What Is Central Pontine Myelinolysis?
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.
The destruction of myelin is generally not spontaneous, according to the National Institutes of Health (NIH). CPM usually happens as the result of another illness or medical condition.
People who have central pontine myelinolysis cannot 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.
Causes 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 National Institute of Neurological Disorders and Stroke explains that the reason for this damage is not entirely clear, but it involves the rapid shift of water in the brain cells (NINDS, 2009).
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 ranging from nausea, vomiting, and muscle cramps to seizures and 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 (NINDS, 2009).
Chronic alcoholism, liver disease, and malnutrition increase your risk of developing CPM. These conditions are likely to cause changes in your sodium levels.
Symptoms of Central Pontine Myelinolysis
Symptoms of central pontine myelinolysis involve both movement and cognitive function. The damage to your myelin sheath can cause damage to the brainstem nerves themselves.
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
- swallowing difficulties
- poor balance
CPM can also damage your brain cells. The damage can affect your mental state 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.
Diagnosing Central Pontine Myelinolysis
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 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.
Treatment for Central Pontine Myelinolysis
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 patients who develop Parkinsonian symptoms
- physical therapy to improve balance and retain range of motion
Outlook for Central Pontine Myelinolysis
People with central pontine myelinolysis 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 (NINDS, 2009). Although some people still die as a result of the damage sustained, many patients with CPM are able to recover to some degree.