By: Dr. Richard L. Bruno
Director, Post-Polio Rehabilitation and Research Service
Kessler Institute for Rehabilitation
Saddle Brook, NJ
For researchers studying post-polio sequelae (PPS)--the disabling fatigue, muscle weaknes and pain experienced by 76 percent of polio survivors decades after the poliovirus has come and gone--1997 was a year of discovery. Some of the new findings are disappointing, and others are even disturbing. But new understanding from this research will become the platform for future treatments, so there's every reason for survivors to keep themselves well-informed.
During the past eight years, my team at the Post-Polio Institute at New Jersey's Englewood Hospital and Medical Center has been studying the cause of post-polio fatigue, the most common and disabling PPS. Fatigue in polio survivors has been found to be associated with a severe inability to focus attention and a marked reduction in the brain-activating hormone ACTH. Magnetic resonance imaging reveals damage to the brain-stem neurons responsible for activating the brain, damage also found during autopsies of polio survivors done 50 years ago.
A study to be published this spring in the Journal of Chronic Fatigue Syndrome describes our measurement of polio survivors' attention, brain waves and the hormone prolactin. Prolactin increases in the blood when there is too little of the most important brain-activating neurochemical dopamine.
Our finding that polio survivors with the worst fatigue had the highest prolactin levels and the slowest brain waves suggests that survivors do not have enough dopamine to fully activate their brains. A dopamine shortage may explain their difficulty in focusing attention and the other symptoms of post-polio "brain fatigue." This conclusion is supported by our 1996 finding that bromocriptine--a drug that substitutes for dopamine in the brain--reduces the symptoms of post-polio brain fatigue in survivors who do not respond to the treatments of choice for fatigue: reducing physical and emotional stress, using assistive devices, conserving energy, resting, and pacing activities.
Last fall, the results of two multi-center drug studies were announced. Robert Miller, of San Francisco's Columbia Pacific Medical Center, led a study of recombinant insulin-like growth factor-1 (IGF-1) in polio survivors. Why study IGF-1? Because a 1995 study at the Milwaukee VA Medical Center had found that male polio survivors with "difficulties in the activities of daily living" had abnormally low blood levels of IGF-1. IGF-1 normally increases muscle size, stimulates extra neuronal growth (a process called sprouting) and slows the progression of amyotrophic lateral sclerosis. So an IGF-1 "menopause" in polio survivors was considered a possible cause of post-polio muscle weakness, and the replacement of IGF-1 a potential treatment.
Miller and his colleagues measured several variables before and after three months of twice-daily under-the-skin injections of either IGF-1 or a placebo: subjective fatigue, ability to function, the force of a maximal muscle contraction after a fatiguing exercise, and the amount of muscle strength recovered 15 minutes after the exercise. Unfortunately, the study found that IGF-1 had no effect on subjective fatigue, functional ability or muscle strength, although muscle force after the 15-minute rest was 13 percent higher. The improved muscle force "was statistically significant for those who received IGF-1," says Miller. But, he adds, "we are not sure how clinically meaningful this would be nor do we understand the mechanism of this finding."
Another multi-center, placebo-controlled study was headed by Neil Cashman, now at the University of Toronto. Cashman and his colleagues gave polio survivors a placebo or pyridostigmine (Mestinon c), a drug that prolongs the action of acetylcholine, the chemical released by motor nerves to make muscles contract. In an earlier study in which subjects knew they were taking the drug, pyridostigmine was found to decrease survivors' "general fatigue" by 56 percent. But the controlled study of pyridostigmine was disappointing. After six months, says researcher Daria Trojan, there was "no significant impact on quality of life, fatigue or muscle strength."
Thus IGF-1 and pyridostigmine join amantadine, an anti-viral drug, and prednisone, a powerful steroid, as once-promising drugs that have not been found to reduce post-polio muscle weakness or fatigue in placebo-controlled studies.
If current drugs are not effective treatments for PPS, might less conventional approaches be helpful? Carlos Valbona, of the Baylor College of Medicine, thought so. He and his colleagues tested the effects of magnets on pain in polio survivors.
