Multidimensional Nature of Pain: Difference between revisions

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'''Original Editor '''- [[User:Alberto Bertaggia|Alberto Bertaggia]].  
'''Original Editor '''- [[User:Alberto Bertaggia|Alberto Bertaggia]].  
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== Introduction  ==
== Introduction  ==


A definition of pain is provided by the International association for the Study of Pain (IASP) as follows<ref name="IASP Pain">IASP Taxonomy - IASP [Internet]. [cited 2016 Mar 18]. Available from: http://www.iasp-pain.org/Taxonomy#Pain</ref>:<br>  
A definition of pain is provided by the International association for the Study of Pain (IASP) as follows:<ref name="IASP Pain">International Association for the Study of Pain. IASP Terminology. Available from: https://www.iasp-pain.org/Education/Content.aspx?ItemNumber=1698. [Accessed 19 July 2020]</ref><br>  
<blockquote>'''"An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage"'''<br> </blockquote>  
<blockquote>'''An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage'''<br> </blockquote>  
Pain is always '''subjective''' and everyone learns the use of this word through experiences related to injury in early life.<br>  
Pain is always '''subjective''' and everyone learns the use of this word through experiences related to injury in early life.<br>  


It is '''a sensation in a part or parts of the body''', but it is also always '''unpleasant and therefore also emotional'''.&nbsp;<br>
Pain is '''a sensation in a part or parts of the body.''' It can vary in intensity, quality, duration and pain can refer to other parts of the body'''.''' Pain is usually an '''unpleasant sensation and therefore it also has an emotional aspect'''. It is strongly linked to suffering.<ref name="Woolf 2004" />
 
Even in the absence of tissue damage or any likely pathophysiological cause, people still report pain; usually this happens for psychological reasons. In these cases, it is challenging to distinguish whether their experience arise from a damaged tissue or not, based only upon the subjective report<ref name="Merskey 1994">Merskey H, Bogduk N. Classification of Chronic Pain: Descriptions of Chronic Pain Syndromes and Definitions of Pain Terms. IASP Press; 1994. 248 p.</ref>.<br>
 
It is important to underline that '''activity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain<ref name="Merskey 1994" />''', which is always the output of a widely distributed neural network in the brain rather than one coming directly by sensory input evoked by injury, inflammation, or other pathology<ref name="Melzack 2001">Melzack R. Pain and the neuromatrix in the brain. J Dent Educ. 2001 Dec;65(12):1378–82.</ref>.<br>


In the following video Karen D. Davis tries to explain why do some people react to the same painful stimulus in different ways.<br> <br> {{#ev:youtube|I7wfDenj6CQ}} <br>  
Even in the absence of tissue damage or any likely pathophysiological cause, people still report pain. This could happen for psychological reasons. In these cases, it is challenging to distinguish whether someone's experience of pain arises from damaged tissue or not, as it can only be based upon the subjective report of such experience.<ref name="Merskey 1994">Merskey H (ed.), Bogduk N (ed.). ''[https://s3.amazonaws.com/rdcms-iasp/files/production/public/Content/ContentFolders/Publications2/FreeBooks/Classification-of-Chronic-Pain.pdf Classification of chronic pain; Descriptions of chronic pain syndromes and definitions of pain terms]''. 2nd ed. Seattle: IASP Press; 1994 Available from: https://s3.amazonaws.com/rdcms-iasp/files/production/public/Content/ContentFolders/Publications2/FreeBooks/Classification-of-Chronic-Pain.pdf [Accessed on 10 May 2019]</ref><br>  


== Relevant anatomy and physiology  ==
In the following video, Karen D. Davis tries to explain why some people react to the same painful stimulus in different ways.<br> <br>{{#ev:youtube|I7wfDenj6CQ}} <br><ref>TED-Ed. How does your brain respond to pain? - Karen D. Davis Available from
https://www.youtube.com/watch?v=I7wfDenj6CQ&feature=emb_logo</ref>


=== Nociceptors  ===
==The Process of Feeling Pain==
Pain is a physiological protective system. It is essential to warn, detect, and minimize contact with damaging stimuli.<ref name="Woolf 2010">Woolf CJ. [https://www.jci.org/articles/view/45178/pdf What is this thing called pain?.] ''The Journal of clinical investigation''. 2010 Nov 1;120(11):3742-4. Available from: https://www.jci.org/articles/view/45178/pdf [Accessed on 10 May 2019]</ref> Nerve endings and sensory receptors in the skin and tissues detect sensory stimuli. This can be thermal, mechanical or chemical stimuli (heat, cold, pressure, etc.). [https://physio-pedia.com/Nociception Nociceptors] (from the Latin word ''nocere'' that means ''"''to hurt") are sensory receptors that respond to damaging or potentially damaging stimuli. With the stimulation of a nociceptor, a noxious stimulus is converted into electrical activity in the peripheral terminals of nociceptor sensory fibres. This is called transduction. The stimulus is carried to the spinal cord (central nervous system) through a process called conduction. The nociceptive nerve fibres terminate and the synaptic transfer and modulation of input from one neuron to another take place. This is called transmission. The neurons in the dorsal horn of the spinal cord transfer nociceptive input to the brainstem, hypothalamus, thalamus and brain cortex. In the brain perception of the experience occurs. This is a subjective process. Only then does the brain create pain as output after processing the stimuli. It is important to underline that activity induced in the nociceptive pathways by a noxious stimulus does not always lead to pain. Nociceptors can be stimulated by potentially damaging stimuli as well as actual damaging stimuli. Only when the brain has processed the stimulus, will it lead to a response of pain or not. Pain is always the output of a widely distributed neural network in the brain rather than one coming directly by sensory input evoked by injury, inflammation or other pathology<ref name="Dubin 2010">Dubin AE, Patapoutian A. [https://www.jci.org/articles/view/42843/pdf Nociceptors: the sensors of the pain pathway]. ''The Journal of clinical investigation''. 2010 Nov 1;120(11):3760-72. Available from: https://www.jci.org/articles/view/42843/pdf [Accessed on 10 May 2019]</ref>.                                                                                                                                                                 


Nociceptors (from the latin ''nocere =&nbsp;''to hurt) are sensory receptors which detect signals from damaged tissue or the threat of damage and indirectly also respond to chemicals released from the damaged tissue. There are free nerve endings present in many types of tissues,&nbsp; and cell bodies located in the dorsal root ganglions or in the cranial nerve ganglia.<br>  
[[File:Nociception Illustration.jpg|center|frame|638x638px|[https://commons.wikimedia.org/wiki/File:Nociception_Illustration.jpg Nociception]]]
<br>


[[Image:Nociceptors.jpg|thumb|center|200px|(A) Somatosensory neurons are located in peripheral ganglia (trigeminal and dorsal root ganglia) located alongside the spinal column and medulla. Afferent neurons project centrally to the brainstem (Vc) and dorsal horn of the spinal cord and peripherally to the skin and other organs. Vc, trigeminal brainstem sensory subnucleus caudalis. (B) Most nociceptors are unmyelinated with small diameter axons (C-fibers, red). Their peripheral afferent innervates the skin (dermis and/or epidermis) and central process projects to superficial laminae I and II of the dorsal horn. (C) A-fiber nociceptors are myelinated and usually have conduction velocities in the Aδ range (red). A-fiber nociceptors project to superficial laminae I and V. from: Dubin AE, Patapoutian A. Nociceptors: the sensors of the pain pathway.  J Clin Invest. 2010 Nov 1;120(11):3760–72. Copyright © 2010, American Society for Clinical Investigation.]] <br> Nociceptors have unmyelinated (C-fiber) or thinly myelinated (A-fiber) axons<ref name="McCleskey 1999">McCleskey EW, Gold MS. Ion channels of nociception. Annu Rev Physiol. 1999;61:835–56.</ref>. C-fibers support conduction velocities of 0.4–1.4 m/s, while A-fibers support conduction velocities of approximately 5–30 m/s<ref name="Dubin 2010">Dubin AE, Patapoutian A. Nociceptors: the sensors of the pain pathway. J Clin Invest. 2010 Nov 1;120(11):3760–72.</ref>.<br>
== Pain Classification ==
Based on the works of Woolf<ref name="Woolf 2010" />, this is a useful way of classifying pain:


