Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Osmotic myelinolysis (central pontine and extrapontine myelinolysis) is an acute, noninflammatory demyelinating disease that can develop following rapid correction of hyponatremia from any cause. It typically appears in the late stages of chronic alcoholism, often in association with Wernicke encephalopathy and polyneuropathy, and a malnourished status. Radiologically, it manifests as regions of increased water content. The classic pontine imaging findings include a high, symmetric T2 signal within the basis pontis, assuming a trident shape, as in this case (A and B, orange arrows). The corticospinal tracts (A and B, yellow arrows) and peripheral pons are spared. Typical extrapontine imaging features include bilateral and symmetric T2 signal hyperintensity abnormalities, most commonly involving the basal ganglia (B and C, stars) and less frequently the thalami (C, orange arrows). Extrapontine myelinolysis may occur with or without central pontine myelinolysis.