Iris Coppieters

Central sensitization in fibromyalgia? A systematic review on structural and functional brain MRI

OBJECTIVES The aim of the present study was to systematically review the literature addressing pain-induced changes in the brain related to central sensitization in patients with fibromyalgia (FM) using specific functional (rs-fMRI and fMRI) and structural (voxel-based morphometry-VBM) brain MRI techniques. METHODS PubMed and Web of Science were searched for relevant literature using different key word combinations related to FM, brain MRI, and central sensitization. Full-text reports fulfilling the inclusion criteria were assessed on risk of bias and reviewed by two independent reviewers. RESULTS From the 61 articles that were identified, 22 met the inclusion criteria and achieved sufficient methodological quality. Overall, eight articles examined structural brain (VBM) changes in patients with FM, showing moderate evidence that central sensitization is correlated with gray matter volume decrease in specific brain regions (mainly anterior cingulate cortex and prefrontal cortex). However, global gray matter volume remains unchanged. A total of 13 articles evaluated brain activity (fMRI) in response to a nociceptive stimulus. Findings suggest a higher but similar pattern of activation of the pain matrix in FM patients compared to controls. There is also evidence of decreased functional connectivity in the descending pain-modulating system in FM patients. Overall, two articles examined intrinsic brain connectivity in FM patients with rs-fMRI. In conclusion, there is moderate evidence for a significant imbalance of the connectivity within the pain network during rest in patients with FM. CONCLUSIONS The included studies showed a moderate evidence for region-specific changes in gray matter volume, a decreased functional connectivity in the descending pain-modulating system, and an increased activity in the pain matrix related to central sensitization. More research is needed to evaluate the cause-effect relationship.

Effect of Ischemic Compression on Trigger Points in the Neck and Shoulder Muscles in Office Workers: A Cohort Study

OBJECTIVE The purpose of this study was to determine the short-term effect of ischemic compression (IC) for trigger points (TPs) on muscle strength, mobility, pain sensitivity, and disability in office workers and the effect on disability and general pain at 6-month follow-up. METHODS Nineteen office workers with mild neck and shoulder complaints received 8 sessions of IC in which deep pressure was given on the 4 most painful TPs identified during examination. Outcome measures were general neck and shoulder complaints on a Numeric Rating Scale, Neck Disability Index (NDI), neck mobility (inclinometer), muscle strength (dynamometer), and pain sensitivity (Numeric Rating Scale and algometry). Subjects were tested at baseline (precontrol), after a control period of no treatment of 4 weeks (postcontrol), and after a 4-week intervention training (posttreatment). At 6-month follow-up, pain and disability were inquired. RESULTS The results showed a statistically significant decrease in general neck/shoulder pain at posttreatment (P = .001) and at 6-month follow-up (P = .003) compared with precontrol and postcontrol. There was no significant main effect for NDI scores. Pressure pain threshold increased at posttreatment in all 4 treated TPs (P < .001). There was a significant increase in mobility and strength from precontrol/postcontrol to posttreatment (P < .05). CONCLUSION This study has demonstrated that a 4-week treatment of TPs for IC resulted in a significant improvement in general neck and shoulder complaints, pressure pain sensitivity, mobility, and muscle strength in the short term in a small sample of office workers with mildly severe chronic pain. At 6-month follow-up, there was a further decrease in general pain, but no change in NDI scores.

Does muscle morphology change in chronic neck pain patients? – A systematic review

BACKGROUND Neck pain is a common disabling worldwide health problem with a high socio-economic burden. Changes underlying the transition to, or the maintenance of a chronic state are still barely understood. Increasing evidence suggests that morphological muscle changes, including changes in cross-sectional area (CSA) or fatty infiltration, play a role in chronic neck pain. However, a structured overview of the current evidence of morphological changes is lacking. OBJECTIVE To systematically review the morphological muscle changes in patients with chronic neck pain, including those with whiplash-associated disorders (WAD) and chronic idiopathic neck pain. STUDY DESIGN & METHODS A systematic review using the PRISMA-guidelines. RESULTS Fourteen of 395 papers were included after extensive screening. Most studies were of moderate methodological quality. A higher CSA was found in all flexor muscles in both patients with WAD and patients with chronic idiopathic neck pain, except for the deeper flexor muscles in patients with chronic idiopathic neck pain. The cervical extensor muscles show an increased CSA at the highest cervical segments in patients with WAD, while most studies in patients with chronic idiopathic neck pain report a decreased CSA in all extensor muscles. Fatty infiltration, which could be accountable for an increased CSA, of both cervical extensors and flexors seems to occur only in patients with WAD. CONCLUSION Some evidence is available for changes in muscle morphology, however more high quality prospective and cross-sectional research is needed to confirm these changes and to identify potential underlying causes that need yet to be discovered.

