Case Report Decreased Diffusion in Central Pontine Myelinolysis

Summary: Two patients with central pontine myelinolysis (CPM) were studied with diffusion-weighted MR imaging 1 week after onset of tetraplegia. In both patients, affected white matter showed hyperintensity on diffusion-weighted images associated with a decrease in apparent diffusion co-efficient (ADC) values. In one patient studied serially, ADC values normalized by 3 weeks after tetraplegia. Early in the clinical course, diagnosis of CPM can sometimes be dif-ficult. Hyperintensity on diffusion-weighted images may therefore have diagnostic utility. Decreased lesional ADC values support the notion that CPM is a consequence of relative intracellular hypotonicity. Central pontine myelinolysis (CPM) is an un-common consequence of certain metabolic de-rangements. These include rapid correction of hy-ponatremia, as well as hyperosmolar conditions, such as hyperglycemia. The microscopic appear-ance of CPM is loss of myelin with sparing of ax-ons, without evidence of inflammation (1, 2). The abnormalities associated with CPM are readily identified on T2-weighted MR imaging scans (3). Little information is available regarding the char-acteristics of CPM revealed by diffusion-weighted (DW) imaging. Such information may be of diag-nostic value and might also provide insight into the pathogenesis of this disorder. The current study considers these issues in reporting DW imaging re-sults in two patients with CPM