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ALTERATIONS IN TEMPORAL SUMMATION OF PAIN AND CONDITIONED PAIN MODULATION ACROSS AN EPISODE OF EXPERIMENTAL EXERCISE-INDUCED LOW BACK PAIN

Low back pain (LBP) is the leading cause of disability worldwide26, yet up to 90% of patients are diagnosed with non-specific LBP, meaning the pathoanatomical source is unclear10. Further, recurrence following an acute episode may be up to 80%25, with little understanding as to why some patients develop ongoing symptoms9. There has recently been increasing focus on alterations in pro-nociceptive and anti-nociceptive mechanisms, purported to explain or contribute to pain exacerbation and persistence across a range of acute to chronic pain conditions34,45,72.

ALTERATIONS IN TEMPORAL SUMMATION OF PAIN AND CONDITIONED PAIN MODULATION ACROSS AN EPISODE OF EXPERIMENTAL EXERCISE-INDUCED LOW BACK PAIN

Orginally Published At: Pain Journal

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CONTRIBUTIONS OF NOCIRESPONSIVE AREA 3A TO NORMAL AND ABNORMAL SOMATOSENSORY PERCEPTION

Somatosensory cortex in the postcentral gyrus of humans and other primates comprises four cytoarchitectonically, connectionally, and physiologically distinct cortical areas – Brodmann areas 3a, 3b, 1, and 2 (Figure 1AB). Each of these areas forms a long strip running along the central sulcus from the midline to the lateral fissure. The most anterior of these areas, area 3a, lies in the fundus of the central sulcus, flanked anteriorly by motor cortical area 4 and posteriorly by somatosensory area 3b.

CONTRIBUTIONS OF NOCIRESPONSIVE AREA 3A TO NORMAL AND ABNORMAL SOMATOSENSORY PERCEPTION

Orginally Published At: Pain Journal

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A novel finger illusion reveals reduced weighting of bimanual hand cortical representations in people with complex regional pain syndrome

Complex regional pain syndrome (CRPS) is characterised by excessive pain, usually in a peripheral limb such as the hand, and affects sensation, movement and function.32 Quantified deficits include higher thresholds for two-point discrimination in the index finger,45 impaired hand size estimation,35,44 finger misidentification,14,33 tactile processing disturbances;28 errors in bilateral limb positioning,30 fine motor26 and motor imagery performance.34,49,50 These deficits implicate distortions in body representation53 and are corroborated by evidence of cortical re-organisation in CRPS,9,10 although much remains unclear.

A novel finger illusion reveals reduced weighting of bimanual hand cortical representations in people with complex regional pain syndrome

Orginally Published At: Pain Journal

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Misdiagnosed for 35 years

Today’s post is about a truly perfect example of my favourite theme lately: surprising causes of pain, chronic pain mysteries that finally get solved. This one’s a doozy.

“When Chronic Pain Is Not “Chronic Pain“: Lessons From 3 Decades of Pain
Taylor et al. Journal of Orthopaedic & Sports Physical Therapy. Volume 47, Number 8, 515–517. Aug 2017.

That paper is all about a patient who had “sciatica” for thirty-five years and was misdiagnosed many times until finally getting not only a definitive diagnosis but a cure. He had a narrowed artery (arterial stenosis causing “claudication,” the pain of impaired circulation). That’s it! Not even a difficult a diagnosis in the end, really. There were some pretty glaring clues there that got ignored by a lot of people who should have known better.

But not only was he misdiagnosed many times over more than three decades, he was misdiagnosed fashionably: that is, each misdiagnosis neatly fit a paradigm in physical therapy, better than it fit his symptoms. This carried on right up to and including the present day fascination with psychosocial factors and sensitization (which served him no better than any of the other paradigms had).

Interestingly, the patient’s belief that something ‘was actually wrong’ had remained with him throughout the journey. This, of course, had been explained away to him (more recently) by current research and evidence-based thinking on central sensitization and pain.

Just fascinating. The authors thoughtfully explore the implications of this rather shameful episode (definitely aimed at pros, some jargon, but readable enough for anyone — and behind a paywall, unfortunately). The bottom line? Good diagnostic skills are never out of fashion. Or shouldn’t be, anyway!

Update: There are criticisms of this paper from a couple of my favourite experts and writers, pointing out in a letter to the journal that one of the “fashionable” paradigms impugned here, the biopsyschosocial model, “includes the considerations [the “bio” part] that eventually cured the patient’s pain.” I like the criticism and I like the authors’ response — I see only healthy debate here.

