Central pontine myelinolysis

  • Definition
    • Central pontine myelinolysis is brain cell dysfunction. It is caused by the destruction of the layer (myelin sheath) covering nerve cells in the middle of the brainstem (pons).

  • Alternative Names
    • Osmotic demyelination syndrome

  • Causes
    • When the myelin sheath that covers nerve cells is destroyed, signals from one nerve to another aren't properly transmitted. Although the brainstem is mainly affected, other areas of the brain can also be involved.

      The most common cause of this disorder is a quick change in the body's sodium levels. This most often occurs when someone is being treated for low blood sodium (hyponatremia) and the sodium is replaced too fast. Sometimes, it occurs when a high level of sodium in the body (hypernatremia) is corrected too quickly.

      This condition does not usually occur on its own. Most often, it's a complication of treatment for other problems, or from the other problems themselves.

      Risks include:

  • Symptoms
  • Exams and Tests
    • The health care provider will perform a physical exam and ask about the symptoms.

      A head MRI scan may reveal a problem in the brainstem (pons) or other parts of the brain. This is the main diagnostic test.

      Other tests may include:

  • Treatment
    • This is an emergency disorder that needs to be treated in the hospital though most people with this condition are already in the hospital for another problem.

      There is no known cure for central pontine myelinolysis. Treatment is focused on relieving symptoms.

      Physical therapy may help maintain muscle strength, mobility, and function in weakened arms and legs.

  • Outlook (Prognosis)
    • The nerve damage caused by central pontine myelinolysis is often long-lasting. The disorder can cause serious long-term (chronic) disability.

  • Possible Complications
    • Complications may include:

      • Decreased ability to interact with others
      • Decreased ability to work or care for self
      • Inability to move, other than to blink eyes ("locked in" syndrome)
      • Permanent nervous system damage
  • When to Contact a Medical Professional
    • There is no real guideline on when to seek medical attention, because this condition is rare in the general community.

  • Prevention
    • In the hospital, slow, controlled treatment of a low sodium level may reduce the risk for nerve damage in the pons. Being aware of how some medicines can change sodium levels can prevent the level from changing too quickly.

  • References
    • Pfennig CL, Slovis CM. Electrolyte disorders. In: Marx JA, Hockberger RS, Walls RM, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 125.

      Weissenborn K, Lockwood AH. Toxic and metabolic encephalopathies. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 84.