Pain
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We report a novel symptom in many patients with low back pain (LBP) that sheds new light on the underlying pain mechanism. By means of quantitative sensory testing, we compared patients with radicular LBP (sciatica), axial LBP (LBP without radiation into the leg), and healthy controls, searching for cutaneous allodynia in response to weak tactile and cooling stimuli on the leg and low back. Most patients with radicular pain (~60%) reported static and dynamic tactile allodynia, as well as cooling allodynia, on the leg, often extending into the foot. ⋯ The presence of central sensitization also provides the first cogent account of shooting pain in sciatica as a wave of activity sweeping vectorially across the width of the sensitized dorsal horn. Finally, the results endorse leg allodynia as a pain biomarker in animal research on LBP, which is commonly used but has not been previously validated. In addition to informing the underlying mechanism of LBP, bedside mapping of allodynia might have practical implications for prognosis and treatment.
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This study investigated the social judgments that are made about people who appear to be in pain. Fifty-six participants viewed 2 video clips of human figures exercising. The videos were created by a motion tracking system, and showed dots that had been placed at various points on the body, so that body motion was the only visible cue. ⋯ As well as judging them to be in more pain, participants evaluated the person who displayed pain behavior as less warm and less competent than the person who did not display pain behavior. In addition, the person who displayed pain behavior was perceived to be in a more negative mood and to have poorer physical fitness than the person who did not, and these perceptions contributed to the impact of pain behaviors on evaluations of warmth and competence, respectively. The implications of these negative social evaluations for social relationships, well-being, and pain assessment in persons in chronic pain are discussed.
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The aim of this study was to find the cut-off points on the visual analogue scale (VAS) to distinguish among mild, moderate, and severe pain, in relation to the following: pain-related interference with functioning; verbal description of the VAS scores; and latent class analysis for patients with chronic musculoskeletal pain. A total of 456 patients were included. Pain was assessed using the VAS and verbal rating scale; functioning was assessed using the domains of the Short Form (36) Health Survey (SF-36). ⋯ Latent class analysis found that a 3-class solution fitted best, resulting in the classes 0.1 to 3.8, 3.9 to 5.7, and 5.8 to 10 cm. Findings from our study agree with those of some other studies, although many other studies found different optimal cut-off point schemes. As there appear to be no universally accepted cut-off points, and in view of the low-to-moderate associations between VAS scores and functioning and between VAS and verbal rating scale scores, the correct classification of VAS scores as mild, moderate. or severe in clinical practice seems doubtful.
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Relationships between the paradoxical painful and non painful sensations induced by a thermal grill.
The simultaneous application of innocuous cutaneous warm and cold stimuli with a thermal grill can induce both paradoxical pain and paradoxical warmth (heat). The goal of this study was to investigate further the relationships between these paradoxical sensations. Stimuli were applied to the palms of the right hands of 21 volunteers with a thermode consisting of 6 bars, the temperature of which was controlled by Peltier elements. ⋯ The intensities of the warmth and unpleasantness evoked by the stimuli were directly related to the magnitude of the warm-cold differential. Our results suggest that there is a continuum between the painful and nonpainful paradoxical sensations evoked by the thermal grill that may share pathophysiological mechanisms. These data also confirm the existence of strong relationships between the thermoreceptive and nociceptive systems and the utility of the thermal grill for investigating these relationships.
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Neuropathic pain (NP) in cancer patients lacks standards for diagnosis. This study is aimed at reaching consensus on the application of the International Association for the Study of Pain (IASP) special interest group for neuropathic pain (NeuPSIG) criteria to the diagnosis of NP in cancer patients and on the relevance of patient-reported outcome (PRO) descriptors for the screening of NP in this population. An international group of 42 experts was invited to participate in a consensus process through a modified 2-round Internet-based Delphi survey. ⋯ Agreement was also reached on clinical examination by soft brush or pin stimulation (MEDs⩾7 and IQRs⩽3) and on the use of PRO descriptors for NP screening (MED=8, IQR=3). Based on the study results, a clinical algorithm for NP diagnostic criteria in cancer patients with pain was proposed. Clinical research on PRO in the screening phase and on the application of the algorithm will be needed to examine their effectiveness in classifying NP in cancer patients.