Valbona identified subjects' "trigger" points, places on the body that hurt when pressed. He then caused pain "by firm application of a blunt object approximately one centimeter in diameter," asking subjects to rate the pain on a scale from zero to 10. On average, the pain was rated about a 9.
Researchers then placed either a magnet or a non-magnetic pad, indistinguishable from the magnets, over the painful trigger point and waited. After 45 minutes, the blunt object was again pressed into the trigger point.
Subjects treated with a magnet rated their pain a 4 on average after the second push. Those treated with the non-magnetic pads rated their pain an 8.
Valbona's methods cannot be faulted. Double-blind, placebo-controlled studies like this one are the gold standard of research. Sadly, the media quickly reported that magnets are a "cure for post-polio pain." Pushing a blunt object into a trigger point does not produce post-polio pain, but rather an experimentally induced pain that is not at all typical of the chronic muscle and joint pain reported by about 75 percent of polio survivors. Without another study, it is not clear that magnets will decrease chronic pain in polio survivors.
It is also unclear why magnets would have any effect on even experimentally induced pain in polio survivors. Valbona implies that the pain-reducing effect of magnets in his study may be related to the Post-Polio Institute's 1985 finding that polio survivors have double the pain sensitivity of those who have not had polio. This heightened pain sensitivity may be related to a 50-year-old finding that the poliovirus kills brain neurons that produce endorphins, the body's own morphine.
But regardless of how magnets might have decreased pain in this study, polio survivors shouldn't think they can run themselves ragged, apply magnets to treat pain, and be just fine. Future studies may indeed show that magnets are helpful for pain. But pain in polio survivors means damage is being done to the body. Masking discomfort--with magnets or morphine--is not a cure for polio survivors' pain.
The most important and sobering finding of 1997 was a study by A.J. McComas of Canada's McMaster University. McComas and his group tested the most widely accepted hypothesis for late-onset muscle weakness in polio survivors: that motor neurons are breaking down and sometimes dying as a result of the initial poliovirus damage and decades of overuse abuse.
McComas actually performed two studies. First, using a technique he developed and has used for 25 years, he counted the number of motor neurons in polio survivors. Muscles known to have been affected by the original polio were found to have lost 59 percent of their motor neurons.
Sixty-five percent of muscles thought not to have been affected had lost 40 percent of their motor neurons. These percentages mirror precisely the findings of pathologist David Bodian, who 50 years ago showed that at least 60 percent of motor neurons had to be killed by the poliovirus for a muscle to show any weakness, and argued that there was no such thing as an "unaffected muscle" in someone who had had paralytic polio.
McComas' second study was equally revealing, but more disturbing. He counted motor neurons in 18 subjects, then followed them for two years. At follow-up, 78 percent of the subjects reported a decrease in muscle strength and had lost an average of 13.5 percent of their motor neurons, approximately twice the rate of loss expected in healthy subjects. Most alarming was the finding that the two survivors who reported the greatest decrease in strength had each lost 50 percent of their motor neurons during the two years.
While these findings are frightening, they are also a guide to a rational treatment for PPS. "Our findings make clear that polio survivors should not be treated using electrical stimulation that causes muscle contraction," warns McComas, "nor should they engage in fatiguing exercise or activities that further stress metabolically damaged neurons that are already overworking."
In a study presented last October, Susan Creange, a research fellow at the Post-Polio Institute, reported that polio survivors with blood sugar levels in the low normal range have as much difficulty focusing attention as do diabetics who have extremely low blood sugars from taking too much insulin. "Polio survivors," Creange says, "often have a 'Type A diet': drinking three cups of coffee for breakfast, not having lunch and eating cold pizza for dinner. When we put polio survivors on a hypoglycemia diet, that requires eating protein at breakfast and small, non-carbohydrate snacks throughout the day, they had a remarkable reduction in nearly all the symptoms of post-polio fatigue."
The question for Creange was not only why polio survivors appear to be hypoglycemic--which she thinks is related to their brain-activating neurons being metabolically damaged--but also why they often eat a "Type A diet" and have such difficulty taking care of themselves.
