Brain Scans Suggest a New, Objective Way to Measure Pain

By Valerie Ross | September 22, 2011 1:27 pm

What’s the News: The best way doctors have to find out how much pain a patient’s in is to ask—but that approach can fall short when someone’s unable to speak, exaggerating or downplaying their condition, or just plain unsure how to rate their pain on a 10-point scale. Because of these problems with self-reporting, scientists have long been looking for an objective, physiological measure to quantify pain. A recent brain scanning study, in which the researchers could pick out painful experiences based on neural activity, brings that goal closer.

How the Heck:

  • The researchers gave each of 24 participants an fMRI scan, which measures blood flow in the brain. They tracked the participants’ brain activity as a small portion of their forearm was exposed to heat, which was either painful (quite hot) or not painful (pleasantly warm). A computer algorithm then analyzed the data for patterns, looking for types of brain activity that occurred in response to painful or not painful heat.
  • The team next had 16 other people do the same thing, getting their brains scanned while their arms were exposed to various levels of heat. This time, the researchers used the computer algorithm—now that it was trained on data from the earlier subjects—to analyze the scans, classifying each heat exposure as painful or not based on brain activity. The computer model could correctly identify which experiences were painful 81% of the time.

Not So Fast:

  • The study was small, and only looked at a yes-no division (does it hurt or not?) rather than trying to tell more or less painful experiences apart.
  • It also used just one type of pain, heat. Larger studies aimed at discriminating different levels of pain will be required to show whether this technique could be useful in the clinic.

The Future Holds: In addition to looking at varying levels of pain, the team wants to see whether this technique can be used for different sorts of pain—for instance, pain from a wound or a pinched nerve rather than heat. They’re also investigating whether brain scans can measure not just single episodes of pain, but chronic pain, as well.

Reference: Justin E. Brown, Neil Chatterjee, Jarred Younger & Sean Mackey. “Towards a Physiology-Based Measure of Pain: Patterns of Human Brain Activity Distinguish Painful from Non-Painful Thermal Stimulation.” PLoS ONE, September 13, 2011. DOI: 10.1371/journal.pone.0024124

MORE ABOUT: fMRI, MRI, neuroscience, pain
  • Iain

    Masochists wanted. Sado’s need not apply.

  • Renton

    The future end of the process begun with this experiment will be a world in which whatever pain you suffer will be as easily known and confirmed as your height or weight. No more need for self-medication. No more large crowds at sleazy “pain clinics.” A much, much easier time for terminal cancer patients. A much, much easier time for GP’s whose patients parade through their consulting rooms complaining that it hurts, doctor. When pain is an objective measurement, the human world as it has been known from the beginning until now will be a very different, and better, place.

  • Erica

    What happens when your brain’s bloodflow is just different than everyone elses, and it shows up on fMRI that you’re “not in pain” when in fact you are? Your doctor will have “proof” that you’re faking it now… even if you really are not. Until this is perfected, it seems like it would be pretty dangerous in the hands of busy medical professionals (speaking as an RN myself).

  • Scott

    Agreed Erica. I wouldn’t buy it yet. 40 people is probably too small of a sample size to induce anything. But I think (or I would hope) that blood flow in the brain has probably been explored and verified as a variable in brain activity on it’s own before use in this study. My concern would be in the variability of hot/cold free nerve endings in the epidermis. Do people with old “dishwater hands” just have a higher pain threshold or have they lowered the concentration of nerve endings as they have aged?

  • john

    ouch !@#
    how much did that hurt?
    on a scale of 1 to 10 ?

  • Don

    As a past sufferer of pain for over seven years I can vouche that doctors do not believe you are in pain even when you are. When I visited neurosurgeons about my pain level they would not believe me because I was able to perform physical activities they could not perform. I stayed active even though the pain I suffered sometimes caused me to walk in circles for hours even though I was on massive pain killers and up to 10 T3’s a day. When I skied or used roller blades or rode my bike (standing ride only) the pain would go away for a while. When I finished I felt flush and out of pain for up to an hour and then the hammer would fall. Still the neurosurgeons did not believe me. One day I was injured again and despite the pain killers I was on and morphine and demarol I virtually started bending the frame of the stretcher I was on trying to relieve the pain. They finally believed me and operated on me a couple of months later. The pain disappeared immediately. I could walk around without pain immediately. I still go through minor bouts of chronic pain because of nerve damage but it is nothing like before.

    If these neurosurgeons had access to a tool like this MRI perhaps my suffering could have been reduced by years…….

  • Rob

    Think what this could do for tort reform. Scam artists could no longer be able act their way into personal injury settlements. Sleazy PI lawyers would go out of business too. Sounds great!

  • Clark Animal Hospita

    Everybody’s ‘scale’ is calibrated differently. My 5 may be yours 9 and vice versa. Although ‘scaling’ of pain gives it a semblance of objectivity, but it is just that …”semblance’, and nothing more. Certainly not objective.


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