Wernicke Encephalopathy

Vitamins are essential nutrients required in tiny amounts by our body for its optimum development. We obtain it from external sources like food as almost all are not synthesized in our body. Although required in small amounts, vitamins serve as critical determinants of overall growth of body and functions. Classified according to the functions that they regulate, absence of these vitamins could lead to severe developmental defects. Some vitamin deficiencies affect brain development that is crucial for healthy body functioning. Any activity that interferes with vitamin absorption and assimilation leads to neurological symptoms.

What is Wernicke encephalopathy?

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Wernicke encephalopathy (WE) is a wide range of neurological conditions related to poor vitamin B1 (thiamine) absorption. Encephalopathy is commonly used to refer malfunction and disease of the brain. The condition was named after the physician who discovered the condition, Dr. Carl Wernicke. Overall, Wernicke encephalopathy is not a common condition. It is often a consequence of chronic alcoholism. Postmortem studies of the alcohol consumers from western countries, report an estimated 12.5 percent with typical WE lesions. In addition, there is evidence of Wernicke encephalopathy in up to 60% of alcohol-related deaths, present WE lesions. However, this does not mean that the condition solely occurs in alcoholics.

Wernicke Encephalopathy Pathophysiology

Brain Lesions

Deficiency of thiamine causes lesions in the brain (WE lesions). While the initial stage of Wernicke encephalopathy presents with vision and attention deficits, memory problems become more apparent in advanced stages. In its later stages, Wernicke encephalopathy incorporates symptoms of Korsakoff syndrome and is then jointly referred as Wernicke-Korsakoff syndrome.

Vitamin B1 in the Body

Thiamine pyrophosphate is the active form of thiamine (vitamin B1), which is required for the optimum activity of enzymes necessary for breaking down carbohydrates. Inhibition of the metabolism-related enzymes overall dampens carbohydrate metabolism. Other affected processes include energy production (ATP synthesis), breakdown of fats and synthesis of amino acids (building blocks of protein) and neurotransmitters (chemical required for brain cell communication). Vitamin B1 obtained from food is absorbed in the blood through the intestine (duodenum) and finally, is transported across blood-brain barrier.

Vitamin B1 and the Brain

Although the body’s store of thiamine is sufficient to sustain the normal level of thiamine for 18 days, beyond that thiamine deficiency leads to eruption of brain lesions. The brain consists of mainly two types of cells – neurons and glia. While neuronal cell relays information from one brain region to another, the glia maintains provides structural support and immunity towards foreign agents. Since there are more glia than neurons, the glia are affected first. Intracellular accumulation of lactate (a carbohydrate breakdown product) reduces pH, causing acidity in localized areas (focal acidosis) of the brain tissue. Death of cells within these acidic spots forms lesions.

Wernicke Encephalopathy Causes

Some of the pre-disposing factors for Wernicke-Korsakoff syndrome are:

Nutritional deficiency

Dietary consumption of vitamin-deprived food. Rice husk is a major source of thiamine, but polishing removes husk from rice grains. Regular consumption of such thiamine-deprived rice could induce Wernicke encephalopathy symptoms.

Excessive alcohol consumption

Large amounts of alcohol damages the internal layer of intestine and impairs vitamin absorption. Alcohol also impairs the conversion of thiamine to thiamine pyrophosphate, the most active form of the vitamin. Alcoholic beverages lack vitamin content but is laden with carbohydrates and therefore, metabolism of alcohol raises need for more vitamin consumption.

Liver problems

Liver damage or dysfunction reduces the nutrient stores and impairs their metabolism. Given the fact that not every alcoholic develop Wernicke encephalopathy, strongly argues for the interplay of genetic constitution and environmental factors for disease development.

Surgery

Surgical procedures that involve removal of a portion of intestine imposes greater risk of developing Wernicke encephalopathy.

Cancer and cancer treatments

Cancer cells compete with the normal cell population for space and nutrition. Therefore, in some cases fast growing cancer cells consume thiamine, causing thiamine deficiency that leads to development of Wernicke encephalopathy. Metabolites of cancer drugs (chemotherapy), like erbulozole or ifosfamide, and not the anti-cancer drug itself may cause vitamin depletion and Wernicke encephalopathy consequently.

Other causes

  • Recurrent vomiting and diarrhoea
  • Vomiting in pregnancy. Even after taking supplements, thiamine deficiency could occur during pregnancy causing hyperemesis gravidarum that may eventually progress into Wernicke encephalopathy.
  • Chronic exposure to chemicals like phenytoin, cephalosporins or tetracyclins
  • Some diseases like AIDS and treatment regimen like dialysis

Wernicke Encephalopathy Symptoms

Wernicke encephalopathy

  • Abnormalities related to vision :
    – double vision (diplopia)
    – involuntary rapid eye movements (nystagmus), also called ‘dancing eyes’
    – retinal bleeding (hemorrhage)
    – paralysis of eye muscles (opthalmoplegia)
  • Confused mental status or indifference towards emotions including passion, excitement and motivation.
  • Non-coordination of limbs and body movements and presentation of a typical dancing motion (ataxic gait).

These three constitute a major triad of symptoms necessary for diagnosing WE. Other symptoms include:

  • Hearing loss
  • Epileptic seizures
  • Increased muscle tone and postural defects.
  • Hallucinations – perception (sight and sound) of unusual visual cues and sound.
  • Coma

Korsakoff Syndrome

In addition, the following symptoms may also be seen in Wernicke-Korsakoff syndrome.

  • Short-term memory deficits – unable to recall any event that occurred in previous half an hour.
  • Confabulations – creating stories of events that never actually happened.
  • The ability to learn new motor skills (like cycling or playing guitar) remains unaffected.

Wernicke Encephalopathy Diagnosis

The level of thiamine along with the presence of any two triad symptoms is usually required for diagnosing Wernicke encephalopathy. Since there are no abnormalities in the cerebrospinal fluid (CSF), brain imaging and EEG, detecting Wernicke encephalopathy heavily relies on clinical diagnosis. Moreover, only about half of Wernicke encephalopathy patients show a typical WE lesions which can be seen on CT (computed tomography) scans and MRI (magnetic resonance imaging). Mostly, Wernicke encephalopathy symptoms are difficult to differentiate from drunken stupor and it is important that clinical assessment occurs when the patient has abstained from alcohol and is sober.

Wernicke Encephalopathy Treatment

Even upon the slightest hint of Wernicke encephalopathy, thiamine should be started either intravenously or intramuscularly. An empirical treatment comprises of 500 mg thiamine hydrochloride, 3 times per day for 3-5 days. Optimum dose varies with individual’s response to administered thiamine, including its uptake and assimilation. Unresponsiveness towards treatment within 2 to 3 days suggests the need for an increase in thiamine doses.

Inappropriate treatment with low doses of thiamine could cause biochemical disturbances leading to irreversible brain damage. Thiamine should be given either before or along with intravenous glucose administration because glucose alone, could aggravate thiamine-deficient symptoms.

Reducing alcohol consumption along with thiamine supplements not only proves to be beneficial but also an important preventive measure for Wernicke encephalopathy. However, many of the clinical features are irreversible by the type alcohol abusers seek medical treatment. Various other treatments are needed to help the patient cope with the disabilities. Alcohol rehabilitation is necessary and recovery is ongoing. Typical patients of Korsakoff syndrome require institutionalization and mental rehabilitation.

 

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