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  • Updated 08.26.2019
  • Released 04.14.2003
  • Expires For CME 08.26.2022

Osmotic demyelination syndromes

Introduction

This article includes discussion of osmotic demyelination syndromes, central pontine myelinolysis, and extrapontine myelinolysis. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Spastic quadriparesis, pseudobulbar palsy, and pseudobulbar affect occurring several days following a rapid rise in serum osmolality are the classical signs of osmotic demyelination syndrome. The author reviews the classic clinical signs and pathophysiology of osmotic demyelination syndrome and includes updates from literature on methods of prevention and potential future treatment options for this infrequent, but preventable, iatrogenic disease.

Key points

• All patients with severe hyponatremia receiving intravenous fluids should have serum sodium measured every 4 hours in order to allow for adjustments in fluid administration, if serum sodium should rise at a rate greater than 0.5 mEq/ml per hour.

• The use of desmopressin to limit water diuresis during correction of severe hyponatremia should be considered for prevention of overcorrection.

• Vaptans have been shown to be efficacious and safe in the treatment of hypervolemic and normovolemic hyponatremia.

• Patients with severe hyponatremia and concomitant hypokalemia are at greater risk for developing osmotic demyelination syndrome, and a slower correction than 12 mEq/ml in a 24-hour period should be considered.

• After development of signs or symptoms of osmotic demyelination syndrome, treatment should be mainly supportive, as no large clinical trials have been performed to examine the efficacy of therapeutic relowering of serum sodium, steroids, plasma exchange, or IVIG.

Historical note and terminology

The original description of osmotic demyelination syndrome was by Adams, Victor, and Mancall in 1959 (02). During their studies of the neuropathology of alcoholism, they recognized a peculiar and unique demyelination occurring in the central pons of 4 individuals with alcoholism and malnutrition. They labeled this disorder “central pontine myelinolysis.” Since this original description, demyelination in other areas of the central nervous system associated with osmotic stress has been described encouraging the use of the more general term “osmotic demyelination syndrome” rather than the more restrictive term “central pontine myelinolysis” (40; 34).

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