Wernicke Encephalopathy

Wernicke Encephalopathy


Introduction:
Wernicke encephalopathy (WE) is a life-threatening neurological condition caused by thiamine (vitamin B1) deficiency. It primarily affects the central nervous system, leading to a range of neurological symptoms. The condition is classically associated with chronic alcoholism but can also arise due to malnutrition, malabsorption syndromes, or after bariatric surgery. Early recognition and treatment are crucial for preventing permanent neurological damage and mortality.

Pathophysiology:

Thiamine is an essential cofactor for several enzymes involved in glucose metabolism, including pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and transketolase. These enzymes are vital for energy production, particularly in the brain. Thiamine deficiency impairs cerebral glucose metabolism, leading to cellular energy deficits, neuronal damage, and areas of brain atrophy, especially in the mamillary bodies, thalamus, hypothalamus, and brainstem.

Etiology and Risk Factors:

  1. Chronic Alcoholism: The most common cause, as alcohol impairs thiamine absorption, storage, and utilization.
  2. Malnutrition: Conditions causing poor nutritional intake (e.g., anorexia nervosa, hyperemesis gravidarum, cancer, and severe systemic illness).
  3. Malabsorption: Bariatric surgery, gastrointestinal disorders (e.g., Crohn’s disease, celiac disease).
  4. Prolonged Intravenous Feeding without thiamine supplementation.
  5. Increased metabolic demand: Due to systemic illness, sepsis, or trauma.

Clinical Features:

The classic triad of WE includes:

  1. Confusion: Acute or subacute mental status changes ranging from mild confusion to stupor or coma.
  2. Ophthalmoplegia: Paralysis or weakness of the eye muscles, causing nystagmus, gaze palsies, or diplopia.
  3. Ataxia: Impaired coordination and gait instability, primarily due to cerebellar involvement.

However, the triad is observed in less than one-third of cases. Other symptoms include peripheral neuropathy, hypotension, hypothermia, and cognitive impairments.


Diagnosis:

WE is a clinical diagnosis supported by history, risk factors, and presentation. A high index of suspicion is essential, especially in chronic alcoholics and malnourished patients.

Diagnostic Criteria (Caine et al. 1997)

Diagnosis is likely if two of the following four criteria are met:

  • Dietary deficiency: Chronic malnutrition or inadequate thiamine intake.
  • Oculomotor abnormalities: Nystagmus or ophthalmoplegia.
  • Cerebellar dysfunction: Ataxia or gait disturbances.
  • Altered mental status: Confusion, memory impairment.

Imaging:

  1. MRI is the imaging modality of choice. Typical findings include:
    • Hyperintensities in the mamillary bodies, medial thalamus, periaqueductal grey matter, and tectal plate on T2-weighted or FLAIR sequences.
    • Diffusion-weighted imaging (DWI) may show restricted diffusion in these areas, indicating cytotoxic edema.
  2. CT scan: Often normal, but may show mamillary body atrophy in chronic cases.

Treatment:

Early intervention is critical to prevent irreversible damage or progression to Korsakoff syndrome.

Thiamine Administration:

  • Dosing recommendations:
    • Intravenous (IV): 500 mg IV thiamine 2-3 times daily for 2-3 days, followed by 250 mg daily for 5-7 days.
    • Switch to oral thiamine (100 mg daily) after IV therapy, depending on clinical response.
  • Route of Administration: IV thiamine is preferred, as oral absorption may be impaired in alcoholics or critically ill patients.

Important: Thiamine must always be given before or alongside glucose administration to avoid exacerbating the condition, as glucose utilization worsens thiamine deficiency.

Prevention:

  • High-risk patients (e.g., chronic alcoholics, malnourished individuals, post-bariatric surgery patients) should receive prophylactic thiamine supplementation:
    • 100 mg IV or IM thiamine daily for at least 3 days before glucose or carbohydrate loading.

Complications:

  1. Korsakoff Syndrome: A chronic neuropsychiatric disorder characterized by severe memory loss, confabulation, and learning difficulties. It is a late-stage manifestation of untreated WE.
  2. Permanent Neurological Deficits: Persistent ataxia, neuropathy, and cognitive dysfunction if left untreated.
  3. Mortality: Untreated WE can lead to death due to associated complications such as coma or sepsis.

Latest Updates & Guidelines:

European Federation of Neurological Societies (EFNS) Guidelines (2023):

  • Early Thiamine Supplementation: Should be administered in any at-risk individual, especially before the administration of glucose.
  • MRI Confirmation: MRI is recommended as the first-line imaging modality to confirm the diagnosis if clinical suspicion is high.
  • Prophylaxis: For individuals at risk (chronic alcohol users, malnourished, etc.), a preventive course of thiamine should be provided, especially before refeeding or glucose administration.

American Society of Addiction Medicine (ASAM) Guidelines (2023):

  • Routine Screening: Routine screening for WE should be done in alcohol-dependent individuals admitted for detoxification or rehabilitation.
  • Long-Term Supplementation: Following initial high-dose thiamine treatment, long-term supplementation with oral thiamine (100 mg daily) is recommended for at least 6 months to prevent recurrence.

Recent Research:

  • Genetic Factors: Emerging evidence suggests a possible genetic predisposition to WE, with certain populations being more vulnerable to thiamine deficiency.
  • Bariatric Surgery: Recent studies emphasize a growing incidence of WE in post-bariatric surgery patients due to malabsorption, highlighting the importance of regular postoperative nutritional assessments.

Prognosis:

  • Favorable Outcomes: Early diagnosis and prompt treatment typically lead to rapid recovery, especially in mild cases.
  • Severe Cases: Delayed treatment increases the risk of developing Korsakoff syndrome, which has a poor prognosis with significant long-term cognitive and functional impairment.

Conclusion:

Wernicke encephalopathy is a medical emergency that requires immediate intervention to prevent lasting neurological damage or death. Thiamine deficiency should always be considered in malnourished or alcohol-dependent patients presenting with neurological symptoms. Early and aggressive thiamine supplementation is the cornerstone of treatment, with intravenous administration preferred in the acute phase.

Table: Summary of Wernicke Encephalopathy Management

Aspect Recommendation
Diagnosis Clinical, MRI confirmation if necessary
Initial Thiamine Dose 500 mg IV 2-3 times/day for 2-3 days
Ongoing Thiamine 250 mg IV daily for 5-7 days
Prophylaxis 100 mg IV/IM daily for 3 days in high-risk patients
Prevention Thiamine before glucose administration


Bibliography

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  6. Galvin, R., Bråthen, G., Ivashynka, A., Hillbom, M., Tanasescu, R., & Leone, M. A. (2010). EFNS guidelines for diagnosis, therapy and prevention of Wernicke encephalopathy. European Journal of Neurology, 17(12), 1408-1418. DOI: 10.1111/j.1468-1331.2010.03153.x

  7. American Society of Addiction Medicine (ASAM). (2023). Clinical Practice Guidelines for Alcohol Withdrawal Management. Retrieved from https://www.asam.org

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  10. Nolte, W., & Zannas, A. S. (2016). Wernicke encephalopathy as a complication of bariatric surgery: Report of two cases and review of the literature. Psychosomatics, 57(1), 81-87. DOI: 10.1016/j.psym.2015.09.006

 

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