A 23-year-old woman with a history of anorexia nervosa is evaluated due to acute-onset confusion while hospitalized. Over the past 6 months, she has been severely restricting her caloric intake and has lost 7 kg (15.4 lb). On admission, she was tachycardic and orthostatic, and her BMI was 15 kg/m2. The patient has been receiving intravenous hydration and parenteral nutrition. Today, her family notes that she seems newly confused and unsteady when walking. Temperature is 36.7 C (98 F), blood pressure is 110/70 mm Hg, and pulse is 86/min. She is not oriented to time or place. Bilateral pupils are equal and reactive. Her lateral gaze is restricted on both sides and evokes a horizontal nystagmus. There is no nuchal rigidity or motor weakness. Bilateral ankle reflexes are diminished. The patient walks slowly with short and wide-based steps. Which of the following is the best next step in management of this patient?
Wernicke encephalopathy | |
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This patient being treated for anorexia nervosa likely has developed Wernicke encephalopathy (WE), a disorder characterized by:
WE occurs in patients with long-term thiamine (vitamin B1) deficiency due to poor dietary intake (eg, anorexia, chronic alcohol use), impaired metabolism, or poor absorption.
WE is diagnosed based on the triad of clinical findings; no laboratory or radiologic studies are necessary. When WE is suspected, intravenous thiamine should be administered immediately. Because the body's requirements for thiamine (a cofactor for many enzymes) increases with high metabolic rate or glucose intake, the administration of glucose before thiamine (as likely occurred in this patient receiving intravenous hydration) can induce or worsen the condition, which can lead to coma or death.
(Choice A) Cobalamin (vitamin B12) deficiency can cause neurologic deficits, including impaired vibratory and positional sense, gait ataxia, and megaloblastic anemia. Mental status changes can also be seen, but oculomotor symptoms would be unusual.
(Choice B) Acyclovir is used to treat herpes simplex encephalitis, a central nervous system (CNS) viral infection that can cause various neurological effects (eg, seizure, altered mental status); however, fever and headache are typically present whereas nystagmus and ataxia are less likely.
(Choice C) Refeeding syndrome (RS), sometimes seen in profoundly malnourished patients receiving aggressive nutritional supplementation, is characterized by hypophosphatemia (requiring parenteral phosphate) and volume overload due to shifting nutrients and fluids, respectively. Although RS is sometimes associated with thiamine deficiency, this patient has no other manifestations of RS (eg, edema, heart failure, seizures). Oculomotor findings and ataxia are atypical.
(Choice D) Systemic glucocorticoids can be used to treat multiple sclerosis, an autoimmune inflammatory demyelinating disorder of the CNS typically causing neurologic deficits disseminated in space and time (eg, sensory loss/paresthesias of the extremities, dizziness, optic neuritis) in women age 15-50. It does not usually begin with acute confusion.
(Choice F) Thrombolytic therapy can be used for an acute stroke causing neurologic deficits. An infarction of the medial vermis can result in vertigo and nystagmus, whereas a lateral cerebellar infarction can cause dizziness, ataxia, and weakness. However, an infarct would be unusual in a young woman without other risk factors.
Educational objective:
Thiamine deficiency can cause Wernicke encephalopathy, which is characterized by encephalopathy, oculomotor dysfunction, and gait ataxia. This is generally seen in malnourished patients (eg, anorexia, chronic alcohol use) and may be induced iatrogenically by the administration of glucose without thiamine.