Clinical Pearls: Wernicke’s Encephalopathy
What are the typical manifestations of Wernicke’s encephalopathy?
Wernicke’s encephalopathy, which is caused by a deficiency of thiamine (vitamin B1), is described as an encephaloneuropathic syndrome consisting of changes in mental status (confusion, confabulation, short-term memory loss, and psychosis), ocular dysfunction (nystagmus, gaze palsies, and ophthalmoplegia), and gait ataxia. Usually beginning with double vision, dysarthria, ataxia, and paresthesias of the legs, Wernicke’s encephalopathy can rapidly progress to Korsakoff’s syndrome, which is characterized by anterograde and retrograde amnesia, confabulation, meager content in conversation, lack of insight, and apathy.
How should thiamine deficiency be treated?
Clinically significant thiamine deficiency is typically treated with at least 200 mg of parenteral thiamine daily for 2 days, with some experts recommending 500 mg three times daily for 2 days, followed by 500 mg once daily for 5 days. On completion of parenteral treatment, the patient should take an oral thiamine supplement daily. Giving patients with thiamine deficiency glucose before administering thiamine can precipitate or worsen Wernicke’s encephalopathy. There should be a low threshold for thiamine administration to prevent heart failure and Wernicke’s encephalopathy in patients at risk for deficiency or in those with symptoms that may be the result of deficiency.
What studies are helpful in making a diagnosis of Wernicke’s encephalopathy?
In some patients with thiamine deficiency, plasma thiamine levels are normal; thus, measurement of the more sensitive whole-blood thiamine level is necessary to confirm the diagnosis. Though generally not required to make the diagnosis, electromyography will often suggest a generalized, length-dependent polyneuropathy with prominent involvement of sensory axons and magnetic resonance imaging of the brain may show enhancement and enlargement of the mammillary bodies.
NEJM July, 2012