Do Patients with Chronic Spinal Pain and Comorbid Insomnia Have More Features of Central Sensitization? A Case-Control Study.

BACKGROUND: Chronic spinal pain (CSP) is a major public health problem worldwide, frequently related to sleep problems. Central sensitization (CS) may worsen the clinical picture of CSP patients with insomnia. The aim of this study was to compare self-reported and objectively measured clinical outcomes between insomniac CSP patients with comorbid insomnia with and without symptoms of CS. METHODS: A case-control study on baseline self-reported sleep, functioning, and psychological distress through online questionnaires. Objective sleep and physical activity parameters and pressure pain thresholds (PPTs) were assessed through polysomnography, actigraphy, and digital algometry, respectively. Independent sample t-test and Mann-Whitney U tests were used to examine possible differences in the outcome measures between the groups. RESULTS: Data from 123 participants were included and revealed no statistically significant group for objective sleep and physical activity parameters. The CS group, however, presented with worse self-reported sleep (quality sleep, insomnia severity, and dysfunctional beliefs about sleep), increased mental and physical fatigue, and higher psychological distress (anxiety and depressive symptoms), and reported lower PPTs. CONCLUSIONS: symptoms of CS may influence perceived sleep and affect functional health and well-being perception but do not seem to affect objective sleep and physical activity.

Relationship, differences, and agreement between objective and subjective sleep measures in chronic spinal pain patients with comorbid insomnia: a cross-sectional study.

ABSTRACT: Sleep disturbances are one of the most frequent reported problems in people with nonspecific chronic spinal pain (nCSP) and presents an additional treatment challenge. Interventions targeting sleep problems are mainly based on subjective sleep complaints and do not take objective sleep into consideration. The aim of this cross-sectional study was to evaluate the relationship and conformity between self-reported and objectively measured sleep parameters (ie, questionnaire vs polysomnography and actigraphy). The baseline data of 123 people with nCSP and comorbid insomnia who are participating in a randomized controlled trial were analyzed. Pearson correlations were used to investigate the relationship between objective and subjective sleep parameters. Differences between objective and subjective sleep parameters were analyzed using t tests. Bland-Altman analyses were performed to quantify and visualize agreement between the different measurement methods. Except for the significant moderate correlation between perceived time in bed (TIB) and actigraphic TIB ( r = 0.667, P < 0.001), all other associations between subjective and objective measures were rather weak ( r < 0.400). Participants underestimated their total sleep time (TST) (mean difference [MD] = -52.37 [-67.94, -36.81], P < 0.001) and overestimated sleep onset latency (SOL) (MD = 13.76 [8.33, 19.20], P < 0.001) in general. The results of this study suggest a discrepancy (differences and lack of agreement) between subjective and objective sleep parameters in people with nCSP and comorbid insomnia. No or weak associations were found between self-reported sleep and objectively measured sleep. Findings suggest that people with nCSP and comorbid insomnia tend to underestimate TST and overestimate SOL. Future studies are necessary to confirm our results.

Predictors for physical activity and its change after active physical therapy in people with spinal pain and insomnia: Secondary analysis of a randomized controlled trial.

BACKGROUND: In healthy people and people with nonspecific chronic spinal pain (nCSP) and/or insomnia, participation in physical activity on a regular basis has several physical and psychological health benefits. However, people with chronic conditions often tend to reduce physical activity participation which can lead to deconditioning over time. Currently, there are no known predictors for an (in)active lifestyle (before and after physical therapy treatment) in people with chronic spinal pain and comorbid insomnia. OBJECTIVE: To examine predictors of pre-treatment moderate-to-vigorous physical activity (MVPA) and to examine determinants for a change in MVPA in response to 14-weeks of active physical therapy treatment in people with nonspecific chronic spinal pain (nCSP) and comorbid insomnia. METHODS: Baseline data and post-treatment data were analyzed for 66 participants. A linear multiple regression analysis was conducted to examine which factors predict MVPA at baseline. Linear mixed-effects modeling was used to identify determinants for change in MVPA in response to an active physical therapy treatment. RESULTS: Physical fatigue (b = -0.9; 95%CI: -1.59, -0.15), less limitations in functioning as a result of emotional problems (b = 0.1; 95%CI: 0.03, 0.10), mental fatigue (b = -1.0; 95%CI: -1.67, -0.43), lower general sleep quality (b= 0.7; 95%CI: 0.22, 1.17), and body mass index (b = -0.5; 95%CI: -0.93, -0.16) were significant predictors of baseline MVPA. The regression model explained 33.3% of the total variance in baseline MVPA. The change of MVPA in response to the treatment ranged from a decrease of 17.5 to an increase of 16.6 hours per week. No determinants for change in MVPA after treatment could be identified. CONCLUSION: People with nCSP and comorbid insomnia are more likely to engage in MVPA if they report, at baseline, lower sleep quality, fewer limitations in functioning resulting from emotional problems, lower body mass index, as well as less physical and mental fatigue.

