CNS nontumor
Toxic and metabolic disorders
Pontine and extrapontine myelinolysis

Author: Kymberly A. Gyure, M.D. (see Authors page)

Revised: 18 August 2017, last major update May 2015

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Pontine myelinolysis CNS

Cite this page: Gyure, K.A. Pontine and extrapontine myelinolysis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/cnspontine.html. Accessed November 20th, 2017.
Definition / general
  • Central pontine and extrapontine myelinolysis are complications of treatment of marked hyponatremia
Terminology
  • Also termed osmotic demyelination syndrome
Epidemiology
  • Occurs most commonly in setting of chronic alcoholism (~40% of cases)
  • Hyperosmolar state and other electrolyte imbalances are common
  • Other associated conditions are hepatic dysfunction / liver transplantation, malnutrition
Sites
  • Most commonly central pons
  • Extrapontine sites are cerebellum and lateral geniculate, regions of extensive gray white matter apposition
Pathophysiology / etiology
  • Associated with rapid correction of hyponatremia, due to disruption of blood brain barrier with edema and myelinolysis
Clinical features
  • Abrupt onset of encephalopathy following recovery from hyponatremia
  • Followed by dysarthria, dysphagia, quadriparesis, possible "locked in" syndrome, neurobehavioral deficits
Diagnosis
  • Typical imaging findings in an appropriate clinical scenario
Radiology description
  • "Trident" or "bat wing" shaped area of restricted diffusion in central pons
  • Symmetric T2 weighted signal abnormalities in cases with extrapontine involvement
Prognostic factors
  • Outcome (death, residual disability or complete recovery) is not predicted by clinical features or extent of radiologic abnormalities
Case reports
Treatment
  • Prevention is most important
  • Once it occurs, corticosteroids and supportive care
Gross description
  • Triangular, T shaped or diamond shaped area of discoloration which may be centrally cavitated in basis pontis
Gross images

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Small lesion

Microscopic (histologic) description
  • Myelin / oligodendrocyte loss with relative preservation of neurons / axons
  • Macrophages may be present but no significant lymphocytic inflammatory infiltrate
Microscopic (histologic) images

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Myelin stain

Differential diagnosis
  • Other causes of demyelination