Diagnostic Blocks

An Exploration of Knowledge and Attitudes of Medical Students and Rheumatologists to Placebo and Nocebo Effects: Threshold Concepts in Clinical Practice

INTRODUCTION

Understanding placebo and nocebo responses (context/meaning effects [CMEs]) is fundamental to physician agency. Specific instruction in CMEs is often lacking in medical education. Patient-practitioner interactions may challenge medical students' understanding of biomedical causality and the nexus between this, practical ethics and professionalism across various conceptual and applied aspects of CMEs. This study compared the corpus of knowledge and phronesis related to CMEs between Australian graduate medical students and rheumatologists to gain a sophisticated understanding of this relationship to inform curriculum development.

METHOD

In 2013 and 2014, the authors surveyed third-year medical students undertaking a graduate programme in an Australian medical school and Australian rheumatologists to ascertain their understanding of placebo and nocebo responses. The survey ascertained (1) the alignment of the respondents' understanding of CMEs with accepted facts and concepts; (2) opinions on the ethical status of CMEs; and (3) responses to 2 scenarios designed to explore matters of biomedical causality, practical ethics and professionalism.

RESULTS

There were 88 completed surveys returned, 53 rheumatologists and 35 students. Similar proportions within each group identified CMEs, with most (n = 79/88 [89.8%]) correctly recognising a placebo (rheumatologists: 50 [94.3%], students: 29 [82.9%]) and approximately three-quarters (n = 65/88 [73.9%]) correctly recognising nocebo effects (rheumatologists: 39 [73.6%], students: 26 [74.3%]). Statistically significant differences between practitioners and students were observed in relation to the following: placebo responders and placebo responsiveness; placebos as a 'diagnostic tool'; placebos usage in clinical practice and research, and nocebo effects.

CONCLUSIONS

Physicians require an awareness of CMEs and the fact that they arise from and influence the effective agency of health care professionals. Curricular emphasis is needed to permit an honest assessment of the components that influence when, how and why patient outcomes arise, and how one's agency might have neutral or negative effects but could be inclined towards positive and away from negative patient outcomes.

Magnitude, response, and psychological determinants of placebo effects in chronic low-back pain: a randomised, double-blinded, controlled trial

Introduction:

Denervation of the lumbar zygapophyseal joints by medial branch radiofrequency neurotomy has shown some benefit in treating chronic low-back pain. Before denervation, a diagnosis is made by one or more blinded injections on separate occasions to ascertain whether the relevant joints are contributing to the pain. Placebo injections have been advocated in a diagnostic regime that also includes local anaesthesia, with a decision to proceed to neurotomy based on response to local anaesthesia and not to placebo.

Objectives:

We investigated the magnitude of and response rate to placebo injections, and the roles of expectation, desire for pain relief, and anxiety as determinants of response to placebo.

Methods:

One hundred twenty patients were randomised to receive placebo and local anaesthetic injections on alternate occasions in a double-blind manner. A smaller control group with 2 local anaesthetic injections was also used. Responses to placebo were characterised, including magnitude and frequency.

Results:

This study demonstrated very large response to placebo injections, both response rate (78%) and magnitude (effect size d = 1.85). Expectation and anxiety were important modulators of response to placebo in this setting, with support given to expectation as a dynamic modulator of placebo responses. Large response to placebo (both in rate and magnitude) was observed when participants reported the belief that they were in the placebo arm.

Conclusion:

This study demonstrated large placebo responses in the context of injections for low-back pain and further characterised the importance of expectation and anxiety as important psychological mediators.

Diagnostic nerve blocks in the management of low back pain secondary to facet joint syndrome

Low back pain is currently one of the main public health problems. Among the multiple causes, pain in the zygapophysial joints, also called facets or posterior vertebral joints, are an important cause, usually secondary to osteoarthritis. The source of low back pain is often difficult to find, making the therapeutic approach to the patient sub-optimal. Diagnostic blocks are a very important tool in establishing an adequate treatment for patients with low back pain, as long as they are performed accurately, with an adequate local anaesthetic volume, with a suitable image and fluoroscopic projection and its result are precisely interpreted. In this article a review is presented on the importance of diagnostic blocks, as well as how they should be performed in order to obtain the maximum information and the greatest therapeutic benefit.

