CENTRAL PONTINE MYELINOLYSIS.

CPM is concentrated, frequently symmetric, noninflammatory demyelination within the central basis pontis. In at least 10% of patients with CPM, demyelination also occurs in extrapontine regions, including the mid brain, thalamus, basal nuclei, and cerebellum.

The exact mechanism that strips the myelin sheath is unknown. One theory proposes that in regions of compact interdigitation of white and gray matter, cellular edema, which is caused by fluctuating osmotic forces, results in compression of fiber tracts and induces demyelination. Prolonged hyponatremia followed by rapid sodium correction results in edema. During the period of hyponatremia, the concentration of intracellular charged protein moieties is altered; reversal cannot parallel a rapid correction of electrolyte status. The term \"osmotic myelinolysis\" is more appropriate than \"central pontine myelinolysis\" for demyelination occurring in extrapontine regions after the correction of hyponatremia.

CPM occurs more frequently in females than in males.

The most consistent examination findings are those of pseudobulbar palsy and spastic quadriplegia caused by demyelination of corticospinal and corticobulbar tracts within the pons. Delirium is extremely common.

MRI is helpful for diagnosis. It shows areas of increased signal intensity in the pons on T2WI and decreased signal intensity on T1WI.The lesions do not enhance on contrast scan