Pain Is In The Eye Of The Beholder

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Pain Is In The Eye Of The Beholder

http://medicalnewscenter.com/recent/science-daily-medical-news.shtml

By manipulating the appearance of a chronically achy hand,

researchers have found they could increase or decrease the pain and

swelling in patients moving their symptomatic limbs. The findings—

reported in the November 25th issue of Current Biology — reveal a

profound top-down effect of body image on body tissues, according to

the researchers.

" The brain is capable of many wonderful things based on its

perception of how the body is doing and the risks to which the body

seems to be exposed, " said G. Lorimer Moseley, who is now at the

Prince of Wales Medical Research Institute in Australia. (The work

was done at the University of Oxford.)

In the study, the researchers asked ten right-handed patients with

chronic pain and dysfunction in one arm to watch their own arm while

they performed a standardized set of ten hand movements. The

participants repeated the movements under four conditions: with no

visual manipulation, while looking through binoculars with no

magnification, while looking through binoculars that doubled the

apparent size of their arm, and while looking through inverted

binoculars that reduced the apparent size of their arm.

While the patients' pain was always worse after movement than it was

before, the extent to which the pain worsened depended on what people

saw. Specifically, the pain increased more when participants viewed a

magnified image of their arm during the movements, and—perhaps more

surprisingly—the pain became less when their arm was seen through

inverted binoculars that minimized its size.

The degree of swelling too was less when people watched a " minified "

image of their arm during movements than when they watched a

magnified or normal image, the researchers reported.

They aren't yet sure how this phenomenon works at the level of

neurons. However, the researchers said, a possible philosophical

explanation comes from the notion that protective responses—including

the experience of pain—are activated according to the brain's

implicit perception of danger level. " If it looks bigger, it looks

sorer and more swollen, " Moseley said. " Therefore, the brain acts to

protect it. "

While he said the findings don't mean that pain is any less real,

they may lead to a new therapeutic approach for reducing pain. His

team is now testing visual manipulations as an analgesic strategy for

use in clinical settings.

The researchers include G. Lorimer Moseley, University of Oxford, UK,

Prince of Wales Medical Research Institute, Sydney, Australia;

J. Parsons, University of Oxford, UK; and Spence,

University of Oxford, UK.