Pain
What is pain?
Merriam Webster Dictionary
pain noun
\ ˈpān
Definition of pain (Entry 1 of 2)
1. PUNISHMENT
the pains and penalties of crime
2
a usually localized physical suffering associated with bodily disorder (such as a disease or an injury)
the pain of a twisted ankle
also : a basic bodily sensation induced by a noxious stimulus, received by naked nerve endings, characterized by physical discomfort (such as pricking, throbbing, or aching), and typically leading to evasive action
the pain of bee stings
b acute mental or emotional distress or suffering : GRIEF
the pain she had felt at those humiliating words
— Morley Callaghan
International Association for the Study of Pain
Pain
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.
Note: The inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment. Pain is always subjective. Each individual learns the application of the word through experiences related to injury in early life. Biologists recognize that those stimuli which cause pain are liable to damage tissue. Accordingly, pain is that experience we associate with actual or potential tissue damage. It is unquestionably a sensation in a part or parts of the body, but it is also always unpleasant and therefore also an emotional experience. Experiences which resemble pain but are not unpleasant, e.g., pricking, should not be called pain. Unpleasant abnormal experiences (dysesthesias) may also be pain but are not necessarily so because, subjectively, they may not have the usual sensory qualities of pain. Many people report pain in the absence of tissue damage or any likely pathophysiological cause; usually this happens for psychological reasons. There is usually no way to distinguish their experience from that due to tissue damage if we take the subjective report. If they regard their experience as pain, and if they report it in the same ways as pain caused by tissue damage, it should be accepted as pain. This definition avoids tying pain to the stimulus. Activity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain, which is always a psychological state, even though we may well appreciate that pain most often has a proximate physical cause.
“It’s whatever the experiencing person says it is, existing whenever and wherever the person says it does.”
Margo McAffery
This question may sound esoteric - some argue that it is a question that can really not be answered. You will note that the note in the IASP definition is significantly longer than the definition itself. The inherent truth for anyone experiencing pain or studying pain is that pain is a wholly subjective experience - while one can infer pain from behaviors, just because a person is exhibiting behaviors associated with pain does not mean that they are truly experiencing pain. In the same vein, just because someone is not displaying pain behaviors does not mean that they are not in pain. The classic examples of pain behaviors, which include grimacing, groaning, bracing, or guarding behaviors that lead to stopping activities and resting, are not real indicators of the presence of pain. Anyone who has worked with children can say that you can see these behaviors in the absence of pain, particularly if the child is frustrated. Similarly, anyone who has worked with high level athletes can tell you that a person can be in tremendous pain, and demonstrate none of these behaviors.
So how do you know if a person is in pain? Ask. Because pain is a subjective experience, the only way to be sure that a person is hurting is to ask them. While this may seem simple enough, training in many of the medical professions often provides biases against this simple way of inquiring about a person’s pain. Many medical practitioners rely instead on observable pain behaviors, although again, those are not a conclusive way to determine if a person is hurting. More than that, biases introduced with the opioid epidemic have led to problems in the opposite direction - such that patient who are exhibiting extreme pain behaviors may be assumed to be malingering, or faking, to acquire pain medications.
An easier question is what is the purpose of pain? Easy enough. Pain is designed as an early warning system, to allow an organism to escape from stimuli that approach tissue damaging range. But there is an inherent caveat in this definition. Pain is not necessarily an indicator of tissue damage - pain indicates that you are being exposed to a stimulus, that if you have prolonged exposure to it, can result in tissue damage. The important lesson here is that a person can feel pain in the complete absence of tissue damage. The implications for this can be profound.
When a child has pain, the lesson that the parent often conveys is that you should avoid whatever it was that you were doing, when you felt that pain. This is a lesson that many carry into adulthood. However, this becomes problematic when you have a person who is in pain, but there is nothing physically wrong, causing that pain. Many persons who develop lower back pain, can have most of the initial injury heal, but may still feel pain. Persons with neuropathic pain can have significant pain in the complete absence of tissue damage - even the lightest stroking touch to the skin can be horrifyingly painful. Persons with fibromyalgia often have significant pain, but standard medical diagnostic techniques often show no evidence of tissue or nerve damage. But to reiterate our first lesson - that does not mean that they are not in pain. Pain is what the patient says it is, and happens when the patient says it does. Pain is, by its nature, defined by the person experiencing it.
One of the most effective ways to improve pain is to increase physical activity. Increasing cardiovascular activity increases the body’s natural pain killers, called endorphins, which are thousands of times more powerful than morphine. Resistance training can also improve a person’s ability to deal with pain, by strengthening muscles surrounding the pain areas, as well as potentially improving pain tolerance. One of the primary causes of lower back pain often involves the lack of tightness in abdominal muscles - this lack of core support requires the lower back to work harder during everyday activities, which can result in pain.
Finally, persons can have pain that appears to not be involved in physiological issues in the body. This is called psychological pain. Many persons report when they go to a physician to discuss their pain issues, they are told that the pain is “in their head.” What a physician means by this is that there are no objective signs that you have tissue damage or injury that would explain the amount of pain that the person is reporting.
