Applied Evidence

A new paradigm for pain?

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From The Journal of Family Practice | 2016;65(9):598-600,602-605.

References

A look at the research

In determining whether a person experiences real pain in the complete absence of physical injury, consider the following research study by Kross et al:14

Forty patients who had recently endured a breakup of an important relationship underwent functional magnetic resonance imaging (fMRI) during the following 4 tasks:

  1. While viewing a headshot of their former partner, they were asked to recall and think about the person who had rejected them.
  2. They viewed a headshot of a same-sex friend while they thought about a recent positive experience they had with that person.
  3. They experienced noxious thermal stimulation on their left arm using a hot heating pad.
  4. They experienced non-noxious thermal stimulation in the same area using a warm heating pad.

The authors found that when the participants thought about being rejected, areas of the brain that support the sensory components of physical pain (the secondary somatosensory cortex and the dorsal posterior insula) became active.

Reassure patients that the pain is not in their head, but rather in their nervous system.

Although the study had numerous limitations, the authors concluded that significant social rejection and physical pain are similar not only in that they are both distressing, but they both activate the same somatosensory brain circuits.14 In other words, brain activity in response to emotional insult mimics physical pain, and it is difficult to tell from images of brain activity whether a person is experiencing one or the other. The study authors noted that other research in their field has shown that intense emotion is insufficient to activate pain pathways, but that activation requires specific feelings, such as those that arise from social rejection.

Our suspicions. There is already evidence that adult trauma leads to changes in pain processing,15,16 and there is preliminary evidence that adverse childhood events change pain processing.17 We believe that future research will continue to cement a connection between adverse childhood events and changes in pain processing that lead pain pathways, particularly the emotional pain circuits, to be active even in the absence of noxious nociceptive stimuli (ie, in the absence of tissue injury).

We also believe that we must broaden our definition of pain since Kross et al’s research demonstrates through objective means that it is possible for a person to feel real pain in response to purely psychological factors that have sensitized the nervous system over weeks and months, in the absence of tissue injury.14 Perhaps this will explain what is happening with some of our patients who complain of pain “all over” and who are often classified as having fibromyalgia. In addition, we propose that much of the frustration with treating chronic pain over the past 40 years and the failures of physical therapy, various procedures, pharmacotherapy, and surgery occurred because we treated patients with sensitized nervous systems as if they had nociceptive pain due to tissue injury.

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