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Balance improved by an average of 20% and strength by an average of 10% among multiple sclerosis (MS) patients who wore a cooling vest for one hour, according to an article in the Sept. 11, 2001, issue of Neurology, the scientific journal of the American Academy of Neurology. Also of interest was the finding that the level of nitric oxide (NO) decreased by 41% in patients receiving the active cooling, compared to a group of participants who received "sham" cooling.
"I don’t think there were any surprises in this article other than the nitric oxide component," says Nicholas G. La Rocca, PhD, director of health care delivery and policy research organization for the National Multiple Sclerosis Society in New York City. "It’s well-known that most people with MS are heat-sensitive. Cooling is something that has been known about in MS for quite a long time, and many, many people with MS use various cooling strategies, including air conditioning, staying out of the sun, or wearing loose clothing, as well as using active or passive cooling vests. Some people I have spoken to have gone so far as to take cold showers and immerse themselves in ice water baths," he explains.
The patients were separated into the two groups and clinical tests were performed before and three hours after the cooling sessions. Fatigue was assessed via questionnaire; sway data were measured via stabilometry, and muscle strength was measured through a calibrated hand-held dynamometer.
"This was a very small study, but somewhat different from anything done earlier," notes La Rocca. "In the treated group, they didn’t actually observe any drop in core body temperature, which seemed a little bit odd. In addition, they looked at the nitric oxide levels, which to my knowledge no one had ever done before."
The reason the researchers wanted to study nitric oxide, La Rocca explains, is that it binds to sodium channels, which tend to increase or proliferate on the demyelinated axons in people who have MS. "By reducing the amount of nitric oxide in the blood, it seems they were able to increase the speed of nerve conduction," he says. This was addressed directly in the authors’ discussion. "The improvement in muscle strength and proprioception may be explained by amelioration of conduction in demyelinated axons of cortico-spinal tracts and dorsal columns,"1 they wrote.
"Active cooling with the cooling garment did not decrease tympanic temperature, which reflects core body temperature. Thus, contrary to popular belief, the beneficial effects of cooling garment treatment cannot simply be explained by a direct cooling of the CNS . . . Active cooling resulted in a significant decrease in leukocyte NO production, and this might provided an explanation for the clinical improvement,"1 they added.
Two types of cooling vests are available for MS patients — active and passive, notes La Rocca. "The passive vest looks like the kind of nylon vest worn by fishermen. Instead of pockets on the outside, it has them on the inside. You put frozen gel strips in the pockets, as well as in the collar. Depending on the ambient temperature, they might provide some cooling for a few hours."
The active type vest, which was used in the study, has plastic tubing running through it, and a special cap as well. "A liquid is pumped through the tubes and chilled to a certain temperature," La Rocca explains. "This requires a separate chilling unit, which makes it somewhat less practical." The unit, an offshoot of NASA technology, used to be the size of two golf bags but is now reasonably portable, he adds. "They have been used extensively in the nuclear industry and in other areas where protective clothing is required. They were also used quite a bit during the Gulf War."
Which type of vest is better? "It depends on who you ask," says La Rocca. "The advantage of the mechanical type is that once you switch it on you can use it pretty much indefinitely. With the passive vest, if the gel strips melt, you have to replace them." The important point, says La Rocca, is that to his knowledge most hospitals don’t keep these vests on hand as a matter of course — and they’re not all that expensive. The active vests, manufactured by Life Enhancement Technologies of Santa Clara, CA, cost about $2,000 apiece. The passive vests (www.steelevest.com), cost about $300.
The authors indicated that more research is needed on the role nitric oxide plays in the symptoms of MS, as it could lead to efforts to mimic the effects of cooling through drugs or other means. "There are currently no drugs on the market that can impact the level of nitric oxide, but people are looking at this experimentally," says La Rocca.
1. Beenakker EAC, Oparina TI, Hartgring A, et al. Cooling garment treatment in MS: Clinical improvement and decrease in leukocyte NO production. Neurology 2001; 15:892-894.
For more information, contact: Nicholas G. La Rocca, PhD, director of healthcare delivery and policy research organization, The National Multiple Sclerosis Society, 733 Third Ave., New York, NY 10017. Telephone: (212) 476-0414. Web site: www.nationalmssociety.org.