Introduction. Wernicke's encephalopathy is a well-described syndrome 
characterized by the classic triad of confusion, ataxia, and ophthalmoplegia. 
Wernicke's encephalopathy results from thiamine (vitamin B1) deficiency. Common 
causes include alcoholism and gastric disorders. Wernicke's has been described 
in patients with acquired immune deficiency syndrome (AIDS); however, given 
these patients' immunosuppressed state, the diagnosis of Wernicke's 
encephalopathy is not apparent. Case Presentation. A 31-year-old previously 
healthy male presented to the ER complaining of progressive dyspnea. Workup 
revealed HIV/AIDS and PCP pneumonia. He was treated and improved. On day 14 he 
became confused and developed nystagmus and ataxia. Considering his 
immunocompromised state, infectious and neoplastic etiologies topped the 
differential diagnosis. CT head was negative. Lumbar puncture was unremarkable. 
Brain MRI revealed increased T2 signal in the medial thalamus bilaterally. 
Intravenous thiamine was administered resulting in resolution of symptoms. 
Discussion. The classic triad of Wernicke's encephalopathy occurs in 10% of 
cases. When immunosuppressed patients develop acute neurologic symptoms 
infectious or neoplastic etiologies must be excluded. However, given the 
relative safety of thiamine supplementation, there should be a low threshold for 
initiating therapy in order to reverse the symptoms and prevent progression to 
Korsakoff dementia, which is permanent.