Combining Cognitive Behavioral Therapy for Insomnia and Chronic Spinal Pain Within Physical Therapy: A Practical Guide for the Implementation of an Integrated Approach.

Most people who have nonspecific chronic spinal pain (nCSP) report comorbid insomnia. However, in current treatment strategies for nCSP, insomnia is usually not addressed. Considering the bidirectional interaction between pain and sleep and its underlying psychophysiological mechanisms, insomnia may increase the risk of developing adverse physical and psychological health outcomes and should thus no longer be left untreated. As suggested by previous pilot studies, adding cognitive behavioral therapy for insomnia to the contemporary evidence-based biopsychosocial physical therapy approach may also improve pain outcomes in nCSP. This manuscript aims to provide practical guidelines on hybrid physical therapy, including the combination of the following components: (1) pain neuroscience education (eg, to reconceptualize pain) and cognition-targeted exercise therapy (eg, graded exposure to functional daily life movements), and (2) cognitive behavioral therapy for insomnia (sleep psychoeducation, behavioral and cognitive therapy, correction of sleep hygiene, and relaxation therapy) can be deployed for the management of patients who have chronic spinal pain. Impact. Due to the major impact sleep disturbances have on pain and disability, insomnia as a comorbidity should no longer be ignored when treating patients with chronic spinal pain.

The Association between Sleep and Chronic Spinal Pain: A Systematic Review from the Last Decade.

Chronic spinal pain, including both neck and low back pain, is a common disabling disorder in which sleep problems are frequently reported as a comorbidity. The complex processes of both sleep and chronic pain seem to have overlapping mechanisms, which may explain their often established bidirectional relationship. This systematic review aims to investigate the assumed association between sleep and chronic spinal pain by providing an overview of the literature from the last decade. Eligible studies were obtained by searching four databases (PubMed, Embase, Web of Science, and PsycARTICLES). Articles were found relevant if they included a human adult population and investigated the possible association between sleep parameters and chronic spinal pain. Only studies published after January 2009 were included, as this review aimed to provide an update of a previous literature overview on this topic. The quality of the studies was assessed by risk of bias and level of evidence. A total of twenty-seven studies (6 cohort, 5 case-control, and 16 cross-sectional studies) were included in this systematic review. The methodological quality of these studies was low to moderate. The majority of studies reported weak to moderate evidence for an association between sleep parameters and chronic spinal pain, with more severe pain accompanied by more disturbed sleep. Addressing frequently reported sleep problems in chronic spinal pain patients therefore appears to be a necessary complement to pain management to achieve optimal treatment outcomes.

Differences in myoelectric activity of the lumbar muscles between recurrent and chronic low back pain: a cross-sectional study.

