3 ms·

Well, the field surrounding pain/injury is large and nuanced, so not only is that a difficult question to answer but it's also sort of the wrong question. And,

Well, the field surrounding pain/injury is large and nuanced, so not only is that a difficult question to answer but it's also sort of the wrong question. And, firstly, I strongly recommend watching the linked video (if you have time). But I'll try my best here anyway. Let's start with injury - what constitutes an injury? As in, how should the word "injury" be defined? This is a more complex issue than one might initially assume; not all pain is associated with an insult to tissue, not all insults lead to mechanical damage, insults that do lead to damage do not necessarily lead to pain, etc. So, mostly, injury tends to be defined as anything that leads to a reduction in function/performance in an organism. The ramifications of this definition are important, because things like a compound fracture, delayed-onset muscle soreness, and pain with no (known) underlying cause all meet the definition's criteria. That last bit is the most important (and why I strongly recommend watching the video), because pain is not an input to the brain, rather it is an output of some function in the brain that takes a large number of inputs other than pain. This is basically the crux of the whole bio-psycho-social model, and why I said the original question is sort of the wrong question regarding injury. So here's the revelatory part, as it relates to the original question: aside from large and obvious traumas like a compound fracture, one cannot conclude that, because they are experiencing pain, physical damage to tissue has taken place. So looking for a heuristic to determine the state of some tissue after experiencing an event that led to pain is not really the right approach from the beginning, as one cannot be confident (and should not assume) that the tissue's state is awry at all.

EnderViaAnsible 7y ago
I'm afraid I must strongly disagree with your comment, or at least your conclusion. The existence of pain itself is predicated on its accurate coupling to injury, since the purpose of pain is inhibitory: this hurts, so stop doing it, [because tissue is injured], and it must not continue to be injured. There are of course some counterexamples where this line of thinking fails: pain localized to previously amputated limbs comes to mind. But overall I can think of very few instances where this is true. The magnitude of pain may or may not be proportional; the location may or may not be correct (as in referred pain); but in the vast majority of cases that can I bring to mind, pain very much does indicate tissue damage. (And the biopsychosocial model of pain doesn't change that! The brain, after all, is tissue.)
- inspector-g 7y ago
  > pain itself is predicated on its accurate coupling to injury, since the purpose of pain is inhibitory > pain very much does indicate tissue damage These statements are not supported by modern research. The bio-psycho-social model indicates that pain is a threat detection and deterrent mechanism, NOT a "status report" from the painful tissue to the brain. In other words, the brain is concerned that something might lead to physical trauma, yet none need to have taken place for pain to be generated. There are certainly biological inputs to the "pain generator" function of the brain (like sensing a foreign object touching one's skin), but psychological factors/contexts and social factors/contexts can be equally strong inputs (and ultimately generate a significant pain experience without any, or with very little, biological input). Think of the magnitude of pain response to a given situation as an indicator sitting somewhere on a spectrum between "benign" and "dangerous". The more psychologically threatened one feels, the more the pain response will be shifted toward the "dangerous" end (i.e. higher magnitude). The more socially threatened one feels, the more the pain response will be shifted toward the "dangerous" end. Here is a somewhat contrived but favorite example of mine. One night, you wake up to go to the bathroom. In the dark, you unexpectedly step on your child's lego brick left on the floor, and it hurts immensely - it feels like the pegs are actually spikes! This is mainly because of how it has surprised you; the context is that it's dark, you expected the trip to the bathroom to be just a few simple steps, and (for sake of argument) have never stepped on a lego before. Your brain feels rather threatened by this surprising situation and generates a large pain response. Now, a night or two later, it happens again, and though it hurts it definitely isn't as bad. Another night or two later, it happens a third time, and barely hurts at all (you're basically to the point of expecting it now). I think we can agree that no tissue damage has really been done, and if pain was simply a state-of-tissue indicator then the magnitude of pain should have been the same each and every night. Additionally, if tissue damage need be present for pain to be present, why did it hurt at all? Lastly, I'll note that lack of apparent examples != lack of evidence.

EnderViaAnsible 7y ago

I'm afraid I must strongly disagree with your comment, or at least your conclusion. The existence of pain itself is predicated on its accurate coupling to injury, since the purpose of pain is inhibitory: this hurts, so stop doing it, [because tissue is injured], and it must not continue to be injured. There are of course some counterexamples where this line of thinking fails: pain localized to previously amputated limbs comes to mind. But overall I can think of very few instances where this is true. The magnitude of pain may or may not be proportional; the location may or may not be correct (as in referred pain); but in the vast majority of cases that can I bring to mind, pain very much does indicate tissue damage. (And the biopsychosocial model of pain doesn't change that! The brain, after all, is tissue.)

inspector-g 7y ago
> pain itself is predicated on its accurate coupling to injury, since the purpose of pain is inhibitory > pain very much does indicate tissue damage These statements are not supported by modern research. The bio-psycho-social model indicates that pain is a threat detection and deterrent mechanism, NOT a "status report" from the painful tissue to the brain. In other words, the brain is concerned that something might lead to physical trauma, yet none need to have taken place for pain to be generated. There are certainly biological inputs to the "pain generator" function of the brain (like sensing a foreign object touching one's skin), but psychological factors/contexts and social factors/contexts can be equally strong inputs (and ultimately generate a significant pain experience without any, or with very little, biological input). Think of the magnitude of pain response to a given situation as an indicator sitting somewhere on a spectrum between "benign" and "dangerous". The more psychologically threatened one feels, the more the pain response will be shifted toward the "dangerous" end (i.e. higher magnitude). The more socially threatened one feels, the more the pain response will be shifted toward the "dangerous" end. Here is a somewhat contrived but favorite example of mine. One night, you wake up to go to the bathroom. In the dark, you unexpectedly step on your child's lego brick left on the floor, and it hurts immensely - it feels like the pegs are actually spikes! This is mainly because of how it has surprised you; the context is that it's dark, you expected the trip to the bathroom to be just a few simple steps, and (for sake of argument) have never stepped on a lego before. Your brain feels rather threatened by this surprising situation and generates a large pain response. Now, a night or two later, it happens again, and though it hurts it definitely isn't as bad. Another night or two later, it happens a third time, and barely hurts at all (you're basically to the point of expecting it now). I think we can agree that no tissue damage has really been done, and if pain was simply a state-of-tissue indicator then the magnitude of pain should have been the same each and every night. Additionally, if tissue damage need be present for pain to be present, why did it hurt at all? Lastly, I'll note that lack of apparent examples != lack of evidence.