The journal of pain : official journal of the American Pain Society
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We evaluated the effect of infiltration of dilute solutions of capsaicin, administered before plantar incision, on 3 pain-related behaviors: guarding pain, heat-withdrawal latency, and mechanical-withdrawal threshold. Perineural application of capsaicin was also studied and the appearance of the wound was also evaluated. Dilute solutions of capsaicin .025% and .10% were infiltrated in the plantar region 1 day before incision. In another group of rats, perineural capsaicin (1%) was applied to the nerves innervating the plantar aspect of the rat hindpaw. Rats were then tested for pain-related behaviors before and after plantar incision and then daily thereafter. Wound appearance was graded and histopathology was evaluated. Infiltration with capsaicin reduced guarding pain and heat hyperalgesia after plantar incision; there were minimal effects on mechanical responses. Perineural-capsaicin application produced a similar result. Both capsaicin infiltration and perineural-capsaicin application impaired wound apposition. Histologic evaluation also confirmed impaired wound apposition after capsaicin infiltration. In conclusion, dilute solutions of capsaicin have differential effects on pain-related behaviors after plantar incision. Based on the antinociception produced by capsaicin both via infiltration and perineural injection, the effect on wound appearance was likely related to its inhibitory effects on pain behaviors and was not necessarily a local effect of the drug. ⋯ This study demonstrated that capsaicin infiltration before plantar incision produced an analgesic effect that depended upon the stimulus modality tested. When evaluating novel treatments for postoperative pain, studies using a single stimulus modality may overlook an analgesic effect by not examining a variety of stimuli.
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Quantification of the human painful sensory experience is an essential step in the translation of knowledge from animal nociception to human pain. Translational models for assessment of pain are very important, as such models can be used in: 1) basic mechanistic studies in healthy volunteers; 2) clinical studies for diagnostic and monitoring purposes; 3) pharmacological studies to evaluate analgesic efficacy of new and existing compounds. Quantitative pain assessment, or quantitative sensory testing (QST), provides psychophysical methods that systematically document alterations and reorganization in nervous system function and, in particular, the nociceptive system. QST is defined as the determination of thresholds or stimulus response curves for sensory processing under normal and pathophysiological conditions. The modern concept of advanced QST for experimental pain assessment is a multimodality, multitissue approach where different pain modalities (thermal, mechanical, electrical, and chemical) are applied to different tissues (skin, muscles, and viscera) and the responses are assessed by psychophysical methods (thresholds and stimulus-response functions). Many new and advanced technologies have been developed to help relieve evoked, standardized, and painful reactions. Assessing pain has become a question of solving a multi-input, multi-output problem, with the solution providing the possibility of teasing out which pain pathways and mechanisms are involved, impaired, or affected. ⋯ Many methodologies have been developed for quantitative assessment of pain perception and involved mechanisms. This paper describes the background for the different methods, the use in basic pain experiments on healthy volunteers, how they can be applied in drug profiling, and the applications in clinical practice.
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Although sex differences have been investigated in chronic pain populations, little is known about sex differences in the pain experience of paediatric oncology patients and also whether their parents rate the pain experience differently for boys and girls. The aim of the present study was to determine if (1) boys and girls with cancer differ in current perception and past recollection of cancer-related pain and (2) if adolescents' and parents' pain ratings differ in relation to the sex of the adolescent. One hundred twelve adolescents with malignant diagnoses (12 to 18 years) and their parents participated in the study. Girls reported higher pain intensity within the last 7 days and 4 weeks despite similar diagnosis, physical status, duration of diagnoses, and main pain causes. When asked for pain intensity that dated back in time, parent and adolescent ratings diverged, with a trend for parents to reporting higher pain intensity in boys and lower pain intensity in girls, particularly for pain in the preceding 7 days. The present study provides preliminary evidence for sex differences in the recalled pain experience of adolescents with malignant diagnoses. Although boys and girls experience present pain similarly and hence should be treated similarly, girls recall higher pain intensity than boys. Future studies should address whether negative memories in girls play a significant role and may have an impact on girls' well-being and pain-related distress. Additionally, psychosocial factors such as gender role expectations may need to be investigated. Parental variables and their impact on parents' pain ratings, especially for ratings of precedent pain, warrants further investigation. ⋯ Girls with malignant diagnoses differ from boys in their recalled pain intensity ratings, with girls reporting higher pain intensity. Additional pain management strategies referring to the memory of pain may need to be implemented.
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This study examined the role of resilience in habituation to heat and cold pain in healthy women (n = 47). Heat and cold pain thresholds were each assessed across 5 equally spaced trials. Resilience, purpose in life, optimism, social support, and neuroticism were assessed using self-report measures. The hypothesis was that the resilience and the associated resilience factors would be positively related to habituation to heat and cold pain while controlling for neuroticism. Multilevel modeling was used to test the hypothesis. When considering each characteristic separately, resilience and purpose in life predicted greater habituation to heat pain while resilience, purpose in life, optimism, and social support predicted greater habituation to cold pain. When controlling for the other characteristics, both resilience and purpose in life predicted greater habituation to heat and cold pain. Resilience and associated characteristics such as a sense of purpose in life may be related to enhanced habituation to painful stimuli. Future research should further examine the relationship between resilience, purpose in life, and habituation to pain and determine whether psychosocial interventions that target resilience and purpose in life improve habituation and reduce vulnerability to chronic pain. ⋯ This article showed that resilience and a sense of purpose in life were both related to the ability to habituate to heat and cold pain in healthy women. These personal characteristics may enhance habituation to pain by providing the confidence and motivation to persist in the face of painful stimuli.
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Randomized Controlled Trial Comparative Study
Qigong and exercise therapy for elderly patients with chronic neck pain (QIBANE): a randomized controlled study.
The aim of this study was to evaluate the effectiveness of qigong compared with exercise therapy and no treatment. Elderly patients with chronic neck pain (>6 months) were randomly assigned to qigong or exercise therapy (each 24 sessions over a period of 3 months) or to a waiting list control. Patients completed standardized questionnaires at baseline and after 3 and 6 months. The main outcome measure was average neck pain on the visual analogue scale after 3 months. Secondary outcomes were neck pain and disability (NPAD) and quality of life (SF-36). One hundred seventeen patients (age, 76 +/- 8 years, 95% women) were included in the intention-to-treat analysis. The average duration of neck pain was 19.0 +/- 14.9 years. After 3 months, no significant differences were observed between the qigong group and the waiting list control group (visual analogue scale mean difference, -11 mm [CI, -24.0; 2.1], P = .099) or between the qigong group and the exercise therapy group (-2.5 mm [ - 15.4; 10.3], P = .699). Results for the NPAD were similar (qigong vs waiting list -6.7 (-15.4; 2.1), P = .135; qigong vs exercise therapy 2.3 (-6.2; 10.8); P = .600). We found no significant effect after 3 months of qigong or exercise therapy compared with no treatment. Further studies should include outcomes more suitable to elderly patients, longer treatment, and patients with less chronic pain. ⋯ In a randomized controlled study, we evaluated whether a treatment of 24 qigong sessions over a period of 3 months is (1) superior to no treatment and (2) superior to the same amount of exercise therapy in elderly patients (age, 76 +/- 8 years, 95% women) with long-term chronic neck pain (19.0 +/- 14.9 years). After 3 and 6 months, we found no significant differences for pain, neck pain, disability, and quality of life among the 3 groups.