Scientific American April 1998 Vol 278 Number 4:36-41

In the first half of the 20th century, the scourge of paralytic poliomyelitis seemed unstoppable. A major polio epidemic hit the New York area in 1916, and in the following decades the epidemics grew in size and became more deadly. The epidemic of 1952, for instance, affected more than 50,000 Americans and had a mortality rate of about 12 percent. It is difficult to realize today the extent of the fear and panic that gripped the public. Polio haunted everyone: families stayed at home; swimming pools were closed; public events were canceled.

Children in particular were at risk. With the introduction of Jonas E. Salk's injected killed-virus polio vaccine in 1955 and Albert B. Sabin's oral live-virus vaccine six years later, the epidemics were brought to an end. By the mid-1960s the number of new polio cases dropped to an average of 20 a year. Polio had been vanquished. Or so it seemed.

For the average American, polio no longer meant a disease but a vaccine. Medically, polio came to be regarded as a static, nonprogressive neurological disorder. It was believed that after rehabilitation and reeducation most survivors could reach a plateau of neurological and functional stability that would last more or less indefinitely--and that is where our understanding of polio as a chronic disease remained until fairly recently.

Then, in the late 1970s, reports began to surface that people who had recovered from paralytic polio decades earlier were developing unexpected health problems such as excessive fatigue, pain in muscles and joints and, most alarming of all, new muscle weakness. Because there was little in modern medical literature about delayed neurological changes in polio survivors, the initial response by many physicians was that the problems were not real. For a time they were dealing with a cluster of symptoms that had no name--and without a name there was, in essence, no disease. Having a name--even if imprecise and misleading as to causation--at least confers an element of credibility.

By sheer weight of numbers, persons experiencing the late effects of polio finally started attracting the attention of the medical community, and in the early 1980s the term post-polio syndrome was coined. Today the syndrome is defined as a neurological disorder that produces a cluster of symptoms in individuals who had recovered from paralytic polio many years earlier. These symptoms typically appear from 30 to 40 years after the acute illness. The major problems are progressive muscle weakness, debilitating fatigue, loss of function and pain, especially in muscles and joints. Less common are muscle atrophy, breathing problems, swallowing difficulties and cold intolerance. Of all these health problems, however, the critical symptom of post-polio syndrome is new progressive weakness.

Patients most at risk for post-polio syndrome are those who had suffered a severe attack of paralytic polio, although some patients who seemingly had a mild attack have also developed the syndrome. The onset of these new problems often is insidious, but in many cases they appear to be precipitated by specific events such as a minor accident, a fall, a period of bed rest or surgery. Patients characteristically say that a similar event several years earlier would not have caused such a large decline in health and function.

My own experience seems to be typical of both recovery from paralytic polio and the new development of post-polio syndrome. I contracted polio during the epidemic of 1954 while traveling in Europe after my freshman year in college. I was 18 years old. My six-month journey of recovery took me from iron lung to wheelchair to foot brace and then to no assistive device at all. At times, improvement in strength seemed to happen overnight. Although my right arm remained paralyzed, the rest of my body regained most of the strength and endurance I had before my illness. As a result, I thought of myself as cured. I returned to college, learned to write with my left hand and even played intramural squash. On the morning of the third anniversary of the onset of my polio, I reached the summit of Mount Fuji in Japan after a climb of over 12,000 feet. As I watched the sun rise, I thought, "Polio is behind me. I have finally conquered it."

With the conquest of Mount Fuji fresh in my mind, I began to look for other mountains to climb. After college, I entered medical school. Internship and residency initiated yet another cycle of physically demanding years. In short, I got on with my life while polio receded ever further in my memory. Several years ago I began developing new weakness in my legs. As the weakness progressed over a period of months, I went from being a full-time walker who jogged up six flights of stairs for exercise to having to use a motorized scooter full-time at work.