BACKGROUND: Altered lower back muscle activity is proposed as a contributing factor to the reoccurrence and chronicity of low back pain (LBP). This study compared lumbar muscle activity during trunk extension in patients with continuous chronic LBP (CLBP), non-continuous CLBP, recurrent LBP (RLBP) and healthy subjects. METHODS: In 75 subjects (16 continuous CLBP, 15 non-continuous CLBP, 23 RLBP, 21 healthy controls), surface electromyographic (EMG) activity of the lumbar erector spinae (ES), multifidus (MF), latissimus dorsi (LD) and gluteus maximus (GM) was recorded during the concentric, holding and eccentric phase of a modified Biering Sorenson exercise. RESULTS: Continuous CLBP patients showed higher EMG activity in the ES and MF muscles compared to healthy controls in the concentric (p = 0.011; p = 0.009 respectively) and the holding phase (p = 0.015; p = 0.013). Higher EMG activity was observed in continuous CLBP compared to RLBP in the ES and MF muscles in the holding phase (p = 0.035; p = 0.037), and in the MF in the concentric phase (p = 0.046), but not in the ES (p = 0.062). No differences in muscle activity were established in either the concentric, holding, and eccentric phase for the LD and GM muscles. No differences were found between non-continuous CLBP and the other groups. CONCLUSIONS: An enhanced muscle activity of the lumbar muscles during the concentric and holding phase was observed during trunk extension in patients with continuous CLBP compared to patients with RLBP and healthy subjects. No differences between groups are present in the GM and LD muscles during concentric and holding phases and for any muscle in the eccentric phase.

Associates of Insomnia in People with Chronic Spinal Pain: A Systematic Review and Meta-Analysis.

Insomnia is a major problem in the chronic spinal pain (CSP) population and has a negative impact on health and well-being. While insomnia is commonly reported, underlying mechanisms explaining the relation between sleep and pain are still not fully understood. Additionally, no reviews regarding the prevention of insomnia and/or associated factors in people with CSP are currently available. To gain a better understanding of the occurrence of insomnia and associated factors in this population, we conducted a systematic review of the literature exploring associates for insomnia in people with CSP in PubMed, Web of Science and Embase. Three independent reviewers extracted the data and performed the quality assessment. A meta-analysis was conducted for every potential associate presented in at least two studies. A total of 13 studies were found eligible, which together identified 25 different potential associates of insomnia in 24,817 people with CSP. Twelve studies had a cross-sectional design. Moderate-quality evidence showed a significantly higher rate for insomnia when one of the following factors was present: high pain intensity, anxiety and depression. Low-quality evidence showed increased odds for insomnia when one of the following factors was present: female sex, performing no professional activities and physical/musculoskeletal comorbidities. Higher healthcare use was also significantly related to the presence of insomnia. One study showed a strong association between high levels of pain catastrophizing and insomnia in people with chronic neck pain. Last, reduced odds for insomnia were found in physically active people with chronic low back pain compared to inactive people with chronic low back pain. This review provides an overview of the available literature regarding potential associates of insomnia in people with CSP. Several significant associates of insomnia were identified. These findings can be helpful to gain a better understanding of the characteristics and potential origin of insomnia in people witch CSP, to identify people with CSP who are (less) likely to have insomnia and to determine directions of future research in this area.

Differences in psychological factors, disability and fatigue according to the grade of chronification in non-specific low back pain patients: A cross-sectional study.

BACKGROUND: Differences in pain processing, muscle structure and function have been reported in patients with low back pain (LBP) with different grades of pain chronicity. OBJECTIVE: The present study aims to examine differences in psychological factors, disability and subjective fatigue between subgroups of LBP based on their chronification grade. METHODS: Twenty-one healthy controls (HC) and 54 LBP patients (categorized based on the grades of chronicity into recurrent LBP (RLBP), non-continuous chronic LBP (CLBP), or continuous (CLBP)) filled out a set of self-reporting questionnaires. RESULTS: The Hospital Anxiety and Depression Scale (HADS) and Multidimensional Pain Inventory (MPI) scores indicated that anxiety, pain severity, pain interference and affective distress were lower in HC and RLBP compared to non-continuous CLBP. Anxiety scores were higher in non-continuous CLBP compared to RLBP, continuous CLBP and HC. The Pain Catastrophizing Scale for Helplessness (PSCH) was higher in non-continuous CLBP compared to HC. The Survey of Pain Attitudes (SOPA) showed no differences in adaptive and maladaptive behaviors across the groups. The Pain Disability Index (PDI) measured a higher disability in both CLBP groups compared to HC. Moreover, the Rolland Morris Disability Questionnaire (RMDQ) showed higher levels of disability in continuous CLBP compared to non-continuous CLBP, RLBP and HC. The Checklist Individual Strength (CIS) revealed that patients with non-continuous CLBP were affected to a higher extent by severe fatigue compared to continuous CLBP, RLBP and HC (subjective fatigue, concentration and physical activity). For all tests, a significance level of 0.05 was used. CONCLUSIONS: RLBP patients are more disabled than HC, but have a tendency towards a general positive psychological state of mind. Non-continuous CLBP patients would most likely present a negative psychological mindset, become more disabled and have prolonged fatigue complaints. Finally, the continuous CLBP patients are characterized by more negative attitudes and believes on pain, enhanced disability and interference of pain in their daily lives.