=== Nociception<br>  ===
* ''Nociceptive pain''. This kind of pain is concerned with the sensing of noxious stimuli. It is a signal of impending or actual tissue damage and is a high-threshold pain only activated in the presence of intense stimuli. It has a protective role requiring immediate attention and responses (i.e. withdrawal reflex). For example, touching something too hot, cold or sharp
* ''Inflammatory pain''. This second kind of pain is important to promote healing and protection of injured tissues. It increases sensory sensitivity through pain hypersensitivity and tenderness. Thus normally innocuous stimuli now elicit pain. It creates an environment which suggests avoidance of movement, contact and stress of the injured body parts. This, in turn, assists in the healing of the injured body part. Inflammatory pain is caused by activation of the immune system that causes inflammation after tissue injury or infection. This type of pain can be seen as a protective mechanism, However, it still needs to be reduced in patients with ongoing inflammation, as with rheumatoid arthritis or in cases of severe or extensive injury.
* ''Pathological pain''. This type of pain is not protective, but rather maladaptive. It is not connected to tissue damage but results from abnormal functioning of the nervous system. To note, this is a low-threshold pain. Pathological pain can occur after damage to the nervous system or even when there is no damage or inflammation, It is largely the consequence of amplified sensory signals in the central nervous system. Conditions that cause this type of pain include fibromyalgia, irritable bowel syndrome, tension-type headache, temporomandibular joint disease etc. Usually, the pain is substantial without any noxious stimulus and minimal or even no peripheral inflammation.


Nociception is a mechanism which comprises the processes of transduction, conduction, transmission and perception<ref name="Woolf 2004">Woolf CJ, American College of Physicians, American Physiological Society. Pain: moving from symptom control toward mechanism-specific pharmacologic management. Ann Intern Med. 2004 Mar 16;140(6):441–51.</ref>. <br>  
'''Acute pain''' is caused by noxious stimuli and is mediated by nociception. It has an early onset and serves to prevent tissue damage. This is why this type of pain is defined as adaptive, it helps to survive and to heal<ref name="Woolf 2004">Woolf CJ. [http://www.smbs.buffalo.edu/acb/neuro/readings/SensitizMolecMech.pdf Pain: moving from symptom control toward mechanism-specific pharmacologic management.] ''Ann Intern Med''. 2004;140:441-51. Available from: http://www.smbs.buffalo.edu/acb/neuro/readings/SensitizMolecMech.pdf [Accessed 12 May 2019]  </ref>  


#''Transduction ''is the conversion of a noxious thermal, mechanical, or chemical stimulus into electrical activity in the peripheral terminals of nociceptor sensory fibers. This process is mediated by specific receptor ion channels expressed only by nociceptors.
'''Chronic pain''' is pain continuing beyond 3 months, or after healing is complete<ref name="Merskey 1994" />. It may arise as a consequence of tissue damage or inflammation or have no identified cause. Chronic pain is a complex condition embracing physical, social and psychological factors, consequently leading to disability, loss of independence and poor quality of life.<ref name="Breivik 2006">Breivik H, Collett B, Ventafridda V, Cohen R, Gallacher D. [http://www.nascholingnoord.nl/presentaties/2012_02_02_Breivik_et_al___Survey_of_chronic_pain_in_Europe.pdf Survey of chronic pain in Europe: prevalence, impact on daily life, and treatment]. ''European journal of pain.'' 2006 May;10(4):287–333. Available from: http://www.nascholingnoord.nl/presentaties/2012_02_02_Breivik_et_al___Survey_of_chronic_pain_in_Europe.pdf [Accessed on 12 May 2019] </ref>  
#''Conduction ''is the passage of action potentials from the peripheral terminal along axons to the central terminal of nociceptors in the central nervous system.
#''Transmission ''is the synaptic transfer and modulation of input from one neuron to another.  
#Projection neurons in the dorsal horn transfer nociceptive input to the brainstem, hypothalamus, and thalamus and then, through relay neurons, to the cortex. Here is where ''perception ''occur as a subjective experience.<br>


=== Types of pain classification  ===
== The Biopsychosocial Model of Pain ==
In the past, psychological and physiological (or pathophysiological) factors were considered as separate components in a dualistic point of view. Later, the recognition that psychosocial factors, such as emotional stress and fear, could impact the reporting of symptoms, medical disorders, and response to treatment lead to the development of the biopsychosocial model of pain<ref name="Gatchel 2007">Gatchel RJ, Peng YB, Peters ML, Fuchs PN, Turk DC. [https://rc.library.uta.edu/uta-ir/bitstream/handle/10106/5000/BIOPSYCHO2006-0750-R-Final-single%20701.pdf?sequence=1 The biopsychosocial approach to chronic pain: scientific advances and future directions]. ''Psychological Bulletin''. 2007 Jul;133(4):581. Available from: https://rc.library.uta.edu/uta-ir/bitstream/handle/10106/5000/BIOPSYCHO2006-0750-R-Final-single%20701.pdf?sequence=1 [Accessed on 12 May 2019]</ref>.<br>


Based upon the works of Woolf<ref name="Woolf 2004" /><ref name="Woolf 2010">Woolf CJ. What is this thing called pain? J Clin Invest. 2010 Nov 1;120(11):3742–4.</ref>, this is a useful types of pain classification:<br>  
The ''bio ''part represents the pathophysiology of the disease or the mechanism of injury, and the relative nociception processes, it considers the physiological aspects of the pain experience.<br>  


#''Nociceptive pain''. This kind of pain is concerned with the sensing of noxious stimuli and is a high-threshold pain only activated in the presence of intense stimuli. It has a protective role requiring immediate attention and responses (i.e. withdrawal reflex).<br>
The ''[[Psychological Basis of Pain|psychosocial]]'' part involves both emotion (the more immediate reaction to nociception and is more midbrain based) and cognition (which attach meaning to the emotional experience). These could trigger additional emotional reactions and thereby amplify the experience of pain, thus perpetuating a vicious circle of nociception, pain, distress, and disability.<ref name="Gatchel 2007" /><br>
#''Inflammatory pain''. This second kind of pain is important to promote protection and healing of the injured tissues by creating an enviroment which suggests avoidance of movement and stress of the body parts. This is made possible by activation of the immune system causing inflammation.<br>
#''Pathological pain''. This type of pain is uncoupled from noxious stimulii and even from tissue damage, it is not protective, and results from abnormal functioning of the nervous system (peripheral or central). To note, this is a low-threshold pain. This time pain is not a symptom, but rather a disease itself.&nbsp; It occurs with peripheral sensitization and central sensitization.


