The journal of pain : official journal of the American Pain Society
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Irritable bowel syndrome (IBS), characterized mainly by abdominal pain, is a functional bowel disorder. The present study aimed to examine changes in the excitability and the activity of the voltage-gated K(+) channel in dorsal root ganglia (DRG) neurons innervating the colon of rats subjected to neonatal maternal separation (NMS). Colonic DRG neurons from NMS rats as identified by FAST DiI™ labeling showed an increased cell size compared with those from nonhandled (NH) rats. Whole cell current-clamp recordings showed that colonic DRG neurons from NMS rats displayed: 1) depolarized resting membrane potential; 2) increased input resistance; 3) a dramatic reduction in rheobase; and 4) a significant increase in the number of action potentials evoked at twice rheobase. Whole cell voltage-clamp recordings revealed that neurons from both groups exhibited transient A-type (I(A)) and delayed rectifier (I(K)) K(+) currents. Compared with NH rat neurons, the averaged density of I(K) was significantly reduced in NMS rat neurons. Furthermore, the Kv1.2 expression was significantly decreased in NMS rat colonic DRG neurons. These results suggest that NMS increases the excitability of colonic DRG neurons mainly by suppressing the I(K) current, which is likely accounted for by the downregulation of the Kv1.2 expression and somal hypertrophy. ⋯ This study demonstrates the alteration of delayed rectifier K current and Kv1.2 expression in DRG neurons from IBS model rats, representing a molecular mechanism underlying visceral pain and sensitization in IBS, suggesting the potential of Kv1.2 as a therapeutic target for the treatment of IBS.
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The purpose of this study was to evaluate the prevalence and characteristics of pain in patients with chronic obstructive pulmonary disease (COPD) compared to a sample from the Norwegian general population. This cross-sectional study evaluated 100 COPD patients with and without pain and 333 individuals from the Norwegian population with pain. After controlling for age and sex, a significantly higher percentage of patients with COPD (45%) reported pain than the general population (34%; P = .02). No differences were found in pain intensity scores, pain interference score, or number of pain locations between COPD patients and the general population. COPD patients reported moderate-to-severe pain located primarily in the chest, shoulders, neck, and thorax. For both groups, the most common pain treatment was analgesic use. Acupuncture/transcutaneous electrical nerve stimulation was used more frequently by COPD patients (P < .001) while physiotherapy was used more frequently by the general population (P = .007) to treat their pain. Pain is a significant problem for COPD patients. Additional research is warranted to replicate these findings and to provide a more detailed characterization of how pain changes over time and influences COPD patients' ability to function and their quality of life. ⋯ Compared to the general population, pain is more common in patients with COPD and ranges from moderate to severe in its intensity.
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The aims of this study were: 1) to examine race and sex differences in primary pain appraisals and catastrophizing; 2) to test the unique ability of race, sex, primary pain appraisals, and catastrophizing to predict experimental pain outcomes; and 3) to conduct mediational analyses testing pain appraisals and catastrophizing as explanatory mechanisms for race and sex differences in pain. One hundred and fifty-five college students at The University of Alabama completed a cold pressor experimental pain task and a questionnaire battery. Statistical methods included multivariable regression models and nonparametric bootstrapping methods for tests of mediation. African-Americans reported higher catastrophizing and had lower pain tolerance than white Americans. Males demonstrated higher challenge appraisals, lower pain intensity, and longer pain tolerance. Challenge appraisals were positively related to pain tolerance, threat/harm appraisals were inversely related to pain tolerance, and pain catastrophizing was positively related to both pain intensity and pain unpleasantness. Pain catastrophizing partially mediated race differences in pain tolerance and mediated sex differences in intensity, whereas primary pain appraisals did not significantly mediate race or sex differences in pain variables. Primary appraisals and catastrophizing appear to be separable constructs related to different aspects of the pain experience. ⋯ This study found that important race and sex differences exist in relation to pain appraisals and catastrophizing, and that these cognitive variables play unique roles in different aspects of the pain experience. Cognitive-behavioral therapies for pain may be enhanced by including a focus on both pain appraisals and pain catastrophizing.
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Fibromyalgia (FM) is a chronic, widespread musculoskeletal pain disorder that is very prevalent in the general population (approximately 5%). Accumulating evidence suggests that FM is associated with central pain processing abnormalities, ie, central sensitization. Several previous studies of chronic pain patients, including FM, have shown gray matter atrophy of brain areas associated with sensory and affective pain processing. These findings, however, have not been confirmed in all FM studies. In this study, we investigated gray matter volumes of brain areas associated with pain-related areas of FM patients identified by functional brain imaging. Using voxel-based morphometric (VBM) analysis of magnetic resonance brain images, we compared 19 pain-related brain areas of 14 female FM patients and 11 healthy controls (NC). We found that FM patients had significantly less gray matter volumes than NC in 3 of these brain regions, including the anterior and mid-cingulate, as well as mid-insular cortices. Importantly, FM patients demonstrated neither global gray matter atrophy nor gray matter changes associated with depression, as shown in some studies. Using a more stringent analysis than other VBM studies, we provide evidence for decreased gray matter volumes in a number of pain-related brain areas in FM. Although the mechanisms for these gray matter changes are presently unclear, they may contribute to some of the core features of this chronic disorder including affective disturbances and chronic widespread pain. ⋯ Increasing evidence supports the association of chronic pain with accelerated gray matter atrophy in pain disorders like low back pain, IBS, and FM syndrome. However, cause-effect relationships between chronic pain and decreased gray matter volumes have not been established yet and will require future prospective studies.
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The Tampa Scale for Kinesiophobia (TSK) is one of the most frequently employed measures for assessing pain-related fear in pain patients. Although the TSK has been translated into different languages, a Spanish version of the TSK has not been available, up to now. Thus, the aim of this study was to validate the Spanish version of the TSK in 2 different pain samples: A heterogeneous chronic pain sample (n = 125) and a musculoskeletal acute pain sample (n = 86). Factor analysis revealed a 2-factor model of 11 items replicated on both samples, named TSK-11. The instrument obtained shows good reliability (internal consistency and stability) and validity (convergent and predictive), with the advantage of brevity. Evidence is provided on discriminant validity between both TSK factors (called Activity Avoidance and Harm). The Harm factor shows the best predictive validity, as it predicts pain persistence, catastrophizing, depression, and pain intensity scores after 6 months. Changes in the Activity Avoidance factor are positively correlated with changes in catastrophizing and anxiety, and negatively associated with changes in functional status. The results of this study point to the relative contribution of both components of pain-related fear to pain adjustment. ⋯ This article presents the Spanish version of the TSK. Factor analysis revealed a 2-factor model (called Activity Avoidance and Harm). The version obtained shows good reliability and validity. Results provide clinicians with access to a measure of pain-related fear for Spanish-speaking pain patients, offering the advantage of brevity.