Post-Polio Syndrome

Post-polio syndrome (PPS) is a disorder of the nervous system that affects many people who had poliomyelitis many years earlier.  Polio (short for poliomyelitis, long ago called infantile paralysis) is a viral disease that disabled or killed thousands of people, predominately children and young adults, each year in the United States and countless others worldwide during the first half of the last century.

Natural polio infections have been eliminated from the Americas for the past two decades, but many survivors of past polio epidemics are developing new problems.

Incidence; Causes and Development

All told, as many as 250,000 U.S. polio survivors may have PPS.

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 in the spinal cord that control muscles (the motor neurons) 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 renewed muscle weakness.

Some research suggests that the normal aging process also plays a role.  After the age of 60, 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.

Signs and Symptoms

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 unaffected 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.

Not all individuals with one or more of the symptoms have PPS.  Some, after medical evaluation, are found to have arthritis, tendonitis and cartilage damage, all of which can occur in the aging process but which are more common when movement and weight-bearing have been altered by the effects of weakened muscles.  Various other conditions also cause progressive muscle weakness or fatigue.

Diagnosis and Tests

Polio survivors who suspect that they may have PPS should consult their physician, who may refer them to neurologists or other specialists, preferably having experience with post-polio patients.  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.  There is no definitive test for PPS.  Continuing care, if needed, usually is supervised by experts in centers for rehabilatative medicine.

Treatment and Prevention

Treatment often can lessen or eliminate some of the symptoms.  Most people with PPS can benefit from some form of exercise: an appropriate, non-fatiguing 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, PPS patients 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 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.