Definition Post polio syndrome (PPS) affects people who have had the poliomyelitis virus, or polio, anywhere from 10 to 40 years before. Of the 300,000 polio survivors in the US, one-quarter to one-half will have symptoms of PPS. If the initial bout with polio was severe, there is a greater chance of developing post polio syndrome. There is also a greater chance of developing more severe PPS symptoms.
What is going on in the body? Individual nerve terminals in the motor units die, causing deterioration. Muscles that were already weakened by the first bout with the polio virus become even weaker.
PPS is usually not life-threatening unless breathing is impaired. Post polio syndrome is not a recurrence of polio. It is a response to polio, rather than a part of it.
What are the signs and symptoms of the disease? People with post polio syndrome can have fatigue, muscle and joint pain, and muscular atrophy. Atrophy means a wasting or decrease in the size of muscles. People with PPS have progressive muscle weakness. Sometimes the muscles in the spine atrophy and the symptoms mimic amyotrophic lateral sclerosis, or ALS, also known as Lou Gehrig's disease. Some people also have an intolerance to cold, and trouble with swallowing, breathing, and sleeping.
What are the causes and risks of the disease? The cause of PPS is the death of individual nerve terminals in the motor units that remain after a bout of polio.
The deterioration may actually result from the process of recovery from polio. During recovery, surviving motor neurons sprout new endings. This allows the body to regain function. The motor units become large and add stress to the body. The person may have normal function for quite some time, even years. But the body may not be able to meet the metabolic demands of all the new sprouts. A slow deterioration can develop. Nerves may be restored again, but eventually the nerve terminals are destroyed. The body develops permanent weakness.
This hypothesis fits with the unpredictable course of post polio syndrome. Post polio syndrome progresses very slowly and there are long periods of stability.
What can be done to prevent the disease? The best way to prevent PPS is for all children to receive the polio vaccine so they don't get polio in the first place. People who have had polio may benefit from a healthy lifestyle. This that means a well-balanced diet, moderate exercise, and regular checkups.
How is the disease diagnosed? Post polio syndrome is difficult to diagnose because it progresses very slowly, and is stable for long periods. It's hard to figure out which muscle and nerve deficits are old and which are new. A neurological examination and laboratory tests can exclude other problems.
To find out what is going on in the body, doctors may use:
analysis of cerebrospinal fluid, obtained with a spinal tap
measurements of muscle force
electrophysiological studies, which examine the body's response to electrical stimulation. These would include electromyography and nerve conduction velocity studies.
What are the long-term effects of the disease? The long term effects differ from person to person. Muscles become progressively weaker over time. The severity of the muscle weakness varies. As people develop more symptoms, they may have depression, anxiety, or lowered self-esteem. Support groups, medication, or counseling may help. Physiotherapy can help people learn how to exercise properly and conserve energy.
What are the risks to others? Post polio syndrome is not contagious, so there are no risks to others.
What are the treatments for the disease? The medication pyridostigmine can make some people feel less tired. Several medications are being studied that may improve strength or help motor neurons to grow.
The role of exercise is much debated. Some doctors think exercise can worsen the condition and that rest will preserve energy. Others believe that exercise, in moderation, can help. The current recommendation is to test people with PPS to find their tolerance. Tolerance is the level at which people begin to get tired or uncomfortable. People are then taught to exercise within their tolerance limits. They are learn to pace themselves so they do not become fatigued. There is ongoing debate about which types of exercise may be helpful and which types may be harmful.
What are the side effects of the treatments? All medications can have side effects. Medications that combat fatigue may cause sleep disorders such as insomnia in some people.
What happens after treatment for the disease? The course of post polio syndrome is unpredictable. However, a healthy lifestyle and exercise within tolerance can increase the individual's quality of life.
How is the disease monitored? Regular visits to the doctor are needed to monitor muscle weakness and fatigue over time.
Author: Terry Mason, MPH Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
