Post-polio syndrome (PPS) is a syndrome that affects some people who have had polio (poliomyelitis) and occurs many years (typically from 10 to 40 years) after recovery from the initial infection. It is characterized by the development of progressive weakness in muscles that were affected by the original polio infection. In addition, those affected may experience extreme fatigue and joint pain. Skeletal deformities, such as scoliosis, may occur as a result of this syndrome. There is variation in the severity of symptoms. In severe cases, symptoms may mimic those of the rare disorder known as Lou Gehrig's disease (amyotrophic lateral sclerosis). The degree of muscle atrophy during the post-polio period appears to reflect the severity of the impact of the initial polio infection. People who were significantly affected by polio are more likely to experience severe symptoms from post-polio syndrome. The cause of this syndrome is not known. Although exact numbers are not available, it has been estimated that there are 300,000 polio survivors in the United States and that from one-fourth to one-half of them may ultimately develop some degree of post-polio syndrome.
Post-polio syndrome occurs at least 10 years after a person has been stricken by polio. It is characterized by gradual deterioration of muscle function and increased weakness that usually occurs in the limbs that were most severely affected by polio. Sometimes, the disorder involves muscles that appeared to be fully recovered or that were not involved in the original polio attack, including muscles necessary for respiration. Other symptoms may include fatigue, muscle pain and twitching (fasciculations).
The fatigue associated with PPS comes on unexpectedly, sometimes as a feeling of total exhaustion throughout the body. Pain in the muscles and joints is not uncommon. Also, the affected person may experience problems related to swallowing, breathing, and sleeping. People with PPS are less able to tolerate the cold, and they are less able to carry on with day-to-day activities such bathing, dressing, and walking.
The cause of post-polio syndrome is not known at this time. One theory is that it may be related to the recovery from the original polio. During recovery from polio, nerve cells in affected muscles may regrow many smaller branches (dendrites) from the message-transmitting large branches (axons) of nerve cells. These sprouts take over the function of neurons killed by the polio virus. It is thought that, after years of functioning beyond capacity, the nerve cells weaken and lose their ability to maintain these tiny dendrites, which then begin to shrink, and the whole muscle becomes weaker. Additional research is needed to determine whether this may, in fact, be the cause of post-polio syndrome.
Although this syndrome sometimes resembles amyotrophic lateral sclerosis (ALS), it is not considered to be a form of that disease.
Post-polio syndrome affects people who have had acute episodes of poliomyelitis. It occurs 10 years or more after the original illness, and can occur as long as 40 years afterward. According to one estimate, 25% to 50% of the 300,000 polio survivors in the United States may develop the syndrome. At the present time, there is no known way to prevent the syndrome.
Diagnosis of post-polio syndrome is made on the basis of a thorough history, a neurological examination, and the process of excluding other possible diseases through various tests. In making the diagnosis, physicians will be aware of three factors. a prior diagnosis of polio, an interval of one or more decades since the original acute episode, and slow, steady, progressive deterioration.
There are no specific treatments for PPS at this time. The goal of management of this disorder is to make the patient as comfortable as possible.
Affected individuals are taught to conserve energy by pacing their activities and combining these with periods of rest. Mechanical assists such as canes, walkers, and scooters may be helpful.
Moderate exercise is seen by many physicians as beneficial for those affected. Swimming is one type of exercise that is sometimes recommended. Speech therapy may be helpful for individuals whose swallowing has been affected.
Also, occupational therapy can lead to adjustments in the home environment that may allow those affected to carry out common activities in ways that are less energy-consuming.
Two clinical trials sponsored by the National Institute of Neurological Disorders and Stroke (NINDS) are being carried out (2005) at the Clinical Center on the NIH campus in Bethesda. For additional information, contact the NIH Clinical Center at the phone numbers or email address listed above.
One is designed to determine whether electromyography (a test of the communication between nerves and muscle cells) is a reliable diagnostic tool for post-polio syndrome. The other is designed to determine whether the drug Modafinil can decrease fatigue in patients with post-polio syndrome.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
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FROM THE INTERNET
NINDS Post-Polio Syndrome Information Page. NINDS. Last updated March 29, 2005. 2pp.
Post-polio syndrome. MayoClinic.com. March 04, 2005. 6pp.
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