[[Image:Pain classification.jpg|thumb|center|200px|Pain can be broadly divided into three classes. (A) Nociceptive pain represents the sensation associated with the detection of potentially tissue-damaging noxious stimuli and is protective. (B) Inflammatory pain is associated with tissue damage and the infiltration of immune cells and can promote repair by causing pain hypersensitivity until healing occurs. (C) Pathological pain is a disease state caused by damage to the nervous system (neuropathic) or by its abnormal function (dysfunctional). From: Woolf CJ. What is this thing called pain? J Clin Invest. 2010 Nov 1;120(11):3742–4. Copyright © 2010, American Society for Clinical Investigation.]]
It could be said that psychological factors, such as fear and anxiety, play an important role in the development of chronic pain. <ref name="Gatchel 2007" />


== Acute and chronic pain<br>  ==
== Psychological Factors in Pain  ==


'''Acute pain''' is caused by a noxious stimuli ad is mediated by nociception. It has early onset and serve to prevent tissues damages. It is also useful to learn to avoid threat of damage, because certain categories of noxious stimulii become linked to the sensation of pain. This is why this type of pain is defined as adaptive, it helps to survive and to heal<ref name="Woolf 2004" />
=== Anxiety  ===


'''Chronic pain''' is pain continuing beyond 3 months or after healing is complete<ref name="Merskey 1994" />. It may arise as a consequence of tissue damage or inflammation or have no identified cause<ref name="Chronic Pain NIH">Chronic Pain: Symptoms, Diagnosis, &amp; Treatment | NIH MedlinePlus the Magazine [Internet]. [cited 2016 Mar 28]. Available from: https://www.nlm.nih.gov/medlineplus/magazine/issues/spring11/articles/spring11pg5-6.html</ref>. It can affect a specific body part (i.e. Complex Regional Pain Syndrome (CRPS), low back pain (LBP), pelvic pain) or be widespread (i.e. fibromyalgia). Chronic pain is a complex condition embracing physical, social and psychological factors, consequently leading to disability, loss of independence and poor quality of life (QoL)<ref name="Breivik 2006">Breivik H, Collett B, Ventafridda V, Cohen R, Gallacher D. Survey of chronic pain in Europe: prevalence, impact on daily life, and treatment. Eur J Pain. 2006 May;10(4):287–333.</ref>.
Health anxious individuals form dysfunctional assumptions and beliefs about pain and other symptoms. This can be disease based and based on past experiences. They will have a tendency to misinterpret somatic information as catastrophic and personally threatening. Some studies report an increase in pain correlated with increased levels of anxiety.<ref name="Moseley 2007">Moseley GL. [https://cdn.bodyinmind.org/wp-content/uploads/Moseley-2007-PTR-conceptualisation1.pdf Reconceptualising pain according to modern pain science.] ''Physical therapy reviews''. 2007 Sep 1;12(3):169-78. Available from: https://cdn.bodyinmind.org/wp-content/uploads/Moseley-2007-PTR-conceptualisation1.pdf [Accessed on 12 May 2019]</ref> Clinically, anxiety can compromise treatments as practitioners can expect to see catastrophization play a big role in these patients' report and they could report greater pain during activities. Thus, there is a need to target attentional focus and interpretation of sensations among health anxious clients. <br>  
=== Depression  ===


== Psychological factors in pain<br> ==
There is strong evidence of established comorbidity of pain and depression.<ref name="Blair 2003">Bair MJ, Robinson RL, Katon W, Kroenke K. [https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/216320 Depression and pain comorbidity: a literature review]. ''Archives of internal medicine''. 2003 Nov 10;163(20):2433-45. Available from: https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/216320 [Accessed on 12 May 2019]</ref> Furthermore, when patients with pain have comorbid depression, they could experience greater pain, have a worse prognosis, and more functional disability. Pain and depression are linked by neurobiological, cognitive, affective and behavioural factors. Thus, the optimal treatment approach for comorbid pain and depression should simultaneously address both physical and psychological symptoms.<br>  


=== Anxiety<br>  ===
=== Expectation  ===


Health anxious individuals form dysfunctional assumptions and beliefs about symptoms and disease based on past experiences and become health anxious when these dysfunctional scheme are triggered by critical incidents<ref name="Hadjistavropoulos 2000">Hadjistavropoulos HD, Hadjistavropoulos T, Quine A. Health anxiety moderates the effects of distraction versus attention to pain. Behaviour Research and Therapy. 2000 May;38(5):425–38.</ref>. Moreover, they will have a tendency to misinterpret somatic information as catastrophic and personally threatening<ref name="Hadjistavropoulos 2000" />.  
When an individual expects to experience pain, the perceived pain may vary based upon the types of cues received (i.e. a cue may indicate a more intense or damaging stimulus, then more intense pain is perceived and vice versa). Cues of an impending treatment could also decrease pain, for example, the process of taking an analgesic, usually decreases pain.<ref name="Moseley 2007" /> Thus, expectation is thought to play a big role in the placebo effect.<br>


Some studies report an increase in pain correlated with increased levels of anxiety, but other suggests it has no effects, thus the effect of anxiety on pain may be dependent on attention<ref name="Moseley 2007">Moseley GL. Reconceptualising pain according to modern pain science. Physical Therapy Reviews. 2007 Sep 1;12(3):169–78.</ref>.<br>
=== Attention and Distraction  ===


Clinically, anxiety can compromise treatments as the practiotioners must expect patients to report catastrophization and greater pain during activities, thus there is need to target attentional focus and interpretation of sensations among health anxious clients<ref name="Hadjistavropoulos 2000" />. <br>
There is strong evidence that attention (and distraction) is highly effective in modulating the pain experience and demonstrate how cognitive processes can interfere with pain perception. When a person is distracted with a cognitive task pain is perceived as less intense, even in chronic pain patients. On the other hand, pain increases when it is the focus of attention. Functional brain imaging and neurophysiological studies have shown that attention and cognitive distraction-related modulations of nociceptive driven activations take place in various pain-sensitive cortical and subcortical brain regions, accompanied by concordant changes in pain perception.<ref name="Bantick 2002">Bantick SJ, Wise RG, Ploghaus A, Clare S, Smith SM, Tracey I. [https://academic.oup.com/brain/article/125/2/310/296978 Imaging how attention modulates pain in humans using functional MRI]. ''Brain''. 2002 Feb 1;125(2):310-9. Available from: https://academic.oup.com/brain/article/125/2/310/296978 [Accessed on 12 May 2019]</ref><br>  
 
=== Depression<br>  ===
 
There are strong evidencies of an established comorbidity of pain and depression<ref name="Miller 2009">Miller LR, Cano A. Comorbid chronic pain and depression: who is at risk? J Pain. 2009 Jun;10(6):619–27.</ref><ref name="Blair 2003">Bair MJ, Robinson RL, Katon W, Kroenke K. Depression and pain comorbidity: a literature review. Arch Intern Med. 2003 Nov 10;163(20):2433–45.</ref>. Furthermore, when patients with pain have comorbid depression, they have greater pain, a worse prognosis, and more functional disability<ref name="Borsbo 2009">Börsbo B, Peolsson M, Gerdle B. The complex interplay between pain intensity, depression, anxiety and catastrophising with respect to quality of life and disability. Disabil Rehabil. 2009;31(19):1605–13.</ref>. Additionally, chronic pain patients with co-morbid depression have higher health care costs compared to pain patients who do not have depression<ref name="Baumeister 2012">Baumeister H, Knecht A, Hutter N. Direct and indirect costs in persons with chronic back pain and comorbid mental disorders--a systematic review. J Psychosom Res. 2012 Aug;73(2):79–85.</ref>.<br>
 
