Wernicke-Korsakoff syndrome
Encyclopedia
Wernicke–Korsakoff syndrome (also called wet brain, Korsakoff's psychosis, alcoholic encephalopathy, Wernicke's disease, and encephalopathy - alcoholic) is a manifestation of thiamine
Thiamine
Thiamine or thiamin or vitamin B1 , named as the "thio-vitamine" is a water-soluble vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B1. Its phosphate derivatives are...

 (vitamin B1) deficiency, or beriberi
Beriberi
Beriberi is a nervous system ailment caused by a thiamine deficiency in the diet. Thiamine is involved in the breakdown of energy molecules such as glucose and is also found on the membranes of neurons...

. This is usually secondary to alcohol abuse
Alcohol abuse
Alcohol abuse, as described in the DSM-IV, is a psychiatric diagnosis describing the recurring use of alcoholic beverages despite negative consequences. Alcohol abuse eventually progresses to alcoholism, a condition in which an individual becomes dependent on alcoholic beverages in order to avoid...

. It mainly causes vision changes, ataxia
Ataxia
Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...

 and impaired memory.

Korsakoff's syndrome and Wernicke's encephalopathy

The syndrome is a combined manifestation of two eponymous disorders, Korsakoff's syndrome
Korsakoff's syndrome
Korsakoff's syndrome is a neurological disorder caused by the lack of thiamine in the brain. Its onset is linked to chronic alcohol abuse and/or severe malnutrition...

 and Wernicke's encephalopathy
Wernicke's encephalopathy
Wernicke encephalopathy is a syndrome characterised by ataxia, ophthalmoplegia, confusion, and impairment of short-term memory.It is caused by lesions in the medial thalamic nuclei, mammillary bodies, periaqueductal and periventricular brainstem nuclei, and superior cerebellar vermis, often...

, named after Sergei Korsakoff
Sergei Korsakoff
Sergei Sergeievich Korsakoff was a Russian neuropsychiatrist.Sergei Korsakoff was the first of great Russian neuropsychiatrists. He studied medicine at the University of Moscow, graduated in 1875 and subsequently became physician to "Preobrazhenski" mental hospital. From 1876 to 1879 he gained...

 and Carl Wernicke.

Wernicke's encephalopathy
Wernicke's encephalopathy
Wernicke encephalopathy is a syndrome characterised by ataxia, ophthalmoplegia, confusion, and impairment of short-term memory.It is caused by lesions in the medial thalamic nuclei, mammillary bodies, periaqueductal and periventricular brainstem nuclei, and superior cerebellar vermis, often...

 is characterized by:
  1. confusion
  2. nystagmus (involuntary eye movement)
  3. ophthalmoplegia (impaired eye movement)
  4. anisocoria
    Anisocoria
    -Causes:In the absence of the iris or eyeball proper, anisocoria is usually the result of a defect in efferent nervous pathways controlling the pupil traveling in the oculomotor nerve or the sympathetic pathways...

     (unequal size of pupils)
  5. ataxia
    Ataxia
    Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...

     (lack of muscle coordination)
  6. sluggish pupillary reflexes
  7. coma
    Coma
    In medicine, a coma is a state of unconsciousness, lasting more than 6 hours in which a person cannot be awakened, fails to respond normally to painful stimuli, light or sound, lacks a normal sleep-wake cycle and does not initiate voluntary actions. A person in a state of coma is described as...

     and death
    Death
    Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

     if untreated


Korsakoff's psychosis
Korsakoff's syndrome
Korsakoff's syndrome is a neurological disorder caused by the lack of thiamine in the brain. Its onset is linked to chronic alcohol abuse and/or severe malnutrition...

 is characterized by:
  1. anterograde amnesia
    Anterograde amnesia
    Anterograde amnesia is a loss of the ability to create new memories after the event that caused the amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact. This is in contrast to retrograde amnesia, where memories...

     (inability to form new memories)
  2. retrograde amnesia
    Retrograde amnesia
    Retrograde amnesia is a loss of access to events that occurred, or information that was learned, before an injury or the onset of a disease....

     (loss of existing memories)
  3. confabulation
    Confabulation
    Confabulation is the process in which a memory is remembered falsely. Confabulations are indicative of a complicated and intricate process that can be led astray at any given point during encoding, storage, or recall of a memory. Two distinct types of confabulation are often distinguished...

