Korsakoff's syndrome
Classification and external resources
Thiamine
ICD-10	F10.6
ICD-9	291.1, 294.0
DiseasesDB	14107
eMedicine	med/2405
MeSH	D020915

Korsakoff's syndrome (Korsakoff's psychosis, amnesic-confabulatory syndrome; also spelled "Korsakov's Syndrome"), is a brain disorder caused by the lack of thiamine (vitamin B₁) in the brain. The syndrome is named after Sergei Korsakoff, the neuropsychiatrist who popularized the theory.

[edit] Symptoms

There are six major symptoms of Korsakoff's syndrome:

1. anterograde amnesia and
2. retrograde amnesia, severe memory loss
3. confabulation, that is, invented memories which are then taken as true due to gaps in memory sometimes associated with blackouts
4. meager content in conversation
5. lack of insight
6. apathy - the patients lose interest in things quickly and generally appear indifferent to change.

These symptoms are caused by a deficiency of thiamine (vitamin B₁), which is thought to cause damage to the medial thalamus and possibly to the mammillary bodies of the hypothalamus as well as generalized cerebral atrophy.^[1]

When Wernicke's encephalopathy accompanies Korsakoff's syndrome, the combination is called the Wernicke-Korsakoff syndrome. Korsakoff's is a continuum of Wernicke's encephalopathy, though a recognised episode of Wernicke's is not always obvious.

Korsakoff's involves neuronal loss, that is, damage to neurons; gliosis which is a result of damage to supporting cells of the central nervous system; and hemorrhage or bleeding in mammillary bodies. Damage to the dorsomedial nucleus or anterior group of the thalamus (limbic-specific nuclei) is also associated with this disorder.

[edit] Signs

• Apathy
• Ataxia
• Coma
• Confabulation
• Paralysis of muscles controlling the eye
• Retrograde and anterograde amnesia
• Tremor
• Lack of insight to the condition

[edit] Treatment

It was once assumed that anyone suffering from Korsakoff's syndrome would eventually need full time care. This is still often the case, but rehabilitation can help regaining some, often limited, level of independence.^[2] Treatment involves the replacement or supplementation of thiamine by intravenous (IV) or intramuscular (IM) injection, together with proper nutrition and hydration. However, the amnesia and brain damage caused by the disease does not always respond to thiamine replacement therapy. In some cases, drug therapy is recommended. If treatment is successful, improvement will become apparent within two years although recovery is slow and often incomplete.

[edit] Causes

Conditions resulting in the vitamin deficiency and its effects include chronic alcoholism, and severe malnutrition. Alcoholism is often an indicator of poor nutrition, which in addition to inflammation of the stomach lining, causes thiamine deficiency.^[3] Other causes include dietary deficiencies, prolonged vomiting, eating disorders, or the effects of chemotherapy. It can also occur in pregnant women who have a form of extreme morning sickness known as hyperemesis gravidarum.^[4] Mercury poisoning can also lead to Korsakoff's syndrome.^{[citation needed]} It has also been caused by centipede (mukade) bites in Japan.^[5]

There is no specific treatment because the previous thiamine deficiency produces irreversible damage to the medial thalamic nuclei and mammillary bodies. Mammillary body atrophy may be visible on high-resolution MRI.^[6]

[edit] Prevention

The most effective method of preventing Korsakoff's syndrome is to avoid B vitamin/thiamine deficiency. In Western nations the most common causes of such deficiency is alcoholism and weight disorders. Thiamine was introduced to alcoholic beverages in the U.S. for a time,^{[citation needed]} but this does not appear to have an effect on Korsakoff's syndrome, as the cause of Korsakoff's syndrome in chronic alcoholics is not a deficiency of thiamine in the diet, but rather a reduction in the body's ability to absorb thiamine in the intestine.^[4] In the U.S., government mandates to adding thiamine to alcoholic beverages have been blocked for this reason and also by political groups asserting that such supplementation would encourage alcohol use.^{[citation needed]}

Also, alcohol is, by itself, neurotoxic. It will cause neural damage taken in excess, especially in the hippocampus. The body responds to alcohol ingestion by releasing cortisol as a neuroprotective mechanism (animals that have been adrenalectomized [i.e. had their adrenal gland removed] may be killed by a fraction of the dose of alcohol that an unadrenalectomized animal may tolerate). Cortisol, specifically, has been shown to cause irreversible damage to the hippocampus when present in large amounts for extended periods of time.^[7] Alcohol in excess may be causal in and of itself in Korsakoff dementia regardless of thiamine addition to spirits. Alcohol toxicity is cumulative; cessation of its use, or never having used it, will reduce risk of korsakoff and other dementias.^{[citation needed]}

[edit] Case studies

A famous case study is recounted by Oliver Sacks in "The Lost Mariner" and "A Matter of Identity", which can be found in The Man Who Mistook His Wife for a Hat. Other cases include German entertainer Harald Juhnke, artist Charles Blackman,^[8] and entertainer Graham Kennedy.^[9]

[edit] In popular culture

• Strangers is a play by Edward Einhorn based on the syndrome.
• In the Half-Life 2 mod Korsakovia, by thechineseroom, the player character Christopher is under treatment for Korsakoff's Syndrome.
• In the television show House, season 1 episode "Histories," Dr. House diagnoses a patient with Korsakoff's syndrome after she gives different explanations for a sprained wrist to different interns who independently take her history.

[edit] References

[edit] External links

• The Merck Manual: Function And Dysfunction Of The Cerebral Lobes - Amnesias - Korsakoff's syndrome
• Simple description of Korsakoff's syndrome
• An Amnesic Patient With An Extraordinary Distorted Memory