The added value of cognitive behavioral therapy for insomnia to current best evidence physical therapy for chronic spinal pain: protocol of a randomized controlled clinical trial.

BACKGROUND: Insomnia is a highly prevalent and debilitating comorbidity that is often not addressed in therapy for chronic spinal pain (CSP). Given the close interaction between insomnia and CSP severity and related disability, targeting sleep problems during therapy could improve treatment outcomes in these patients. OBJECTIVE: Can cognitive behavioral therapy for insomnia (CBT-I) combined with the modern neuroscience approach (i.e. pain neuroscience education and cognition-targeted exercise therapy) reduce pain and improve sleep, physical activity and function in people with CSP and comorbid insomnia? METHODS: Participants: One-hundred-twenty participants with chronic spinal pain and comorbid insomnia Intervention: CBT-I combined with the modern neuroscience approach (experimental) compared to the modern neuroscience approach alone (control). Both interventions start with three sessions of pain neuroscience education, followed by six sessions of CBT-I and nine sessions of cognition-targeted exercise therapy in the experimental group, or 15 sessions of cognition-targeted exercise therapy in the control group. MEASUREMENTS: Primary outcome measure: self-reported pain severity (Brief Pain Inventory). SECONDARY OUTCOME MEASURES: pain sensitivity (pressure pain thresholds, and online questionnaires), sleep-related outcomes (home-based polysomnography and online questionnaires), physical activity (actigraphy), and function (online questionnaires). Online questionnaires will be completed at baseline, directly post-treatment, and at 3, 6 and 12 months post-treatment. Polysomnography, pressure pain thresholds and actigraphy will be carried out at baseline, post-treatment and at 12 months follow-up. DISCUSSION: Findings may provide (1) a novel therapeutic approach for people with CSP and comorbid insomnia to improve pain, sleep, physical activity and function, and (2) new treatment guidelines for professionals. TRIAL REGISTRATION: Clinicaltrials.gov NCT03482856 (https://clinicaltrials.gov/ct2/show/NCT03482856).

The association between back muscle characteristics and pressure pain sensitivity in low back pain patients.

