These Machines Feel Your Pain

2:00 a.m. Aug. 16, 2002 PDT
SAN DIEGO, California -- Where does it hurt and how much does it hurt?

Only patients can answer those questions, and their responses aren't always
precise. But brain-scan technology is on the verge of allowing doctors to
assign a number to a person's pain, just like a body temperature or blood
count.

"It's a kind of holy grail," said Dr. Sandra Chaplan, a professor of
medicine at the University of California at San Diego, who studies pain.
"You'd like to put something in a patient's chart that everybody can agree
on."

This weekend, Chaplan and thousands of other pain experts will meet in San
Diego at the l0th World Congress on Pain and examine ways to use body
scanning machines to evaluate pain.

But the world of hurt is so complex that some doctors say the colorful blobs
on a brain scan monitor could miss the big picture and mislead everyone who
looks at them. Or the scans might work just fine but provide no more
information than someone could get from what doctors call a "good
historian" -- a patient who accurately reports how he or she feels.

For now, nurses and doctors measure pain in the same way they have since
their professions were invented: They ask patients about it and decide
whether to accept the answers. "We have no marker of pain," said Dr. Mark
Wallace, director of a pain clinic at UC San Diego. "You can't measure it,
you can't see it. We have to take the patient's word for the level of pain
they have."

Thanks to lobbying from pain treatment advocates, many hospital charts now
include a space for nurses and doctors to note the self-described pain level
of patients. The number, on a scale of 1 to 10, goes right next to the four
traditional vital signs -- body temperature, blood pressure, respiration
rate and pulse rate.

According to medical experts, the answers from patients are surprisingly
reliable. But the problem is that pain -- quite literally -- is all in your
head. Only the brain is in charge of whether a person feels pain, and dozens
of factors affect what we feel when we break a leg, suffer a concussion or
cut ourselves shaving.

"There's a lot of psychological issues that muddy the waters," Wallace said.
People suffering from stress, for example, feel pain more acutely. "If I
have someone who's extremely depressed, they won't respond as well to pain
treatment," he said. "If they're overly anxious or have family issues, they
report less relief of their pain."

Over the past five years, scientists have increasingly deployed MRI and PET
scanners in the search for a greater understanding of pain. They watch as
parts of the brain light up when a subject feels pain, and they try to link
what they see to the source of the pain and its severity.

The researchers consider the scanning devices to be fairly reliable because
they seem to reflect the pain that test subjects say they feel. "The
technology certainly works," said Dr. A. Vania Apkarian, an associate
professor of physiology at Northwestern University who patented a way of
using brain scanners to sense pain. "On the other hand, interpreting those
results remains a major challenge. The system is a lot more complicated than
we naively assumed."

And the machines themselves have limitations. "These things can only look so
far. They can't look at everything that happens in the brain," said Richard
H. Gracely, chief of a pain measurement research department at the National
Institutes of Health.

While the machines may not always be accurate, doctors might still use them
routinely to evaluate patients who can't communicate. Babies, for instance,
can't say where it hurts except by moving their bodies, forcing their
doctors to become detectives. Many stroke patients can't pinpoint their pain
either, robbing them of the chance to warn doctors of what's going on
inside.

Patients who can talk just fine might also demand to use the machines to
show the world that they're not phonies. "The problem with being a pain
patient is that you're guilty (of fakery) until proven innocent," Gracely
said. "This is only appreciated by people in that situation.... You're
really suffering but there's no physical sign whatsoever and many people
think you might be making it up."

On the other hand, scanning machines could indicate that some people are
indeed faking their symptoms. But Gracely suspects the number of those
patients, known as malingerers, is small.

Apkarian doubts that the pain-measuring machines will ever become as common
as an IV drip or a heart monitor. While the information they provide is
"richer and more insightful" than anything available before, he thinks the
scanners will probably serve mainly as research tools.

Research remains vital, however. Pain is still one of the least understood
but most crippling of all medical problems. An estimated 30 percent of
cancer patients with severe pain are immune to all the aspirin and morphine
and Oxycontin in the world. They hurt, and nobody can help them. But
Apkarian thinks that may change.

"We are at the crest of a whole revolution in understanding what pain is,"
he said. "We are moving away from managing pain to curing pain. But we're
not there yet."