Warning for COVID Long Haulers From Polio Survivors

Sarah DeWeerdt

October 22, 2020

When working as a family doctor in Denver, Marny Eulberg, MD, noticed that she had begun to feel weaker and more tired than usual and was having trouble lifting the front part of her foot off the ground when she walked. One day, doing rounds at a local hospital, she fell and landed hard on her outstretched wrists.

"I probably ought to pay attention to this," Eulberg recalls thinking. The year was 1985. She was in a solo private practice and knew that if she were to fall and injure herself, she could be out of commission long enough to destroy her livelihood. She sought advice from a physical therapist at the hospital, who suggested that she wear a brace to stabilize her leg.

Eulberg was aghast: The idea of wearing a brace "felt like failure," she said. When Eulberg was 4 years old, in the fall of 1950, she had contracted polio, which partially paralyzed her left leg. After 6 months in the hospital, extensive rehabilitation, and seven orthopedic surgeries, she gradually progressed from using crutches and a long-leg brace to a short-leg brace. When she was in junior high school, she was finally able to leave these reminders of her illness behind.

During her rehabilitation, Eulberg had been exhorted to "just do one more, work a little harder," as had many children who contracted polio during the epidemics that swept the United States in the 1940s and 1950s. She was told, she explained, that "if you work hard enough, you can get rid of your braces, crutches, whatever." From the experience, she emerged with a kind of matter-of-fact grit common among polio survivors of her generation.

So she devised an experiment to prove the physical therapist wrong. First, she counted how many times a day she tripped and almost fell while going about her daily routine: 14. Then she borrowed a short-leg brace and wore it for a few days, again counting how many times she tripped: 0. "So much for the experiment," Eulberg said.

Polio is considered a disease of the past. A vaccine for the virus that causes it was developed in the 1950s, and the disease was eradicated in the United States by 1979. But there are still up to half a million polio survivors in the country. And, like Eulberg, many of them have developed new pain and disability that can be traced to the disease they thought they had recovered from decades before — a condition that has become known as postpolio syndrome.

It is still an under-researched and poorly understood syndrome. There's no definitive way to diagnose it, its cause remains unclear, and no treatment is known to slow or halt its progression. Yet there are effective ways to manage symptoms, say physicians who treat postpolio patients.

The syndrome is thought to affect between 20% and 85% of those who have recovered from the disease, meaning the condition likely affects tens of thousands of people in the United States and many more around the world. Their experience is a timely reminder that epidemics can ripple through the decades, sometimes in unexpected ways, even after the pathogens that cause them are eradicated.

Trouble Years Later

According to diagnostic criteria developed by the March of Dimes, postpolio syndrome is new muscle weakness or decreased endurance that occurs in people with a history of paralytic polio, after partial or complete recovery from the infection and a long interval — typically 15 to 30 years — of stable functioning. The weakness comes on gradually, persists for at least a year, progresses slowly, and can be accompanied by fatigue, muscle wasting, and muscle and joint pain. Some patients also develop breathing problems and difficulty swallowing.

French neurologist Jean-Martin Charcot first described symptoms similar to postpolio syndrome in 1975, but the condition only became widely recognized in the 1980s. That's likely because polio was a sporadic disease until the 20th century, so postpolio syndrome would have been sporadic too, and its symptoms difficult to ascribe to a specific cause. It was only when a critical mass of survivors of the epidemics in the 1940s and 1950s, Eulberg among them, entered middle age and began to develop these problems that the medical community recognized the pattern as a distinct syndrome.

But early on, some patients faced skepticism and misdiagnosis from medical professionals. "I ended up going to several different doctors and they all told me something completely different," said Sunny Roller, who contracted polio at the age of 4, in 1952, and developed postpolio syndrome 3 decades later. Roller, a former high-school teacher, was a hall director in a college dorm and, in her mid-30s, working on a master's degree when pain and weakness from the condition forced her to move back home with her parents. One doctor said she needed spinal surgery, another advised her to lose weight, and yet another told her it was all in her head, she explained. In fact, what she needed was rehabilitation and eventually a scooter to help her get around.

A Tricky Diagnosis

Even today, postpolio syndrome can be difficult to diagnose. There's no biomarker for the condition and no specific test that can identify it with certainty. Often it is a diagnosis that emerges over time, after laboratory and clinical tests have ruled out other common causes of fatigue, such as thyroid problems, and once it's clear that a patient's symptoms are persistent.