Brain changes associated with cognitive and emotional factors in chronic pain: A systematic review

An emerging technique in chronic pain research is MRI, which has led to the understanding that chronic pain patients display brain structure and function alterations. Many of these altered brain regions and networks are not just involved in pain processing, but also in other sensory and particularly cognitive tasks. Therefore, the next step is to investigate the relation between brain alterations and pain related cognitive and emotional factors. This review aims at providing an overview of the existing literature on this subject. Pubmed, Web of Science and Embase were searched for original research reports. Twenty eight eligible papers were included, with information on the association of brain alterations with pain catastrophizing, fear‐avoidance, anxiety and depressive symptoms. Methodological quality of eligible papers was checked by two independent researchers. Evidence on the direction of these associations is inconclusive. Pain catastrophizing is related to brain areas involved in pain processing, attention to pain, emotion and motor activity, and to reduced top‐down pain inhibition. In contrast to pain catastrophizing, evidence on anxiety and depressive symptoms shows no clear association with brain characteristics. However, all included cognitive or emotional factors showed significant associations with resting state fMRI data, providing that even at rest the brain reserves a certain activity for these pain‐related factors. Brain changes associated with illness perceptions, pain attention, attitudes and beliefs seem to receive less attention in literature.

Relations Between Brain Alterations and Clinical Pain Measures in Chronic Musculoskeletal Pain: A Systematic Review

UNLABELLED Compelling evidence has shown chronic widespread and exaggerated pain experience in chronic musculoskeletal pain (MSKP) conditions. In addition, neuroimaging research has revealed morphological and functional brain alterations in these patients. It is hypothesized that brain alterations play a role in the persistent pain complaints of patients with chronic MSKP. Nevertheless, lack of overview exists regarding the relations between brain alterations and clinical measures of pain. The present systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, to investigate the relations between structural or functional brain alterations, using magnetic resonance imaging scans, and clinical pain measures in patients with chronic MSKP. PubMed, Web of Science, Cinahl, and Cochrane databases were searched. First, the obtained articles were screened according to title and abstract. Second, the screening was on the basis of full-text. Risk of bias in included studies was investigated according to the modified Newcastle-Ottawa Scale. Twenty studies met the inclusion criteria. Moderate evidence shows that higher pain intensity and pressure pain sensitivity are related to decreased regional gray matter (GM) volume in brain regions encompassing the cingulate cortex, the insula, and the superior frontal and temporal gyrus. Further, some evidence exists that longer disease duration in fibromyalgia is correlated with decreased total GM volume. Yet, inconclusive evidence exists regarding the association of longer disease duration with decreased or increased regional GM volume in other chronic MSKP conditions. Inconclusive evidence was found regarding the direction of the relation of pain intensity and pressure pain sensitivity with microstructural white matter and functional connectivity alterations. In conclusion, preliminary to moderate evidence demonstrates relations between clinical pain measures, and structural and functional connectivity alterations within brain regions involved in somatosensory, affective, and cognitive processing of pain in chronic MSKP. Nevertheless, inconclusive results exist regarding the direction of these relations. Further research is warranted to unravel whether these brain alterations are positively or negatively correlated to clinical pain measures. PERSPECTIVE Structural and functional brain alterations within regions involved in somatosensory, affective, and cognitive pain processing play a crucial role in the persistent pain of chronic MSKP patients. Accordingly, these brain alterations have to be taken into account when assessing and treating patients with chronic MSKP.

Interrelationships between pain processing, cortisol and cognitive performance in chronic whiplash-associated disorders

The present study aims at studying interactions between cognitive performance and conditioned pain modulation in patients with chronic whiplash-associated disorders (WAD) and healthy controls. In addition, the relation between cortisol concentrations and cognitive performance will be studied in patients with chronic WAD. Thirty-one subjects, 16 healthy subjects and 15 patients with chronic WAD, were enrolled and subjected to several self-report and physiological measures. Self-report measures encompassed pain rating during a procedure evaluating conditioned pain modulation. Afterward, they were subjected to physiological measures, which are cognitive tests (Stroop task, psychomotor vigilance task, and operation span task) preceded and followed by salivary cortisol concentration measurements. Chronic WAD patients performed worse in recall at the operation span task and presented longer reaction times at the psychomotor vigilance task and at the Stroop task when sleep-related words were shown (p < .05). Conditioned pain modulation and cortisol concentrations were not significantly different between patients and controls (p > .05). Only in the healthy subjects, conditioned pain modulation and baseline cortisol concentrations were correlated to cognitive performance (p < .05). This is the first study addressing the relation between pain inhibition and cognitive performance in chronic WAD. We did not reveal impaired pain inhibition but did reveal cognitive dysfunctions in patients with chronic WAD. In healthy subjects, pain inhibition was related to cognitive performance but not in the patient group.