BACKGROUND AND AIMS: Some low back pain (LBP) patients recover after every pain episode whereas others develop chronicity. Research indicates that the amount of atrophy and fat infiltration differs between patients with LBP. Also enhanced pain sensitivity is present only in a subgroup of LBP patients. The relationship between pain sensitivity and muscular deformations in LBP, is however unexplored. This study examined the association between pressure pain sensitivity and the structural characteristics of the lumbar muscles in three different groups of non-specific LBP patients. METHODS: This cross-sectional study examined the total cross-sectional area (CSA), fat CSA, muscle CSA and muscle fat index (MFI) of the lumbar multifidus (MF) and erector spinae (ES) at level L4 by magnetic resonance imaging in 54 patients with non-specific LBP (23 recurrent LBP, 15 non-continuous chronic LBP and 16 continuous chronic LBP). Pressure pain thresholds were measured at four locations (lower back, neck, hand and leg) by a manual pressure algometer and combined into one "pain sensitivity" variable. As a primary outcome measure, the association between pain sensitivity and muscle structure characteristics was investigated by multiple independent general linear regression models. Secondly, the influence of body mass index (BMI) and age on muscle characteristics was examined. RESULTS: A positive association was found between pain sensitivity and the total CSA of the MF (p=0.006) and ES (p=0.001), and the muscle CSA of the MF (p=0.003) and ES (p=0.001), irrespective of the LBP group. No association was found between pain sensitivity and fat CSA or MFI (p>0.01). Furthermore, a positive association was found between BMI and the fat CSA of the MF (p=0.004) and ES (p=0.006), and the MFI of the MF (p<0.01) and ES (p=0.003). Finally, a positive association was found between age with the fat CSA of the MF (p=0.008) but not with the fat CSA of the ES (p>0.01), nor the MFI of the MF (p>0.01) and ES (p>0.01). CONCLUSIONS: A higher pain sensitivity is associated with a smaller total and muscle CSA in the lumbar MF and ES, and vice versa, but results are independent from the LBP subgroup. On the other hand, the amount of fat infiltration in the lumbar muscles is not associated with pain sensitivity. Instead, a higher BMI is associated with more lumbar fat infiltration. Finally, older patients with LBP are associated with higher fat infiltration in the MF but not in the ES muscle. IMPLICATIONS: These results imply that reconditioning muscular tissues might possibly decrease the pain sensitivity of LBP patients. Vice versa, therapy focusing on enhancement of pain sensitivity might also positively influence the CSA and that way contribute to the recovery of LBP. Furthermore, the amount of lumbar muscle fat seems not susceptible to pain sensitivity or vice versa, but instead a decrease in BMI might decrease the fat infiltration in the lumbar muscles and therefore improve the muscle structure quality in LBP. These hypothesis apply for all non-specific LBP patients, despite the type of LBP.

Sleep Disturbances in Chronic Pain: Neurobiology, Assessment, and Treatment in Physical Therapist Practice.

Among people with chronic pain, insomnia is highly prevalent, closely related to the mechanism of central sensitization, characterized by low-grade neuroinflammation, and commonly associated with stress or anxiety; in addition, it often does not respond effectively to drug treatments. This review article applies the current understanding of insomnia to clinical practice, including assessment and conservative treatment of insomnia in people with chronic pain. Cognitive-behavioral therapy for insomnia can be efficacious for improvements in sleep initiation, sleep maintenance, perceived sleep quality, and pain interference with daily functioning in people with chronic pain. A recent systematic review concluded that with additional training, physical therapist-led cognitive-behavioral interventions are efficacious for low back pain, allowing their implementation within the field. Cognitive-behavioral therapy for insomnia, as provided to people with chronic pain, typically includes education, sleep restriction measures, stimulus control instructions, sleep hygiene, and cognitive therapy.

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.

OBJECTIVE: 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. METHODS: One hundred sixteen patients with nonspecific CSP were included in the present study. Patients completed the CSI, were subjected to pressure pain thresholds (PPTs) and a conditioned pain modulation (CPM) paradigm, and completed questionnaires for current pain intensity, quality of life, pain disability, and pain catastrophizing. RESULTS: Higher CSI scores were weakly correlated with lower PPTs (-0.276 ≤ r ≤ -0.237; all P ≤ 0.01) and not with CPM efficacy (r = 0.017; P = 0.858). Higher CSI scores were moderately correlated with higher current pain intensity (r = 0.320; P < 0.001), strongly correlated with lower physical (r = -0.617; P < 0.001) and emotional (r = -0.635; P < 0.001) quality of life, and moderately correlated with higher pain disability (r = 0.472; P < 0.001) and higher pain catastrophizing (r = 0.464; P < 0.001). CONCLUSION: The CSI was weakly associated with PPTs and not with CPM efficacy in CSP patients. Moderate to strong associations were found with current pain intensity, quality of life, disability, and catastrophizing. The current results illustrate that the CSI does not reflect a direct measure of CS, yet is a representation of general distress, possible originating from CS symptoms.

In the spine or in the brain? Recent advances in pain neuroscience applied in the intervention for low back pain.