[Go to this post on PainScience.com]

Misdiagnosed for 35 years


Orginally Published At: Pain Science

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Higher Dispositional Optimism Predicts Lower Pain Reduction During Conditioned Pain Modulation

Optimism, or a generalized expectancy for positive outcomes, is associated with lower pain sensitivity, higher placebo analgesia, and better adjustment to chronic pain [8,9,26]. The initial conceptualization of optimism was developed from a broader model of behavioral self- regulation [10,32,33]. Based on this model, optimists are people who expect positive outcomes, making them more likely to engage in health promoting behaviors [33]. While optimism is viewed as a stable individual personality difference, it is also associated with coping strategies and positive affect, which lead to better health outcomes [10,26,31].

Higher Dispositional Optimism Predicts Lower Pain Reduction During Conditioned Pain Modulation

Orginally Published At: Pain Journal

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Design and reporting characteristics of clinical trials of select chronic and recurrent pediatric pain conditions: An ACTTION systematic review

Chronic and recurrent pain are common in the pediatric population, with median prevalences ranging from 11-38% reported in the literature depending on the type of pain and criteria used to define chronic and recurrent pain.25 However, a paucity of clinical trials is available that provide adequate evidence to inform pediatric pain management and evidence-based treatment guidelines.13 Many of the current pediatric pain treatment recommendations, therefore, rely on efficacy data extrapolated from studies that included only adults.

Design and reporting characteristics of clinical trials of select chronic and recurrent pediatric pain conditions: An ACTTION systematic review

Orginally Published At: Pain Journal

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Neuropsychological humility

Memories influence not just how we interpret what we see, but literally what we actually see. Dr. Steven Novella, summarizing some recent science on this topic:

Memory is explicitly involved in this construction process [generating what we perceive]. It’s a fundamental aspect of neuropsychological humility: just understanding how your brain works is critical to being skeptical. After listening to this show you should no longer say things like ‘I know what I saw’ or ‘I clearly remember.’

Dr. Novella coined the term “neuropsychological humility” back in 2013:

Neuropsychological humility [is] the understanding that our perceptions and memories are deeply flawed and biased. There appears to be almost no limit to the extent to which people can deceive themselves into believing bizarre things.

Neuropsychological humility is relevant to my work here on PainScience.com in many ways. It’s why the words “in my experience” are the “three most dangerous words in medicine” (Crislip), why there’s such chronic tension between clinical experience and evidence-based medicine, why anecdotes can’t be trusted, why patients think they were helped even by “treatments” that are actually harmful, why massage therapists think they can feel things that aren’t there, why we perceive the things that we want to believe, why “obvious” explanations for pain are usually wrong, even why pain is such a weird and unreliable sensation.

[Go to this post on PainScience.com]

Neuropsychological humility


Orginally Published At: Pain Science

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Pain with surprising causes, or literally no specific cause at all

Drawing of a knob representing the intensity of back pain, dialed up to 11.

[Image caption: There many paths to pain that never make the headlines.]

The question that haunts everyone with unexplained chronic pain: “What if there’s a cause that’s been missed? What if it’s treatable?”

It can happen, and most people are aware of at least a couple ways it can happen. But not many people suspect how many surprising ways to hurt there are.

I’ve recently “completed” a major reboot and expansion of my article, Surprising Causes of Pain: Trying to understand pain when there is no obvious explanation. There’s more to do (always), and suggestions and requests for additions are very welcome (even more than usual), but it’s definitely now a much more comprehensive survey of all non-obvious causes of pain. I hope this will become one of the most useful articles on PainScience.com.

The article has always been inspired by the many fascinating stories I’ve heard over the years about people who eventually discovered a specific cause of their pain, like a sneaky drug side effect or a slowly worsening disease, problems with clearly biological origins. However, pain that truly has no particular source is yet another fascinating kind of problem, and likely all-too-real. Here’s an excerpt from the article about that bizarre idea:

Like other complicated things in life, pain may not have any specific cause at all. Although we often speak of pain being multifactorial, we still tend to assume that just one of those factors is the specific cause of pain, and the others — sleep loss, stress, etc — are only piling on, making a bad situation worse. That picture may be wrong: some chronic pain is probably an emergent property of a big mess of synergistic stresses, with literally no specific cause. It may crop up only with an unholy combination of many factors.

