Pain detection?

Factual Questions
1

Just wondering,
Why can’t medical science detect pain and not just it’s symptoms?

For example, a doctor sees some abnormal swelling on a scan or xray and deduces that there most be pain present. However as it stands if the body does not indicate something is not right- yet there is still pain present in the subject/patient is there another option to find the orgin of the problem?

Medically we hardly ever see first-hand what the problem is only when the problem gets out of hand enough to create symptoms do we even have a clue.

Is there anything out there being developed that might one day change the state of things?

2

IANAD, but I would hazard a guess that pain is a specific kind of nerve signal, which I don’t think we can interpret that well.

3

If it was as simple as a specific kind of nerve signal, we’d be able to detect it with existing technology.

Pain is not a nerve signal, but rather a state-change in the complex ‘program’ that we call the consciousness. Here’s a vastly oversimplified overview of what happens:

Nociceptive sensors in the body detect tissue damage. They do this by detecting certain chemicals in places where they don’t belong. When they’re activated, they send impulses to the spinal column. From there, the impulses run up the spinothalamic tract in the spinal column. From there, they run to the thalamus, and from there to the postcentral gyrus of the cerebral cortex, in the parietal lobe of the brain.

However, this “signal” is not a dedicated point-to-point channel. At a number of places along the way, it is modulated by other inputs. So just because sensors in your hand are transmitting at maximum intensity, does not mean that the signal will be at maximum when it reaches the level of the brainstem. It may be attenuated or modulated by other sensory inputs from elsewhere. This may also happen in the thalamus, which has sensory channels from throughout the body running through it.

Furthermore, other systems in the brain will affect how this signal is interpreted. It’s been shown that when people are comforted, they actually feel less pain than if they’re not. This means that the systems of the brain that integrate information weigh the nociceptive input less when you know you are being taken care of.

So in short, “pain” isn’t what your nerves transmit. “Pain” is an abstract input to your consciousness by the underlying machinery, based on the evaluation and integration of various pieces of information, only one of which is the nociceptive signal from the tissue-damage sensors in your body.

4

I’d also like to add that if I’m poking a bruise that I have I feel pain, but it doesn’t hurt. When someone else pokes the same bruise, however, I both feel pain and it hurts. The point here being the same base signals (bruise getting poked) can be interpreted in different ways, so even if the signals themselves could be reliably detected and traced it doesn’t follow that I’m actually feeling any pain.

Additionally, the underlying machinery can misbehave. For example, phatom pain (sure, it’s a wikipedia cite, but it’s a fairly well known thing). This pain is felt just because something sent a signal which your brain thought was pain in a missing limb. There doesn’t have to be any damage related reason for the signal getting sent, as it’s fairly obvious that there is no body part for the damaged signals to be sent from. The treatment for such pain can include destroying the nerves sending the wayward signals, though that is the extreme case.

5

Your question talks about two unrelated concepts: medical direct detection of pain, and medical detection of abnormality below the level of overt symptoms. Those are two very different things.

I am NOT an expert in either of these. I have read some fascinating articles (no handy cite) on the idea that most chronic pain that does not respond to anagesics is psychological, not physical. The theory is that it is essentally the same mental process as worrying. These theories seem to be gaining ground in the chronic pain management community, but again I’m no expert.

Just like you can have an unpleasant memory that involuntarily keeps coming back, say of combat or a horriffic accident or a loved one’s illness & death, you can “remember” the pain you had from some injury.

To you, ie to your consciousness, it “feels” just like the real thing; you feel pain. But there is nothing going on anywhere in your body to support that. You’re just remembering the pain from a prior real event. And since this “remembering” is happening at a subconscious level, you not only don’t know that it’s effectively an illusion, you can’t control it.

And all nerve-calming pain deadening drugs in the world won’t do anything for it, since the problem doesn’t exist at the level where they work.
So as far as the OP’s question about pain detection, if this theory is true or mostly true, pain detection would really be psychological state detection, ie mind reading. That’s not a machine we’re gonna see in the clinic any time soon.
Turning to detection of abnormality before overt symptoms…

Heck, that’s what modern medicine is all about. All our chemical tests & scans & whatnot are all about learning more sooner than can be detected by the patient through overt sensations.

For a made-up example, the lower limit of detectability of a stomach tumor by the patient is when a big bulge forms poking out of his skin. That’s a symptom. With a CT or MRI scan the same tumor can be detected when it’s 2mm in diameter. And a sensitive enough antibody test might be able to detect it when it’s .02 mm in diameter & consists of just a few hundred cells.

So, yes, things like that are being developed every day to improve early detection of various abnormalities at an ever lowering thresholds.

But the idea that there would ever be a generalized abnormality detector is silly. There might be one box that can run 10,000 tests, but it’s still 10,000 individual checks for 10,000 individual abnormalities.