Apparent diffusion coefficient map based on diffusion-weighted magnetic resonance imaging is useful in diagnosing the brainstem variant of reversible posterior leukoencephalopathy syndrome with uremia.

A 54-year-old Japanese man entered our hospital for investigation of appetite loss. His blood pressure was 201/113 mmHg, and laboratory findings revealed renal failure and hyponatremia. On physical examination, disorientation and dysarthria were observed. Hemodialysis was performed the same day. Magnetic resonance imaging (MRI) after hemodialysis revealed swelling of the brainstem and a high signal intensity on fluid-attenuated inversion recovery (FLAIR) imaging, similar to findings of central pontine myelinolysis (CPM), which is generally irreversible. However, on an apparent diffusion coefficient (ADC) map based on diffusion-weighted MRI, higher signal intensity was observed in the area of the high signal intensity on FLAIR imaging, which is not seen in CPM. The abnormal neurological symptoms improved within a few days, and MRI findings also normalized. We diagnosed the lesion as the brainstem variant of reversible posterior leukoencephalopathy syndrome (RPLS) with uremia. ADC map was very useful in diagnosing RPLS with uremia.