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.
Wernicke's encephalopathy is diagnosed when patients seek medical attention and have the classic trio of signs: mental confusion, eye movement disorders, and ataxia. The diagnosis of Korsakoff syndrome is given when anterograde amnesia is present in an individual with a history of chronic, heavy drinking or malnutrition.
When Korsakoff syndrome follows Wernicke's encephalopathy, the entire Wernicke-Korsakoff syndrome diagnosis is appropriate. The diagnosis is supported by neuroimaging or autopsy findings showing degeneration of the thalamus and mammillary bodies and loss of brain volume in the area surrounding the fourth ventricle - a fluid-filled cavity near the brainstem.
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.
When diagnosis is based on postmortem findings, the estimated prevalence of Wernicke-Korsakoff syndrome is between 1 and 2% of the population. The classic presentation with acute onset of Wernicke's encephalopathy is fairly rare, about 0.05% of all hospital admissions, although this does not account for patients who do not seek medical attention.
Wernicke-Korsakoff syndrome usually follows many years of chronic alcoholism or malnutrition and is seldom seen among people under 20. Most patients are 40 years of age or older. The disorder is apparently more common in alcoholic individuals who are particularly vulnerable to malnutrition such as indigent or homeless people.
