Osmotic demyelination syndromeODS; Central pontine demyelination; Central pontine myelinolysis
Osmotic demyelination syndrome (ODS) leads to 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 ...Read Article Now Book Mark Article
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 blood 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 blood sodium is a condition in which the sodium level in the blood is lower than normal. The medical name of this condition is hyponatremia....Read Article Now Book Mark Article
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
Alcohol use disorder is when your drinking causes serious problems in your life, yet you keep drinking. You may also need more and more alcohol to f...Read Article Now Book Mark Article
- Liver disease
- Malnutrition from serious illnesses
Malnutrition is the condition that occurs when your body does not get enough nutrients.Read Article Now Book Mark Article
- 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...Read Article Now Book Mark Article
Delirium is sudden severe confusion due to rapid changes in brain function that occur with physical or mental illness.Read Article Now Book Mark Article
Hallucinations involve sensing things such as visions, sounds, or smells that seem real but are not. These things are created by the mind.Read Article Now Book Mark Article
- Balance problems, tremor
- Problem swallowing
- Reduced alertness, drowsiness or sleepiness, lethargy, poor responses
Decreased alertness is the most severe state of reduced awareness and is a serious condition. A coma is a state of decreased alertness from which a p...Read Article Now Book Mark Article
Drowsiness or sleepiness
Drowsiness refers to feeling more sleepy than normal during the day. People who are drowsy may fall asleep in when they do not want to or at times w...Read Article Now Book Mark Article
Fatigue is a feeling of weariness, tiredness, or lack of energy.Read Article Now Book Mark Article
- 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...Read Article Now Book Mark Article
Other tests may include:
- Blood sodium level and other blood tests
Blood sodium level
The sodium blood test measures the concentration of sodium in the blood. Sodium can also be measured using a urine test.Read Article Now Book Mark Article
- Brainstem auditory evoked response (BAER)
Brainstem auditory evoked response
Brainstem auditory evoked response (BAER) is a test to measure the brain wave activity that occurs in response to clicks or certain tones.Read Article Now Book Mark Article
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: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 84.
Yaqoob MM, McCafferty K. Water balance, fluids and electrolytes. In: Feather A, Randall D, Waterhouse M, eds. Kumar and Clarke's Clinical Medicine. 10th ed. Philadelphia, PA: Elsevier; 2021:chap 9.
Brain structures - illustration
The structures of the brain include the brainstem, consisting of the spinal cord, the medulla oblongata, the pons and the midbrain; the cerebellum; the cerebrum (one half, or hemisphere shown), and the diencephalon.
Review Date: 4/25/2022
Reviewed By: Joseph V. Campellone, MD, Department of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.