eMedicine Specialties > Emergency Medicine > Neurology
Wernicke Encephalopathy: Differential Diagnoses & Workup
Updated: Jan 13, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Differential Diagnoses
Alcohol and Substance Abuse Evaluation
Alcoholic Ketoacidosis
Delirium Tremens
Delirium, Dementia, and Amnesia
Stroke, Ischemic
Withdrawal Syndromes
Other Problems to Be Considered
Psychosis
Normal pressure hydrocephalus
Cerebrovascular accident
Chronic hypoxia
Closed-head injury
Hepatic encephalopathy
Postictal state
Workup
Laboratory Studies
Patients with Wernicke encephalopathy present with altered mental status and other neurologic abnormalities. Careful history, physical examination, laboratory workup, and radiographic evaluation are essential to exclude other causes of CNS dysfunction. No specific laboratory test is available for diagnosing Wernicke encephalopathy. Wernicke encephalopathy is a clinical diagnosis, and normal electrolyte levels may only give false reassurance and delay therapy. This is particularly the case where malnutrition is likely to be present. The motto should be "If in doubt, treat," as administration of thiamine does not pose potential harm.
- The history and initial evaluation guide selection of laboratory and radiographic tests. Although Wernicke encephalopathy remains a clinical diagnosis with no characteristic abnormalities in diagnostic studies, it remains important to exclude alternate or coexisting medical conditions.
- Biomarkers, including an assay for thiamine, are not typically available for timely diagnostic purposes. Further, no study has clearly described the sensitivity, specificity, and accuracy of thiamine levels in relation to active disease.9 However, the thiamine levels can help the clinician assuming care of the patient in ambiguous cases, and obtaining a thiamine level can be considered for diagnostic dilemmas.1
- Complete blood cell (CBC) count rules out severe anemias and leukemias as causes of altered mental status.
- Alterations in serum electrolyte levels, such as hypernatremia or hypercalcemia, can cause altered mental status and must be excluded.
- A recent case series suggested that patients with Wernicke encephalopathy may exhibit a distinctive acid-base pattern consisting of a primary metabolic acidosis in conjunction with a primary respiratory alkalosis. The primary metabolic acidosis is secondary to thiamine's role in aerobic metabolism and the Krebs cycle; without thiamine, aerobic metabolism cannot progress and metabolic products, including lactate and pyruvate, are produced, which result in an anion gap acidosis. The role of thiamine in causing a primary respiratory alkalosis is unclear.9
- Obtain serum glucose levels to exclude hypoglycemia and hyperglycemia.
- Obtain pulse oximetry and/or arterial blood gases (ABGs) measurement to exclude hypoxia and hypercarbia.
- Perform toxic drug screening to exclude some causes of drug-induced altered mental status.
- Consider lumbar puncture (LP) to exclude CNS infections if indicated.
- Erythrocyte transketolase levels reliably detect thiamine deficiency but are not necessary for the diagnosis of Wernicke encephalopathy. In the erythrocyte transketolase activity assay, the extent of thiamine deficiency is expressed in percentage stimulation compared with baseline levels (the thiamine pyrophosphate effect). Normal values range from 0-15%; a value of 15-25% indicates thiamine deficiency, and greater than 25% indicates severe deficiency.6
- Blood pyruvate and lactate measurements, although not specific for thiamine deficiency illnesses, are sensitive and helpful, as thiamine is a cofactor of the pyruvate dehydrogenase enzyme, an important enzyme in aerobic metabolism.6
Imaging Studies
- A head computed tomography (CT) scan is a vital initial test for emergency diagnosis of focal neurologic disease such as intracerebral hemorrhage. In patients who are comatose, CT scan can detect not only intracranial lesions but also fractures of the skull and minute amounts of blood. However, CT of the head does not appear to be useful in screening for Wernicke-Korsakoff syndrome.7
- Magnetic resonance imaging (MRI) offers the best way to make a definitive diagnosis antemortem, but the sensitivity is poor and obtaining an MRI for this indication is typically impractical and unnecessary in the ED.1 Although the clinical evidence for the utility of MRI is based on a study in which the sample size was small, the reported sensitivity of MRI was 53% and specificity was 93% for both acute and chronic Wernicke-Korsakoff syndrome. The same study reported 13% sensitivity for CT scanning.7 Because of the low sensitivity of MRI for Wernicke encephalopathy, particularly an acute presentation, and because many patients with Wernicke encephalopathy may not exhibit diagnostic features on MRI, means that normal MRI results should not be used to exclude the diagnosis of acute illness. The low sensitivity of CT scan for Wernicke encephalopathy means that CT does not have a role in the routine screening for this typeofencephalopathy.7
- The appearance of acute Wernicke encephalopathy on MRI demonstrates abnormal hyperdensity of the mammillary bodies and periaqueductal gray matter with associated abnormal enhancement on T1-weighted images.10 In chronic Wernicke encephalopathy and Korsakoff syndrome, radiographic imaging, especially MRI, may be normal or may show symmetric low-density abnormalities in periventricular areas, the diencephalon, the midbrain, excessive mamillary body, cerebellar, and cerebral shrinkage.7 Such symmetric lesions are uncommon in other cerebral encephalopathic disorders and are suggestive of Wernicke-Korsakoff syndrome.7
- Morphometric studies of MRI imaging confirm that patients with Wernicke-Korsakoff syndrome show excessive mamillary body and cerebellar shrinkage indicating that these are highly specific MRI findings for this kind of encephalopathy.7
Other Tests
- Consider an electroencephalogram (EEG) if nonconvulsive status epilepticus is suspected as a potential cause of coma and altered mental status.
More on Wernicke Encephalopathy |
| Overview: Wernicke Encephalopathy |
 Differential Diagnoses & Workup: Wernicke Encephalopathy |
| Treatment & Medication: Wernicke Encephalopathy |
| Follow-up: Wernicke Encephalopathy |
| References |
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References
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Blass JP, Gibson GE. Abnormality of a thiamine-requiring enzyme in patients with Wernicke-Korsakoff syndrome. N Engl J Med. Dec 22 1977;297(25):1367-70. [Medline].
Henry GL. Coma and altered states of consciousness. In: Emergency Medicine. 4th ed. 1996:225-233.
Hoffman RS. Thiamine hydrochloride. In: Goldfrank's Toxicologic Emergencies. 5th ed. 1994:825-6.
Hung SC, Hung SH, Tarng DC, et al. Thiamine deficiency and unexplained encephalopathy in hemodialysis and peritoneal dialysis patients. Am J Kidney Dis. Nov 2001;38(5):941-7. [Medline].
Marx JA. The varied faces of Wernicke's encephalopathy. J Emerg Med. 1985;3(5):411-3. [Medline].
Reuler JB, Girard DE, Cooney TG. Current concepts. Wernicke's encephalopathy. N Engl J Med. Apr 18 1985;312(16):1035-9. [Medline].
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Willett WC, Stampfer MJ. Clinical practice. What vitamins should I be taking, doctor?. N Engl J Med. Dec 20 2001;345(25):1819-24. [Medline].
Further Reading
Keywords
Wernicke encephalopathy, Wernicke's encephalopathy, Wernicke-Korsakoff syndrome, thiamine deficiency, vitamin B-1 deficiency, Wernicke's disease, Wernicke-Korsakoff psychosis, mental confusion, ataxia, ophthalmoplegia, Korsakoff's amnestic syndrome, Korsakoff amnestic syndrome, memory loss, confabulation, vitamin B deficiencies, alcoholism, malnutrition, AIDS