Pain and depression are associated by neurobiological, cognitive, affective and behavioral factors, thus the optimal treatment approach for comorbid pain and depression should simultaneously address both physical and psychological symptoms<ref name="Goesling 2013">Goesling J, Clauw DJ, Hassett AL. Pain and Depression: An Integrative Review of Neurobiological and Psychological Factors. Curr Psychiatry Rep. 2013 Nov 10;15(12):1–8.</ref>.<br>
 
=== Expectation<br>  ===
 
Pain perceived when expected may vary based upon the types of cues received (i.e. cues indicates a more intense or damaging stimulus, then more intense pain is perceived, and viceversa) and even cues of an impending decrease in pain, for example the process of taking an analgesic, usually decrease pain<ref name="Moseley 2007" />. Thus, expectation is thought to play a major role in placebo analgesia<ref name="Pollo 2001">Pollo A, Amanzio M, Arslanian A, Casadio C, Maggi G, Benedetti F. Response expectancies in placebo analgesia and their clinical relevance. Pain. 2001 Jul;93(1):77–84.</ref><ref name="Benedetti 2003">Benedetti F, Pollo A, Lopiano L, Lanotte M, Vighetti S, Rainero I. Conscious expectation and unconscious conditioning in analgesic, motor, and hormonal placebo/nocebo responses. J Neurosci. 2003 May 15;23(10):4315–23.</ref>.<br>
 
=== Attention and distraction<br>  ===
 
There is strong evidence that attention (and distraction) is highly effective in modulating the pain experience and demonstrate how cognitive processes can interfere with pain perception<ref name="Bantick 2002">Bantick SJ, Wise RG, Ploghaus A, Clare S, Smith SM, Tracey I. Imaging how attention modulates pain in humans using functional MRI. Brain. 2002 Feb;125(Pt 2):310–9.</ref><ref name="Buhle 2010">Buhle J, Wager TD. Performance-dependent inhibition of pain by an executive working memory task. Pain. 2010 Apr;149(1):19–26.</ref><ref name="Eccleston 1995">Eccleston C. Chronic pain and distraction: an experimental investigation into the role of sustained and shifting attention in the processing of chronic persistent pain. Behav Res Ther. 1995 May;33(4):391–405.</ref><ref name="Valet 2004">Valet M, Sprenger T, Boecker H, Willoch F, Rummeny E, Conrad B, et al. Distraction modulates connectivity of the cingulo-frontal cortex and the midbrain during pain--an fMRI analysis. Pain. 2004 Jun;109(3):399–408.</ref><ref name="Villemure 2002">Villemure C, Bushnell MC. Cognitive modulation of pain: how do attention and emotion influence pain processing? Pain 95, 195-199. Pain. 2002;95(3):195–9.</ref><ref name="Wiech 2005">Wiech K, Seymour B, Kalisch R, Stephan KE, Koltzenburg M, Driver J, et al. Modulation of pain processing in hyperalgesia by cognitive demand. Neuroimage. 2005 Aug 1;27(1):59–69.</ref><ref name="Tracey 2002">Tracey I, Ploghaus A, Gati JS, Clare S, Smith S, Menon RS, et al. Imaging attentional modulation of pain in the periaqueductal gray in humans. J Neurosci. 2002 Apr 1;22(7):2748–52.</ref>. When a person is distracted with a cognitive task pain is perceived as less intense<ref name="Bantick 2002" /><ref name="Valet 2004" /><ref name="Petrovic 2000">Petrovic P, Petersson KM, Ghatan PH, Stone-Elander S, Ingvar M. Pain-related cerebral activation is altered by a distracting cognitive task. Pain. 2000 Mar;85(1-2):19–30.</ref><ref name="Bingel 2007">Bingel U, Rose M, Gläscher J, Büchel C. fMRI reveals how pain modulates visual object processing in the ventral visual stream. Neuron. 2007 Jul 5;55(1):157–67.</ref><ref name="Frankenstein 2001">Frankenstein UN, Richter W, McIntyre MC, Rémy F. Distraction modulates anterior cingulate gyrus activations during the cold pressor test. Neuroimage. 2001 Oct;14(4):827–36.</ref>, even in chronic pain patients<ref name="McCracken 2002">McCracken LM, Turk DC. Behavioral and cognitive-behavioral treatment for chronic pain: outcome, predictors of outcome, and treatment process. Spine. 2002 Nov 15;27(22):2564–73.</ref>. Conversely, pain increases when the pain is in the focus of attention<ref name="Quevedo 2007">Quevedo AS, Coghill RC. Attentional modulation of spatial integration of pain: evidence for dynamic spatial tuning. J Neurosci. 2007 Oct 24;27(43):11635–40.</ref>. Functional brain imaging and neurophysiological studies have shown that attention- and cognitive distraction-related modulations of nociceptive-driven activations take place in various pain-sensitive cortical und subcortical brain regions, accompanied by concordant changes in pain perception<ref name="Bantick 2002" /><ref name="Valet 2004" /><ref name="Villemure 2002" /><ref name="Wiech 2005" /><ref name="Petrovic 2000" /><ref name="Frankenstein 2001" /><ref name="Hauck 2007">Hauck M, Lorenz J, Engel AK. Attention to Painful Stimulation Enhances γ-Band Activity and Synchronization in Human Sensorimotor Cortex. J Neurosci. 2007 Aug 29;27(35):9270–7.</ref>. At present time, there are various hypothesis on the physiological bases of these phenomenons, although it is likely that a top-down modulation occur<ref name="Corbetta 2002">Corbetta M, Shulman GL. Control of goal-directed and stimulus-driven attention in the brain. Nat Rev Neurosci. 2002 Mar;3(3):201–15.</ref><ref name="Gilbert 2007">Gilbert CD, Sigman M. Brain states: top-down influences in sensory processing. Neuron. 2007 Jun 7;54(5):677–96.</ref>. Previous studies on pain processing have demonstrated that key regions of the descending pain control system show enhanced responses during attentional distraction<ref name="Bantick 2002" /><ref name="Valet 2004" /><ref name="Petrovic 2000" /><ref name="Tracey 2002" />.<br>  


=== Fear  ===
=== Fear  ===


Pain-related fear is a general term to describe several forms of fear with respect to pain<ref name="Gebhart 2013">Gebhart GF, Schmidt RF, editors. Fear of Pain. In: Encyclopedia of Pain [Internet]. Springer Berlin Heidelberg; 2013 [cited 2016 Mar 29]. p. 1267–1267. Available from: http://link.springer.com/referenceworkentry/10.1007/978-3-642-28753-4_200800</ref>. Fear of pain can be directed toward the occurrence or continuation of pain, toward physical activity, or toward the induction of (re)injury or physical harm<ref name="Helsen 2013">Helsen K, Leeuw M, Vlaeyen JWS. Fear and Pain. In: Gebhart GF, Schmidt RF, editors. Encyclopedia of Pain [Internet]. Springer Berlin Heidelberg; 2013 [cited 2016 Mar 29]. p. 1261–7. Available from: http://link.springer.com/referenceworkentry/10.1007/978-3-642-28753-4_1482</ref>.<br>  
[[Fear Avoidance Model|Pain-related fear]] is a general term to describe several forms of fear with respect to pain. Fear of pain can be directed toward the occurrence or continuation of pain, toward physical activity, or toward (re)-injury or physical harm. Fear toward physical activity is also known as kinesiophobia. It can be defined as “an excessive, irrational, and debilitating fear of physical movement and activity resulting from a feeling of vulnerability to painful injury or re-injury”.<ref name="Lundberg 2006">Lundberg M, Larsson M, Ostlund H, Styf J. [https://www.researchgate.net/profile/Maria_Larsson2/publication/7231013_Kinesiophobia_among_patients_with_musculoskeletal_pain_in_primary_healthcare/links/0deec5273c91556bb2000000.pdf Kinesiophobia among patients with musculoskeletal pain in primary healthcare]. ''Journal of Rehabilitation Medicine''. 2006 Jan 1;38(1):37-43. Available from: https://www.researchgate.net/profile/Maria_Larsson2/publication/7231013_Kinesiophobia_among_patients_with_musculoskeletal_pain_in_primary_healthcare/links/0deec5273c91556bb2000000.pdf [Accessed on 12 May 2019]</ref> If pain, possibly caused by an injury, is interpreted as threatening, pain-related fear will lead to avoidance behaviours and hypervigilance to bodily sensations. This, in turn, will lead to disability, disuse and depression. This will maintain the pain experience, thereby fueling the vicious circle of increasing fear and avoidance.<br>  