For a study published in 1997, Creange mailed anonymous surveys to all patients who had been evaluated by the Post-Polio Institute team. Patients were asked about their PPS symptoms and completed surveys that measured loneliness, self-concept and how Type A--hard-driving, pressured, time-conscious, perfectionistic and overachieving--they were. Patients were also asked how often they rested during the day, asked for help from others, and used braces, canes, crutches, wheelchairs or scooters.
"Patients with a high Type A score were less likely to take rest breaks, a cornerstone of the treatment of PPS," says Creange. "Patients who used wheelchairs were more lonely and had a poorer self-concept, crutch users also had poorer self-concept, while those who asked co-workers for help had a more positive self-concept." Further, the most Type A patients were the loneliest; the lonelier they were, the poorer their self-concept.
"Polio survivors will not rest, use assistive devices or ask for help if they feel badly about themselves," says Creange. "Friends and family members must help polio survivors feel better about themselves if they are to slow down, accept lifestyle changes and use the new assistive devices needed to treat their PPS."
Another study presented last year also asked why polio survivors are so Type A and take such poor care of themselves. The 1995 International Survey, performed by Nancy Frick of Harvest Center in Hackensack, N.J., surveyed more than 1,700 polio survivors and nondisabled controls. Frick, a polio survivor herself, measured Type A behavior and sensitivity to criticism and failure, and asked whether polio survivors had been evaluated or treated for their PPS. The survey also asked about experiences surrounding the original polio, including hospitalization, surgeries, and emotional and physical abuse by family members, peers and medical professionals.
"As in our two previous post-polio surveys," says Frick, "polio survivors were 21 percent more Type A and 15 percent more sensitive to criticism and failure as compared to nondisabled controls." A more upsetting finding was that polio survivors reported 34 percent more emotional abuse and 94 percent more physical abuse than did controls.
"All of the 'extra' abuse was related to polio survivors appearing obviously disabled," says Frick. Polio survivors who were abused were at least 15 percent more Type A and sensitive to criticism than those who were not abused. "It is no mystery why polio survivors today refuse assistive devices that make them look more disabled," says Frick. "Using crutches or a wheelchair feels like painting a bulls-eye on your chest above the words, 'Abuse me, I'm disabled!'"
Frick's findings may also explain why polio survivors are so reticent about even being evaluated for PPS. "About 78 percent of polio survivors said they were not treated with concern by the medical staff when they had polio," she says. Polio survivors who were treated well by medical personnel are significantly less Type A and less sensitive to criticism than those who were treated poorly. Those who were not treated well became more Type A and more sensitive to criticism and failure as adults.
Frick's research suggests that Type A behavior developed as a protection against criticism and failure, and that polio survivors who are most Type A today are most likely to refuse evaluation or treatment for their PPS. Frick concludes, "Type A polio survivors refuse to treat their PPS and use assistive devices as a protection from the kind of abuse they experienced as children."
Research during the past decade has shown that conservative treatments for PPS--reducing physical and emotional stress, using assistive devices, conserving energy, resting, and pacing activities--are very effective. The problem is that polio survivors have such difficulty applying these simple measures.
"The treatments for PPS may sound simple, but they are not," says Frick.
"Polio survivors have to deal not only with their bodies giving out on them again, but also with their long-buried emotional pain." And it is those painful experiences of the past, the fear of giving up "protective" Type A behavior, and a terror of looking disabled that stop polio survivors from treating their PPS.
The most difficult aspect of treating PPS is not deciding whether a short- or long-leg brace will be most helpful. The challenge is helping polio survivors face the pain of their abusive pasts and accept appearing more disabled now--by slowing down, asking for help and using new adaptive equipment--so they won't become more disabled later in life.
Richard Louis Bruno is director of the Post-Polio Institute at Englewood (New Jersey) Hospital and Medical Center and is chairperson of the International Post-Polio Task Force. Papers describing the research performed at the Post-Polio Institute can be found in the online PPS Library.