Wernicke Encephalopathy: A Complication of Parenteral Nutrition Diagnosed by Magnetic Resonance Imaging

Abstract

THIAMIN (vitamin B1) is a water-soluble vitamin involved in glucose metabolism. Its deficiency affects the cardiovascular (wet beriberi) and nervous (dry beriberi) systems, and in industrialized countries, it is commonly linked to chronic alcoholism. Wernicke encephalopathy (WE), a metabolic encephalopathy due to thiamine depletion, is clinically characterized by at least two among four features1: nutritional deficit, oculomotor abnormalities, ataxia, and stupor. Laboratory tests (measurement of serum thiamine or erythrocyte transketolase activity) are diagnostic, but the radiologic confirmation can be achieved by magnetic resonance imaging (MRI) with abnormal hyperintense signal in the periaqueductal gray matter, the mamillary bodies, and around the third ventricle on fluid-attenuated inversion recovery and T2MRI scans.2We report a case of non alcoholic WE complicating postoperative total parenteral nutrition (TPN) lacking micronutrient supply and confirmed by MRI.The diagnosis of benign gastric tumor was established after a gastroscopy with gastric biopsy in a 30-yr-old mother of two children without any relevant medical history but prolonged gastric intolerance and 8 kg weight loss. She underwent an elective laparoscopic partial gastrectomy. On the fourth postoperative day, she had a wound dehiscence and developed peritonitis that required an emergency laparotomy with peritoneal lavage and suture. After this procedure, TPN and adapted antibiotherapy were administered. She developed a digestive tract fistula, and TPN had to be continued. After 30 days, the patient reported fatigue, and hyponatremia (127 mm) and hypophosphatemia developed and were corrected, but she had to be transferred to the intensive care unit for stupor (Glasgow Coma Scale score of 8) without any focal signs, and she was intubated and ventilated. Cerebral computed tomography scan was normal; her sodium concentration went to 150 mm. Micronutrients (polyvitamins and trace elements) were added to TPN. After 3 days, her neurologic status improved, allowing extubation, but the clinical examination showed a horizontal nystagmus and a lateral ophthalmoplegia. MRI showed no sign of central pontine myelinolysis but hyperintense lesions in the medial thalami on fluid-attenuated inversion recovery and T2 MRI scans (fig. 1). After inquiry, it turned out that TPN before intensive care admission had been administered without micronutrient supplementation. Thiamine administration was increased (200 mg/day), and oculomotor and MRI signs regressed, but a severe cognitive deficit along with vertigo and loss of sphincter control persisted. More than 2 yr later, these symptoms are still present, and the patient is totally dependent and disoriented with memory disturbances.In the Western world, thiamine deficiency is characteristically associated with chronic alcoholism, because it affects thiamine uptake and utilization. However, WE may develop in nonalcoholic conditions, as in prolonged starvation,3hyperemesis gravidarum,4bariatric surgery,5and even healthy infants given the wrong formulas.6Thiamine is a cofactor of several enzymes involved in glucose metabolism and cerebral energy utilization, and its depletion could lead to the neuronal damage as seen on MRI, i.e. , T2 and fluid-attenuated inversion recovery hyperintense signaling in the mamillary bodies, periventricular thalamus, and periaqueductal gray matter,7as well as diffusion-weighted imaging to differentiate vasogenic from cytotoxic edema.8Subsequent MRIs may show regression of the signal abnormalities, but there is no correlation with improvement in clinical conditions.7Interestingly, metabolic disturbances such as hyponatremia and hypophosphatemia have been associated with WE and can be misleading,9as in our case. Lactic acidosis, however, is evocative of thiamine deficiency, especially in children.10Our case report emphasizes the diagnostic difficulties leading astray from WE in atypical settings and the usefulness of MRI to correct the diagnosis. However, the main issue is to remind us that TPN is not a harmless and easy technique, and that micronutrients should always be administered on a daily basis during TPN.11