The patient presented with symptoms of ataxia, nystagmus and vertical gaze palsy. The patient was awake, NIHSS = 0, although disorientated to time and space. The additional neuropsychological testing revealed no hallucinations or delusions, but a mild amnestic syndrome with antegrade and retrograde deficits. Events of the last few days were not correctly remembered.

The patient underwent bariatric surgery 2 months before presentation (sleeve-gastrectomy) which led to the neurological deficits in this case of thiamine deficiency-induced Wernicke encephalopathy.

Laboratory results showed thiamine (vitamin B₁) deficiency (13.5 ng/mL, normal: 20-100 ng/mL) and folate deficiency (0.8 ng/mL, normal: 4.6 - 18.7 ng/mL).

The MRI shows some typical signs of Wernicke encephalopathy in this non-alcoholic patient: FLAIR/T2 - hyperintensity periaqueductal involving the quadrigeminal plate and hyperintensity of the mammillary bodies.

The patient was treated with supplementary vitamins and folate and recovered within 2 weeks.