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Post-polio syndrome (PPS) is a condition that affects many people who had poliomyelitis many years earlier. Polio (short for poliomyelitis, once called infantile paralysis) is a viral disease that can infect the nervous system, sometimes resulting in paralysis. Until the 1950s, polio disabled or killed thousands of people, predominately children and young adults, each year in the United States and countless others worldwide. Thanks to the Salk vaccine, and soon afterward the Sabin oral vaccine, natural polio infections have been eliminated from the United States for nearly three decades (1). Both vaccines were developed five decades ago with funding from the March of Dimes. However, many survivors of past polio epidemics are developing new problems.

What are the symptoms of PPS?
The main symptom of PPS is new muscle weakness that gradually worsens. It often is accompanied by decreased muscle endurance during activities, muscle and joint pain, muscle wasting and severe fatigue. Even muscles that were believed to be unharmed by the previous bout with polio may be affected. Less frequently, breathing difficulties and swallowing problems may occur. These symptoms usually develop 15 years or more after the original illness (2, 3).

There are more than 440,000 survivors of paralytic polio in the United States (3). Experts estimate that between 25 to 50 percent of these individuals may be affected with PPS (3). However, not all individuals with one or more of PPS symptoms have PPS. Some, after medical evaluation, are found to have arthritis, tendonitis or cartilage damage. All of these conditions can occur in the aging process, but they are more common when weakened muscles alter movement and weight-bearing. Various other conditions also cause progressive muscle weakness or fatigue.

What causes PPS?
The causes of PPS are not completely understood. However, many researchers believe that PPS symptoms result, at least in part, from the unusual stress placed on surviving nerve cells. During the initial attack of polio, some of the nerve cells (called motor neurons) in the spinal cord that control muscles are damaged or destroyed. Without impulses from these nerve cells, a muscle cannot function. Fortunately, some motor neurons usually survive the polio attack and send out new nerve connections to the orphaned muscle cells in an attempt to take over the function of the nerve cells that were destroyed. This process enables an individual to regain at least some use of affected muscles. However, after many years, the overburdened nerve cells may begin to fail, resulting in new muscle weakness.

The normal aging process also may play a role. With age, most people have a decrease in the number of motor neurons in their spinal cords. Persons who have not had polio can lose a considerable number of motor neurons as they age without experiencing any serious muscle weakness. However, among polio survivors who already have lost a considerable number of motor neurons, this age-related loss may contribute to new muscle weakness. Both overuse and underuse of muscles also may contribute to muscle weakness.

How is PPS diagnosed?
Polio survivors who suspect that they may have PPS should consult their physician, who may refer them to a specialist in neuromuscular disorders, preferably one having experience with post-polio syndrome. Such specialists may include neurologists, physiatrists (rehabilitation specialists) and orthopedists. In addition to the neurological examination, doctors often recommend tests, such as imaging studies (computerized tomography and magnetic resonance imaging), to rule out other disorders with similar symptoms. However, there is no definitive test for PPS. Continuing care, if needed, usually is supervised by experts in centers for rehabilitative medicine.

How is PPS treated?
There is no cure for PPS. However, treatment often can lessen or eliminate some of the symptoms. Most people with PPS can benefit from some form of exercise. An appropriate, nonfatiguing exercise program designed by a physician or physical therapist knowledgeable about PPS may help improve muscle strength and functioning. Some individuals are able to participate in some forms of aerobic training, while many others may benefit from gentle stretching or yoga. However, affected individuals who are too weak and fatigued from their normal daily activities may be advised to avoid exercise.

Fatigue is best treated with lifestyle changes, including regular rest periods and daytime naps. Individuals with muscle fatigue limited to specific muscle groups should pace themselves carefully, interspersing bouts of physical activity with rest periods over the course of a day. They may want to consider discontinuing unnecessary energy-consuming activities, such as bed-making, and sit instead of stand, whenever possible. Weight loss also may be beneficial. In some cases, changing to a more sedentary job or working fewer hours may be helpful. Assistive devices (such as braces, canes, orthotics, and intermittent use of wheelchairs or motorized scooters for long distances) can help conserve energy.

There are a number of causes of pain in PPS. In some cases, treatment of other conditions, such as arthritis and tendonitis, will ease symptoms. Muscle overuse is another common cause of pain in PPS patients. Physical therapy and the lifestyle modifications discussed may help ease pain. Use of moist heat, ice and massage also may help. A number of medications also may be prescribed, when necessary, to ease pain.

Individuals with breathing problems should have yearly flu shots and receive the pneumococcal vaccine, which helps prevent pneumonia. These individuals also may benefit from nighttime breathing assistance, which may help improve sleep and energy levels. Instruction on special swallowing techniques and diet alterations can make eating easier for those with swallowing problems.

Is there any way to prevent PPS?
There is currently no known way to prevent PPS in individuals who had paralytic polio in the past.

What is the March of Dimes role?
The March of Dimes provides information to PPS patients and concerned professionals, and has provided grant support for research projects seeking improved treatments for PPS. In May 2000, the March of Dimes, in collaboration with the Roosevelt Warm Springs Institute for Rehabilitation, held an international conference on PPS, during which leading experts in the field shared information on its causes, diagnosis and treatment. A report of the conference's proceedings has been published and distributed to medical professionals in order to help improve the care of PPS patients (2, 4).

For more information
Post-Polio Health International

References

1. Centers for Disease Control and Prevention (CDC). The Pink Book: Epidemiology and Prevention of Vaccine-Preventable Diseases, 10th Edition, February 2007.
2. March of Dimes Steering Committee on Post-Polio Syndrome. March of Dimes International Conference on Post-Polio Syndrome: Identifying Best Practices in Diagnosis and Care. White Plains, N.Y., 2002.
3. National Institute of Neurological Disorders and Stroke. Post-Polio Syndrome Fact Sheet. April 17, 2007.
4. March of Dimes. Guidelines for People Who Have Had Polio. White Plains, N.Y., 2002.

November 2007
 

See also: Post-Polio Syndrome: Identifying Best Practices in Diagnosis & Care (PDF, 7mb)