What is pain threshold?
Can pain be measured? If so, how? What are the units?
Hmm. There is the concept of a pain threshold - pressure applied to one point "starts" to hurt at some point as the pressure applied goes from very low to high. The "starts" point is the pain threshold. As is normal with humans, this varies from person to person. When this response is used for diagnosis, the physician may use an algometer to quantify a pressure induced pain threshold. There are gizmos used to induce pain for special problems, but it seems that applying calibrated pressure (pushing small flat-ended round rod into places on the body, and asking the patient to say stop when it first begins to hurt) with an algometer is a standard approach. Units are Newtons - a unit of force.
Also - Triage staff in clinics sometimes will ask you to evaluate your pain, from 1 to 10, with 1 being slight pain and 10 being the worst ever.
If you ask a woman giving birth, your pain will never ever be a 10.
A comic did a thing on that, and he got his pain down to a 1 comparing it to other pains. The doctor gave him an aspirin.
It's been years since I took a nuerophyschology (or was it neuroscience) course but I distinctly remember it's relative to the individual and his/her state of mind and many other variables. Can it be quantified? Possibly to some degree but the perception of pain is a very complex phenomenon. For instance, you can stick someone with a needle and measure the number of nerve cells activated by their action potential but many people will perceive this stimulus in varying degrees of pain. Why? Because you also have to take into account what happens within the brain (and a lot happens in there). Other factors may include the amount of myelin sheath around the nerves that holds the capacitance of the action potential within a neuron and so forth.
The psychology aspect cannot be undermined and plays a very important aspect of the perception of pain. No where is this apparent than when going to the gym. When bodybuilders or athletes move up in weight (or increase reps to go into muscle fatigue), the number of neurons firing increases but because they've become so accustomed to the pain they subconsciously ignore it. Personally, I've been doing a lot CrossFit lately. On Friday, we had an Army Ranger do one of the most intense workouts I've experienced in years. Within 15 minutes I was drenched (I mean completely soaked) in sweat and my muscles were shaking. It was pure agony. At this point I wanted to quite. I put on some headphones and listened to military cadences by drill instructors. The degree of pain I felt, at that point, lessened. As a matter of fact this is the reason why the military (Army & Marine Corp) use cadence so much in their training schools. They know that psychologically, cadence helps listen the perception of pain because it shifts the focus on the cadence itself. Matter of fact, this is why gyms play loud music.
Please post what your research on this has shown.
As already alluded to, in many medical situations, we use a scale of 1-10 (there are no units). We ask the following question of our patients (Pts): "On a scale of 1-10, with 1 being very little pain, and 10 being the worst pain you've ever felt in your life, how would you rank this pain?"
But as already mentioned, different Pts have very different pain thresholds and pain tolerance. I had a Pt once that I was assessing for chest pain. When I asked the question above, he answered, "It's about a 7 or an 8." Now, chest pain that strong is normally a load-and-go to get to the hospital and Cath Lab as quickly as possible. But I have learned to follow up with the question, "And what was the worst pain you ever felt in your life?" To which he responded, "Well, I sprained my ankle one time pretty badly and that *really* hurt!". Whew, we were able to slow it all down a bit and spend some more time deciding what to do with him.
EDIT -- My own personal answer to the second question is probably getting road rash cleaned out (debriding). Either that or sneezing one time when I had broken ribs. Hoo-boy!
I was debriding extensive road rash on a racer one time who had crashed his bike in an Ironman Triathlon, but who had gotten back up and finished the race (as a bloody mess). He was an ex-Marine in amazing shape. I knew that what I was doing was hurting him like crazy, so I asked him the 1-10 pain question. He answered with a stoic face and calm voice, "It doesn't matter, just keep doing what you're doing." Wow.
YES... Hoo-boy! ...
