Central pontine myelinolysis

Answer 1

Definition

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

Alternative Names

CPM

Causes, incidence, and risk factors

The destruction of the myelin sheath that covers nerve cells prevents signals from being properly transmitted in the nerve. This decreases the nerve's ability to communicate with other cells.

The most common cause of central pontine myelinolysis is a quick change in the body's sodium levels. This most often occurs when someone is being treated for low levels of sodium (hyponatremia) and the levels rise too fast. It also can occasionally occur when high levels of sodium in the body (hypernatremia) are corrected too quickly.

This condition does not occur on its own. It is a complication of treatment for other conditions or from the other conditions themselves.

Risks include:

• Alcoholism
• General ill health
• Low sodium levels from any cause
• Malnutritionfrom serious illnesses
• Wernicke-Korsakoff syndrome

Symptoms

• Confusion, delirium
• Difficulty swallowing
• Double vision
• Muscle spasmsin the face, arms, or legs
• Reduced alertness, drowsiness or sleepiness, lethargy, poor responses
• Reduced vision
• Speech changes, poor enunciation
• Weakness in the face, arms, or legs, usually affecting both sides of the body

Other possible symptoms include:

• Constipation
• Different size pupils in the eyes
• Hallucinations
• Hand tremor
• Uncontrollable eye movements

Signs and tests

An examination may show:

• Abnormal reflexes
• Cranial nerve VI paralysis (see cranial mononeuropathy VI)
• Involvement of all four arms and legs (spastic quadriplegia)
• Loss of eye muscle control
• Weakness of the face, arms, and legs (upper motor neuron syndromes)

A head MRI scan would reveal an abnormality in the brainstem (pons). This is the main diagnostic test.

Other tests may include:

• Blood sodium levels and other blood tests
• Brainstem auditory evoked response (BAER)

Treatment

This is an emergency disorder. You will need to go to a hospital for diagnosis and treatment.

There is no known cure for central pontine myelinolysis. 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 nerve damage caused by central pontine myelinolysis is usually long-lasting. The disorder can cause serious long-term (chronic) disability.

Complications

• 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

Calling your health care provider

There is no real guideline on when to seek medical attention, because this condition is rare in the general community.

Prevention

Gradual, controlled treatment of low or high sodium levels may reduce the risk of nerve damage in the pons. Being aware of how some medications can change sodium levels can prevent these levels from changing too quickly.

Answer 2

Definition

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

Alternative Names

Osmotic demyelination syndrome

Causes, incidence, and risk factors

The destruction of the myelin sheath that covers nerve cells prevents signals from being properly transmitted in the nerve. This decreases the nerve's ability to communicate with other cells.

The most common cause of central pontine myelinolysis is a quick rise in the body's sodium levels. This most often occurs when someone is being treated for low blood levels of sodium (hyponatremia) and the levels rise too fast. It also can occasionally occur when high levels of sodium in the body (hypernatremia) are corrected too quickly.

This condition does not occur on its own. It is a complication of treatment for other conditions or from the other conditions themselves.

Risks include:

• Alcoholism
• Liver disease
• Malnutritionfrom serious illnesses

Symptoms

• Confusion, delirium
• Balance problems
• Difficulty swallowing
• Hallucinations
• Reduced alertness, drowsiness or sleepiness, lethargy, poor responses
• Speech changes, poor enunciation
• Tremor
• Weakness in the face, arms, or legs, usually affecting both sides of the body

Signs and tests

An examination may show:

• Abnormal reflexes
• Confusion
• Involvement of all four arms and legs (spastic quadriplegia)
• Weakness of the face, arms, and legs (upper motor neuron syndromes)

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

Other tests may include:

• Blood sodium levels and other blood tests
• Brainstem auditory evoked response (BAER)

Treatment

This is an emergency disorder. You will need to go to a hospital for diagnosis and treatment. However, most people with this condition are already in the hospital for another condition.

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.

Expectations (prognosis)

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

Complications

• 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

Calling your health care provider

There is no real guideline on when to seek medical attention, because this condition is rare in the general community.

Prevention

Gradual, controlled treatment of low sodium levels may reduce the risk of nerve damage in the pons. Being aware of how some medications can change sodium levels can prevent these levels from changing too quickly.

References

Skorecki K, Ausiello D. Disorders of sodium and water homeostasis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 117.

Reviewed By

Review Date: 08/27/2010

David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.