Fear toward physical activity is also know as kinesiophobia, and is defined as “an excessive, irrational, and debilitating fear of physical movement and activity resulting from a feeling of vulnerability to painful injury or re-injury”<ref name="Kori 1990">Kori SH, Miller RP, Todd DD. Kinisophobia: A new view of chronic pain behavior. Pain manage. 1990 Jan 1;3(1):35–43.</ref><ref name="Lundberg 2006">Lundberg M, Larsson M, Ostlund H, Styf J. Kinesiophobia among patients with musculoskeletal pain in primary healthcare. J Rehabil Med. 2006 Jan;38(1):37–43.</ref>.
[[File:Fear-avoidance-picture.jpg|center|570x570px|[https://commons.wikimedia.org/wiki/File:Fear-avoidance_model.jpg Fear-avoidance model]
 
]]
[[Image:Final Fear avoidance model.png|thumb|left|600px]] If pain, possibly caused by an injury, is interpreted as threatening (pain catastrophizing), pain-related fear evolves leading to avoidance behaviors, and hypervigilance to bodily sensations followed by disability, disuse and depression. This will maintain the pain experiences thereby fueling the vicious circle of increasing fear and avoidance<ref name="Vlaeyen 2000">Vlaeyen JWS, Linton SJ. Fear-avoidance and its consequences in chronic musculoskeletal pain: a state of the art. Pain. 2000 Apr 1;85(3):317–32.</ref>.<br>
<br>  
 
In non-catastrophizing patients, no pain-related fear and rapid confrontation with daily activities is likely to occur, leading to fast recovery<ref name="Vlaeyen 2000" />.
 
These concepts are explained by the Fear-Avoidance (FA) model, which was largely hypothetical in the beginning, but currently there is ample evidence to support the validity of the original FA model<ref name="Crombez 2012">Crombez G, Eccleston C, Van Damme S, Vlaeyen JWS, Karoly P. Fear-avoidance model of chronic pain: the next generation. Clin J Pain. 2012 Jul;28(6):475–83.</ref>.<br>
 
As of today, the FA model is considered to be a component in the development of disability in a variety of conditions, such as low back pain, chronic headache, whiplash disorder, osteoarthritis, knee injury pain, chronic-fatigue syndrome, fibromyalgia and neuropathic pain <ref name="Wertli 2014">Wertli MM, Rasmussen-Barr E, Weiser S, Bachmann LM, Brunner F. The role of fear avoidance beliefs as a prognostic factor for outcome in patients with nonspecific low back pain: a systematic review. The Spine Journal. 2014 May 1;14(5):816–36.e4.</ref><ref name="Nijs 2013">Nijs J, Roussel N, Oosterwijck JV, Kooning MD, Ickmans K, Struyf F, et al. Fear of movement and avoidance behaviour toward physical activity in chronic-fatigue syndrome and fibromyalgia: state of the art and implications for clinical practice. Clin Rheumatol. 2013 May 3;32(8):1121–9.</ref><ref name="Leeuw 2007">Leeuw M, Goossens MEJB, Linton SJ, Crombez G, Boersma K, Vlaeyen JWS. The fear-avoidance model of musculoskeletal pain: current state of scientific evidence. J Behav Med. 2007 Feb;30(1):77–94.</ref> <br>
 
== Social and cultural factors in pain<br> ==


Culture is defined as "the beliefs, customs, arts, etc., of a particular society, group, place, or time" or "a particular society that has its own beliefs, ways of life, art, etc."<ref name="Culture">Definition of CULTURE [Internet]. [cited 2016 Mar 31]. Available from: http://www.merriam-webster.com/dictionary/culture</ref>.<br>
== [[Sociological Basis of Pain|Social and Cultural Factors in Pain]]   ==


Culturally-specific attitudes and beliefs about pain can influence the manner in which individuals view and respond both to their own pain and to the pain of others<ref name="Shavers 2010">Shavers VL, Bakos A, Sheppard VB. Race, ethnicity, and pain among the U.S. adult population. J Health Care Poor Underserved. 2010 Feb;21(1):177–220.</ref>. Cultural factors related to the pain experience include pain expression, pain language, lay remedies for pain, social roles, and expectations and perceptions of the medical care system<ref name="Shavers 2010" />.<br>Race/ethnicity, by virtue of their culturally-specific attitudes and beliefs, seems to have an impact on pain processing, including emotional and behavioural responses associated with chronic pain, larger in later stages<ref name="Campbell 2012">Campbell CM, Edwards RR. Ethnic differences in pain and pain management. Pain Manag. 2012 May;2(3):219–30.</ref><ref name="Riley 2002">Riley JL, Wade JB, Myers CD, Sheffield D, Papas RK, Price DD. Racial/ethnic differences in the experience of chronic pain. Pain. 2002 Dec;100(3):291–8.</ref>.<br>  
Culturally-specific attitudes and beliefs about pain can influence the manner in which individuals view and respond both to their own pain and to the pain of others. Cultural factors related to the pain experience include pain expression, pain language, lay remedies for pain, social roles, expectations and perceptions of the medical care system.<ref name="Shavers 2010">Shavers VL, Bakos A, Sheppard VB. [https://www.researchgate.net/profile/Vanessa_Sheppard/publication/41510004_Race_Ethnicity_and_Pain_among_the_US_Adult_Population/links/55761d4708ae75363751a782.pdf Race, ethnicity, and pain among the US adult population]. ''Journal of health care for the poor and underserved''. 2010;21(1):177-220. Available from: https://www.researchgate.net/profile/Vanessa_Sheppard/publication/41510004_Race_Ethnicity_and_Pain_among_the_US_Adult_Population/links/55761d4708ae75363751a782.pdf [Accessed on 12 May 2019]</ref><br>  


Another psychosocial factor that may influence differences in pain sensitivity response is the gender role: individuals who considered themselves more masculine and less sensitive to pain have been shown to have higher pain thresholds and tolerances<ref name="Alabas 2012">Alabas OA, Tashani OA, Tabasam G, Johnson MI. Gender role affects experimental pain responses: a systematic review with meta-analysis. Eur J Pain. 2012 Oct;16(9):1211–23.</ref>.<br>  
Another psychosocial factor that may influence differences in pain responses is the gender role. Individuals who considered themselves more masculine and less sensitive to pain have been shown to have higher pain thresholds and tolerances.<ref name="Alabas 2012">Alabas OA, Tashani OA, Tabasam G, Johnson MI. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1532-2149.2012.00121.x Gender role affects experimental pain responses: a systematic review with meta‐analysis]. ''European Journal of Pain''. 2012 Oct;16(9):1211-23. Available from: https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1532-2149.2012.00121.x [Accessed on 12 May 2019]</ref><br>  


