RESUMO
INTRODUCTION: Bariatric surgery has peripheral or central neurological complications in 5-10% of patients. CASE: We report the case of a 39-year-old man with metabolic syndrome who underwent gastric by-pass surgery and then lost 40 kg over a period of 2.5 months. He subsequently developed symptoms suggestive of Wernicke-Korsakoff encephalopathy, secondary to stenosis of the gastrojejunal anastomosis, which led to repeated unreported vomiting. DISCUSSION: This neurological syndrome, linked to thiamine deficiency, can be found with insufficient nutrition after surgery or severe vomiting after bariatric surgery. The complications are essentially peripheral neuropathy and metabolic dysfunctions, including iron and vitamin (B12, D, folate) deficiencies. This case reminds us that bariatric surgery requires close metabolic follow-up with periodic assays of vitamin levels, including thiamine, even when supplementation was prescribed.