Progressive supranuclear palsy responding to intravenous thiamine: superimposed Wernicke's encephalopathy?

Progressive supranuclear palsy (PSP) may be a risk factor for thiamine deficiency. The classic symptoms of PSP (postural instability, supranuclear vertical gaze palsy and dementia) overlap with the clinical triad of Wernicke's encephalopathy (cognitive impairment, gait problems and ocular abnormality). Therefore, superimposed thiamine deficiency in patients with PSP may aggravate the pre-existing symptoms of PSP. Here, we are reporting a 64-year-old woman having supranuclear ocular palsy, gait instability and dementia for the past 2-3 years. The patient fulfilled the diagnostic criteria of PSP. In parallel, she fulfilled the Caine's criteria of Wernicke's encephalopathy. Her serum thiamine level was low. Supplementation of thiamine led to marked improvement in the symptoms which had been present for many years. These symptoms were originally presumed to be due to PSP. This case highlights the needs to identify superimposed thiamine deficiency in patients with PSP.