This is a “systems” perspective on pain, and it overlaps substantially with sensitization — it’s basically saying that sensitization may be triggered by a bunch of different stresses — but it’s a different enough perspective to be worth considering separately. The idea of pain that truly has no specific cause is something more patients probably need to consider.

Pain without no one cause is a good news scenario in the sense that it might be treated by relieving enough of the contributing factors… but bad news in the sense that it may be like fighting a hydra.

This is line of thinking was directly inspired by a pair of articles by Todd Hargrove:

Do you have a story about pain that was eventually clearly explained? Or never was? Again, I’m more than usually interested in suggestions from both patients and professionals on this topic. I’d love to create the most complete possible list of “surprising ways to hurt,” and I know there’s more than I’ve included so far. Send me an email, or reply to the Tweet or Facebook post.

[Go to the link featured in this post]

[Go to this post on PainScience.com]

Pain with surprising causes, or literally no specific cause at all


Orginally Published At: Pain Science

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Costs and consequences of chronic pain due to musculoskeletal disorders from a health system perspective in Chile

Background:
Chronic
pain is a prevalent and distressing condition caused by an unceasing pain lasting more than 3 months or a pain that persists beyond the normal healing time. There is evidence of inadequate management partly explained by the unawareness regarding the magnitude of the problem.
Objectives:
To estimate the annual expected costs and consequences of chronic pain caused by musculoskeletal diseases from the health system perspective in Chile.
Methods:
A Markov cohort model was built to represent chronic pain and estimate expected costs and consequences over 1-year time horizon. Transition probabilities were obtained through expert elicitation. Consequences examined were: years lost to disability (YLD), depression, anxiety, and productivity losses. Direct health care costs were estimated using local sources. Probabilistic sensitivity analysis was performed to characterize second-order uncertainty.
Results:
The annual expected cost due to musculoskeletal chronic pain was estimated in USD $1387.2 million, equivalent to 0.417% of the national GDP. Lower back pain and osteoarthritis of the knee explained the larger proportion of the total cost, 31.8% and 27.1%, respectively. Depression attributed to chronic pain is another important consequence accounting for USD $94 million (Bayesian credibility interval 95% $49.1–$156.26). Productivity losses were also important cost, although early retirement and presenteeism were not measured. Chronic pain causes 137,037 YLDs.
Conclusion:
Chronic pain is not only an important cause of disability but also responsible for high social and financial burden in Chile. Public health programs focused on managing chronic pain may decrease burden of disease and possibly reduce costs.
This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Corresponding author. Address: Health Technology Assessment Unit, Department of Public Health, Center of Clinical Research, Faculty of Medicine, Pontificia Universidad Católica de Chile, Diagonal Paraguay 362, 2nd Floor, Santiago, 8330194, Chile. Tel.: +562 2354-6807. E-mail address: maespinoza@med.puc.cl (M.A.Espinoza).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Received July 18, 2017
Received in revised form February 15, 2018
Accepted March 28, 2018
© 2018 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The International Association for the Study of Pain.

Costs and consequences of chronic pain due to musculoskeletal disorders from a health system perspective in Chile


Orginally Published At: PAIN Reports

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Unique aspects of clinical trials of invasive therapies for chronic pain

Nearly all who review the literature conclude that the role of invasive procedures to treat chronic pain is poorly characterized because of the lack of “definitive” studies. The overt nature of invasive treatments, along with the risks, technical skills, and costs involved create challenges to study them. However, these challenges do not completely preclude evaluating invasive procedure effectiveness and safety using well-designed methods. This article reviews the challenges of studying outcomes of invasive therapies to treat pain and discuss possible solutions. Although the following discussion can apply to most invasive therapies to treat chronic pain, it is beyond the scope of the article to individually cover every invasive therapy used. Therefore, most of the examples focus on injection therapies to treat spine pain, spinal cord stimulation, and intrathecal drug therapies.
This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Corresponding author. Address: 9500 Gilman Drive, MC 0898, La Jolla, CA 92093-0898. Tel.: 858-822-0776; fax: 858-534-7080. E-mail address: mswallace@ucsd.edu (M. Wallace).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Received May 07, 2018
Accepted August 07, 2018
© 2018 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The International Association for the Study of Pain.

Unique aspects of clinical trials of invasive therapies for chronic pain


Orginally Published At: PAIN Reports