Being a chronic pain sufferer, having a rebuilt broken neck and mass arthritis since, I can tell you that there is certainly a psychological component to pain, an avoidance reaction that slowly builds itself into one's routine, however, I have for years lived with neck and back pain that I considered a 7-8, and then last year was hospitalized with heavy vomiting and 'some pain', about the same level as my neck and back pain. Well, I am on 120 mg morphine/day with oxycodone for breakthrough days, so I am well prepared, normally, for living with this condition. what I felt in my upper abdomen was "heavy discomfort verging on real pain", to me admitting that yeah, I was really hurting there (as my last dose of pain meds wore off and the pain levels climbed, rapidly).
So, in the hospital, CAT Scans and Ultrasound later, they found that I had a major gall stone that was blocking the common bile duct and creating a massive backup in not just the gall bladder, but massive swelling of the pancreas as well: I had a major case of pancreatitis, which most doctors would accept as most people's "Greatest Pain Ever", yet for me it only matched my normal pain levels. So, the doctors had to rethink what my Base Pain Level is and admit that I do have a much higher tolerance to pain than others, but this has been because it has built up over time and, yes, I hurt, constantly, but I still have to live. But, now I also know that I am quite well vindicated in that my neck and back pain is Very Real and the doctors now have a real quality/quantity of pain in my case.
Obviously this is subjective. I was talking to a nurse about my pain levels, they had Finally brought mine under control and I was able to deal with it (a full week in the hospital is just no fun) and as we were talking another patient down the hall was yelling and carrying on that she was hurting so bad and so on, and the nurse confided to me that the individual had a sprained ankle bad enough to require them to administer blood thinners to prevent clotting and were holding her overnight to make sure that there was no problem. She had never had such pain before, as she clearly let all of us on the floor know. The nurse told me that she was already properly medicated. She and I just quietly agreed that some folks are lucky in that they never have to experience the extreme pain levels that Can happen yet when they DO get injured they make much more of a fuss than someone that has been in a state of chronic pain. So there is certainly a wide range of psychological and physiological differences that go along with pain, and every body is different so their experience of pain is greatly subjective rather than something that can be specifically quantified, at this point. Perhaps there will be some sort of way to quantify pain in the future, but presently we do not seem to have a specific Actual Pain Monitor at this point.
the least stimulus intensity at which a subject perceives pain
It is an entirely subjective phenomenon (Wikipedia)
Perception of pain is different in some individuals. I have a back injury that sometimes causes numbness or the absence of feeling all together Other times its burning sometimes its very mild sometimes unbearable. Some times I don't have reflex reactions in my right leg. And since I have multiple disc involved from c spine through L spine stopping at s1. Its like pinches in a garden hose, each pinch diminishes sensation to a degree but doesn't stop them altogether. During flare ups they can cause unbearable pain.
As Steelwolf said the longer you deal with pain the more you "get use to it". And I also have very weak ankles and have broken each multiple times, its very intense pain indeed. And can be equal to any back pain I have experienced,... not worse just different.
As well as individual differences in pain perception, I believe context is important. I think fear can exacerbate pain. Though it could be it simply prompts a more extreme reaction to a similar pain which does not arouse so much fear.
As for people making excessive fuss, perhaps there is some sense in it. I have seen reports of research showing that tolerance of pain is increased by shouting and swearing. (Sci. Am. & WikiP. )
Mythbusters did an episode on it and swearing did help them tolerate pain longer, IMHO I think vocalization of any type if done with intensity would tend to help, 1. its a distraction, 2. if said with enough intensity it may release more adrenalin into the blood stream.
In sports such as karate when sparing and training they are taught to "yell" when striking this serves to tighten the muscles "incase of counter strikes" and to increase and control the fight or flight response.
Just a comment:
Regarding psychological parameters, objective measures are not an easy matter. Some parameters are by subjective, which is also exactly the problem with subjective self-assessment techniques (ie rate you pain from 0-10). Objective from psychophysiolgy have the problem that you aren't sure that the measure correlate with what you think you are looking for. (ie the problem of defining the measure and WHAT to measure are somewhat inseparable)
Anyway, skin conductanse reseponse (both frequency and tonic level) are one way to _measure_ pain, but it's an unspecific measure. It measures rather sympthatetic activity, which can be triggered by things other than pain.
In infants - who obviously can't answer a self-assessment form, skin conductance measurements are common method.
