Central Pontine Myelinolysis (Osmotic Demyelination Syndrome)

What is central pontine myelinolysis?

Central pontine myelinolysis (CPM) is a condition affecting myelin and nerve cells in the middle part of your brainstem called the pons. Your brainstem relays information between your spinal cord and the larger “thinking” part of your brain. It also helps control essential functions like breathing, digestion and heart rate. Another name for CPM is osmotic demyelination syndrome.

In central pontine myelinolysis (CPM), damage to the myelin sheath — the protective covering around nerve cells— happens and can lead to the injury and death of nerve cells in the pons. This damage most commonly occurs when your sodium levels rise too quickly, usually as a result of being treated for low sodium levels.

CPM has a wide range of symptoms, including muscle weakness, paralysis, difficulty speaking and behavioral changes. Many people with CPM recover fully. Others may have ongoing disabilities that interfere with their daily lives. In rare cases, CPM leads to death.

Who is at risk of central pontine myelinolysis?

Any disease or condition that leads to low sodium levels can increase the risk for CPM. People with low sodium levels for more than 48 hours are at the highest risk of CPM.

The main conditions associated with CPM are:

• Alcohol use disorder.
• Liver transplantation.
• Burns.
• Hyperemesis gravidarum (severe nausea and vomiting during pregnancy).
• Malnutrition.

How common is central pontine myelinolysis?

Healthcare providers aren’t sure how often CPM occurs. One reason is that many people with mild CPM don’t have symptoms.

Severe CPM is most common in people with alcohol use disorder, liver transplantation and other serious illnesses.

What causes central pontine myelinolysis?

The most frequent cause of central pontine myelinolysis is a rapid increase in sodium levels. This can happen during treatment to correct low sodium levels (hyponatremia).

Sodium is an important electrolyte in your body and helps maintain fluid balance in your cells. Excess alcohol use, liver disease and many other health conditions can cause low sodium levels. Untreated hyponatremia can lead to severe illness and hospitalization.

Once hospitalized, healthcare providers correct low sodium levels with an intravenous (IV) sodium solution. CPM can happen when your sodium level rises too fast.

How does central pontine myelinolysis occur?

When sodium levels in your blood rise quickly, water moves out of nerve cells and they become dehydrated. This dehydration can damage nerve cells and the myelin sheath that surrounds and insulates them, causing myelinolysis.

Nerve cells in the pons of the brainstem are especially prone to myelinolysis.

What is the difference between central pontine myelinolysis and extrapontine myelinolysis?

Myelinolysis doesn’t always occur in the pons (the middle part of your brainstem). Extrapontine myelinolysis (EPM) is when myelinolysis occurs outside the pons in other parts of your brain. EPM rarely occurs without CPM. About 1 in 4 people with CPM also have EPM.

What are the symptoms of central pontine myelinolysis?

Symptoms of CPM usually appear several days after the rapid correction of sodium levels. These can vary depending on where in your brain the myelination is and how much damage there is, but may include:

• Behavioral changes.
• Confusion.
• Difficulty speaking (dysarthria).
• Difficulty swallowing (dysphagia).
• Facial paralysis.
• Muscle weakness.
• Loss of balance and coordination.
• Involuntary muscle movement and tremors.
• Irregular eye movements (oculomotor dysfunction).
• Parkinsonism (Parkinson’s disease-like symptoms, such as tremors and speech difficulties).
• Quadriparesis (weakness in both arms and legs).

In severe cases, CPM causes paralysis of all muscles except for your eye muscles (locked-in syndrome), coma or death.

How is central pontine myelinolysis diagnosed?

To diagnose CPM, your healthcare provider will:

• Ask about your symptoms.
• Review possible causes, including your sodium levels from when you were treated.
• Perform an MRI.

An MRI allows your healthcare provider to view the lesions (damaged areas) caused by myelinolysis. These lesions may not be visible with MRI for up to two weeks after symptoms begin.

How is central pontine myelinolysis treated?

There isn’t a standard treatment for CPM. The goal of treatment is usually to manage the symptoms. For example, dopaminergic drugs (drugs that increase dopamine) can be effective for people with symptoms similar to Parkinson’s disease (tremors or speech difficulties).

Healthcare providers have successfully treated CPM by bringing sodium levels back down, then very slowly bringing them back up again. However, this treatment isn’t always effective for all people with CPM.

How can I prevent central pontine myelinolysis?

Be aware if you have a health condition that can cause low sodium levels. If you have alcohol use disorder, ask your healthcare provider for help. Alcohol use disorder causes hyponatremia. It can also lead to liver failure and transplantation, the other main cause of CPM.

Is central pontine myelinolysis reversible?

Recent studies report that 94% of people survive CPM, and between 25% and 40% of people make a complete recovery.

About 25% of people with CPM don’t fully recover. These people may need lifelong support. Therapies such as speech, occupational and physical therapy can help them function in their daily lives.

How can I live with CPM?

Your healthcare provider will provide instructions for your care. By following this treatment plan, you can manage your symptoms that may be interfering with your everyday activities.

You and your family may also benefit from supportive services. Talk to your healthcare provider about services available to you, such as in-home care and support groups and resources.

How can I get help for alcohol use disorder?

Healthcare providers treat alcohol use disorder with behavioral therapy and medications. Support groups are also widely available to provide encouragement and accountability.

People with alcohol use disorder have several options for where they receive treatment, including the hospital, a residential rehabilitation facility or outpatient services.

The first step in recovering from alcohol use disorder is to admit there may be a problem. When you seek help from your healthcare provider, you improve your chances of recovery.

A note from Cleveland Clinic

Healthcare providers can prevent central pontine myelinolysis (CPM) by following current clinical guidelines for safely increasing sodium levels in people with hyponatremia (below normal sodium level). You can reduce your own risk of hyponatremia and CPM by eliminating alcohol consumption if you have alcohol use disorder. If you need help, talk to your healthcare provider. They can help connect you with the support and resources you need to change your lifestyle and adopt healthier habits.