Does motor cortex engagement during movement preparation differentially inhibit nociceptive processing in patients with chronic whiplash associated disorders, chronic fatigue syndrome and healthy controls? An experimental study

Background: Patients with chronic fatigue syndrome (CFS) and chronic whiplash associated disorders (cWAD) present a reduced ability to activate central descending nociceptive inhibition after exercise, compared to measurements before exercise. It was hypothesised that a dysfunctional motor-induced inhibition of nociception partly explains this dysfunctional exercise-induced hypoalgesia. This study investigates if engagement of the motor system during movement preparation inhibits nociception-evoked brain responses in these patients as compared to healthy controls (HC). Methods: The experiment used laser-evoked potentials (LEPs) during three conditions (no task, mental task, movement preparation) while recording brain activity with a 32-channel electroencephalogram in 21 patients with cWAD, 20 patients with CFS and 18 HC. Two-factor mixed design Analysis of variance were used to evaluate differences in LEP amplitudes and latencies. Results: No differences in N1, N2, N2P2, and P2 LEP amplitudes were found between the HC, CFS, and cWAD groups. After nociceptive stimulation, N1, N2 (only at hand location), N2P2, and P2 LEP amplitudes significantly decreased during movement preparation compared to no task (within group differences). Conclusion: Movement preparation induces a similar attenuation of LEPs in patients with CFS, patients with cWAD and HC. These findings do not support reduced motor-induced nociceptive inhibition in these patients

Graph measure based connectivity in chronic pain patients : a systematic review

Background: Chronic pain affects 20 to 30% of the adult population worldwide and is consequently the leading cause of disability. Current developments in brain imaging technology are increasing the understanding of the pathophysiology of (chronic) pain and enabling the possibility to objectify pain. As a result, our view of the brain has evolved from a static organ to a dynamic organ that constitutes an adaptable network of linked regions. Graph theory has emerged as a framework to analyze such networks and can be applied to investigate a range of topological properties of both the functional and structural brain network or connectome, thus providing meaningful information about the organization of human brain networks. Objectives: The aim of this systematic review is to determine whether connectivity differs between chronic pain patients and healthy controls by integrating previous studies that performed graph analyses on structural or functional connectivity. A secondary aim was to determine whether graph measures correlate to clinical outcomes. Study design: Systematic review. Methods: Relevant articles were searched for in PubMed and Web of Science. These were screened against certain criteria and assessed for quality. Results: On a global level the transitivity, betweenness centrality, intramodular degree, and rich club organization differed between chronic pain patients and healthy controls, but the path length, modularity, degree, and (Hub Disruption Index [HDI] of) participation coefficient did not differ between both groups, along with the small-worldness. Conflicting evidence still remains about a number of global graph measures, namely the global efficiency, local efficiency, clustering coefficient, and HDI of degree. Significant correlations were found between several nodal and global graph measures on one hand, and clinical outcomes related to pain, disability, and motor control on the other hand. Limitations: No clear conclusions could be made about the majority of the nodal measures, as they were often based on single studies. Conclusion: Differences between chronic pain patients and healthy controls were mostly observed for the global graph measures. Future research is still needed to validate the obtained findings and to expand this knowledge to the chronic pain populations that were not discussed in the included papers

Reliability and discriminative validity of a screening tool for the assessment of neuromuscular control and movement control in patients with neck pain and healthy individuals

Background:To evaluate the reliability and discriminative validity of a proposed adapted tool for the assessment of movement control in patients with and without neck pain. Method:A cross-sectional study at a University hospital center involving 25 pain-free healthy controls and 25 patients suffering from neck pain. Participants were assessed by two raters for inter-rater reliability and 1 week afterwards by a same rater for intra-rater reliability. The assessment involved a test for the axioscapular (adapted scapular holding test; SHT) and craniocervical (adapted craniocervical flexion test; CCFT) region for which intra-class correlation coefficients (ICCs) were computed to define the reliability. Discriminative validity to distinguish patients from controls was assessed by cross-validated computation of sensitivity, specificity, positive and negative likelihood ratios, overall accuracy, and area under the curve. Results:The proposed tool was able to reliably assess sensorimotor impairment in participants at the craniocervical region (ICCintra= [0.52-0.82]; ICCinter= [0.60-0.85]), left axioscapular region (ICCintra= [0.43-0.77]; ICCinter= 0.71-0.90), and right axioscapular region (ICCintra= [0.47-0.79]; ICCinter= [0.42-0.77]). Furthermore, the tool yielded a sensitivity of 0.86, a specificity of 0.57, and accuracy of 0.71 (based on cross-validation). Conclusion:The proposed tool is able to reliably evaluate patients based on their sensorimotor performance in the craniocervical and axioscapular region

Acupuncture versus sham-acupuncture : a meta-analysis on evidence for non-immediate effects of acupuncture in musculoskeletal disorders

