlikely.[citation needed]
[edit] References
- ^ MedlinePlus Medical Encyclopedia: Wernicke-Korsakoff syndrome
- ^ a b MedlinePlus - Wernicke-Korsakoff syndrome
- ^ Zimitat C, Nixon P (2000). "Glucose loading precipitates encephalopathy in thiamine-deficient rats". Metabolic Brain Disease 14 (1): 1–10. doi:10.1023/A:1020653312697. PMID 10348310.
- ^ Navarro D, Zwingmann C, Chatauret N, Butterworth RF (March 2008). "Glucose loading precipitates focal lactic acidosis in the vulnerable medial thalamus of thiamine-deficient rats". Metab Brain Dis 23 (1): 115–22. doi:10.1007/s11011-007-9076-z. PMID 18034292.
- ^ Watson, A. J.; Walker, J. F.; Tomkin, G. H.; Finn, M. M.; Keogh, J. A. (1981). "Acute Wernickes encephalopathy precipitated by glucose loading". Irish journal of medical science 150 (10): 301–303. PMID 7319764.
- ^ Mann K, Agartz I, Harper C, Shoaf S et al. (2001). "Neuroimaging in alcoholism: ethanol and brain damage". Alcohol Clin Exp Res 25 (5 Suppl ISBRA): 104S–109S. PMID 11391058.
- ^ Nixon P, Kaczmarek M, Tate J, Kerr R, Price J (1984). "An erythrocyte transketolase isoenzyme pattern associated with the Wernicke-Korsakoff syndrome". Eur J Clin Invest 14 (4): 278–81. doi:10.1111/j.1365-2362.1984.tb01181.x. PMID 6434322.
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