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 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]

Korsakoff's Psychosis and Wernicke's encephalopathy

The syndrome is a combined manifestation of two eponymous disorders, Korsakoff's Psychosis and Wernicke's encephalopathy, named after Drs. Sergei Korsakoff and Carl Wernicke.

Wernicke's encephalopathy is characterized by:

1. confusion
2. nystagmus
3. ophthalmoplegia
4. anisocoria
5. ataxia
6. sluggish pupillary reflexes
7. coma and death if untreated

Korsakoff's psychosis is characterized by

1. anterograde and retrograde amnesia.
2. confabulation.
3. hallucinations ^[2]

Causes

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 TCA Cycle, and catalyse 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 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 or intensive care unit (ICU) stays. 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 especially is associated with atrophy 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]

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. 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.

Treatment

Treatment consists of reversing the thiamine deficiency by giving supplemental thiamine, usually by starting 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 unlikely.^{[citation needed]}

References

1. ^ MedlinePlus Medical Encyclopedia: Wernicke-Korsakoff syndrome
2. ^ ^{a b} MedlinePlus - Wernicke-Korsakoff syndrome
3. ^ 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. 
4. ^ 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. 
5. ^ Watson AJ, Walker JF, Tomkin GH, Finn MM, Keogh JA (1981). Acute Wernickes encephalopathy precipitated by glucose loading. Ir J Med Sci 150:301–303 PubMed
6. ^ 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. 
7. ^ 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.