Objective: Acupuncture is a common modality in the therapy of musculoskeletal disorders. The evidence for acupuncture has been examined frequently, but a clear synthesis of previous research is currently lacking. This meta-analysis aimed to summarize the evidence for nonimmediate effects of acupuncture on pain, functionality, and quality of life in patients with musculoskeletal disorders, when compared with sham acupuncture. Methods: Search results from PubMed and Web of Science were brought together. All screening procedures were executed twice by 2 independent researchers. The pooled standardized mean difference (SMD) with its confidence interval (CI) was estimated at follow-up at 6 months. Results: For pain, the SMD equalled respectively −0.47 (CI −0.76 to −0.19), −0.27 (CI −0.44 to −0.11), −0.32 (CI −0.51 to −0.13) and −0.12 (CI −0.36 to 0.11) for 6 months follow-up. For functionality, the pooled SMD equalled −0.43 (CI −0.76 to −0.10), −0.41 (CI −0.76 to −0.05), 0.07 (CI −0.22 to 0.36), and −0.13 (−0.46 to 0.19). In the area of QOL, pooled SMD of respectively 0.20 (CI 0.04 to 0.35), 0.19 (CI −0.01 to 0.39), 0.02 (CI −0.09 to 0.14) and −0.04 (CI −0.25 to 0.16) were obtained. Discussion: A significant difference in therapy effect, favoring acupuncture, was found for pain at <1 month, 1 to 3 months, and 3 to 6 months, as well as on quality of life at <1 month, and on functionality at <1 month and 1 to 3 months

Are pain beliefs, cognitions, and behaviors influenced by race, ethnicity, and culture in patients with chronic musculoskeletal pain : a systematic review

Background: Chronic pain has been considered as a biopsychosocial condition in which cognitive and emotional factors as well as biological factors significantly affect perception of pain. Race, ethnicity and culture have a crucial impact on illness beliefs, health care preferences, help-seeking behaviors, and acceptance of medical interventions. Objectives: The aim of the present study was to systematically review the current evidence regarding the racial, ethnic and cultural alterations and differences in pain beliefs, cognitions, and behaviors in patients with chronic musculoskeletal pain (MSKP). Study Design: Systematic review. Methods: This systematic review was conducted and reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-analyses guidelines (PRISMA). PubMed and Web of Science were searched. A first screening was conducted based on title and abstract of the articles. In the second screening, full-texts of the remaining articles were evaluated for the fulfilment of the inclusion criteria. The risk of bias was assessed with the modified Newcastle-Ottawa Scale. Results: A total of 11 articles were included. The methodological quality of the included studies ranged from low to moderate. There is moderate evidence that African-Americans use more praying, hoping, and emotion-focused coping strategies than Caucasians. There is also preliminary evidence regarding the differences in some coping strategies such as distraction, catastrophizing, and problem-focused solving between African-Americans and Caucasians. Preliminary evidence exists regarding the differences in pain coping strategies between the US and Portugal; the US and Singapore; and among 4 French-speaking countries. It is found that Spanish patients with fibromyalgia (FM) have more negative illness perceptions than Dutch patients. There is preliminary evidence that Caucasians have higher self-efficacy than African-Americans. There is also preliminary evidence that New Zealanders have more internal health expectancies than patients from the US. Preliminary evidence is demonstrated that Caucasians with rheumatoid arthritis (RA) have more positive control beliefs than African-Americans. Lastly, there is preliminary evidence that patients from the US believe that they are more disabled, while Singaporeans interpret the pain more by a traditional biomedical perspective. Limitations: Only 11 articles were included. The small number of articles, wide range of assessment methods, and substantial risk of bias in the included studies led the investigator to draw conclusions cautiously. Conclusion: Preliminary to moderate evidence shows the differences in coping strategies, illness perceptions, self-efficacy, fear avoidance beliefs, locus of control, and pain attitudes in different populations. Further prospective and longitudinal studies using standard definitions for race, ethnicity or culture and valid questionnaires for each population are warranted to explore the racial, ethnic and cultural discrepancies in pain beliefs, cognitions, and behaviours

Suffering from chronic tinnitus, chronic neck pain, or both : does it impact the presence of signs and symptoms of central sensitization?

Chronic subjective tinnitus is a prevalent symptom, which has many similarities with chronic pain. Central sensitization is considered as a possible underlying mechanism of both symptoms. Central sensitization has already been investigated in chronic pain populations but not in patients with chronic subjective tinnitus. Therefore, the main objective of this cross-sectional study was to compare signs and symptoms, indicative for central sensitization, in tinnitus patients with and without chronic idiopathic neck pain, patients with chronic idiopathic neck pain only, and healthy controls. Also, differences in psychological and lifestyle factors, possibly influencing the association between central sensitization and tinnitus, were examined as well as correlations between signs and symptoms of central sensitization, and tinnitus, pain, psychological and lifestyle factors. Differences in signs and symptoms of central sensitization were examined using the self-report Central Sensitization Inventory and QST protocol (local and distant mechanical and heat hyperalgesia, conditioned pain modulation). Tinnitus, pain, psychological and lifestyle factors were evaluated using self-report questionnaires. Symptoms of central sensitization and local mechanical hyperalgesia were significantly more present in both tinnitus groups, compared to healthy controls, but were most extensive in the group with chronic tinnitus+chronic idiopathic neck pain. Distant mechanical hyperalgesia, indicative for central sensitization, was only observed in the group with both chronic tinnitus+chronic idiopathic neck pain. This group also displayed a significantly higher psychological burden and poorer sleep than patients with chronic tinnitus only and healthy controls. Signs and symptoms of central sensitization were also shown to be associated with tinnitus impact, pain-related disability, psychological burden and sleep disturbances. This study shows preliminary evidence for the presence of central sensitization in patients with chronic tinnitus+chronic idiopathic neck pain. This could be explained by the higher perceived tinnitus impact, psychological burden and sleep problems in this group