The journal of pain : official journal of the American Pain Society
-
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.
-
An 8-item version of the Chronic Pain Acceptance Questionnaire (CPAQ-8) has recently been proposed and validated. The aims of this study were to further investigate the reliability and validity of the CPAQ-8 in a new sample. Questionnaires were completed by 550 people with chronic pain (478 online survey, 72 paper survey). A demographic and pain history questionnaire was administered along with the CPAQ-8 and measures of pain self-efficacy, pain catastrophizing, psychological flexibility in pain, anxiety, and mood. In addition, 105 respondents completed the CPAQ-8 within 6 weeks to provide test-retest reliability data. The 2-factor structure of the CPAQ-8 (Activity Engagement [AE] and Pain Willingness [PW]) was confirmed and had reasonable-to-good scale score reliability and test-retest reliability. Pain acceptance as measured by the CPAQ-8 was associated with less depression, anxiety, pain interference, fear of reinjury, pain catastrophizing, and psychological inflexibility in pain, and higher levels of satisfaction with life, pain self-efficacy, and general acceptance. Furthermore, pain acceptance fully mediated the relationship between reported pain severity and emotional distress (anxiety and depression) and partially mediated the relationship between pain severity and pain interference in a structural equation model. The test-retest reliability after 4 to 6 weeks ranged from .68 for PW to .86 for AE; the overall score correlation was .81. We conclude that the CPAQ-8 is a reliable and valid measure of pain acceptance and that the 2 subscales of the measure each make an individual contribution to the prediction of adjustment in people with chronic pain. ⋯ The present study provides further evidence for the reliability and validity of the CPAQ-8. Support was found for the 2 related subscales, PW and AE, which appear to work in synergy to influence levels of pain interference and emotional distress in people living with chronic pain.
-
We have shown previously that electrical stimulation of the motor cortex reduces spontaneous painlike behaviors in animals with spinal cord injury (SCI). Because SCI pain behaviors are associated with abnormal inhibition in the inhibitory nucleus zona incerta (ZI) and because inactivation of the ZI blocks motor cortex stimulation (MCS) effects, we hypothesized that the antinociceptive effects of MCS are due to enhanced inhibitory inputs from ZI to the posterior thalamus (Po)-an area heavily implicated in nociceptive processing. To test this hypothesis, we used a rodent model of SCI pain and performed in vivo extracellular electrophysiological recordings in single well-isolated neurons in anesthetized rats. We recorded spontaneous activity in ZI and Po from 48 rats before, during, and after MCS (50 μA, 50 Hz; 300-ms pulses). We found that MCS enhanced spontaneous activity in 35% of ZI neurons and suppressed spontaneous activity in 58% of Po neurons. The majority of MCS-enhanced ZI neurons (81%) were located in the ventrorateral subdivision of ZI-the area containing Po-projecting ZI neurons. In addition, we found that inactivation of ZI using muscimol (GABAA receptor agonist) blocked the effects of MCS in 73% of Po neurons. Although we cannot eliminate the possibility that muscimol spread to areas adjacent to ZI, these findings support our hypothesis and suggest that MCS produces antinociception by activating the incertothalamic pathway. ⋯ This article describes a novel brain circuit that can be manipulated, in rats, to produce antinociception. These results have the potential to significantly impact the standard of care currently in place for the treatment of patients with intractable pain.
-
Review Meta Analysis
Inserting needles into the body: a meta-analysis of brain activity associated with acupuncture needle stimulation.
Acupuncture is a therapeutic treatment that is defined as the insertion of needles into the body at specific points (ie, acupoints). Advances in functional neuroimaging have made it possible to study brain responses to acupuncture; however, previous studies have mainly concentrated on acupoint specificity. We wanted to focus on the functional brain responses that occur because of needle insertion into the body. An activation likelihood estimation meta-analysis was carried out to investigate common characteristics of brain responses to acupuncture needle stimulation compared to tactile stimulation. A total of 28 functional magnetic resonance imaging studies, which consisted of 51 acupuncture and 10 tactile stimulation experiments, were selected for the meta-analysis. Following acupuncture needle stimulation, activation in the sensorimotor cortical network, including the insula, thalamus, anterior cingulate cortex, and primary and secondary somatosensory cortices, and deactivation in the limbic-paralimbic neocortical network, including the medial prefrontal cortex, caudate, amygdala, posterior cingulate cortex, and parahippocampus, were detected and assessed. Following control tactile stimulation, weaker patterns of brain responses were detected in areas similar to those stated above. The activation and deactivation patterns following acupuncture stimulation suggest that the hemodynamic responses in the brain simultaneously reflect the sensory, cognitive, and affective dimensions of pain. ⋯ This article facilitates a better understanding of acupuncture needle stimulation and its effects on specific activity changes in different brain regions as well as its relationship to the multiple dimensions of pain. Future studies can build on this meta-analysis and will help to elucidate the clinically relevant therapeutic effects of acupuncture.
-
The verbal numerical rating scale (vNRS-11) is one of the most widely used scales for assessing pediatric pain intensity. The literature shows that it is a valid instrument for assessing pain intensity in children above 8 years of age. The aim of this work was to study whether the vNRS-11 is also a valid instrument when it is used with Catalan-speaking children between 6 and 8 years old. A total of 126 schoolchildren (mean age, 6.87; SD, .68) were interviewed individually. Participants reported the maximum intensity of the most frequent pain they had experienced in the previous 3 months, and the intensity they would experience in 3 circumstances, using the vNRS-11 and other widely used scales: the Faces Pain Scale-Revised (FPS-R), the mechanical visual analog scale (VAS), and the colored analog scale (CAS). They rated their affective state in relation to the pain experience and reported their pain-related disability. Participants also indicated which of the 4 scales they preferred. The vNRS-11 showed a high convergent construct validity (r = .73-.86), adequate discriminant validity (z = 2.05-5.55), and adequate criterion-related validity (r = .45-.70). The vNRS-11 was the second most preferred scale. ⋯ This study contributes to the increasing literature that supports the use of the vNRS-11 to assess pain intensity in children. Specifically, it shows that it can be used in children as young as 6 years of age.