Central pontine myelinolysis (CPM) is a neurological disorder that affects the brain. “Pontine” refers to the stem of the brain, called the pons. “Myelinolysis” means that the myelin — a covering that protects the pontine nerve cells — is being destroyed.

CPM usually happens as the result of another illness or medical condition. The destruction of myelin is generally not spontaneous.

People who have CPM can’t be cured, but their symptoms can be treated. The nerve damage can become chronic and may lead to permanent disabilities. Some people will need assistance dressing, feeding themselves, and accomplishing other routine tasks.

In rare cases, CPM can lead to locked-in syndrome, coma, or even death. Locked-in syndrome is a condition in which all mobility and muscle control is lost. People with locked-in syndrome can move only their eyes.

Symptoms of CPM involve both movement and cognitive function. The damage to your myelin sheaths can cause damage to the brainstem nerves.

Nerve damage interferes with the communication between the nervous system and muscles. As a result, you may suffer from:

  • muscle weakness in the face, arms, and legs
  • delayed or poor reflexes and responses
  • slowed speech and poor enunciation
  • tremors
  • swallowing difficulties
  • poor balance

CPM can also damage your brain cells. The damage can affect your mental health as well as your physical health. You may experience mental confusion or hallucinations, or you may appear to be in a delirious state. Some people suffer from intellectual impairment as a result of central pontine myelinolysis.

The most common cause of CPM is a rapid increase in blood sodium levels. Sodium is an electrolyte mineral that carries an electrical charge in your body. Sodium helps regulate your fluid levels, making sure that your cells are well hydrated. Central pontine myelinolysis can occur when your blood sodium levels increase sharply and quickly. The reason for this damage is not entirely clear yet, but it involves the rapid shift of water in the brain cells.

People who are treated for hyponatremia have an increased risk of developing CPM. Hyponatremia is the state of low blood sodium levels. Hyponatremia can cause a variety of health conditions. These can include:

  • nausea
  • vomiting
  • muscle cramps
  • seizures
  • coma

Treatment for low sodium levels includes the intravenous infusion of a sodium solution and can cause the sodium level to rise too quickly. You are more likely to develop central pontine myelinolysis if you put off treatment for hyponatremia for two days or more.

Chronic alcoholism, liver disease, and malnutrition increase your risk of developing CPM. These conditions are likely to cause changes in your sodium levels.

Your doctor will run blood tests to measure your sodium levels to help diagnose CPM. Magnetic resonance imaging, or MRI, is a test that uses radio waves to create images of your internal organs. An MRI of your head can show any damage to your brainstem.

You may also take a brainstem auditory evoked response (BAER) test. Your doctor will attach electrodes to your head and ears, and then play a series of clicks and other sounds through headphones. BAER measures your response time and brain activity when you hear each sound.

CPM is a serious medical condition and must be treated on an emergency basis. Get medical care as soon as possible if you experience symptoms consistent with the condition. Treatment is geared toward managing your symptoms, and can include:

  • fluids and medication to safely regulate your sodium levels
  • dopaminergic medications (such as levodopa) to increase dopamine and control tremors and difficulties with speech and swallowing in people who develop Parkinsonian symptoms
  • physical therapy to improve balance and retain range of motion

People with CPM can improve with appropriate treatment, but may still have chronic problems with balance, mobility, and response time. CPM was originally believed to have a mortality rate of 50 percent, but early diagnosis has improved the outlook. Although some people still die as a result of the damage sustained, many people with CPM are able to recover. Most people who have recovered from CPM will still need some ongoing therapy and supportive care to manage the effects on a long-term basis.

It’s important to manage your blood sodium levels to help prevent CPM. If you have a condition that puts you at risk for hyponatremia, make sure you’re aware of the signs of low blood sodium and stay on top of your treatment.

It’s important to stay properly hydrated to maintain fluid balance and sodium levels in your body. Staying hydrated on a daily basis is always recommended.