[Wernicke encephalopathy in a chronic peritoneal dialysis patient--correlation between diffusion MR and pathological findings].

Wernicke encephalopathy (WE) is a neurologic disorder caused by a nutritional deficiency of thiamine. Since the lesion in WE consists of brain edema, diffusion weighted imaging (DWI) is quite useful for detecting the pathologic changes in WE, and can differentiate between reversible extracellular (vasogenic) and irreversible cellular (cytotoxic) edema. We report here a 16-year-old man with WE who had been treated with continuous ambulatory peritoneal dialysis for chronic renal failure. He underwent repeated DWI and postmortem examination. DWI, which was performed 8 days after the onset of neurological symptoms, showed high intensity areas in the bilateral thalami, mammillary bodies, tegmentum mesencephali and pons. Apparent diffusion coefficient (ADC) map also showed slightly high intensity in the periaqueductal gray matter and pons, which indicated extracellular edema. On the other hand, ADC map showed low intensity areas in the most medial part of the thalami and marginal area of the tegmentum mesencephali, which indicated cellular edema. In the postmortem examination, the areas that showed low intensity on ADC map exhibited mild neuronal loss. Based on the correlation between the DWI and pathologic findings, the cytotoxic edema of the bilateral medial thalami and marginal tegmentum mesencephali in this patient was considered to be glial cell edema which may protect against neuronal cell damage.