Conservative, surgical and pharmacological strategies for chronic low back pain (CLBP) management offer at best modest effect sizes in reducing pain and related disability, indicating a need for improvement. Such improvement may be derived from applying contemporary pain neuroscience to the management of CLBP. Current interventions for people with CLBP are often based entirely on a "biomedical" or "psychological" model without consideration of information concerning underlying pain mechanisms and contemporary pain neuroscience. Here we update readers with our current understanding of pain in people with CLBP, showing that CLBP is not limited to spinal impairments, but is also characterised by brain changes, including functional connectivity reorganisation in several brain regions and increased activation in brain regions of the so-called 'pain matrix' (or 'pain connectome'). Indeed, in a subgroup of the CLBP population brain changes associated with the presence of central sensitisation are seen. Understanding the role of these brain changes in CLBP improves our understanding not only of pain symptoms, but also of prevalent CLBP associated comorbidities such as sleep disturbances and fear avoidance behaviour. Applying contemporary pain neuroscience to improve care for people with CLBP includes identifying relevant pain mechanisms to steer intervention, addressing sleep problems and optimising exercise and activity interventions. This approach includes cognitively preparing patients for exercise therapy using (therapeutic) pain neuroscience education, followed by cognition-targeted functional exercise therapy.

Lack of Gender and Age Differences in Pain Measurements Following Exercise in People with Chronic Whiplash-Associated Disorders.

BACKGROUND: Individuals with chronic whiplash associated disorders (WAD) present persistent pain in the absence of structural pathology. In these people, altered central pain processing and central sensitization are observed. The role of personal factors, such as gender and age, on pain processing mechanisms in chronic WAD, however, is still unclear. OBJECTIVES: This study investigated possible gender- and age-related differences in self-reported and experimental pain measurements in people with chronic WAD. Besides the exercise-induced response on pain measurements between gender and age subgroups was recorded. STUDY DESIGN: Case-control study. SETTING: University Hospital, Brussels. METHODS: Self-reported pain and experimental pain measurements (pressure pain thresholds [PPT], occlusion cuff pressure, temporal summation, and conditioned pain modulation) were performed in 52 individuals (26 chronic WAD patients and 26 healthy controls), before and after a submaximal cycle exercise. RESULTS: Lower PPTs and occlusion cuff pressures were shown in chronic WAD in comparison with healthy controls. No gender and age differences regarding PPTs, occlusion cuff pressures and conditioned pain modulation were found in chronic WAD. Within the chronic WAD group, men showed higher self-reported pain compared to women and younger adults showed enhanced generalized pain facilitation compared to older adults. In addition, chronic WAD patients are able to inhibit exercise-induced hyperalgesia, but no gender and age differences in pain response following exercise were found. LIMITATIONS: This study was sufficiently powered to detect differences between the chronic WAD and control group. However, a sufficient power was not reached when patients were divided in age and gender groups. Furthermore, only mechanical stimuli were included in the experimental pain measurements. Besides, psychosocial factors were not taken into account. CONCLUSION: Some alterations of altered pain processing are present in chronic WAD patients, however not in response to exercise. No gender and age differences in pain measurements were observed in people with chronic WAD.Key words: Neck pain, whiplash associated disorders, chronic pain, personal factors, age, gender, central sensitization, exercise induced hyperalgesia, pressure pain thresholds, self reported pain.

Lumbar muscle structure and function in chronic versus recurrent low back pain: a cross-sectional study.

