Wernicke's encephalopathy (WE) is a disease caused by thiamine deficiency related to alcoholism, hyperemesis, or thiamine malabsorption. The clinical manifestations of WE are mental change, ataxia, and ophthalmoplegia. The typical magnetic resonance imaging (MRI) findings of WE are symmetrical involvement of medial thalamus, periventricular region of the third ventricle, periaqueductal area, and mammillary body. The atypical MRI findings are more common in nonalcoholic WE. Since the increasing population of obesity and the preference of weight loss surgery, the risk of developing thiamine deficiencies associated with weight loss surgery has become a considerable etiology of WE. We herein reported a case reminds clinicians that WE can be a possible diagnosis in patient who developed acute altered mental status with atypical MRI lesion involving bilateral centrum semiovale and corona radiata after receiving bariatric surgery.