Socioeconomic factors (e.g. lower levels of education and income) seems to be correlated with a higher incidence of chronic pain diagnosis<ref name="Joud 2014">Jöud A, Petersson IF, Jordan KP, Löfvendahl S, Grahn B, Englund M. Socioeconomic status and the risk for being diagnosed with spondyloarthritis and chronic pain: a nested case-control study. Rheumatol Int. 2014 Sep;34(9):1291–8.</ref> and pain perception level<ref name="Miljkovic 2014">Miljković A, Stipčić A, Braš M, Dorđević V, Brajković L, Hayward C, et al. Is experimentally induced pain associated with socioeconomic status? Do poor people hurt more? Med Sci Monit. 2014;20:1232–8.</ref>.<br>  
Socioeconomic factors (e.g. lower levels of education and income) seem to correlate with a higher incidence of chronic pain diagnosis and pain perception level.<ref name="Miljkovic 2014">Miljković A, Stipčić A, Braš M, Đorđević V, Brajković L, Hayward C, Pavić A, Kolčić I, Polašek O. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4111652/ Is experimentally induced pain associated with socioeconomic status? Do poor people hurt more?]. ''Medical science monitor: international medical journal of experimental and clinical research''. 2014;20:1232. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4111652/ [Accessed on 12 May 2019]</ref><br>  


== The biopsychosocial model of pain<br>  ==
== Clinical Implications  ==


In the past, psychological and physiological (or patophysiological) factors were considered as separated components in a dualistic point of view. Later, the recognition that psychosocial factors, such as emotional stress, could impact the reporting of symptoms, medical disorders, and response to treatment lead to the development of the biopsychosocial model of pain<ref name="Gatchel 2007">Gatchel RJ, Peng YB, Peters ML, Fuchs PN, Turk DC. The biopsychosocial approach to chronic pain: scientific advances and future directions. Psychol Bull. 2007 Jul;133(4):581–624.</ref>.<br>
There is a direct relationship between physiological, psychological, and social factors in any individual's pain experience.<ref name="Moseley 2007" /> This can perpetuate or may even worsen the clinical presentation.<ref name="Gatchel 2007" /><br>
 
* There is a need for sound knowledge of how these factors interact. Clinicians must have the knowledge of not only anatomy, biomechanics and pathophysiology etc., but also of diagnostic tools, outcome measures, tissue healing, peripheral and central sensitisation, and any psychological and social factors that could influence the patient's perception of pain.<ref name="Moseley 2007" />  
The ''bio '' part is rapresented by the pathophysiology of the disease, or the mechanism of injury, and the relative nociception processes, considering the physiological aspects.<br>
* Patients should be helped and taught to base their reasoning about their condition and their pain on similar information as mentioned in the previous point. It is important to teach patients about more modern pain neuroscience in a way that they could understand. This could help them to change their attitudes and beliefs about pain and decrease chronic pain and disability.<ref name="Moseley 2007" />
 
* Targeting psychosocial factors should be a key component of any pain intervention. Treatment programs must be individually-tailored in order to specifically address the patients' attitudes and beliefs to improve treatment adherence and outcome. Treatments should also be targeted at the different pain mechanisms responsible. <ref name="Woolf 2010" />
The ''psychosocial factors'' (as explaned above) involve both emotion (the more immediate reaction to nociception and is more midbrain based) and cognition (which attach meaning to the emotional experience)<ref name="Gatchel 2007" />. These could trigger additional emotional reactions and thereby amplify the experience of pain, thus perpetuating a vicious circle of nociception, pain, distress, and disability<ref name="Gatchel 2007" />.<br>  
 
As of today there are evidencies of psychological factors, such as fear and anxiety, play an important role in the development of chronic pain<ref name="Hasenbring 2014">Hasenbring MI, Chehadi O, Titze C, Kreddig N. Fear and anxiety in the transition from acute to chronic pain: there is evidence for endurance besides avoidance. Pain Management. 2014 Sep 1;4(5):363–74.</ref>. <br>
 
<br>
 
== Clinical implications<br>  ==
 
It has to be understood that there is an interaction among physiologic, psychological, and social factors<ref name="Moseley 2007" />, which perpetuates and may even worsen the clinical presentations<ref name="Gatchel 2007" />.<br>
 
*There is the need to have sound knowledge of these interaction mechanism<ref name="Moseley 2007" />.<br>  
*Targeting psychosocial factors should be a key component of physiotherapist-led intervention<ref name="Woby 2007">Woby SR, Roach NK, Urmston M, Watson PJ. The relation between cognitive factors and levels of pain and disability in chronic low back pain patients presenting for physiotherapy. Eur J Pain. 2007 Nov;11(8):869–77.</ref>.<br>
*Treatment programs must be individually-tailored in order to specifically address the patients' attitudes and beliefs to improve treatment adherence and outcome<ref name="Nijs 2013">Nijs J, Roussel N, Paul van Wilgen C, Köke A, Smeets R. Thinking beyond muscles and joints: Therapists’ and patients’ attitudes and beliefs regarding chronic musculoskeletal pain are key to applying effective treatment. Manual Therapy. 2013 Apr;18(2):96–102.</ref>.


== Resources  ==
== Resources  ==


=== Other [http://www.physio-pedia.com/Main_Page Physiopedia] Pages  ===
=== Other [http://www.physio-pedia.com/Main_Page Physiopedia] Pages  ===
 
* [http://www.physio-pedia.com/Category:Pain All Physiopedia pages with PAIN as their category.]
[http://www.physio-pedia.com/Pain_Course Pain Course] [http://www.physio-pedia.com/Category:Pain All Physiopedia pages with PAIN as their category.] [http://www.physio-pedia.com/Psychological_approaches_to_pain_management Psychological approaches to pain management]  
* [http://www.physio-pedia.com/Psychological_approaches_to_pain_management Psychological approaches to pain management]
* [[Psychological Basis of Pain]]
* [[Pain Mechanisms]]
* [[Pain Behaviours]]  


=== External links  ===
=== External links  ===


*[http://www.iasp-pain.org/ International Asociation for the Sudy of Pain (IASP)] site<br>
*[http://www.iasp-pain.org/ International Asociation for the Study of Pain (IASP)] (website)
*[https://www.painscience.com/ Pain Science] site
*[https://www.painscience.com/ Pain Science] (website)
*[http://www.pain-ed.com/ Pain-ed] site
*[http://www.pain-ed.com/ Pain-ed] (website)
*[[Www.bodyinmind.org|Body in mind]] site
*[https://bodyinmind.org Body in Mind] (website)
*[http://www.paincommunitycentre.org/professional-issues/multidimensional-nature-pain Pain community centre] page on multidimensional nature of pain


== Recent Related Research (from Pubmed)  ==
<div class="researchbox"><rss>http://www.ncbi.nlm.nih.gov/entrez/eutils/erss.cgi?rss_guid=1roWqUHnCMOr0K_yCXIgKL9axp0nseFe1vheeJkAKThHiWkIwZ http://www.ncbi.nlm.nih.gov/entrez/eutils/erss.cgi?rss_guid=1JCQdWPbmm1k3hzYOqcwFIYYKKytAH4L94Y-hicfMSUDbXNcPk http://www.ncbi.nlm.nih.gov/entrez/eutils/erss.cgi?rss_guid=1z1pzJaapA61Pq_ij_0P1Pia2CPTiVDCt_IA_WYDTL2DiIQQzE|charset=UTF-8|short|max=10</rss></div>
== References  ==
== References  ==
<references />  
<references />  


<br>  
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[[Category:Pain]] [[Category:PPA_Project]]
[[Category:Pain]]  
[[Category:PPA_Project]]
[[Category:Physiology]]
[[Category:Neurology]]
[[Category:Course Pages]]
[[Category:Plus Content]]

Latest revision as of 11:20, 18 August 2022

Original Editor - Alberto Bertaggia.