     (false perceptions or memories)
  4. hallucination
    Hallucination
    A hallucination, in the broadest sense of the word, is a perception in the absence of a stimulus. In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid,...

    s

Causes

Wernicke-Korsakoff syndrome results from thiamine deficiency. It is generally agreed that Wernicke's encephalopathy results from severe acute deficiency of thiamine
Thiamine
Thiamine or thiamin or vitamin B1 , named as the "thio-vitamine" is a water-soluble vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B1. Its phosphate derivatives are...

 (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
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....

 or coenzyme in glucose metabolism. The enzymes which are dependent on thiamine diphosphate are associated with the citric acid cycle
Citric acid cycle
The citric acid cycle — also known as the tricarboxylic acid cycle , the Krebs cycle, or the Szent-Györgyi-Krebs cycle — is a series of chemical reactions which is used by all aerobic living organisms to generate energy through the oxidization of acetate derived from carbohydrates, fats and...

 (also known as the Kreb's cycle), and catalyze the oxidation of pyruvate
Pyruvate dehydrogenase
Pyruvate dehydrogenase complex is a complex of three enzymes that transform pyruvate into acetyl-CoA by a process called pyruvate decarboxylation. Acetyl-CoA may then be used in the citric acid cycle to carry out cellular respiration, and this complex links the glycolysis metabolic pathway to the...

, alphaketoglutarate and branched chain amino acids. Thus, anything that encourages glucose metabolism will exacerbate an existing clinical or sub-clinical
Sub-clinical
Sub-clinical is a medical term referring to a disease process that has initiated but has not yet manifested symptoms.One example is sub-clinical hypothyroidism, where a patient will manifest none of the typical symptoms of hypothyroidism, and blood tests will show a normal T3 and T4, but an...

 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
Intensive Care Unit
thumb|220px|ICU roomAn intensive-care unit , critical-care unit , intensive-therapy unit/intensive-treatment unit is a specialized department in a hospital that provides intensive-care medicine...

 (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
White rice
White rice is the name given to milled rice that has had its husk, bran, and germ removed. This alters the flavour, texture and appearance of the rice and helps prevent spoilage and extend its storage life. After milling, the rice is polished, resulting in a seed with a bright, white, shiny...

, which is thiamine-deficient. The resulting nervous system ailment is called beriberi
Beriberi
Beriberi is a nervous system ailment caused by a thiamine deficiency in the diet. Thiamine is involved in the breakdown of energy molecules such as glucose and is also found on the membranes of neurons...

. 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.

Wernicke-Korsakoff syndrome in alcoholics particularly is associated with atrophy
Atrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...

 of specific regions of the brain, especially the mamillary bodies. Other regions include the anterior region of the thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...

 (accounting for amnesic symptoms), the medial dorsal thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...

, the basal forebrain
Basal forebrain
The basal forebrain is a collection of structures located ventrally to the striatum. It is considered to be the major cholinergic output of the central nervous system . It includes a group of structures that lie near the bottom of the front of the brain, including the nucleus basalis, diagonal band...

, and median and dorsal raphe nuclei
Raphe nuclei
The raphe nuclei are a moderate-size cluster of nuclei found in the brain stem. Their main function is to release serotonin to the rest of the brain...

.

One as-yet-unreplicated study has associated susceptibility to this syndrome with a hereditary deficiency of transketolase
Transketolase
Transketolase, an enzyme of both the pentose phosphate pathway in animals and the Calvin cycle of photosynthesis, catalyzes two important reactions, which operate in opposite directions in these two pathways...

, an enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 that requires thiamine as a coenzyme.

Diagnosis and findings

Diagnosis of Wernicke-Korsakoff syndrome is by clinical impression and can sometimes be confirmed with formal neuropsychological assessment. Wernicke's encephalopathy
Encephalopathy
Encephalopathy means disorder or disease of the brain. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of global brain dysfunction; this syndrome can be caused by many different illnesses.-Terminology:...

 typically presents with ataxia
Ataxia
Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...

 and nystagmus, and Korsakoff's psychosis with anterograde and retrograde amnesia
Amnesia
Amnesia is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Memory appears to be stored in several parts of the limbic system of the brain, and any condition that interferes with the function of this system can cause 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
Papez circuit
Described by James Papez in 1937, the Papez circuit of the brain is one of the major pathways of the limbic system and is chiefly involved in the cortical control of emotion. The Papez circuit plays a role in storing memory....

.

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
Amnesia
Amnesia is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Memory appears to be stored in several parts of the limbic system of the brain, and any condition that interferes with the function of this system can cause amnesia...

 and psychosis
Psychosis
Psychosis means abnormal condition of the mind, and is a generic psychiatric term for a mental state often described as involving a "loss of contact with reality"...

have occurred, complete recovery is extremely unlikely.
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