19 November 2016

Abnormal sensory states

From the IASP, a helpful summary of some of the terms which describe altered thresholds, responses, and perceptions of pain:
Allodynia: lowered threshold: stimulus and response mode differ
Hyperalgesia: increased response: stimulus and response mode are the same
Hyperpathia: raised threshold: stimulus and response mode may be the increased response: same or different
Hypoalgesia: raised threshold: stimulus and response mode are the same lowered response:
The above essentials of the definitions do not have to be symmetrical and are not symmetrical at present. Lowered threshold may occur with allodynia but is not required. Also, there is no category for lowered threshold and lowered response - if it ever occurs.


05 October 2016

More on pain rating scales, xkcd weighs in

Following up on Hyperbole and a Half's critique of the Wong-Baker Scale, xkcd weighs in on anchors of common assessment scales.

Comic on worst pain imaginable

His mouseover caption presses the point: "If it were a two or above, I couldn't answer because it would mean a pause in the screaming."

This reminds me of a conversation with a friend about the pragmatics of rating the pain which brought you to the doctor's office. Our consensus: Rating the pain a 6 is high enough that the doctor will take you seriously, but not so high that they think you're lying or make the wrong diagnosis.

10 August 2016

Catrastrophizing in pain paper

Blackwell Synergy - Pain Medicine, OnlineEarly Articles (Article Abstract)
Jo Nijs PhD, Karen Van de Putte MSc, Fred Louckx PhD, Steven Truijen PhD, Kenny De Meirleir PhD (2007)
Exercise Performance and Chronic Pain in Chronic Fatigue Syndrome: The Role of Pain Catastrophizing

Exercise Performance and Chronic Pain in Chronic Fatigue Syndrome: The Role of Pain Catastrophizing
Objectives. This study aimed to examine the associations between bodily pain, pain catastrophizing, depression, activity limitations/participation restrictions, employment status, and exercise performance in female patients with chronic fatigue syndrome (CFS) who experience widespread pain.

Design. Cross-sectional observational study.

Setting. A university-based clinic.

Patients. Thirty-six female CFS patients who experienced widespread pain.

Outcome Measures. Patients filled in the Medical Outcomes Short-Form 36 Health Status Survey, the Chronic Fatigue Syndrome Activities and Participation Questionnaire, the Beck Depression Inventory, and the Pain Catastrophizing Scale, and underwent a maximal exercise stress test with continuous monitoring of electrocardiographic and ventilatory parameters.

Results. Pain catastrophizing was related to bodily pain (r = −0.70), depression (r = 0.55), activity limitations/participation restrictions (r = 0.68), various aspects of quality of life (r varied between −0.51 and −0.64), and exercise capacity (r varied between −0.41 and −0.61). Based on hierarchical multiple regression analysis, pain catastrophizing accounted for 41% of the variance in bodily pain in female CFS patients who experience chronic widespread musculoskeletal pain. Among the three subscale scores of the Pain Catastrophizing Scale, helplessness and rumination rather than magnification were strongly related to bodily pain. Neither pain catastrophizing nor depression was related to employment status.

Conclusions. These data provide evidence favoring a significant association between pain catastrophizing, bodily pain, exercise performance, and self-reported disability in female patients with CFS who experience widespread pain. Further prospective longitudinal studying of these variables is required.

28 May 2016

The Almost Discovery Of Anesthesia : NPR

Here's an NPR story on the discovery of nitrous oxide. The transcript and podcast are here:

No, Thank You; We Like Pain: The Almost Discovery Of Anesthesia : NPR

Today's Quantified Self practitioners take note, you've got nothing on young Humphry Davy.

07 March 2016

Placebo ethics related papers

ScienceDirect - Pain : Don’t ask, Don’t tell? Revealing placebo responses to research participants and patients
An NIMH perspective on the use of placebosBiological Psychiatry
Biological Psychiatry, Volume 47, Issue 8, 15 April 2000, Pages 689-691Steven E. Hyman and David Shore
The placebo in modern medicine
Gastrointestinal Endoscopy, Volume 43, Issue 2, Part 1, 1996, Pages 76-79
Stephen E. Silvis

 Classical conditioning and the placebo effect
Pain, Volume 72, Issues 1-2, August 1997, Pages 107-113
Guy H. Montgomery and Irving Kirsch

Stimulus substitution models posit that placebo responses are due to pairings of conditional and unconditional stimuli. Expectancy theory maintains that conditioning trials produce placebo response expectancies, rather than placebo responses, and that the expectancies elicit the responses. We tested these opposing models by providing some participants with information intended to impede the formation of placebo expectancies during conditioning trials and by assessing placebo expectancies. Although conditioning trials significantly enhanced placebo responding, this effect was eliminated by adding expectancies to the regression equation, indicating that the effect of pairing trials on placebo response was mediated completely by expectancy. Verbal information reversed the effect of conditioning trials on both placebo expectancies and placebo responses, and the magnitude of the placebo effect increased significantly over 10 extinction trials. These data disconfirm a stimulus substitution explanation and provide strong support for an expectancy interpretation of the conditioned placebo enhancement produced by these methods.

Placebo and Nocebo in Cardiovascular Health: Implications for Healthcare, Research, and the Doctor-Patient RelationshipJournal of the American College of Cardiology, Volume 49, Issue 4, 30 January 2007, Pages 415-421
Brian Olshansky

Despite treatments proven effective by sound study designs and robust end points, placebos remain integral to elicit effective medical care. The authenticity of the placebo response has been questioned, but placebos likely affect pain, functionality, symptoms, and quality of life. In cardiology, placebos influence disability, syncope, heart failure, atrial fibrillation, angina, and survival. Placebos vary in strength and efficacy. Compliance to placebo affects outcomes. Nocebo responses can explain some adverse clinical outcomes. A doctor may be an unwitting contributor to placebo and nocebo responses. Placebo and nocebo mechanisms, not well understood, are likely multifaceted. Placebo and nocebo use is common in practice. A successful doctor-patient relationship can foster a strong placebo response while mitigating any nocebo response. The beneficial effects of placebo, generally undervalued, hard to identify, often unrecognized, but frequently used, help define our profession. The role of the doctor in healing, above the therapy delivered, is immeasurable but powerful. An effective placebo response will lead to happy and healthy patients. Imagine instead the future of healthcare relegated to a series of guidelines, tests, algorithms, procedures, and drugs without the human touch. Healthcare, rendered by a faceless, uncaring army of protocol aficionados, will miss an opportunity to deliver an effective placebo response. Wise placebo use can benefit patients and strengthen the medical profession.
The placebo in modern medicine, ,Gastrointestinal Endoscopy, Volume 43, Issue 1, January 1996, Pages 76-79
Stephen E. Silvis

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Don’t ask, Don’t tell? Revealing placebo responses to research participants and patients
Francis KeefeCorresponding Author Contact Information, a, E-mail The Corresponding Author, Amy P. Abernethyb, Jane Wheelerb and Glenn Affleckc
aPain Prevention and Treatment Research Program, Duke University Medical Center, Suite 340, 2200 Main Street, Durham, NC 27705, USA
bDuke Cancer Care Research Program, Division of Medical Oncology, Department of Medicine, 25165 Morris Building, Duke University Medical Center, Durham, NC 27710, USA cUniversity of Connecticut Health Center, USA

Available online 20 February 2008.

Refers to: Revelation of a personal placebo response: Its effects on mood, attitudes and future placebo responding
Pain, Volume 132, Issue 3, 5 December 2007, Pages 281-288
S. Karen Chung, Donald D. Price, G. Nicholas Verne and Michael E. Robinson