Many factors can influence psychological pains. One of the theories surrounding psychological pain focuses on the fact that persons often find that they can get very little understanding and sympathy for psychological distress - however, most people are appropriately sympathetic to complaints of physical pain. This is called “concretizing” or making solid psychic pain. The is not faking, it is not malingering, and it is factitious disorder, where people display medical symptoms in an effort to get attention.
Similarly psychological stressors can lead to physical symptoms, not only by somatization, which is a psychic process, but by physiological processes that can be initiated by psychological distress. Psychological stressors can have a direct impact on health, recovery, and aging. In one study, persons who had recently lost someone they loved were found to be 21 times more likely to have a heart attack, compared to others who were not suffering bereavement.
Patients with psychological pain often have subjective complaints that are much greater than their objective findings. In other words, they report a severity of pain that is not supported by clinical testing. Many factors can influence these behaviors. In some cases, persons recognize, consciously or unconsciously, that they receive more attention when they exhibit pain behaviors, and will exaggerate those behaviors in an effort to get more attention. This is not malingering. This is not faking symptoms in an effort to assume the sick role or to acquire a desired outcome. Many times, these patients exhibit clear signs of pain behavior. The question that arises is whether the pain is physiologically driven or if it is a factor related to psychological factors.
It is very important to recognize that psychological pain is real. Just because the pain may be driven by psychological issues, this does not mean that the person does not hurt, is not in pain, or is not suffering. Psychological pain is NOT malingering or faking. The person is genuinely in pain.
Most importantly, modern scientific techniques cannot definitely say that a person’s pain is psychological. There are several pain syndromes, including central pain syndrome, in which the fibers that carry pain in the human body become hypersensitive, such that stimuli which would not normally trigger a response in pain fibers, such a light touch, can cause frank pain. Allodynia and hyperalgesia are also syndromes that involve physiological responses to stimuli that, in a normal person, would not register as pain. In a normal, healthy person, the experience of allodynia can be related to one’s experience of a large bruise. If a person has an extensive bruise, oftentimes stimuli that would not normally be painful, such a light touch or stroking, can be frankly painful if you touch the bruised tissue. This is an example of allodynia - where light touch causes pain, because the receptors in the area are sensitized, which means that they respond to stimuli that they would not normally respond to.
Pain Vocabulary
Allodynia - Pain due to a stimulus that does not normally provoke pain.
Note: The stimulus leads to an unexpectedly painful response. This is a clinical term that does not imply a mechanism. Allodynia may be seen after different types of somatosensory stimuli applied to many different tissues.
Analgesia
Absence of pain in response to stimulation which would normally be painful.
Note: As with allodynia (q.v.), the stimulus is defined by its usual subjective effects.
Causalgia
A syndrome of sustained burning pain, allodynia, and hyperpathia after a traumatic nerve lesion, often combined with vasomotor and sudomotor dysfunction and later trophic changes.
Hyperalgesia -
Increased pain from a stimulus that normally provokes pain.
Hyperesthesia
Increased sensitivity to stimulation, excluding the special senses.
Hyperpathia
A painful syndrome characterized by an abnormally painful reaction to a stimulus, especially a repetitive stimulus, as well as an increased threshold.
Hypoalgesia
Diminished pain in response to a normally painful stimulus.
Neuropathic pain*
Pain caused by a lesion or disease of the somatosensory nervous system.
Central neuropathic pain*
Pain caused by a lesion or disease of the central somatosensory nervous system.
Peripheral neuropathic pain*
Pain caused by a lesion or disease of the peripheral somatosensory nervous system.
Neuropathy*
A disturbance of function or pathological change in a nerve: in one nerve, mononeuropathy; in several nerves, mononeuropathy multiplex; if diffuse and bilateral, polyneuropathy.
Nociception*
The neural process of encoding noxious stimuli.
Note: Consequences of encoding may be autonomic (e. g. elevated blood pressure) or behavioral (motor withdrawal reflex or more complex nocifensive behavior). Pain sensation is not necessarily implied.
Nociplastic pain*
Pain that arises from altered nociception despite no clear evidence of actual or threatened tissue damage causing the activation of peripheral nociceptors or evidence for disease or lesion of the somatosensory system causing the pain.
Sensitization*
Increased responsiveness of nociceptive neurons to their normal input, and/or recruitment of a response to normally subthreshold inputs.
Note: Sensitization can include a drop in threshold and an increase in suprathreshold response. Spontaneous discharges and increases in receptive field size may also occur. This is a neurophysiological term that can only be applied when both input and output of the neural system under study are known, e.g., by controlling the stimulus and measuring the neural event. Clinically, sensitization may only be inferred indirectly from phenomena such as hyperalgesia or allodynia.
Central sensitization*
Increased responsiveness of nociceptive neurons in the central nervous system to their normal or subthreshold afferent input.
Note: See note for sensitization and nociceptive neuron above. This may include increased responsiveness due to dysfunction of endogenous pain control systems. Peripheral neurons are functioning normally; changes in function occur in central neurons only.
Peripheral sensitization*
Increased responsiveness and reduced threshold of nociceptive neurons in the periphery to the stimulation of their receptive fields
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