The impact of judges' perceptions of credibility in fibromyalgia claims

Fibromyalgia (FM) is a confusing and controversial diagnosis, characterized by widespread pain and tenderness at specific anatomical sites. The cause of this syndrome is unknown, and the course of the condition is difficult to predict. Without a known cause, predictable course, or effective treatment, it is not surprising that FM is a contentious diagnosis from a medical perspective, as well as a civil litigation and disability insurance industry perspective. The purpose of this study was to investigate judges' perceptions of credibility in litigated cases involving FM claims in the Canadian courts, and the relation between perceived credibility and awards granted. A systematic review was conducted of every trial-by-judge litigated FM claim in Canada (N=194 cases) up to 2003. The cases were examined in relation to credibility factors. The role and responsibility of the plaintiff was central in claims involving issues of misrepresentation, fraud, non-disclosure, failure to mitigate, and contributory negligence. The presence of these issues suggested a possible decrease or loss in the claim as a result of the plaintiff's conduct. In regards to the actions of defendants, the presence of investigative and surveillance information alone did not affect the awards granted. However, the credibility of that information had a large effect on the amount of award granted. Plaintiff credibility played a similar role, indicating that plaintiffs perceived as more credible were typically granted greater awards. An examination of medical expert credibility revealed that judges appear to perceive experts as more credible overall than plaintiffs, regardless of the expert's role in the case.

Evidence-informed management of chronic low back pain with facet injections and radiofrequency neurotomy

The management of chronic low back pain (CLBP) has proven to be very challenging in North America, as evidenced by its mounting socioeconomic burden. Choosing amongst available nonsurgical therapies can be overwhelming for many stakeholders, including patients, health providers, policy makers, and third-party payers. Although all parties share a common goal and wish to use limited health-care resources to support interventions most likely to result in clinically meaningful improvements, there is often uncertainty about the most appropriate intervention for a particular patient. To help understand and evaluate the various commonly used nonsurgical approaches to CLBP, the North American Spine Society has sponsored this special focus issue of The Spine Journal, titled Evidence-Informed Management of Chronic Low Back Pain Without Surgery. Articles in this special focus issue were contributed by leading spine practitioners and researchers, who were invited to summarize the best available evidence for a particular intervention and encouraged to make this information accessible to nonexperts. Each of the articles contains five sections (description, theory, evidence of efficacy, harms, and summary) with common subheadings to facilitate comparison across the 24 different interventions profiled in this special focus issue, blending narrative and systematic review methodology as deemed appropriate by the authors. It is hoped that articles in this special focus issue will be informative and aid in decision making for the many stakeholders evaluating nonsurgical interventions for CLBP.

Hyperexcitable polymodal and insensitive nociceptors in painful human neuropathy

Six patients with chronic pain, mechanical and thermal hyperalgesia/allodynia, and cutaneous vasodilatation starting distally in their extremities, were evaluated using clinical and neurophysiological methods and microneurography. Evidence of small-fiber polyneuropathy was documented in all, but the etiology remained cryptogenic in several. Different forms of hyperexcitability were detected by microneurography in both common polymodal and mechanically insensitive C nociceptors, which explain all the somatosensory abnormalities. Signs of hyperexcitability included reduced receptor threshold (accounting for mechanical and heat allodynias), spontaneous C nociceptor discharge (explaining spontaneous "burning" pain and antidromic vasodilatation), and multiplied nociceptor responses to stimulation (accounting for hyperalgesia). The clinical and electrophysiological profiles of these patients resemble the experimental syndrome evoked by application of capsaicin to the skin. This similarity, and the striking heat dependence of the spontaneous pain, suggest that a common feature may be altered expression or modulation of vanilloid 1 receptor, provoking abnormal nociceptor discharges.

Detection of Feigned Tactile Sensory Loss Using a Forced-Choice Test of Tactile Discrimination and Other Measures of Tactile Sensation

OBJECTIVE

Intentional exaggeration of disability is a risk in work injuries but is hard to reliably detect clinically. This study examined the accuracy of tactile sensory threshold and forced-choice discrimination measures in detecting feigned sensory loss.

METHODS

Participants (n = 80) were randomly assigned to one of four sensory loss groups: (1) none; (2) partial; (3) full; or (4) feigned. Sensory data were collected for the upper extremities.

RESULTS

Tactile thresholds greater than 0.5 g, discriminability less than 0.50, or forced-choice scores less than 90% were associated with a very low probability of false-positive errors.

CONCLUSIONS

Below-chance scores are definitive evidence that the sensory loss is intentionally feigned. Scores beyond cut-offs should raise the clinician's suspicion of malingering if there is no physical basis for sensory loss.