Differences Between Women With Traumatic and Idiopathic Chronic Neck Pain and Women Without Neck Pain: Interrelationships Among Disability, Cognitive Deficits, and Central Sensitization

Background To date, a clear differentiation of disability, cognitive deficits, and central sensitization between chronic neck pain of a traumatic nature and that of a nontraumatic nature is lacking. Objective This study aimed to examine differences in disability, cognitive deficits, and central sensitization between women with traumatic and idiopathic (nontraumatic) chronic neck pain and women who were healthy. In addition, interrelationships among these variables were investigated. Design This was a case-control study. Methods Ninety-five women (28 women who were healthy [controls], 35 women with chronic idiopathic neck pain [CINP], and 32 women with chronic whiplash-associated disorders [CWAD] [traumatic]) were enrolled in the study. First, all participants completed standardized questionnaires to investigate pain-related disability and health-related quality of life. Next, cognitive performance was assessed. Finally, pressure pain thresholds and conditioned pain modulation were examined to investigate central sensitization. Results Pain-related disability, reduced health-related quality of life, and cognitive deficits were present in participants with CWAD and, to a significantly lesser extent, in participants with CINP. Local hyperalgesia was demonstrated in participants with CWAD and CINP but not in women who were healthy. However, distant hyperalgesia and decreased conditioned pain modulation efficacy were shown only in participants with CWAD; this result is indicative of the presence of central sensitization. Moderate to strong Spearman correlations (ρ=.456-.701) among disability, cognitive deficits, and hyperalgesia (local and distant) were observed in participants with CWAD. In participants with CINP, only local hyperalgesia and subjective cognitive deficits were moderately (ρ=.463) correlated. Limitations No conclusions about the causality of the observed correlations can be drawn. Conclusions This innovative research revealed important differences between women with CWAD and women with CINP and thus provided evidence of the clinical importance of distinguishing the assessment and rehabilitation approaches for both pain conditions.

Convergent validity of the Dutch Central Sensitization Inventory : associations with psychophysical pain measures, quality of life, disability, and pain cognitions in patients with chronic spinal pain

Symptoms of central sensitization (CS) have been described in patients with chronic spinal pain (CSP). Although a gold standard to diagnose CS is lacking, psychophysical pain measures are often used. The Central Sensitization Inventory (CSI) is proposed as an alternative method and indirect tool for the evaluation of CS symptomatology. The aim of the current study was to evaluate the convergent validity of the CSI by investigating the association with psychophysical pain measures and self‐reported measures of current pain intensity, quality of life, disability, and catastrophizing in CSP patients.

Comparing Trigger Point Dry Needling and Manual Pressure Technique for the Management of Myofascial Neck/Shoulder Pain: A Randomized Clinical Trial

Objective The aim of this study was to investigate short‐term and long‐term treatment effects of dry needling (DN) and manual pressure (MP) technique with the primary goal of determining if DN has better effects on disability, pain, and muscle characteristics in treating myofascial neck/shoulder pain in women. Methods In this randomized clinical trial, 42 female office workers with myofascial neck/shoulder pain were randomly allocated to either a DN or MP group and received 4 treatments. They were evaluated with the Neck Disability Index, general numeric rating scale, pressure pain threshold, and muscle characteristics before and after treatment. For each outcome parameter, a linear mixed‐model analysis was applied to reveal group‐by‐time interaction effects or main effects for the factor “time.” Results No significant differences were found between DN and MP. In both groups, significant improvement in the Neck Disability Index was observed after 4 treatments and 3 months (P < .001); the general numerical rating scale also significantly decreased after 3 months. After the 4‐week treatment program, there was a significant improvement in pain pressure threshold, muscle elasticity, and stiffness. Conclusion Both treatment techniques lead to short‐term and long‐term treatment effects. Dry needling was found to be no more effective than MP in the treatment of myofascial neck/shoulder pain.

Chronic Whiplash-Associated Disorders: Reorganization of the Brain?

A wide range of human brain imaging techniques has provided the opportunity to explore in vivo the neurophysiological processes of the brain (Schmidt-Wilcke, 2015, Baliki and Apkarian, 2015). This neuroimaging research has shown neuronal plasticity, which refers to the possibility of the central nervous system including the brain to adapt but also to maladapt structure, function and organization (Davis and Moayedi, 2013). Subsequently, the role of maladaptive brain alterations in the persistent complaints of various chronic pain conditions (e.g., fibromyalgia, chronic low back pain, temporomandibular disorders) has been gradually elucidated (Schmidt-Wilcke, 2015, Baliki and Apkarian, 2015, Davis and Moayedi, 2013). Emerging evidence indicates that different chronic pain conditions are each associated with distinct brain reorganization, which is referred to as the neural pain signature (Kucyi and Davis, 2015). In addition, changes in resting state interactions between brain networks implicated in default states, salience, attention, and reward have been demonstrated in chronic pain patients (Baliki and Apkarian, 2015, Kucyi and Davis, 2015). The results of longitudinal imaging studies suggest that brain alterations are involved in the transition to chronic pain (Hashmi et al., 2013). In particular, the corticolimbic circuitry, which is a key system for reward and motivated behavior, has been reported as a mediator for this transition (Vachon-Presseau et al., 2016).