Many clinicians perform electromyography, which records electrical activity in muscles and the nerves that control them, as part of postpolio syndrome diagnosis. The test can't distinguish between a patient with postpolio syndrome and one who has a history of polio but whose condition is stable. But electromyography can confirm that a muscle has been affected by polio — sometimes one that was not thought to be involved at the time of the initial illness — and can help assess a patient's prognosis, said Jan Lexell, MD, PhD, a rehabilitation physician and researcher who runs a postpolio clinic at Lund University Hospital in Sweden.

Researchers are also unsure of what brings on postpolio syndrome. For a while, it looked like reactivation of the poliovirus might be to blame, but studies haven't consistently been able to identify viral genetic material or evidence of a poliovirus-specific immune response in patients with the syndrome. Other researchers, building on evidence of elevated inflammatory markers in some patients, have suggested an inflammatory or autoimmune process, but again, these changes aren't present in all patients and their relation with the progression of symptoms is not clear.

The Search for a Cause

Although these theories haven't been definitively ruled out, the scientific consensus has coalesced around the idea that the cause of postpolio syndrome is a straightforward one, involving degeneration of motor neurons and the consequent weakening of muscle fibers they control. Still, the details of this process remain somewhat murky.

The poliovirus causes paralysis by infecting and killing motor neurons that innervate muscle fibers in the legs, arms, or other parts of the body. During recovery from acute polio, neighboring motor neurons that remain sprout new projections and reinnervate muscle fibers that had lost their connections. A motor neuron can innervate up to seven times as many muscle fibers as normal in polio survivors. With time, this extra stress on the remaining motor neurons can cause them to wear out, leading to the characteristic weakness of postpolio syndrome.

In support of this scenario is the fact that doctors have observed that postpolio syndrome is more pronounced in patients who had severe cases of acute polio and then made the most complete recoveries. They say this is consistent with a very small number of surviving neurons doing a large share of extra work.

Normal aging processes likely contribute, too. "We all get weaker as we get older," losing muscle mass at a rate of about 1% per year after age 30, said Carol Vandenakker-Albanese, MD, a rehabilitation physician who runs a postpolio clinic at the University of California, Davis. In a patient whose muscles are already weakened by polio, this seemingly minor loss is "making a much bigger impact on the strength and functionality of a muscle." The slowly progressive nature of postpolio syndrome and the fact that those who suffered milder cases of acute polio typically develop postpolio syndrome later in life lend heft to this theory.

Altered body mechanics in polio survivors might also contribute to pain, fatigue, and weakness. Weakness of a polio-affected limb can cause deformities in bones and joints, leading to excess wear and tear, said Vandenakker-Albanese. "Often then their good limb will develop arthritis as well because they're so dependent on that," she added.

"I'm a lot more disabled now than I was immediately after my acute attack," said Daniel Wilson, PhD, a retired history professor who taught at Muhlenberg College in Allentown, Pennsylvania and has written several books about the history of polio epidemics in the United States. Wilson had polio in 1955, when he was 5 years old. The virus affected the right side of his body and resulted in scoliosis, which was corrected with spinal fusion surgery when he was 10. Over time, the spinal curvature returned above and below the fusion, causing him severe breathing difficulties.

Technically, such problems are termed "late effects of polio," whereas postpolio syndrome is restricted to neuromuscular problems. Wilson also developed weakness in his right leg in the mid-1980s, roughly 3 decades after his bout of acute polio. But some researchers use one term or the other — or use them interchangeably — to refer to the complete suite of problems that polio survivors can experience in their later years.

Hit-and-Miss Treatments

Despite a variety of studies since the 1980s, "we still have no medical treatment proven to have any benefit for postpolio syndrome," said Fred Maynard, MD, a retired rehabilitation physician who was active in early efforts to define postpolio syndrome in the 1980s and who treated patients at the University of Michigan postpolio clinic in Ann Arbor. Maynard was the physician who finally prescribed the correct course of management for Roller's postpolio symptoms, and the two later collaborated on studies of the condition.

