Central Pontine Myelinolysis

What is Central Pontine Myelinolysis?

It is a brain cell dysfunction resulting from destruction of the myelin sheath or the layer that covers the nerve cells in the region of the brainstem known as the Pons. This is an acute neurological condition that is also referred to as “Osmotic Demyelination Syndrome”.

Central pontine myelinolysis Symptoms

Some of the main signs and symptoms of Central pontine myelinolysis (CPM) are:

  • Constipation
  • Delirium
  • Difficulties in swallowing
  • Drowsiness or sleepiness
  • Hallucinations
  • Lethargy
  • Loss of consciousness
  • Mental confusion
  • Muscle paralysis
  • Poor diction
  • Poor responses
  • Problems in maintaining balance
  • Reduced level of alertness
  • Slurred speech
  • Tremor
  • Weakness in muscles in the arms, legs or face (generally affecting both sides of the human body)

Some patients also suffer from a condition in which they are actually conscious and aware but seem to be unresponsive. This is known as “locked in state”. This usually occurs due to damage to the myelin sheath that acts as a covering for the nerve cells. The myelin sheath damage interferes with the ability of the nerves to properly transmit signals to each other. It also reduces the ability of the nerves to communicate information with other cells.

It can also cause long term disabilities or even death. Many patients enter into a comatose state as a result of this damage. Most sufferers experience at least a few lingering effects due to the presence of this disorder.

Central pontine myelinolysis Causes

It is not clearly known how the myelin sheath damage occurs. However, changes in sodium levels can lead to rapid movement of fluids in and out of the myelin sheath. This can give rise to damages in the myelin.

The condition commonly results from a rapid increase in the sodium levels of the human body. A rapid rise often occurs in patients who are being treated for Hyponatremia, a condition characterized by low sodium in bloodstream. Doctors infuse Hyponatremia patients with salts to restore the balance of sodium in their body. If this is carried out very fast, patients may suffer from CPM. This is particularly true in cases where low level of sodium persists for two or more days. Occasionally, it may also occur when medications quickly decrease sodium levels in patients of Hypernatremia, a condition marked by too much sodium in the bloodstream. Bringing down sodium levels too fast may cause damage to the myelin sheath in the Pons.

Central Pontine Myelinolysis Risk Factors

This disease does not arise on its own. It usually arises as a complication of treatments designed to address conditions or due to the conditions themselves. The risk factors for this disease include:

  • Alcoholism
  • Anorexia
  • Burn injuries
  • Bulimia
  • Dehydration
  • Liver disease
  • Malnutrition from acute disorders

Central pontine myelinolysis Diagnosis

A head MRI scan is the main diagnostic examination for this problem. It can display a problem in the Pons area of the brainstem.

Other tests may involve:

  • Blood tests
  • Examination of sodium levels in the bloodstream
  • Brainstem auditory evoked response (BAER)

Magnetic Resonance Imaging (MRI) scans can also be used to detect sure signs of brain damage resulting from CPM. Such diagnostic tests may help reveal problems like confusion, abnormal reflexes and involvement of all four limbs (Spastic Quadriplegia). It can also indicate weakness of muscles in the face, legs and arms (Upper Motor Neuron Syndrome).

Central pontine myelinolysis Treatment

There is no known treatment for this condition. Curative approach mainly focuses on providing supportive care to relieve symptoms and involves:

  • Physical therapy – It involves administering ventilator support to patients to help them breathe. It may help people affected with CPM maintain mobility, muscle strength and function in weakened limbs.
  • Language therapy – If patients are unable to speak, developing alternative communication modes can be a good curative method.
  • Alternative diet – If patients cannot eat, providing them with supplementary nutrition can be effective in managing the condition.

While some patients may retain their capability and achieve progress from this brain injury during recovery, others may need permanent hospitalization or personal assistance for survival. This is an emergency condition and requires immediate diagnosis and medical treatment. In some cases, patients may have to be hospitalized on an immediate basis. However, most people affected by this disorder are already admitted to hospitals due to the presence of some other condition.

Central pontine myelinolysis Prognosis

The condition usually gives rise to long-term nerve damage as well as chronic cases of disability. Overall, the disease is found to have a poor prognosis. The degree of recovery actually depends on the actual number of axons that are damaged.

Most patients with CPM manage to survive even though some of them die. One-third of surviving patients recovers gradually; one-third lives independently but with disabilities and one-third is found to survive with severe disabilities. Permanent disabilities can vary from small tremors and ataxia to more acute brain damages like Locked-in syndrome and Spastic quadriparesis. Once the condition stabilizes, some patients show improvements during the first several months.

Central pontine myelinolysis Complications

If not treated in time, this condition may give rise to various complications like

  • Reduced ability to work or take care of self or others
  • Lowered ability to communicate with others
  • Inability to move about, control muscles or perform any activity other than blinking eyes (known as “Locked in” Syndrome)
  • Permanent damage to the nervous system

Central pontine myelinolysis Prevention

There are no specific measures that can help one prevent this condition. However, it has been advocated that avoiding rapid change of sodium levels can help one avoid this disorder. Slow and controlled treatment of low levels of sodium may lessen the risk of nerve damage in the brain region known as the Pons. It may also help being aware of how certain drugs can change sodium levels too quickly.

As this is a rare disorder in general, medical researchers do not have an idea on when patients should seek medical treatment. However, it is ideal to seek medical attention at the first signs of difficulties like muscular weakness, tremors or slurred speech. Even if the underlying condition is not Central Pontine Myelinolysis, medical assistance can be useful in averting other complicated syndromes.

References:

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001779/

http://emedicine.medscape.com/article/1174329-overview

http://www.mayoclinicproceedings.com/content/76/5/559.full.pdf

http://patients.aan.com/disorders/index.cfm?event=view&disorder_id=875