Top Contributors - Alberto Bertaggia, Nina Myburg, Admin, Kim Jackson, Vidya Acharya, Michelle Lee, Lauren Lopez, 127.0.0.1, WikiSysop, Jess Bell and Jo Etherton  

Introduction[edit | edit source]

A definition of pain is provided by the International association for the Study of Pain (IASP) as follows:[1]

An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage

Pain is always subjective and everyone learns the use of this word through experiences related to injury in early life.

Pain is a sensation in a part or parts of the body. It can vary in intensity, quality, duration and pain can refer to other parts of the body. Pain is usually an unpleasant sensation and therefore it also has an emotional aspect. It is strongly linked to suffering.[2]

Even in the absence of tissue damage or any likely pathophysiological cause, people still report pain. This could happen for psychological reasons. In these cases, it is challenging to distinguish whether someone's experience of pain arises from damaged tissue or not, as it can only be based upon the subjective report of such experience.[3]

In the following video, Karen D. Davis tries to explain why some people react to the same painful stimulus in different ways.


[4]

The Process of Feeling Pain[edit | edit source]

Pain is a physiological protective system. It is essential to warn, detect, and minimize contact with damaging stimuli.[5] Nerve endings and sensory receptors in the skin and tissues detect sensory stimuli. This can be thermal, mechanical or chemical stimuli (heat, cold, pressure, etc.). Nociceptors (from the Latin word nocere that means "to hurt") are sensory receptors that respond to damaging or potentially damaging stimuli. With the stimulation of a nociceptor, a noxious stimulus is converted into electrical activity in the peripheral terminals of nociceptor sensory fibres. This is called transduction. The stimulus is carried to the spinal cord (central nervous system) through a process called conduction. The nociceptive nerve fibres terminate and the synaptic transfer and modulation of input from one neuron to another take place. This is called transmission. The neurons in the dorsal horn of the spinal cord transfer nociceptive input to the brainstem, hypothalamus, thalamus and brain cortex. In the brain perception of the experience occurs. This is a subjective process. Only then does the brain create pain as output after processing the stimuli. It is important to underline that activity induced in the nociceptive pathways by a noxious stimulus does not always lead to pain. Nociceptors can be stimulated by potentially damaging stimuli as well as actual damaging stimuli. Only when the brain has processed the stimulus, will it lead to a response of pain or not. Pain is always the output of a widely distributed neural network in the brain rather than one coming directly by sensory input evoked by injury, inflammation or other pathology[6].

Nociception


Pain Classification[edit | edit source]

Based on the works of Woolf[5], this is a useful way of classifying pain:

  • Nociceptive pain. This kind of pain is concerned with the sensing of noxious stimuli. It is a signal of impending or actual tissue damage and is a high-threshold pain only activated in the presence of intense stimuli. It has a protective role requiring immediate attention and responses (i.e. withdrawal reflex). For example, touching something too hot, cold or sharp
  • Inflammatory pain. This second kind of pain is important to promote healing and protection of injured tissues. It increases sensory sensitivity through pain hypersensitivity and tenderness. Thus normally innocuous stimuli now elicit pain. It creates an environment which suggests avoidance of movement, contact and stress of the injured body parts. This, in turn, assists in the healing of the injured body part. Inflammatory pain is caused by activation of the immune system that causes inflammation after tissue injury or infection. This type of pain can be seen as a protective mechanism, However, it still needs to be reduced in patients with ongoing inflammation, as with rheumatoid arthritis or in cases of severe or extensive injury.
  • Pathological pain. This type of pain is not protective, but rather maladaptive. It is not connected to tissue damage but results from abnormal functioning of the nervous system. To note, this is a low-threshold pain. Pathological pain can occur after damage to the nervous system or even when there is no damage or inflammation, It is largely the consequence of amplified sensory signals in the central nervous system. Conditions that cause this type of pain include fibromyalgia, irritable bowel syndrome, tension-type headache, temporomandibular joint disease etc. Usually, the pain is substantial without any noxious stimulus and minimal or even no peripheral inflammation.

Acute pain is caused by noxious stimuli and is mediated by nociception. It has an early onset and serves to prevent tissue damage. This is why this type of pain is defined as adaptive, it helps to survive and to heal[2]

Chronic pain is pain continuing beyond 3 months, or after healing is complete[3]. It may arise as a consequence of tissue damage or inflammation or have no identified cause. Chronic pain is a complex condition embracing physical, social and psychological factors, consequently leading to disability, loss of independence and poor quality of life.[7]

The Biopsychosocial Model of Pain[edit | edit source]

In the past, psychological and physiological (or pathophysiological) factors were considered as separate components in a dualistic point of view. Later, the recognition that psychosocial factors, such as emotional stress and fear, could impact the reporting of symptoms, medical disorders, and response to treatment lead to the development of the biopsychosocial model of pain[8].

The bio part represents the pathophysiology of the disease or the mechanism of injury, and the relative nociception processes, it considers the physiological aspects of the pain experience.

The psychosocial part involves both emotion (the more immediate reaction to nociception and is more midbrain based) and cognition (which attach meaning to the emotional experience). These could trigger additional emotional reactions and thereby amplify the experience of pain, thus perpetuating a vicious circle of nociception, pain, distress, and disability.[8]

It could be said that psychological factors, such as fear and anxiety, play an important role in the development of chronic pain. [8]

Psychological Factors in Pain[edit | edit source]

Anxiety[edit | edit source]

Health anxious individuals form dysfunctional assumptions and beliefs about pain and other symptoms. This can be disease based and based on past experiences. They will have a tendency to misinterpret somatic information as catastrophic and personally threatening. Some studies report an increase in pain correlated with increased levels of anxiety.[9] Clinically, anxiety can compromise treatments as practitioners can expect to see catastrophization play a big role in these patients' report and they could report greater pain during activities. Thus, there is a need to target attentional focus and interpretation of sensations among health anxious clients.

Depression[edit | edit source]

There is strong evidence of established comorbidity of pain and depression.[10] Furthermore, when patients with pain have comorbid depression, they could experience greater pain, have a worse prognosis, and more functional disability. Pain and depression are linked by neurobiological, cognitive, affective and behavioural factors. Thus, the optimal treatment approach for comorbid pain and depression should simultaneously address both physical and psychological symptoms.

Expectation[edit | edit source]

When an individual expects to experience pain, the perceived pain may vary based upon the types of cues received (i.e. a cue may indicate a more intense or damaging stimulus, then more intense pain is perceived and vice versa). Cues of an impending treatment could also decrease pain, for example, the process of taking an analgesic, usually decreases pain.[9] Thus, expectation is thought to play a big role in the placebo effect.

Attention and Distraction[edit | edit source]

There is strong evidence that attention (and distraction) is highly effective in modulating the pain experience and demonstrate how cognitive processes can interfere with pain perception. When a person is distracted with a cognitive task pain is perceived as less intense, even in chronic pain patients. On the other hand, pain increases when it is the focus of attention. Functional brain imaging and neurophysiological studies have shown that attention and cognitive distraction-related modulations of nociceptive driven activations take place in various pain-sensitive cortical and subcortical brain regions, accompanied by concordant changes in pain perception.[11]

Fear[edit | edit source]

Pain-related fear is a general term to describe several forms of fear with respect to pain. Fear of pain can be directed toward the occurrence or continuation of pain, toward physical activity, or toward (re)-injury or physical harm. Fear toward physical activity is also known as kinesiophobia. It can be defined as “an excessive, irrational, and debilitating fear of physical movement and activity resulting from a feeling of vulnerability to painful injury or re-injury”.[12] If pain, possibly caused by an injury, is interpreted as threatening, pain-related fear will lead to avoidance behaviours and hypervigilance to bodily sensations. This, in turn, will lead to disability, disuse and depression. This will maintain the pain experience, thereby fueling the vicious circle of increasing fear and avoidance.

