[A case of extrapontine myelinolysis precipitated by correction of a hyper-osmolar state].

We report a case of extrapontine myelinolysis (EPM) precipitated by correction of a hyper-osmolar state. A 7-year-old boy presented with disturbed consciousness. Serum BUN and Na level were 48 mg/dl and 196 mmol/L, respectively. T2-weighted images and FLAIR images of MRI visualized symmetrical bilateral high signal intensity areas in the external capsule and in the thalamus. In addition, the splenium of the corpus callosum showed high signal intensity. All these lesions showed high signal intensity on diffusion-weighted images. Extrapontine myelinolysis is precipitated not only by the rapid correction of a hypo-osmolar state but also by that of a hyper-osmolar state.