Attention to pain and fear of pain in patients with chronic pain

To investigate how acceptance of illness affects chronic pain in terms of attention towards pain and fearful thinking of pain. 62 participants (50 women) with chronic pain carried a palmtop computer for 2 weeks. Eight times each day auditory signals were delivered to cue participants to complete questions about their experience. Multilevel analyses indicated that on moments with more intense pain, more fearful thinking about pain, and less positive emotions, attention to pain was increased. Illness acceptance did not moderate the relation between pain intensity and attention to pain. Results further indicated that on moments with more intense pain, more negative emotions, and less positive emotions, fearful thinking about pain was increased. Of particular interest was the finding that the relationship between pain intensity and fearful thinking about pain was less strong for those high in acceptance. Pain captures attention and elicits fearful thinking about pain. Acceptance may be a useful avenue to lower negative thinking about pain, and to increase well-being in patients with chronic illnesses.     

条件性疼痛调节的影响因素与慢性疼痛

作为评价内源性镇痛强度的新方法,条件性疼痛调节(CPM)受损意味着机体痛觉下行抑制作用减弱,发生慢性疼痛的概率增加,而年龄、心理因素和体育锻炼等均能对个体CPM产生影响。同时,采取统一标准的CPM检测方法对不同研究间进行比较有重要意义。     

Joint pain

Both inflammatory and degenerative diseases of joints are major causes of chronic pain. This overview addresses the clinical problem of joint pain, the nociceptive system of the joint, the mechanisms of peripheral and central sensitization during joint inflammation and long term changes during chronic joint inflammation. While the nature of inflammatory pain is obvious the nature and site of origin of osteoarthritic pain is less clear. However, in both pathological conditions mechanical hyperalgesia is the major pain problem, and indeed, both joint nociceptors and spinal nociceptive neurons with joint input show pronounced sensitization for mechanical stimulation. Molecular mechanisms of mechanical sensitization of joint nociceptors are addressed with an emphasis on cytokines, and molecular mechanisms of central sensitization include data on the role of excitatory amino acids, neuropeptides and spinal prostaglandins. The overview will also address long-term changes of pain-related behavior, response properties of neurons and receptor expression in chronic animal models of arthritis.     

TRPM2在损伤性神经性疼痛过程中参与急性疼痛向慢性疼痛的转化

目的 探究TRPM2在损伤性神经性疼痛中的作用和可能机制.方法 建立坐骨神经慢性缩窄性损伤(CCI)大鼠模型,体外培养原代背根神经节(DRG)细胞并完成siRNA的转染,CCI大鼠早期(CCI术后1～4 d)或晚期(CCI术后7～10 d)每天给予阴性对照或siTRPM2处理.RT-PCR检测CCI大鼠DRG和脊髓中T...     

Effects of catastrophizing on pain perception and pain modulation

The multidimensional experience of pain is thought to be partially influenced by the pain modulation system as well as by individual psychological components. Recent studies demonstrated possible common neural network mediating both domains. The present study examined the relationships between pain perception, pain modulation, and catastrophizing in healthy subjects. Forty-eight participants (29 females and 19 males) completed the pain catastrophizing scale (PCS) and underwent psychophysical tests in order to evaluate the modulation of pain, using the diffuse noxious inhibitory control (DNIC) paradigm. Contact heat pain (47.0°C applied for 1 min), which was used as the “test” stimulation, was applied before and after a physical effort that induces pain (repeated squeezing of a hand grip device), which was used as a “conditioning” stimulus. Numeric pain scale intensities (NPS, 0–10) were evaluated four times during each of two separate consecutive runs of heat stimulation. Results showed a significant positive correlation of PCS with heat pain (r = 0.48, p < 0.0005) and with muscle pain (r = 0.31, p = 0.03). In addition, significant negative correlations were found between PCS and DNIC effect (r = −0.34, p = 0.02). Moreover, once catastrophizing was entered into the regression analysis, the previously significant effect of gender was no longer found. In conclusion, individuals with high catastrophizing levels demonstrated higher pain intensities and lower effects of DNIC indicating that catastrophizing might have a significant impact on pain perception via an association with pain modulation.     

Altered cardiovascular/pain regulatory relationships in chronic pain

In healthy individuals, there is an inverse relationship between resting blood pressure (BP) and pain sensitivity. This study examined possible dysregulation of this adaptive relation in chronic pain patients, and tested whether the extent of this dysregulation is a function of pain duration, Continuous resting BP_s were assessed for 5 min after a 5-min rest period in 121 chronic benign pain patients. Unlike the inverse relationship observed previously in normals, mean resting diastolic BP_s during the assessment period were correlated positively with ratings of pain severity. A Pain Duration x Systolic BP i nteraction emerged (p > .05) such that the magnitude of the BP-pain relation was greatest in patients with the longest duration of pain, r(38) = .50, p > .001. A hypothesized progressive alteration in endogenous pain regulatory systems in chronic pain patients was supported. A possible role of endogenous opioid dysfunction in accounting for these alterations is discussed. This investigation was supported by Grant BRSG S07 RR05366-28. awarded to John W. Burns by the Biomedical Research Grant Program, Division of Research Resources, National Institutes of Health. We thank Kathleen Kiselica and Ronald Pawl for allowing access to their patients at the Center for Rehabilitation at Lake Forest Hospital in Lake Forest, IL.     

