[A case of thiamine deficiency neuropathy with acute progression mimicking Guillain-Barré syndrome].

A 64-year-old man living alone with markedly unbalanced dietary habits presented to the prior hospital with distal sensory disturbances and weakness in all four extremities. After admission, he experienced a rapid progression of lower limb weakness, rendering him unable to walk, for which he was subsequently transferred to our department. During his stay at the previous hospital, he had received lactated Ringer's solution. Laboratory findings revealed a profound deficiency in serum thiamine (vitamin B1). Thiamine supplementation resulted in rapid clinical improvement, confirming a diagnosis of vitamin B1 deficiency neuropathy. Although this condition typically follows a subacute course, it can occasionally present acutely, mimicking Guillain-Barré syndrome (GBS), as seen in this case. Our findings suggest that even glucose-free infusions may exacerbate latent vitamin B1 deficiency by increasing metabolic demand through lactate metabolism and enhancing urinary excretion via diuresis. It is essential to consider vitamin B1 deficiency in the differential diagnosis of patients presenting with an acute progressive clinical course resembling GBS.