Central pontine myelinolysis is a condition characterized by nerve damage caused by the destruction of the covering layer ( myelin sheath) of nerve cells in the brainstem (pons).

Alternative Names

CPM

Causes, incidence, and risk factors

The destruction of the myelin sheath that coats nerves inhibits impulse conduction within the cell and thus decreases its ability to communicate with other cells. The most common cause of central pontine myelinolysis is a rapid, drastic change in sodium levels in the body. Most commonly, this occurs when someone is being treated for low levels of sodium ( hyponatremia ) and the levels rise too fast, but it can occasionally occur when high levels of sodium in the body (hypernatremia) are corrected too quickly. This condition does not occur spontaneously; it is a complication of either treatment for other conditions or the other conditions themselves. Risks include hyponatremia from any cause. Alcoholism , Wernicke-Korsakoff syndrome , and general ill health and malnutrition associated with serious illnesses (cachexia) increase the risk of central pontine myelinolysis.

Signs and tests

Examination may indicate involvement of all four extremities (spastic quadriplegia) or

weakness of face, arms and legs (upper motor neuron syndromes). Reflexes may be abnormal. Eye examination may show loss of control of eye muscles, particularly cranial nerve VI paralysis (see cranial mononeuropathy VI ). A cranial MRI scan shows abnormality in the brainstem (pons). This is the primary diagnostic study. Other procedures:

Blood tests including sodium levels

Abnormal brainstem

evoked response audiometry (BERA) This disease may also alter the results of the following tests:

Nerve biopsy

Nerve conduction velocity

Treatment

This is an emergency disorder that requires hospitalization for initial diagnosis and treatment. There is no known cure for central pontine myelinolysis and treatment is focused on relieving symptoms.

Double vision may be reduced with the use of an eye patch. Physical therapy may help maintain muscle strength, mobility and function in weakened arms and legs.

Expectations (prognosis)

The neurologic damage caused by central pontine myelinolysis is usually persistent. The disorder can cause serious chronic disability.

Complications

Permanent neurologic losses

Decreased ability to work or care for self

Decreased ability to interact with others

Calling your health care provider

Go to the emergency room or call the local emergency number (such as 911) if seizures , muscle weakness , or other symptoms of central pontine myelinolysis occur.

Prevention

Gradual controlled correction of hyponatremia or hypernatremia may reduce the risk of damage to the nerves of the pons. Awareness of the side effects of several medications on sodium levels can prevent sodium levels from inadvertently being changed too quickly.