Dynamics of pain: fractal dimension of temporal variability of spontaneous pain differentiates between pain States

Spontaneous pain is a common complaint in chronic pain conditions. However, its properties have not been explored. Here we study temporal properties of spontaneous pain. We examine time variability of fluctuations of spontaneous pain in patients suffering from chronic back pain and chronic postherpetic neuropathy and contrast properties of these ratings to normal subjects' ratings of either acute thermal painful stimuli or of imagined back pain. Subjects are instructed to continuously rate their subjective assessment of the intensity of pain over a 6- to 12-min period. We observe that the fluctuations of spontaneous pain do not possess stable mean or variance, implying that these time series can be better characterized by fractal analysis. To this end, we apply time and frequency domain techniques to characterize variability of pain ratings with a single parameter: fractal dimension, D. We demonstrate that the majority of ratings of spontaneous pain by the patients have fractal properties, namely they show a power law relationship between variability and time-scale length; D is distinct between types of chronic pain, and from ratings of thermal stimulation or of imagined pain; and there is a correspondence between D for pain ratings and D for brain activity, in chronic back pain patients using fMRI. These results show that measures of variability of spontaneous pain differentiate between chronic pain conditions, and thus may have mechanistic and clinical utility.     

Associations among pain,pain attitudes,and pain behaviors in patients with metastatic breast cancer

Metastatic breast cancer (MBC) patients often experience pain which can trigger pain behaviors, such as distorted ambulation. Psychological variables, such as individuals’ attitudes toward pain, play a role in pain intervention. In this study, we used the cognitive-behavioral model of pain to examine the influence of patients’ attitudes toward pain (as measured by the survey of pain attitudes or SOPA) on their pain behaviors (as measured by the pain behaviors checklist). Two hundred-one MBC patients completed surveys at treatment initiation and again 3 and 6 months later. Linear Mixed Model with repeated measures analyses showed that SOPA-solicitude, SOPA-emotions, SOPA-cure, SOPA-disability, and SOPA-medication pain attitudes were consistently significantly associated with pain behaviors at each assessment time point. Additionally, the belief that a medical cure for pain exists buffered the positive association between pain severity and pain behaviors. Our findings support and extend the cognitive-behavioral model of pain and suggest that it may be useful to target pain attitudes in pain management interventions for MBC patients.     

Intra-osseous local anaesthetic patellar pain catheter suppresses osteoarthritic patello-femoral pain

Background

The source of pain in patellofemoral osteoarthritis is not fully understood. The purpose of this study was to identify the origin of pain using intraosseous pain catheters and to show early results with an osteotomy that is potentially denervating and hydrostatic pressure-relieving.

Acute and chronic pain: pain dimensions and psychological status

One hundred and ten outpatients with either acute or chronic low-back pain completed the McGill Pain Questionnaire, Beck Depression Inventory, State-Trait Anxiety Inventory, and Life Experiences Survey. Acutes and chronics did not differ on dimensions of pain, but significant correlations between pain dimensions and depression and state anxiety were found for chronics. Both groups showed elevated state anxiety; chronics also evidenced mild depression. Combined scores on depression, anxiety, and negative life change predicted sensory and affective pain for the pooled sample. These results confirm the role of psychological variables in the experience of clinical pain and underscore the highly affective nature of chronic pain.     

TRPs and pain

Nociception is the process of transmission of painful signals by nociceptors in the primary afferent nerve fibers, which specifically respond to noxious stimuli. These noxious stimuli are detected by nociceptors and converted into electrical signals, which are then transmitted to the spinal cord, thalamus, and the cerebral cortex, where pain is finally sensed. Transient receptor potential (TRP) ion channels have emerged as a family of evolutionarily conserved ligand-gated ion channels that function as molecular detectors of physical stimuli. Several member of this family, at least six channels from three TRP family subtypes (TRPV1–4, TRPM8, and TRPA1), are expressed in nociceptors, where they act as transducers for signals from thermal, chemical, and mechanical stimuli and play crucial roles in the generation and development of pathological pain perception. This review focuses on the increasing evidence of TRP channel involvement and contribution in nociceptive pain and the pain hypersensitivity associated with peripheral inflammation or neuropathy, and on the renewed interest in targeting TRP channels for pain relief.