April 11, 2013
Researchers say they have found a way to "see" one type of pain on a brain scan. In the future, such an approach may help to tell whether babies or others who can't communicate well are feeling pain. The study included 114 healthy volunteers. They were hooked up to a functional MRI (fMRI) machine to show activity in different parts of the brain. First, people were tested using a heating element applied to the forearm. Sometimes the heat was painful but not burning (116 degrees Fahrenheit). Other times it was just warm. Researchers saw a "pain signature" in the fMRI pattern for painful heat, compared with warmth. More than 90% of the time, these patterns matched what people said about whether they felt pain. Researchers also looked at "social pain." Of those in the study, 40 recently had a romantic breakup. They were shown photographs of the partners who had dumped them. The fMRI results were similar to the pattern for physical pain. However, researchers were able to tell them apart. Scans also showed a reduction in physical pain after people were treated with a pain reliever. The New England Journal of Medicine published the study. The Associated Press wrote about it April 11.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
"Is this pain all in my head?" I hear this question a lot. It comes up because frequently no cause can be found for the pain patients describe.
I also have patients who express relief when a test result (such as an X-ray or MRI) does reveal a clear cause of pain: "Well, at least we know now I'm not just imagining it."
These situations reflect an assumption of doctors and patients that "real" pain should have a reason that can be proven. Yet that's frequently not the case. The physical examination and even extensive testing may be normal. Inevitably, this leads to speculation. Could the pain be somehow "imagined" or caused by psychological distress (such as anxiety or depression)?
Pain whose cause can't be found affects millions of people. Examples include migraines, fibromyalgia and many cases of back pain. These diagnoses rely mainly on symptoms reported by the patient. Tests can rule out other causes. However, they cannot confirm the cause or even the existence of pain.
But this may soon change. New research explores the idea that because certain parts of the brain are active when we feel pain, it may be possible to "see" pain with a brain scan. The New England Journal of Medicine published the study results today.
Researchers performed a special type of brain MRI on 114 people while a warm or uncomfortably hot (116 degrees Fahrenheit) object was applied to the forearm. This functional MRI (fMRI) showed which areas of the brain were most active when people felt the painful heat.
Other scans showed "social pain." People in this part of the study had recently been through a romantic breakup. Scans measured their reactions when they were shown pictures of the former partner who had rejected them.
The researchers found that:
You may wonder, as I did, so what? If two people report severe back pain and no cause can be found, should their fMRI results help determine treatment? Or, if the fMRI does not show the "pain signature," should that patient's pain be taken less seriously? In my view, we're a long way from knowing what to do with the results reported today!
And even if we did know what to do, remember that the scans were not perfect in identifying pain.
On the other hand, this study is among the first to show that pain can be reflected in a particular pattern of brain activity. This could advance our understanding of how people feel pain and eventually lead to better treatments.
What Changes Can I Make Now?
If you have pain you can't explain, and it isn't getting better, see your doctor. Don't assume it's because you're getting older or something you just have to tolerate. If a cause can be found, there may be a specific treatment. And even if a cause cannot be found, effective treatment may still be available.
Pain can be treated in several ways. They included:
If you aren't getting better, ask your doctor whether you should be referred to a specialist in pain management. These are doctors trained in the treatment of pain, regardless of its cause.
If your doctor talks with you about psychological sources of pain, that doesn't mean he or she doubts that you have pain. In fact, there is currently no reliable way to distinguish between psychological and physical causes of pain.
In my experience, it's rarely helpful to question whether a person is actually feeling pain. An editorial published with this new research made a similar point: "We may ultimately have to acknowledge that 'pain is pain' and can be reported only by the patient."
What Can I Expect Looking to the Future?
More study will be needed to determine how the findings of this study may lead to better assessment of pain or its treatment.
You can expect researchers to confirm and extend the findings of this new study. For example, the current study analyzed heat-induced pain. What about other types of pain? Can these scans be used to assess pain in people who cannot communicate well? Only time will tell.
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