Wernicke's encephalopathy

3. Wernicke's encephalopathy
The three components of the classic triad of WE are encephalopathy, ataxic gait, and some variant of oculomotor dysfunction. However, a complicating factor of WE identification is that its presentation may not be associated with the classical clinical triad in up to 90% of patients.

Consideration for WE should be given to patients with any evidence of long-term alcohol abuse or malnutrition and any of the following: acute confusion, ataxia, ophthalmoplegia, memory disturbance, hypothermia with hypotension, and delirium tremens.

A high proportion of patients with acute WE who survive develop WKS, characterized by potentially irreversible retrograde amnesia (inability to recall information) and anterograde amnesia (inability to assimilate new information), with varying degrees of other cognitive deficits.

Consider WE when any patient with long-term malnutrition presents with confusion or altered metal status. Significant overlap exists between WE and Korsakoff psychosis. For this reason, the two entities are often described together as WKS.

Alcohol abuse, AIDS, malignancy, hyperemesis gravidarum, prolonged total parenteral nutrition, iatrogenic glucose loading in any predisposed patient, and other disorders associated with grossly impaired nutritional status are associated with WKS.

Bariatric surgery (there are more than 100,000 weight-loss procedures performed annually in the United States) has been associated with both malnutrition and WE. Post–bariatric surgery patients have a limited capacity for food intake during the initial weeks after a bariatric procedure and a body's reserves of thiamine can be depleted after only 20 days of inadequate supply. Post–bariatric surgery patients may still be frankly obese when presenting with WE symptoms caused by thiamine deficiency.
Presentation
History
The three components of the classic triad of WE are encephalopathy, ataxic gait, and some variant of oculomotor dysfunction. However, a complicating factor of WE identification is that its presentation may not be associated with the classical clinical triad in up to 90% of patients.

Consideration for WE should be given to patients with any evidence of long-term alcohol abuse or malnutrition and any of the following: acute confusion, ataxia, ophthalmoplegia, memory disturbance, hypothermia with hypotension, and delirium tremens.

A high proportion of patients with acute WE who survive develop WKS, characterized by potentially irreversible retrograde amnesia (inability to recall information) and anterograde amnesia (inability to assimilate new information), with varying degrees of other cognitive deficits.[13]

Consider WE when any patient with long-term malnutrition presents with confusion or altered metal status. Significant overlap exists between WE and Korsakoff psychosis. For this reason, the two entities are often described together as WKS.

Alcohol abuse, AIDS, malignancy, hyperemesis gravidarum, prolonged total parenteral nutrition, iatrogenic glucose loading in any predisposed patient, and other disorders associated with grossly impaired nutritional status are associated with WKS.

Bariatric surgery (there are more than 100,000 weight-loss procedures performed annually in the United States) has been associated with both malnutrition and WE.[9] Post–bariatric surgery patients have a limited capacity for food intake during the initial weeks after a bariatric procedure and a body's reserves of thiamine can be depleted after only 20 days of inadequate supply. Post–bariatric surgery patients may still be frankly obese when presenting with WE symptoms caused by thiamine deficiency.[9]

Physical Examination
Ocular abnormalities are the hallmarks of WE. The oculomotor manifestations are: nystagmus, bilateral lateral rectus palsies, and conjugate gaze palsies reflecting cranial nerve involvement of the oculomotor, abducens, and vestibular nuclei. Less frequently noted manifestations are: pupillary abnormalities such as sluggishly reactive pupils, ptosis, scotomata, and anisocoria. The most common ocular abnormality is nystagmus, not abducens (Cranial Nerve VI) ophthalmoplegia.

Encephalopathy is characterized by a global confusional state, disinterest, inattentiveness, or agitation. The most common presenting symptoms of WE are mental status changes. Stupor and coma are rare.

Gait ataxia is often a presenting physical examination manifestation.[8] Ataxia is likely to be a combination of polyneuropathy, cerebellar damage, and vestibular paresis. Vestibular function, usually without hearing loss, is universally impaired in the acute manifestation of WE. In less severe cases, patients walk slowly with a broad-based gait. However, gait and stance may be so impaired as to make walking impossible. Cerebellar testing in bed with finger-to-nose and heel-to-shin tests may not illicit any notable deficit; thus, it is important to test for truncal ataxia with the patient sitting or standing.

In addition to ophthalmoplegia and ataxia, 80% of adults will have some degree of peripheral neuropathy, which may include weakness, foot drop, and decreased proprioception.

Thiamine deficiency has recently been associated with a gastrointestinal syndrome of nausea, vomiting, abdominal pain, and lactic acidosis.

Other symptoms that may occur in addition to, or in place of, the classic triad include hypothermia, hypotension, and coma. Thiamine deficiency often affects the temperature-regulating center in the brainstem, which can result in hypothermia.

Hypotension can be secondary to thiamine deficiency either through cardiovascular beriberi or thiamine deficiency–induced autonomic dysfunction. Coma is rarely the sole manifestation of WE.

Of patients surviving WE, an important percentage will manifest WKS, characterized by the following: retrograde amnesia (inability to recall information), anterograde amnesia (inability to assimilate new information), decreased spontaneity and initiative, and confabulation.

Other manifestations of thiamine deficiency involve the cardiovascular system (wet beriberi) and peripheral nervous system (nutritional polyneuropathy).

Manifestations of thiamine deficiency in infants are constipation, agitation, apathy, vomiting, lack of appetite, and later, diarrhea, grunting, nystagmus, convulsions, unconsciousness, and cardiomyopathy.