Osmotic demyelination syndromeODS; Central pontine demyelination
Osmotic demyelination syndrome (ODS) 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).
Myelin is an insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty ...
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 ODS 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.
Low sodium level is a condition in which the amount of sodium in the blood is lower than normal. The medical name of this condition is hyponatremia....
ODS does not usually occur on its own. Most often, it's a complication of treatment for other problems, or from the other problems themselves.
- Alcohol use
- Liver disease
- Malnutrition from serious illnesses
- Radiation treatment of the brain
- Severe nausea and vomiting during pregnancy
Symptoms may include any of the following:
- Confusion, delirium, hallucinations
Confusion is the inability to think as clearly or quickly as you normally do. You may feel disoriented and have difficulty paying attention, remembe...
Delirium is sudden severe confusion due to rapid changes in brain function that occur with physical or mental illness.
- Balance problems, tremor
- Problem swallowing
- Reduced alertness, drowsiness or sleepiness, lethargy, poor responses
Decreased alertness is a state of reduced awareness. A coma is a state of decreased alertness from which a person cannot be awakened. A long-term co...
Drowsiness or sleepiness
Drowsiness refers to feeling abnormally sleepy during the day. People who are drowsy may fall asleep in inappropriate situations or at inappropriate...
- Slurred speech
- Weakness in the face, arms, or legs, usually affecting both sides of the body
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.
A head MRI (magnetic resonance imaging) is an imaging test that uses powerful magnets and radio waves to create pictures of the brain and surrounding...
Other tests may include:
ODS 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.
The nerve damage caused by central pontine myelinolysis is often long-lasting. The disorder can cause serious long-term (chronic) disability.
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 ODS is rare in the general community.
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.
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.
Yaqoob MM, McCafferty K. Water, electrolytes and acid–base balance. In: Kumar P, Clark M, eds. Kumar and Clark's Clinical Medicine. 9th ed. Philadelphia, PA: Elsevier; 2017:chap 9.
Central nervous system and peripheral nervous system - illustration
The central nervous system is comprised of the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.
Central nervous system and peripheral nervous system
Review Date: 4/30/2018
Reviewed By: Amit M. Shelat, DO, FACP, Attending Neurologist and Assistant Professor of Clinical Neurology, SUNY Stony Brook, School of Medicine, Stony Brook, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.