Fear-avoidance model


Social and Cultural Factors in Pain[edit | edit source]

Culturally-specific attitudes and beliefs about pain can influence the manner in which individuals view and respond both to their own pain and to the pain of others. Cultural factors related to the pain experience include pain expression, pain language, lay remedies for pain, social roles, expectations and perceptions of the medical care system.[13]

Another psychosocial factor that may influence differences in pain responses is the gender role. Individuals who considered themselves more masculine and less sensitive to pain have been shown to have higher pain thresholds and tolerances.[14]

Socioeconomic factors (e.g. lower levels of education and income) seem to correlate with a higher incidence of chronic pain diagnosis and pain perception level.[15]

Clinical Implications[edit | edit source]

There is a direct relationship between physiological, psychological, and social factors in any individual's pain experience.[9] This can perpetuate or may even worsen the clinical presentation.[8]

  • There is a need for sound knowledge of how these factors interact. Clinicians must have the knowledge of not only anatomy, biomechanics and pathophysiology etc., but also of diagnostic tools, outcome measures, tissue healing, peripheral and central sensitisation, and any psychological and social factors that could influence the patient's perception of pain.[9]
  • Patients should be helped and taught to base their reasoning about their condition and their pain on similar information as mentioned in the previous point. It is important to teach patients about more modern pain neuroscience in a way that they could understand. This could help them to change their attitudes and beliefs about pain and decrease chronic pain and disability.[9]
  • Targeting psychosocial factors should be a key component of any pain intervention. Treatment programs must be individually-tailored in order to specifically address the patients' attitudes and beliefs to improve treatment adherence and outcome. Treatments should also be targeted at the different pain mechanisms responsible. [5]

Resources[edit | edit source]

Other Physiopedia Pages[edit | edit source]

External links[edit | edit source]

References[edit | edit source]

  1. ↑ International Association for the Study of Pain. IASP Terminology. Available from: https://www.iasp-pain.org/Education/Content.aspx?ItemNumber=1698. [Accessed 19 July 2020]
  2. ↑ 2.0 2.1 Woolf CJ. Pain: moving from symptom control toward mechanism-specific pharmacologic management. Ann Intern Med. 2004;140:441-51. Available from: http://www.smbs.buffalo.edu/acb/neuro/readings/SensitizMolecMech.pdf [Accessed 12 May 2019]
  3. ↑ 3.0 3.1 Merskey H (ed.), Bogduk N (ed.). Classification of chronic pain; Descriptions of chronic pain syndromes and definitions of pain terms. 2nd ed. Seattle: IASP Press; 1994 Available from: https://s3.amazonaws.com/rdcms-iasp/files/production/public/Content/ContentFolders/Publications2/FreeBooks/Classification-of-Chronic-Pain.pdf [Accessed on 10 May 2019]
  4. ↑ TED-Ed. How does your brain respond to pain? - Karen D. Davis Available from https://www.youtube.com/watch?v=I7wfDenj6CQ&feature=emb_logo
  5. ↑ 5.0 5.1 5.2 Woolf CJ. What is this thing called pain?. The Journal of clinical investigation. 2010 Nov 1;120(11):3742-4. Available from: https://www.jci.org/articles/view/45178/pdf [Accessed on 10 May 2019]
  6. ↑ Dubin AE, Patapoutian A. Nociceptors: the sensors of the pain pathway. The Journal of clinical investigation. 2010 Nov 1;120(11):3760-72. Available from: https://www.jci.org/articles/view/42843/pdf [Accessed on 10 May 2019]
  7. ↑ Breivik H, Collett B, Ventafridda V, Cohen R, Gallacher D. Survey of chronic pain in Europe: prevalence, impact on daily life, and treatment. European journal of pain. 2006 May;10(4):287–333. Available from: http://www.nascholingnoord.nl/presentaties/2012_02_02_Breivik_et_al___Survey_of_chronic_pain_in_Europe.pdf [Accessed on 12 May 2019]
  8. ↑ 8.0 8.1 8.2 8.3 Gatchel RJ, Peng YB, Peters ML, Fuchs PN, Turk DC. The biopsychosocial approach to chronic pain: scientific advances and future directions. Psychological Bulletin. 2007 Jul;133(4):581. Available from: https://rc.library.uta.edu/uta-ir/bitstream/handle/10106/5000/BIOPSYCHO2006-0750-R-Final-single%20701.pdf?sequence=1 [Accessed on 12 May 2019]
  9. ↑ 9.0 9.1 9.2 9.3 9.4 Moseley GL. Reconceptualising pain according to modern pain science. Physical therapy reviews. 2007 Sep 1;12(3):169-78. Available from: https://cdn.bodyinmind.org/wp-content/uploads/Moseley-2007-PTR-conceptualisation1.pdf [Accessed on 12 May 2019]
  10. ↑ Bair MJ, Robinson RL, Katon W, Kroenke K. Depression and pain comorbidity: a literature review. Archives of internal medicine. 2003 Nov 10;163(20):2433-45. Available from: https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/216320 [Accessed on 12 May 2019]
  11. ↑ Bantick SJ, Wise RG, Ploghaus A, Clare S, Smith SM, Tracey I. Imaging how attention modulates pain in humans using functional MRI. Brain. 2002 Feb 1;125(2):310-9. Available from: https://academic.oup.com/brain/article/125/2/310/296978 [Accessed on 12 May 2019]
  12. ↑ Lundberg M, Larsson M, Ostlund H, Styf J. Kinesiophobia among patients with musculoskeletal pain in primary healthcare. Journal of Rehabilitation Medicine. 2006 Jan 1;38(1):37-43. Available from: https://www.researchgate.net/profile/Maria_Larsson2/publication/7231013_Kinesiophobia_among_patients_with_musculoskeletal_pain_in_primary_healthcare/links/0deec5273c91556bb2000000.pdf [Accessed on 12 May 2019]
  13. ↑ Shavers VL, Bakos A, Sheppard VB. Race, ethnicity, and pain among the US adult population. Journal of health care for the poor and underserved. 2010;21(1):177-220. Available from: https://www.researchgate.net/profile/Vanessa_Sheppard/publication/41510004_Race_Ethnicity_and_Pain_among_the_US_Adult_Population/links/55761d4708ae75363751a782.pdf [Accessed on 12 May 2019]
  14. ↑ Alabas OA, Tashani OA, Tabasam G, Johnson MI. Gender role affects experimental pain responses: a systematic review with meta‐analysis. European Journal of Pain. 2012 Oct;16(9):1211-23. Available from: https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1532-2149.2012.00121.x [Accessed on 12 May 2019]
  15. ↑ Miljković A, Stipčić A, Braš M, Đorđević V, Brajković L, Hayward C, Pavić A, Kolčić I, Polašek O. Is experimentally induced pain associated with socioeconomic status? Do poor people hurt more?. Medical science monitor: international medical journal of experimental and clinical research. 2014;20:1232. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4111652/ [Accessed on 12 May 2019]


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