Survivors of Childhood Polio Do Well Decades Later As They Age
Mayo Clinic researchers have found that years after experiencing childhood polio, most survivors do not experience declines greater than expected in their elderly counterparts, but rather experience only modest increased weakness which may be commensurate with normal aging.
“Other researchers have suggested that polio is a more aggressive condition later in life, but we’ve actually found it to be relatively benign,” said Eric Sorenson, MD, Mayo Clinic neurologist and lead study researcher. “Our results suggest that polio survivors may not age any differently than those in the normal population— they’re not doing too badly compared to their peers. This tells us that the cause for the decline in muscle strength in polio survivors may be aging alone.”
Polio is a contagious, viral illness that peaked in the United States in 1952, when 3,000 people died of the disease. Mass immunizations in the mid-1950s began to slow the spread of the disease, and the last case of polio in an unvaccinated individual occurred in the United States in 1979. The effects of polio run the gamut from a complete return to normal function to paralysis of limbs to death. Following the illness, most patients are worried about their long-term prognoses, according to Dr. Sorenson.
To conduct this study, the researchers randomly selected a group of 50 polio survivors from the general population of Olmsted County, home of Mayo Clinic, and followed them for 15 years. The average age of participants at the study’s start was 53, and the patients were an average of 40 years past their childhood experience with polio. The researchers measured strength and loss of neurons at the beginning of this period, and then again five and 15 years later with electrophysiological testing, strength testing and timed tests of performing basic functions. They found modest declines. Each patient also completed questionnaires about symptoms of progressive weakness at the beginning and end of the study period.
Though the majority complained of progressive weakness during the time they were studied, these symptoms did not correspond with their actual magnitudes of decline over time. Rather, the researchers found patients’ symptoms experienced were associated with the degree of residual weakness immediately following their polio infections.
“Overall, we found that strength changed very little in these polio survivors as they grew older, and we discovered the neurons dropped off at a rate comparable to other non-polio survivors as they aged,” said Dr. Sorenson. “We concluded this was normal aging on top of their old deficits. Very few had to change their homes or add adaptive equipment. Those who had weakness problems during our study had a larger deficit at the end of their childhood disease, making them more likely to develop symptoms. So, as deficits at the end of the disease increase, the probability of experiencing post-polio symptoms increases.”
The discrepancy between what some of the patients experienced with growing weakness and their actual measurements of strength and neuronal loss likely is due to increased sensitivity due to their disease experiences, according to Dr. Sorenson.
“Patients feel their weakness progressing, but when you measure it, it’s very modest,” he says. “Likely, they lost so much strength at the time of their illness that any change is very noticeable to them. Though the likelihood is high that patients who have had childhood polio will complain of weakness later in life, they can expect years of stability without the need for major lifestyle modifications.” For more information, please visit the Mayo Clinic Web site at www.mayoclinic.org/news/.
MS Rates for Canadian Women Alarms Researchers
A study conducted by researchers from Oxford University has found that the rate of women being diagnosed with MS in Canada outnumbers men by more than 3 to 1 and that this ratio has been increasing for the past 50 years.
In 1931, for every one man diagnosed with MS, 1.8 women were diagnosed. In 1940, the rate of men diagnosed remained relatively the same; however, the number of women diagnosed increased. By 1980 women diagnosed with MS outnumbered men by more than 3 to 1. Researchers believe that this trend may be occurring worldwide and that this shift in MS to a more female-dominated disease may be due to some unknown underlying factors, such as Vitamin D deficiency from a lack of sun exposure, the changing role of women in the work force, dietary habits, increase in smoking among women, use of oral contraceptives, and changes in the timing of childbearing years. The study also found that babies conceived during the summer, when their mothers have higher levels of vitamin D in their blood are less likely to develop MS later in life. “Some of the risk appears to be gestational, and very early in life,” said Dr. George Ebers of Oxford University.
Canada and other Northern European nations have some of the highest rates of MS in the world. Scientists speculate that this may be due to geographical location and distance from the equator. If researchers can pinpoint what risk factors are involved, it may lead to improved methods in preventing MS.
The findings were published in the November edition of the The Lancet Neurology Journal. For more information, please visit www.thelancet.com/journals/laneur.
Discovery in SCI Pain Relief
A study published in the November 28, 2006 issue of Neurology showed that the drug pregabalin was useful in the management of nerve pain associated with SCI, a problem that affects approximately 40% of patients. Pregabalin, which is manufactured by Pfizer, Inc., is currently used to treat diabetic nerve pain and pain after an outbreak of shingles (rash or blisters on the skin caused by the same virus that causes chicken pox).
The 12-week study involved 137 Australian adults and is one of the largest randomized controlled clinical trials of nerve pain in patients with SCI ever conducted. During the study, half of the group received pregabalin and the other half received a placebo. At the end of the 12-week period, researchers found that less than 16% of the patients who received pregabalin had experienced severe pain compared to 43% in the placebo group. In addition, over one-third in the pregabalin group had experienced very mild pain or none at all. Pregabalin also helped reduce sleep and anxiety problems.
Study Author Philip J. Siddall, MBBS, PhD, with Royal North Shore Hospital in Sydney, Australia, said “Pregabalin was significantly more effective in relieving pain, improving sleep, anxiety, and overall wellbeing in patients with SCI compared to placebo. Fifty-seven percent of patients taking pregabalin said they felt better overall compared to 21 percent in the placebo group.”
For more information, please visit the American Academy of Neurology Web site at www.aan.com.
re: Survivors of Childhood Polio Do Well Decades Later As They Age Mayo (above) “To conduct this study, the researchers randomly selected a group of 50 polio survivors from the general population of Olmsted County, home of Mayo Clinic, and followed them for 15 years.”
Mayo’s done it again … this was a pre-select group. Futhermore, it was not a replicated study, and the “n” was far too small to warrent the conclusion.
For scientific research to ignore a segement of the population that have survived a disease that had limitless impact on the CNS is grossly unfair to the survivors, and other researchers who have done so much to inform, assist, and prepare those who had Polio to remain healthy, independent individuals. There are far too many with PPS who have had their symptoms, and lives, minimized to the point that advocates work daily with survivors who have unknowingly exhuasted themselves every day — or worse, believe the old addage, “Use it or lose it,” and they do. Neuro-networking is not pan-applicable to PPS.