如何量化疼痛的程度？

DAVID GREENE, HOST: All right. Let's hear now about some new research. Scientists believe they have found a way to measure how much pain someone is experiencing. They do it by scanning a patient's brain. Researchers hope this technique could help doctors treat pain better, but as NPR's Rob Stein reports, the advance is also raising concerns about whether this could interfere with doctors doing it the old fashioned way - just listening to their patients.

ROB STEIN, BYLINE: Right now, when someone is in pain, their doctor has no way to know how bad it is except to ask them questions. Like, how ranks on a scale of one to 10. And Tor Wager of the University of Colorado says, that's often not good enough.

TOR WAGER: We all have trouble communicating our pain and other feelings under different circumstances.

STEIN: Many people just have a hard time finding the right words. Some exaggerate how bad it is. Others are too stoic - they downplay their pain. And some are simply physically incapable of explaining what they're feeling at all.

WAGER: Children and adults who can't fully report pain accurately are particularly vulnerable.

STEIN: That includes people who, say, suffered a stroke or are very sick. So, Wager and his colleagues decided to see if they could measure pain objectively using brain scans. In a series of experiments involving 114 adults, the researchers measured brain activity as they administered pain with a special device.

WAGER: It's a computer-controlled hot plate that goes on a person's arm or another part of the body. And it can produce a safe, very reliable source of painful input to the brain.

STEIN: The first question was whether brain scans could tell how much pain the hot plate was causing. In a paper being published in The New England Journal of Medicine, Wager and his colleagues report what they found.

WAGER: We can measure, fairly accurately, how much pain a person is experiencing. It is between 90 and 100 percent accurate.

STEIN: But the researchers wanted to find out if the scans could do something even harder: Tell the difference between physical and emotional pain.

WAGER: When people experience social pain - especially pain that's elicited by a recent break up and people feel rejected in love - that produces a brain pattern that looks remarkably similar to the pattern elicited by physical pain.

STEIN: So for the next part of their experiment, the researchers studied only people who had recently been dumped.

WAGER: And they were - still felt rejected. And they weren't over their the break-up.

STEIN: The researchers showed the subjects pictures of the people who had broken their hearts and of people who were just friends, and compared what was going on in their brains when they used the computer-controlled hot plates on their arms.

WAGER: We tested our physical pain signature, our pattern, to see whether it was fooled into believing that the romantic rejection or social pain was like physical pain. And we found that it wasn't.

STEIN: And the researchers went even further, showing that the scans could tell when a powerful prescription painkiller was working.

WAGER: The hope is if we could peer into people's brain, we can understand that different kinds of pain are created by very different brain systems. And we could tailor our treatments to those systems.

STEIN: Other scientists praised the research. Lynn Webster is the president of the American Academy of Pain Medicine.

LYNN WEBSTER: It's fascinating. For a long time we've tried to find objective ways to measure pain and it's been elusive.

STEIN: But Webster says brain scans for pain could be misused. Insurance companies might try to use them to deny paying for pain drugs. Some doctors might use them to question whether their patients are telling the truth, or instead of simply listening to their patients.

WEBSTER: If a patient believes their doctor understands and cares about them and believes in their pain that can have as much of a 30 percent reduction in their pain. So this connection, this belief, can be enormously powerful.

STEIN: Tor Wager agrees that the scans should be used very carefully.

WAGER: The bad scenario would be, you come in pain, the physician scans your brain and says, Well, we don't see the pain here so we think it's in your mind. We don't think it's really pain. I don't think that this kind of method can or should ever be used as a pain lie detector.

STEIN: Instead, Wager hopes the technology will open a helpful new window. Not only into how pain really works in the brain, but also other feelings as well.

Rob Stein, NPR News.

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