“How bad is your pain today?” You’ve answered that question dozens of times by rating yourself on a pain scale from one to 10. But did you ever wonder what your answer tells your doctor? Does he know what an “eight” feels like? 

He should, if he's paying attention to the latest research. The medical community has questioned the validity of self-reporting pain levels, but imaging studies have demonstrated that they are accurate.

In a study published in the Proceedings of the National Academy of Sciences in 2003, brain imaging confirmed that people process pain sensations in their brain differently, and some people truly are more sensitive to pain than others. In the study, 17 healthy men and women had a computer-controlled heat stimulator placed on their leg. The device heated a small patch of skin to 120 degrees Fahrenheit, and the participants were asked to gauge their pain from one to 10.

The reactions varied widely – from one to nine. Meanwhile researchers watched the participants’ brain activity using magnetic resonance imaging (MRI). When the heat was applied, all 17 participants had about the same amount of activity in the thalamus – the portion of the brain that transmits pain signals from the spinal cord to other brain regions. The people who reported greater pain had more activity in the regions of the brain that interpret unpleasant feelings and perceive the location of the pain.

Brain imaging results give doctors confidence in their patients’ pain reports, and researchers hope the findings will lead to better pain management and encourage more people to try new techniques to head off painful episodes.

“Until now there was no objective evidence confirming that individual differences in pain sensitivity were in fact real,” says Roger Coghill, PhD, professor of neurobiology and anatomy at Wake Forest University School of Medicine and North Carolina Baptist Hospital in Winston-Salem, NC. Coghill believes that everyone’s spinal cord sends information to the brain in the same way, but the brain itself may process the pain messages differently based on a person’s emotional state, his expectations about pain and his past experiences with pain.

According to Coghill, many people might not consider going to a psychologist for a physical problem like pain, so they keep trying medication. “But now that people can see there is a neurochemical component to pain, they may be more willing to investigate other treatments,” says Coghill.

(Source: Proceedings of the National Academy of Sciences; Vol. 100, No. 8)