Acute nutritional axonal neuropathy and Wernicke's encephalopathy status post Roux-en-Y gastric bypass

We describe an unusual case of a woman in her 30s who had recently undergone Roux-en-Y gastric bypass and presented to the emergency department with a 6-week history of intractable nausea and vomiting, accompanied by progressively worsening bilateral leg weakness. Examination revealed persistent upbeat nystagmus, paraparesis, areflexia in the lower extremities, brisk reflexes in the upper extremities and diminished sensation across all modalities in lower limbs. Brain and spine MRIs were unremarkable, there was no nerve root enhancement. Laboratory tests revealed thiamine deficiency, with a level of 28 nmol/L (reference range: 70-108 nmol/L). No gangliocyte antibodies were detected. Cerebrospinal fluid study showed no albuminocytological dissociation. Electrodiagnostic studies showed evidence of lumbosacral polyradiculopathy. The patient was eventually diagnosed with thiamine deficiency-related acute nutritional axonal neuropathy and Wernicke's encephalopathy. After aggressive thiamine supplementation and 8 weeks of physical rehabilitation, her leg strength improved, but she still requires assistance to ambulate.