BACKGROUND CONTEXT: Heterogeneity exists within the low back pain (LBP) population. Some patients recover after every pain episode, whereas others suffer daily from LBP complaints. Until now, studies rarely make a distinction between recurrent low back pain (RLBP) and chronic low back pain (CLBP), although both are characterized by a different clinical picture. Clinical experiences also indicate that heterogeneity exists within the CLBP population. Muscle degeneration, like atrophy, fat infiltration, alterations in muscle fiber type, and altered muscle activity, compromises proper biomechanics and motion of the spinal units in LBP patients. The amount of alterations in muscle structure and muscle function of the paraspinal muscles might be related to the recurrence or chronicity of LBP. PURPOSE: The aim of this experimental study is to evaluate differences in muscle structure (cross-sectional area and lean muscle fat index) and muscle activity of the multifidus (MF) and erector spinae (ES) during trunk extension, in patients with RLBP, non-continuous CLBP, and continuous CLBP. STUDY DESIGN AND SETTING: This cross-sectional study took place in the university hospital of Ghent, Belgium. Muscle structure characteristics and muscle activity were assessed by magnetic resonance imaging (MRI). PATIENT SAMPLE: Fifty-five adults with non-specific LBP (24 RLBP in remission, 15 non-continuous CLBP, 16 continuous CLBP) participated in this study. OUTCOME MEASURES: Total cross-sectional area, muscle cross-sectional area, fat cross-sectional area, lean muscle fat index, T2-rest and T2-shift were assessed. METHODS: A T1-weighted Dixon MRI scan was used to evaluate spinal muscle cross-sectional area and fat infiltration in the lumbar MF and ES. Muscle functional MRI was used to evaluate the muscle activity of the lumbar MF and ES during a lumbar extension exercise. Before and after the exercise, a pain assessment was performed. This study was supported by grants from the Special Research Fund of Ghent University (DEF12/AOP/022) without potential conflict of interest-associated biases in the text of the paper. RESULTS: Fat cross-sectional area and lean muscle fat index were significantly higher in MF and ES in continuous CLBP compared with non-continuous CLBP and RLBP (p<.05). No differencesbetween groups were found for total cross-sectional area and muscle cross-sectional area in MF or ES (p>.05). Also, no significant differences between groups for T2-rest were established. T2-shift, however, was significantly lower in MF and ES in RLBP compared with, respectively, non-continuous CLBP and continuous CLBP (p<.05). CONCLUSIONS: These results indicate a higher amount of fat infiltration in the lumbar muscles, in the absence of clear atrophy, in continuous CLBP compared with RLBP. A lower metabolic activity of the lumbar muscles was seen in RLBP replicating a relative lower intensity in contractions performed by the lumbar muscles in RLBP compared with non-continuous and continuous CLBP. In conclusion, RLBP differs from continuous CLBP for both muscle structure and muscle function, whereas non-continuous CLBP seems comparable with RLBP for lumbar muscle structure and with continuous CLBP for lumbar muscle function. These results underline the differences in muscle structure and muscle function between different LBP populations.

Differences in Pain Processing Between Patients with Chronic Low Back Pain, Recurrent Low Back Pain, and Fibromyalgia.

BACKGROUND: The impairment in musculoskeletal structures in patients with low back pain (LBP) is often disproportionate to their complaint. Therefore, the need arises for exploration of alternative mechanisms contributing to the origin and maintenance of non-specific LBP. The recent focus has been on central nervous system phenomena in LBP and the pathophysiological mechanisms underlying the various symptoms and characteristics of chronic pain. Knowledge concerning changes in pain processing in LBP remains ambiguous, partly due to the diversity in the LBP population. OBJECTIVE: The purpose of this study is to compare quantitative sensory assessment in different groups of LBP patients with regard to chronicity. Recurrent low back pain (RLBP), mild chronic low back pain (CLBP), and severe CLBP are compared on the one hand with healthy controls (HC), and on the other hand with fibromyalgia (FM) patients, in which abnormal pain processing has previously been reported. STUDY DESIGN: Cross-sectional study. SETTING: Department of Rehabilitation Sciences, Ghent University, Belgium. METHODS: Twenty-three RLBP, 15 mild CLBP, 16 severe CLBP, 26 FM, and 21 HC participated in this study. Quantitative sensory testing was conducted by manual pressure algometry and computer-controlled cuff algometry. A manual algometer was used to evaluate hyperalgesia as well as temporal summation of pain and a cuff algometer was used to evaluate deep tissue hyperalgesia, the efficacy of the conditioned pain modulation and spatial summation of pain. RESULTS: Pressure pain thresholds by manual algometry were significantly lower in FM compared to HC, RLBP, and severe CLBP. Temporal summation of pain was significantly higher in FM compared to HC and RLBP. Pain tolerance thresholds assessed by cuff algometry were significantly lower in FM compared to HC and RLBP and also in severe CLBP compared to RLBP. No significant differences between groups were found for spatial summation or conditioned pain modulation. LIMITATIONS: No psychosocial issues were taken into account for this study. CONCLUSION: The present results suggest normal pain sensitivity in RLBP, but future research is needed. In mild and severe CLBP some findings of altered pain processing are evident, although to a lesser extent compared to FM patients. In conclusion, mild and severe CLBP presents within a spectrum, somewhere between completely healthy persons and FM patients, characterized by pain augmentation.