Trials have shown that drugs — such as pyridostigmine, a medication used to treat myasthenia gravis; amantadine, which is beneficial in patients with Parkinson's disease; and the steroid prednisone — have little effect on patients with postpolio syndrome. Similarly, studies of supplements such as coenzyme Q10 and creatinine have been a wash. Nonpharmaceutical treatments, such as transcranial direct current stimulation and whole-body vibration, haven't panned out either.

Still, some researchers remain optimistic about intravenous immunoglobulin therapy in postpolio syndrome. A randomized controlled trial is now underway to clarify its benefits, whether it will only help a subgroup of patients, and the most effective dose.

The mainstay of treatment is rehabilitation and exercise therapy, usually involving a multidisciplinary team of medical professionals. But it has been difficult to establish an evidence base for even this. For example, researchers in the Netherlands conducted a randomized trial to see whether physical training or cognitive behavioral therapy were effective for patients with postpolio syndrome. Neither intervention helped patients preserve muscle strength or functioning.

The nature of postpolio syndrome makes it a difficult subject of treatment trials, said Frans Nollet, MD, PhD, a researcher at the University of Amsterdam who led the study. The condition progresses slowly, so it's difficult to see an effect of treatment — let alone differences between treatments — unless a study is very long (and therefore very expensive). "The second big problem is that it's not a uniform disease," he added. The muscles affected, the degree to which they are damaged, and the compensations patients have made since their acute illness all vary widely from one patient to the next.

After the disappointing results of their study, Nollet and his colleagues took a closer look at the patients in the physical-training group. "We saw that we did not have the right intensity of training for each patient," he acknowledged. "So for some it was too intense and for others it was not intense enough." The team is now conducting a randomized trial of individually prescribed exercise, he reported.

Lessons for COVID Long Haulers

Despite underwhelming results from studies of treatment for postpolio syndrome, many clinicians who treat these patients are upbeat about their ability to make a difference in patients' lives, precisely because an individualized approach is possible in the clinic. "It's a really careful assessment of what exactly their activity level is, what they are doing, what muscles they are stressing, what muscles are overstressed, and whether those muscles need rest or protection," said Vandenakker-Albanese. "So sometimes using exercise to strengthen is the solution and sometimes doing less exercise is the solution."

The problem is that this kind of expertise is becoming rare.

After addressing her own symptoms, Eulberg started a clinic in Denver for polio survivors in collaboration with the physical therapist who had helped her. Today, she is retired but continues to see a small number of postpolio patients on a volunteer basis. "I keep thinking I'm going to have seen everybody in Colorado," she said. But every year, new patients come.

Vandenakker-Albanese sees several hundred patients each year at her postpolio clinic. As other clinics have closed, the geographic area she serves has expanded beyond California. She now sees patients from Arizona, Hawaii, Nevada, and Oregon, and even from outside the United States (around the world, there are an estimated 15 to 20 million polio survivors).

Moreover, as the generation of American polio survivors who first brought attention to postpolio syndrome passes into history, the younger generations behind them will be at risk of developing postpolio syndrome. An increasing proportion of patients seen at American and European polio clinics are immigrants who acquired their polio overseas. Many of the millions of patients with polio around the world are just now entering adulthood. As a result, postpolio syndrome will remain a significant public health problem for decades. The understanding of postpolio syndrome that rehabilitation doctors in North America and Europe have developed since the 1980s needs to be maintained and shared in other parts of the world, Lexell said.

Postpolio experts also see a resonance between polio and the coronavirus currently affecting the world, particularly in the experience of so-called long-haul COVID-19 patients who have lingering symptoms for many months, or longer. These patients should be followed in a uniform way, Nollet argued. "You really have to take it serious," he said. "Start looking at what interventions are effective" and believe patients when they say they have new limitations.

The memories of polio survivors can provide a guide, and perhaps also a cautionary tale. "When I had polio, our culture kind of wrapped us up and gave us a big hug in so many ways," Roller said. From the network of rehabilitation centers throughout the country, to assistance with medical expenses from the March of Dimes, to the inspiring example of President Franklin D. Roosevelt, himself a polio survivor, "it was like our whole culture wanted to help."

But that help has to remain for as long as survivors need it, and it has to encompass new difficulties that emerge over time. Today, with the gradual erosion of expertise and a drop off in research on postpolio syndrome, many people with the condition feel left behind. "I think that researchers aren't interested in polio because it's just seen as a disease of the past," Roller said. "People don't realize that we're still here."


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