Also most of psychophysiological measures are relative. That have no absolute meaning. You need strict experimental control to compare pain between situation A and B. Absolute scales are rarely well defined.
Nerve conduction I also find as inadequate measure of both pain and muscle response, I was given a test and it measured the conductivity of the nerves in my legs. On the right side which is the side most affected I couldn't even feel nor did I even flinch as these long needles were pushed into my leg and then electricity was applied to measure the amount of conductivity. Although sometimes my pain on that side is excruciating it varies between tingling, burning, aching and numb. The test said the nerves were working...lol Then they tested the left side which I felt and the test was horrible, the left side came back slightly abnormal even though every time they shocked me I nearly jumped off the table. On the right side the feeling is so diminished at times I don't even have "reflexes" or the Dr, just can't find it, which with the test being "normal" I found very odd.
Having nervedisorders or simply jammed nerves in the back or inflamed muscles is probably a separate discussion. Jammed nerves can of course causr both pain and loss of sensation depending on bundles. Ans are also generally assymmetrical in the body. And regulation of heart for example ia not symmetrical and this ia how assymmetric brain processes such as some stress conditions can cause left/right and imbalance of heart and arrythmia.
Most psychophysiological measurements are influenced by soo many things that the quality of inferences stand and fall by the ability of strict experimental control in the context of a paradigm.
I think this is about the most accurate ranking you're going to get if it's dealt honestly by the patient. Junkies will always walk in the office and say it's 9.5 everytime because of drug-seeking behavior but every one of them knows the real number.
It's not just with pain, it's with every introspective report, IMO. I had physiological psychology prof in undergraduate school I've mentioned here before and he said something one day in class that has stuck with me ever since. He said something along the lines of... that if you get yourself in a quiet space and ask yourself how you really feel about a given topic, then that's what the right answer is.
That can also apply to someone in sever pain, many ER docs and GP's forget that in (some cases not all) that if an honest person can deal with a pain or take care of it themselves they will, that's what Ibuprofen, Tylenol, Aleve are for. SO when they do go to Doctors or the ER is because they are SEEKING drugs. For relief not for getting a fix. IMHO a way of distinguishing from those types of patients (chronic pain sufferers and legitimate patients in sever pain) from (junkies and druggies) is required. Many people are sent from the Doctor's or ER or Walkin-clinic with prescriptions they can get over the counter,( Ibuprofen, Aleve ) then they are left with an outrageous bill for basically first aid advice and the equivalent of a home remedy, its a shame that a few bad apples can spoil the bunch.
BTW what is a good way of distinguishing a patient in true distress from a junkie or druggie? I have had to deal with chronic pain for several years and have been mistaken for the latter at times. Seems like I wasn't taken seriously until I showed up in the Dr. office in full uniform. But as the doctor has explained to me it seems there are more of them (,junkies and druggies) then there are of us. And opiate deaths are on the rise in many states. Oxycontin seems to be one of the more sought after street scrips now, people call it "hillbilly heroine" and I know of at least 4 people who have O.Ded on it from street sources. Luckily here we have pain management contracts, if you do get prescribed any opiate you have to sign a contract and are regularly drug tested.
One technique we use in EMS that sometimes helps when a patient is complaining of pain from an injury, is to palpate the injury in a way that the patient can't see what we are doing. We may gently palpate it a few times, usually eliciting an "ouch that hurts", and then we fake touching it again and ask "does that hurt?". We sometimes get another "ouch that hurts" answer, which helps us to understand that at least part of the pain that is being reported is not real. This only works in some situations, but it's a useful tool that we do take advantage of sometimes.
I think anyone going to a doctor seeking pain meds should be drug tested first. If they come up positive check for a prescriber, if none can be found assess, run test and try and find a legitimate cause for pain (x-ray, MRI, CT, ultra sound) If none can be found then give an NSAIDs and first aid instruction, referral to an appropriate practitioner for evaluation.
My experience (in the past) has usually been a motor function test, grip test, strength test. Then not much of anything else, NSAIDs and first aid information. It took several MRI's to even get minimal pain control which I am thankful I have gotten. Way to many people fall through the cracks.
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