The journal of pain : official journal of the American Pain Society
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More than a third of breast cancer patients undergoing aromatase inhibitor (AI) treatment report joint pain. We conducted a longitudinal study to characterize the course of AI-induced joint pain and other symptoms and to identify potential predictors for developing these symptoms. Patients were recruited before AI initiation. The Brief Pain Inventory, M. D. Anderson Symptom Inventory, and a joint-pain questionnaire were administered at baseline and then biweekly for 1 year. Analysis included logistic regression, Cox models, and mixed-effects models. Of 47 patients assessed, 16 (34%) reported joint pain at least once. Median time to first report of joint pain was 7 weeks (range, 1-38). Baseline pain was the only predictor for both incidence of joint pain and time to first event. In the first 6 weeks, emergence of joint pain was associated with increase in general pain, fatigue, disturbed sleep, hot flashes, vaginal dryness, and decreased sexual activity. After week 6, having joint pain was associated with increase in general pain and with persistently high fatigue. Having AI-associated joint pain correlated with increase in or persistence of other symptoms likely related to AI therapy. Further research is needed to validate predictors of AI-associated symptoms. ⋯ We demonstrate for the first time that AI-induced joint pain associates with development of other symptoms and that pretreatment pain level is a potential, measurable predictor of symptom development during treatment. Because baseline pain is easily assessed with a brief questionnaire, it can be applied clinically with minimal patient burden.
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The way in which individuals attend to pain-related stimuli is thought to affect their pain experience. Early and late stages of processing, with shifts from attentional engagement to disengagement (avoidance), have been identified, but rarely investigated in the same protocol. Therefore, the present study aimed to consider 2 time frames that might be indicative of attentional engagement and disengagement. One hundred pain-free individuals performed a modified dot-probe task with pictorial stimuli displaying affective facial expressions (ie, pain, anger, joy, neutral face), presented either for 100 ms or for 500 ms. Because fear of pain has been found to moderate attentional processing of pain stimuli, the Fear of Pain Questionnaire (FPQ III) was also administered. Results indicated both early attentional engagement and later disengagement (avoidance) for negative facial expressions (anger, pain). This pattern was most prominent for pain faces and among those participants high in pain-related fear. Taken together, these findings provide evidence that the dot-probe task is suitable to investigate different stages of attentional processing for pain-related stimuli. In accordance with the vigilance-avoidance hypothesis, pain-related stimuli seem to attract attention quickly, but attentional avoidance may occur shortly after. ⋯ We focused on different stages of attentional processing of pain faces in pain-free individuals. Results highlight the importance of distinguishing between early (engagement) and later (disengagement) components of attention, as well as considering the role that fear of pain has in understanding the nature of these effects.
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Little is known about treatment mechanisms underlying acceptance strategies. Acceptance is a strategy that is expected to increase pain tolerance more than distraction, while distraction should lead to lower pain intensity. The effect of cognitive restructuring on experimental pain has not yet been investigated. The present study aimed to explore differential short-term effects of acceptance, distraction, and cognitive restructuring on pain tolerance and intensity. Pain was induced in a sample of 109 female students using a thermode. We conducted analyses of covariance with instruction as the independent variable and posttest scores on pain variables as dependent variables, covarying for pretest scores. In addition, adherence to instructions and credibility of instructions were included as covariates. Acceptance led to a higher increase in pain tolerance than did cognitive restructuring of pain-related thoughts. No differences were detected between either acceptance and distraction or distraction and cognitive restructuring with respect to pain tolerance. Distraction led to lower pain intensity compared to acceptance. Cognitive restructuring did not differ from either acceptance or distraction with respect to pain intensity. As a short-term strategy, cognitive restructuring was not as useful as acceptance in increasing pain tolerance. Further studies should evaluate the preconditions under which different strategies are most effective. ⋯ This study demonstrated that acceptance was superior to cognitive restructuring in increasing tolerance for experimentally induced pain, but was inferior to distraction with respect to decreasing pain intensity. Knowledge about the types of strategies that are useful in targeting diverse pain-related outcome measures is important for efforts to refine the treatment of chronic pain.
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The knee osteoarthritis (KOA) model is a convenient and coherent archetype that is frequently used in pharmaceutical trials of drugs with analgesic and/or anti-inflammatory properties; yet, little is known about its specific pathophysiology. The presumed chronic inflammatory etiology of osteoarthritis suggests that nociceptive processes and neurogenic inflammation predominate in this condition. However, most chronic pain conditions are associated with changes in peripheral and central processing. Recent data corroborate this as an important mechanism in KOA. We compared psychophysical characteristics (including thermal Quantitative Sensory Testing); thermal, mechanical, and functional wind-up; thermal and mechanical aftersensations; and pressure algometry of 37 subjects with KOA with 35 age- and sex-matched controls. A third of the KOA subjects demonstrated hypoesthesia to vibration and the 4.56 von Frey fiber, yet few showed allodynia in their worse knee. The majority of subjects had abnormalities to pinprick (41% were hyperalgesic and 27% were hypoesthetic). Compared to controls, the more painful knee was hypoesthetic to cold detection and had greater thermal wind-up, lower pressure-pain thresholds, thermal and mechanical aftersensations, and twice the pain ratings of controls after stair climb. Substantial intraindividual differences were found in KOA subjects and controls for mechanical wind-up and algometric thresholds. ⋯ These results develop the KOA model and suggest mechanistic hypotheses. Certain of these tests may ultimately prove to be responsive, quasi-objective, and quantitative outcomes for research and lend empirical support to the notion of measurable sensitization in osteoarthritis.
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Pain is associated with stimulation of some behaviors (eg, withdrawal reflexes) but depression of many other behaviors (eg, feeding, locomotion, positively reinforced operant behavior). Drugs that block reuptake of serotonin, norepinephrine, and/or dopamine are widely used to treat depression, and they have also emerged as useful drugs for treatment of pain. This study compared effects of selective and mixed-action inhibitors of serotonin, norepinephrine, and/or dopamine reuptake in assays of acute pain-stimulated and pain-depressed behavior. Intraperitoneal injection of dilute acid served as a noxious stimulus to stimulate a writhing response or depress intracranial self-stimulation (ICSS) in Sprague Dawley rats. Selective reuptake inhibitors of serotonin (citalopram, clomipramine) and norepinephrine (nisoxetine, nortriptyline) and a mixed-action reuptake inhibitor of serotonin and norepinephrine (milnacipran) blocked acid-stimulated writhing but failed to block acid-induced depression of ICSS. Selective dopamine reuptake inhibitors (RTI-113 [3ß-(4-chlorophenyl)tropane-2ß-carboxylic acid phenyl ester hydrochloride], bupropion) and a triple reuptake inhibitor of dopamine, serotonin, and norepinephrine (RTI-112 [3ß-(3-methyl-4-chlorophenyl)tropane-2ß-carboxylic acid methyl ester hydrochloride]) blocked both acid-stimulated writhing and acid-induced depression of ICSS, although these drugs also produced an abuse-related facilitation of ICSS in the absence of the noxious stimulus. These results support further consideration of dopamine reuptake inhibitors as candidate analgesics, although abuse liability remains a concern. ⋯ Monoamine reuptake inhibitors are used to treat depression and some forms of pain. This study examined effects of monoamine reuptake inhibitors in a preclinical assay of pain-related behavioral depression. The results support further consideration of dopamine reuptake inhibitors as candidate analgesics under selected circumstances, although abuse liability remains a concern.