What is the pathophysiology of central pontine myelinolysis (CPM)?

Updated: Oct 09, 2017
  • Author: Christopher Luzzio, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Central pontine myelinolysis is a concentrated, frequently symmetric, noninflammatory demyelination within the central basis pontis. In at least 10% of patients with central pontine myelinolysis, 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. [4, 5, 6, 7]

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