Central pontine myelinolysis (CPM) is a rare neurological disorder that affects the brain. It’s more common in adults than in children.

“Pontine” refers to the pons, a part of the brain stem. “Myelinolysis” means that the myelin — the covering that protects nerve cells, including the pontine nerve cells — is being destroyed.

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

The disorder can’t be cured, but its symptoms can be treated.

CPM is one of the two types of osmotic demyelination syndrome (ODS). The other type, known as extrapontine myelinosis (EPM), occurs when myelin is destroyed in areas of the brain that aren’t in the brain stem.

Around 10 percent of people with CPM also have EPM, according to the National Institute of Neurological Disorders and Stroke (NINDS).

On the other hand, EPM rarely occurs without CPM.

Symptoms of CPM involve both physical movement and cognitive function.

The damage to your myelin can cause damage to your brain stem nerves. Nerve damage interferes with the communication between the nervous system and muscles. As a result, you may experience:

CPM can also damage your brain cells, which can affect your mental health as well as your physical health.

You may experience confusion or hallucinations, or you may appear to be in a delirious state. Some people experience intellectual impairment as a result of CPM.

The most common cause of CPM is a rapid increase in blood sodium levels.

Sodium is an electrolyte mineral that helps regulate your fluid levels, ensuring that your cells are well hydrated.

CPM can occur when your blood sodium levels increase sharply and quickly. Experts aren’t entirely clear on the reason for this damage, but it involves the rapid shift of water in the brain cells.

People who are treated for hyponatremia, or low blood sodium levels, have an increased risk of developing CPM. Hyponatremia can cause a variety of symptoms and conditions, including:

Treatment for low sodium levels includes the intravenous (IV) infusion of a sodium solution. However, if administered improperly, it can cause the body’s sodium level to rise too quickly.

You’re more likely to develop CPM if your hyponatremia goes untreated for at least 2 days.

Chronic alcohol misuse, liver disease, and malnutrition also increase your risk for developing CPM. These conditions are likely to cause changes in your sodium levels.

To help diagnose CPM, your doctor will run blood tests to measure your sodium levels.

An MRI of your head can show any damage to your brain stem.

You may also take a brainstem auditory evoked response (BAER) test. During this test, your doctor will attach electrodes to your head and ears.

Then they’ll 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. If you have symptoms consistent with the condition, get medical care as soon as possible.

Treatment is geared toward managing your symptoms and can include:

  • fluids and medication to safely regulate your sodium levels
  • physical therapy to improve balance and retain range of motion
  • dopaminergic medications, such as levodopa (Inbrija), for people who develop Parkinson-like symptoms

Dopaminergic medications are used to:

  • increase dopamine
  • manage tremors
  • manage difficulties with speech or swallowing

People with CPM can see their symptoms improve with appropriate treatment, but they may still have chronic problems with balance, mobility, and response time.

The nerve damage can become chronic too 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
  • even death

Locked-in syndrome is a condition in which a person loses all mobility and muscle control. People with locked-in syndrome can move only their eyes.

CPM was originally believed to have a mortality rate over 50 percent, but early diagnosis has improved the outlook.

Although some people still die as a result of the brain damage sustained, many people with CPM are able to recover. Recent research puts the survival rate at around 94 percent.

Between 25 and 40 percent of people recover without undergoing any longlasting effects.

However, most people who’ve recovered from CPM will still need some ongoing therapy and supportive care to manage its effects on a long-term basis.

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

Staying hydrated on a daily basis is also recommended. It will help your body maintain fluid balance and proper sodium levels.