Pain
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This paper reports upon: (1) the value of acceptance of pain in predicting well-being in patients suffering from chronic pain and (2) the construct validity of acceptance by comparing two questionnaires designed to measure acceptance (the Chronic Pain Acceptance Questionnaire, CPAQ, unpublished doctoral dissertation, University of Nevada, Reno, NV, 1992 and the Illness Cognitions Questionnaire, ICQ, J Consult Clin Psychol 69 (2001) 1026). The results of two independent cross-sectional studies are reported. Study 1 included 120 patients seeking help in tertiary care settings. ⋯ Acceptance in both instruments was strongly related to a cognitive control over pain. Study 2 further revealed that the correlation between the CPAQ and the ICQ is moderate, indicating that both instruments measured different aspects of acceptance. It is concluded that acceptance of chronic pain is best conceived of as the shift away from pain to non-pain aspects of life, and the shift away from a search for a cure with an acknowledgement that pain may not change.
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The objective of this study was to adapt the concept of 'episode-free day', a metric for measuring symptom relief in daily units, to the clinical outcome literature for persistent pain. The episode-free day metric is widely used in other medical literature, but no analogous measure exists in pain literature. Prior focus groups with this population suggested that a 'Day of Manageable Pain Control' was an appropriate name for the metric. ⋯ For both patient samples, '5' was the cut-point that optimally distinguished groups on pain-related interference. '5-8' and '5-7' were double cut-point solutions that optimally divided LBP and OA samples into three categories (e.g. lowest, medium and highest average pain), respectively. Derived cut-points were confirmed using a variety of measures of functional disability. Together with research that showed that average pain ratings of approximately 5 and below permit increased function and quality of life in patients with moderate to severe low back pain and osteoarthritis, our findings provide support for the use of 0-5 on a 0-10 numeric average pain severity scale as one possible criterion for a Manageable Day.
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PSD-93/chapsin-110 is a neuronal PDZ domain-containing protein that binds to and clusters the N-methyl-D-aspartate receptor (NMDAR) at synapses in the central nervous system. It also assembles a specific set of signaling proteins around the NMDAR and mediates downstream signaling by the NMDAR. Thus, PSD-93/chapsin-110 might be involved in many physiological and pathophysiological actions triggered via the activation of the NMDAR. ⋯ The present results indicate that the deficiency of spinal cord PSD-93/chapsin-110 protein significantly attenuates thermal and mechanical hyperalgesia in complete Freund's adjuvant- or peripheral nerve injury-induced chronic pain. This suggests that spinal cord PSD-93/chapsin-110 might be involved in the central mechanism of chronic pain. Our work might provide a new target for the therapy of chronic pain.
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Randomized Controlled Trial Multicenter Study Clinical Trial
Efficacy of lidocaine patch 5% in the treatment of focal peripheral neuropathic pain syndromes: a randomized, double-blind, placebo-controlled study.
Peripheral neuropathic pain syndromes (PNPS) are difficult to treat because commonly used analgesics are often ineffective when, for example, touch-evoked allodynia, hyperalgesia, and pain paroxysms are present. To investigate whether lidocaine patch 5% treatment is also effective in postherpetic neuropathy (PHN) and in other PNPS, 40 patients with various forms and localizations of PNPS completed a prospective, randomized, placebo-controlled, two-way, cross-over study in three medical hospitals. Patients suffering from pain in a localized skin area with intensity above 40 mm visual analog scale (VAS) and a stable consumption of pain medication were included in this study. ⋯ When, after the wash-out period, the pain intensity scores did not return to the pre-treatment values (+/-20%), these patients were excluded from the study. The present study revealed that, as an add-on therapy, the lidocaine patch 5% was clearly effective in reducing ongoing pain (P=0.017) and allodynia (P=0.023) during the first 8 h after application and that the patches also worked well over a period of 7 days (P=0.018) in diverse focal PNPS. Calculation of the numbers needed to treat (NNT) to obtain one patient with more than 50% relief of ongoing pain revealed that the NNT of 4.4 in the present study compared reasonably well with other studies of PHN, such as topically applied capsaicin (NNT: 5.3-infinity) or systemic treatment with gabapentin (NNT: 3.2-5.0).
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Randomized Controlled Trial Comparative Study Clinical Trial
Naloxone provokes similar pain facilitation as observed after short-term infusion of remifentanil in humans.
In contrast to an expected preventive analgesic effect, clinical observations suggest that intraoperatively applied opioids can induce postoperative hyperalgesia. We tested the development of post-infusion hyperalgesia in a newly developed experimental model of electrically induced pain and secondary mechanical hyperalgesia. In a double-blind, placebo controlled, cross-over study, 13 subjects received either saline placebo, remifentanil (0.05 or 0.1 microg/kg/min) or naloxone (0.01 mg/kg). ⋯ Naloxone infusion similarly resulted in increased pain (anti-analgesia) (p<0.001) and mechanical hyperalgesia (p<0.01). Increased pain ratings following withdrawal of remifentanil significantly correlated to anti-analgesia evoked by the mu-opioid antagonist naloxone (p<0.01) and was of similar magnitude, suggesting inhibition of endogenous opioids as an underlying mechanism. In contrast, hyperalgesia after remifentanil was more pronounced than hyperalgesia after naloxone administration and did not correlate to the observed anti-analgesic effects, suggesting the involvement of additional receptors systems other than the endorphin system.