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.

Recognition and Treatment of Central Sensitization in Chronic Pain Patients: Not Limited to Specialized Care.

Modern pain neuroscience has substantially improved our understanding of the (development of) chronic musculoskeletal pain. The time has come for orthopaedic and sports physical therapists to implement modern pain neuroscience in specialized, but definitely also in primary, care settings, including the role of central sensitization (CS) in amplifying and explaining the presence of the pain experience. Central sensitization dominates the clinical picture in a subgroup of the musculoskeletal pain population, ranging from tennis elbow over shoulder pain to osteoarthritis and whiplash. Applying modern pain neuroscience to clinical practice implies (1) recognizing those patients having predominant CS pain, and (2) accounting for CS when designing the treatment plan in those with predominant CS pain. Future work in this area should (1) examine the validity of the proposed clinical classification algorithm for identifying CS pain in patients with orthopaedic and sports injuries, and (2) explore evidence-based treatment options for patients having predominant CS pain. J Orthop Sports Phys Ther 2016;46(12):1024-1028. doi:10.2519/jospt.2016.0612.

Structural Changes of Lumbar Muscles in Non-specific Low Back Pain: A Systematic Review.

BACKGROUND: Lumbar muscle dysfunction due to pain might be related to altered lumbar muscle structure. Macroscopically, muscle degeneration in low back pain (LBP) is characterized by a decrease in cross-sectional area and an increase in fat infiltration in the lumbar paraspinal muscles. In addition microscopic changes, such as changes in fiber distribution, might occur. Inconsistencies in results from different studies make it difficult to draw firm conclusions on which structural changes are present in the different types of non-specific LBP. Insights regarding structural muscle alterations in LBP are, however, important for prevention and treatment of non-specific LBP. OBJECTIVE: The goal of this article is to review which macro- and/or microscopic structural alterations of the lumbar muscles occur in case of non-specific chronic low back pain (CLBP), recurrent low back pain (RLBP), and acute low back pain (ALBP). STUDY DESIGN: Systematic review. SETTING: All selected studies were case-control studies. METHODS: A systematic literature search was conducted in the databases PubMed and Web of Science. Only full texts of original studies regarding structural alterations (atrophy, fat infiltration, and fiber type distribution) in lumbar muscles of patients with non-specific LBP compared to healthy controls were included. All included articles were scored on methodological quality. RESULTS: Fifteen studies were found eligible after screening title, abstract, and full text for inclusion and exclusion criteria. In CLBP, moderate evidence of atrophy was found in the multifidus; whereas, results in the paraspinal and the erector spinae muscle remain inconclusive. Also moderate evidence occurred in RLBP and ALBP, where no atrophy was shown in any lumbar muscle. Conflicting results were seen in undefined LBP groups. Results concerning fat infiltration were inconsistent in CLBP. On the other hand, there is moderate evidence in RLBP that fat infiltration does not occur, although a larger muscle fat index was found in the erector spinae, multifidus, and paraspinal muscles, reflecting an increased relative amount of intramuscular lipids in RLBP. However, no studies were found investigating fat infiltration in ALBP. Restricted evidence indicates no abnormalities in fiber type in the paraspinal muscles in CLBP. No studies have examined fiber type in ALBP and RLBP. LIMITATIONS: Lack of clarity concerning patient definitions, exact LBP symptoms, and applied methods. CONCLUSIONS: The results indicate atrophy in CLBP in the multifidus and paraspinal muscles but not in the erector spinae. No atrophy was shown in RLBP and ALBP. Fat infiltration did not occur in RLBP, but results in CLBP were inconsistent. No abnormalities in fiber type in the paraspinal muscles were found in CLBP. KEY WORDS: Low back pain, non-specific, chronic, recurrent, acute, muscle structure, fat infiltration, cross-sectional area, fiber type, review.