Wernicke's Encephalopathy - Causes, Signs, Symptoms, and Treatment

Introduction

Wernicke’s encephalopathy (WE) is an acute condition. It has a triad of ophthalmoplegia, ataxia, and confusion. Ophthalmoplegia is the weakness of the eye muscles, and ataxia consists of coordination, balance, and speech disorders. WE is different from Korsakoff syndrome. It is because Korsakoff syndrome is a late manifestation of WE. However, both can occur together.

What Is the Etiology of Wernicke's Encephalopathy?

The most frequent trigger of WE is an acute infection. However, various causes and predisposing factors can cause WE.

1. Thiamine Deficiency: Thiamine (vitamin B1) deficiency is implicated in WE. The most important cause of thiamine deficiency is a high-carbohydrate diet. Thiamine is an essential nutrient required by the brain for energy production. Thiamine deficiency affects the active brain regions. The most affected part is the hypothalamus. The hypothalamus regulates temperature, appetite, emotions, and growth.

2. Chronic Alcoholism: Alcohol reduces the absorption of thiamine from the intestine. Further, it diminishes thiamine stores in the liver and affects the enzyme that converts thiamine into an active state. Chronic alcohol consumption does not lead to WE if dietary thiamine intake is optimum. However, it may induce thiamine deficiency through genetic predisposition, thiamine transport problems, and excessive requirements for alcohol metabolism.

3. Malnutrition: Starvation, eating disorders (for example, anorexia), and prolonged vomiting (vomiting during pregnancy) can precipitate WE. In addition, chronic disorders, such as cancer, AIDS, stomach, and kidney disorders may also cause WE.

How Common Is Wernicke's Encephalopathy?

The incidence of WE is higher in developing countries such as India. There is a slight male predominance. But there is no ethnic predisposition.

What Are the Clinical Features of Wernicke's Encephalopathy?

The cardinal features of WE include eye abnormalities, movement disorders, and altered mental status.

1. Eye Abnormalities: The hallmark sign of WE is eye abnormalities. Double vision and rapid involuntary eye movements (nystagmus) are encountered. Cranial nerves such as oculomotor (III), abducens (VI), and vestibular nerve (VIII) are also involved. Oculomotor nerve paralysis leads to ophthalmoplegia. Pupillary weakness, drooping of the eyelids, and unequal pupil size (anisocoria) are less common.

2. Movement Disorders: Gait (walking manner of a person) ataxia is a significant finding in WE patients. WE patients have a slow walk with a broad-based gait. Patients are unable to walk in advanced cases.

3. Encephalopathy: Encephalopathy encompasses confusion, disorientation, lethargy, inattentiveness, drowsiness, and indifference. WE affect many nerves. Hence, it causes arms and legs weakness. The sense of self-movement, force, and body position (proprioception) is also decreased. Later, there is hyperthermia (increased body temperature) and hypotension (low blood pressure). Seizures and progressive hearing loss follow. Advanced stages of the acute phase lead to coma and death.

How Is Wernicke's Encephalopathy Diagnosed?

The WE diagnosis involves a thorough patient history and a dedicated physical examination. A person’s nutrition and daily drinking habits identify long-term alcohol abuse. The clinical diagnosis of WE is achieved through two of the following: dietary deficiency, eye signs, cerebellar signs, and an altered mental state. Other investigations include:

Thiamine Deficiency Tests: Whole blood thiamine testing is superior to available alternative tests for assessing thiamine status. Serum thiamine testing has poor sensitivity and specificity.

• Erythrocyte Transketolase Levels: It measures thiamine availability for red blood cells (erythrocytes).

• Liquid Chromatography-tandem Mass Spectrometry: It measures the active form of thiamine (thiamine diphosphate, TDP). It is the most sensitive, specific, and precise method to check the thiamine nutritional status.

Neuroimaging: Neuroimaging findings may improve early diagnosis of WE.

• Computed Tomography (CT): CT can detect edematous (fluid-filled) lesions. CT can ascertain cerebral cortex, frontal lobe, and cerebellum lesions.

• Magnetic Resonance Imaging (MRI): The specificity of MRI is 93 percent in revealing WE. Various advancements in MRI are helpful in early diagnosis and prompt treatment. Hence, MRI is a valuable and preferred imaging modality for WE in clinical settings.

• Electroencephalography (EEG): EEG rules out status epilepticus as the cause of coma and altered mental status.

Laboratory studies such as a complete blood count, serum glucose levels, liver function tests, ammonia levels, toxic drug screening, and serum electrolyte tests (sodium and calcium alterations) exclude other causes.

What Is the Differential Diagnosis of Wernicke's Encephalopathy?

The WE are reversible. Therefore, the early diagnosis of WE permits treatment. It can also improve the patient's nutritional, metabolic, and neurological status. However, there are certain conditions that should be distinguished from WE for better management. The differential diagnosis of WE includes:

1. Hepatic Encephalopathy (HE): Severe liver disease precipitates HE. Liver involvement differentiates HE from WE.

2. Alcohol Withdrawal Syndrome (AWS): AWS occurs when a person suddenly stops drinking alcohol. The symptoms depend upon the time since alcohol is stopped. Delirium tremens start about three days after alcohol withdrawal. The characteristics are confusion, high blood pressure, heavy sweating, fever, and a pounding heartbeat.

3. Stroke: It is brain damage caused by an interruption of blood flow. Hence, it is a medical emergency.

4. Psychosis: Psychosis is a mental disorder. A psychosis patient experiences hallucinations or delusions.

5. Closed-Head Injury: Closed-head injury can cause brain damage. It includes concussion, contusion, and intracranial hematoma (blood collection).

6. Normal Pressure Hydrocephalus (NPH): NPH is a brain condition in which excess cerebrospinal fluid (CSF) accumulates in the brain.

How Is Wernicke's Encephalopathy Treated?

The WE is an emergency requiring immediate intervention. Emergency attention is important in these conditions. The acute and chronic phases of the disease are also managed through different approaches.

1. Emergency Phase: Very little thiamine is required (2 milligrams, mg) to reverse WE symptoms. Intravenous (into the vein) is preferred over intramuscular (into the muscle) administration. Thiamine has a short half-life. Therefore, multiple doses are required. The preferred intravenous dose is 500 mg twice or thrice daily.

2. Inpatient Care: A patient is admitted with suspected or confirmed WE to an inpatient internal medicine or neurology department.

3. Outpatient Care: Malnourished patients need thiamine supplementation. Patients with chronic alcoholism must be referred for counseling. Further, alcohol withdrawal monitoring is mandatory.

WE is a serious condition with extensive disabilities. Some patients do not exhibit any improvement. Therefore, mental deficits persist in many cases. Unfortunately, they develop Korsakoff’s psychosis. Complications include neurological injury, ataxia, Korsakoff’s syndrome, heart failure, and lactic acidosis (excessive lactic acid accumulation in the body).

Conclusion

Early detection of WE is challenging. Further, the high rate of underdiagnosis of WE is due to the varied clinical presentations. The management of WE is difficult and requires a team approach. Close communication between the team members and the patient is vital to ensuring a high standard of treatment. Furthermore, consultation with the endocrinologist, psychiatrist, and neurologist is paramount.