The late effects of poliomyelitis have been recorded in the literature since 1875 by various authors. These new problems occur at an average of 35 years after the acute onset, and thus it was not until the 1980s that the large number of survivors from the great epidemics of 1940 to 1957 made an impact on the medical system. The postpolio sequella or syndrome (PPS) is a combination of neurological, musculoskeletal, and psychosocial manifestations. The most common physical problems are profound fatigue, pain, and new weakness with decreased function, safety concerns, and decrease in quality of life. Other physical problems include muscle fasciculation and cramps, hypoventilation, swallowing difficulties and sleep disturbances. (1) The most common ADL problems reported are with walking, stair climbing, and dressing.

US National Center for Health Statistics has estimated that there are over 650,000 survivors of paralytic polio in the US alone. Over half of these polio survivors have been, or potentially may develop new difficulties that are related to their “old polio.” (4) Statistics from another source report it appears that there are at least 55,880 persons who were paralyzed by poliomyelitis and are experiencing new symptoms. (3) However, it has become clear that individuals who were diagnosed as having had non-paralytic poliomyelitis also can develop new symptoms. There are at least 414,557 persons alive today who are at risk for developing new symptoms. The new symptoms were found to appear approximately 30 years after the acute infection. (3) Acute poliomyelitis occurred more frequently in males, but post-polio syndrome occurs more often in females. (5) The research study by Frick and Bruno, (3) identified four factors which if present during the acute phase of polio, predict an increased likelihood of developing new symptoms. They include having been hospitalized, having been 10 years of age or older at the time of acute infection, having had paralytic involvement of all four limbs, and having used a ventilator. Trojan (6) felt that the best predictive factors of who will develop PPS is indicated by those patients who had a greater weakness at acute polio, are currently older, have muscle pain with exercise, a recent weight gain, and experience joint pain.

Post polio syndrome is defined as a clinical syndrome of new weakness, fatigue, and pain in those who have recovered from acute paralytic poliomyelitis. PPS is the most prevalent progressive motor neuron disease in North America today. (6) The course of post polio syndrome is unpredictable but it is neither entirely benign nor drastically progressive. Its pace may be slow, with periods of stability lasting as long as one to 10 years. Impairment is usually limited. (5) Often, the onset of PPS is gradual, however, it may be precipitated by other changes in health status such as trauma or an illness requiring bed rest. Decreases in functional performance demonstrated with its onset may be dramatic if the persons functional reserve has been marginal. (7)

Criteria used to make a diagnosis of PPS include a history of paralytic poliomyelitis, recovery of function, and a period of neurologic stability, followed by the onset of new weakness which is not attributable to other causes. (7) The diagnosis is one of exclusion.

Diagnostic Criteria for Post-Polio Syndrome as established by Bartfield. (5)

1) Prior episode of paralytic poliomyelitis, confirmed by history, examination, and electromyography that shows motor neuropathy and excludes neuropathy, rediculopathy, and myopathy.

2) Functional stability or recovery for at least 10 years.

3) Residual asymmetric limb weakness and areflexia, or residual respiratory or bulbar weakness with normal sensation.

4) New complaints of progressive muscle weakness, with or without excessive fatigue, decreased endurance or function, myalgia, cold sensation, arthralgia, or muscle atrophy.

5) Exclusion of medical, musculoskeletal, neurologic, and psychiatric illnesses that could cause health problems listed in criteria 4.

The most likely etiology of new weakness many years after recovery from paralytic polio is a distal degeneration of the abnormally enlarged motor units. New weakness decades after recovery from acute paralytic polio may be a result of the recovery process itself. Surviving motor neurons which may have permanent abnormalities from earlier polio and are now innervating many more muscle fibers than normal, may be unable to sustain such a great metabolic demand. Over time, terminal axonal sprouts may degenerate, with subsequent denervation of individual muscle fibers. It is possible that some of these denervated muscle fibers may become reinnervated by sprouts from neighboring motor neurons, producing a continuous remodeling of the post-polio motor unit. However, some muscle fibers will become irreversibly denervated, causing a reduction in size of the motor unit, and will produce a clinically apparent weakness in the patient. (8)