Central sensitization in chronic low back pain: A narrative review

Temporal relationships between pain, functioning, and human assumed central sensitization in patients with chronic low back pain; a single-case design

BACKGROUND

Interdisciplinary pain rehabilitation (IPR) aims to improve functioning in people with chronic low back pain (CLBP), and is not primary aimed at pain reduction. Many patients however also report a decrease in pain. An explanation could be that IPR results in a decrease in Central Sensitization (CS). As CS is not directly assessable in humans the term Human Assumed Central Sensitization (HACS) is used in this study. It is unknown whether a decrease in HACS precedes a decrease in pain and improved functioning or vice versa.

OBJECTIVES

This study aimed to gain understanding into the temporal relationships between changes in pain, functioning, and HACS in patients with CLBP during IPR.

DESIGN

Longitudinal observational small-N-study.

METHOD

Twelve patients filled in frequently repeated self-reports 1 week before, during the 12-week IPR program, and 2 weeks after IPR. Pain was assessed by Visual Analogue Scale for pain (daily), functioning by Pain Disability Index (weekly) and Work Ability Score (daily), and HACS by Central Sensitization Inventory part A (bi-weekly). Analyses were performed by visual inspection and time series cross-correlation analyses.

RESULTS

Visual inspection showed large fluctuations within and between individual participants in patterns over time. Cross-correlation analyses showed that in most participants, relationships between pain, functioning, and HACS were strongest when analyzed at the same time (55% of comparisons). Strength and direction of (strongest) correlations showed high interindividual variability (neg: 0.33-0.97; pos: 0.22-0.99).

CONCLUSION

Overall, relationships between pain, functioning, and HACS did not show consistent temporality in patients with CLBP.

Indication for spinal sensitization in chronic low back pain: mechanical hyperalgesia adjacent to but not within the most painful body area

Introduction

In 85% of patients with chronic low back pain (CLBP), no specific pathoanatomical cause can be identified. Besides primary peripheral drivers within the lower back, spinal or supraspinal sensitization processes might contribute to the patients' pain.

Objectives

The present study conceptualized the most painful area (MP) of patients with nonspecific CLBP as primarily affected area and assessed signs of peripheral, spinal, and supraspinal sensitization using quantitative sensory testing (QST) in MP, a pain-free area adjacent to MP (AD), and a remote, pain-free control area (CON).

Methods

Fifty-nine patients with CLBP (51 years, SD = 16.6, 22 female patients) and 35 pain-free control participants individually matched for age, sex, and testing areas (49 years, SD = 17.5, 19 female participants) underwent a full QST protocol in MP and a reduced QST protocol assessing sensory gain in AD and CON. Quantitative sensory testing measures, except paradoxical heat sensations and dynamic mechanical allodynia (DMA), were Z-transformed to the matched control participants and tested for significance using Z-tests (α = 0.001). Paradoxical heat sensations and DMA occurrence were compared between cohorts using Fisher's exact tests (α = 0.05). The same analyses were performed with a high-pain and a low-pain CLBP subsample (50% quantile).

Results

Patients showed cold and vibration hypoesthesia in MP (all Ps < 0.001) and mechanical hyperalgesia (P < 0.001) and more frequent DMA (P = 0.044) in AD. The results were mainly driven by the high-pain CLBP subsample. In CON, no sensory alterations were observed.

Conclusion

Mechanical hyperalgesia and DMA adjacent to but not within MP, the supposedly primarily affected area, might reflect secondary hyperalgesia originating from spinal sensitization in patients with CLBP.

Job stress and chronic low back pain: incidence, number of episodes, and severity in a 4-year follow-up of the ELSA-Brasil Musculoskeletal cohort

ABSTRACT

We investigated the association between job stress, as assessed by the effort-reward imbalance model, and the incidence of chronic low back pain (CLBP) over a 4-year period. A total of 1733 participants from the ELSA-Brasil Musculoskeletal cohort, who were free from LBP at baseline (2012-2014), were included. Episodes of LBP in the past 30 days, intensity, and the presence of disability were investigated in annual telephone follow-ups (2015-2018). Chronic LBP was defined as episodes of LBP lasting >3 months with at least moderate intensity. We analyzed the incidence of at least one episode of CLBP (yes/no), the number of CLBP episodes (0, 1, ≥2), and CLBP severity/disability (absent, nondisabling, severe/disabling). The association between these outcomes and tertiles of the effort-to-reward ratio, as well as each dimension of the effort-reward imbalance model, was investigated using multinomial logistic and Poisson regression models adjusting for sociodemographic and occupational variables. The cumulative incidence of CLBP over 4 years was 24.8%. High effort-reward imbalance increased the chances of experiencing multiple CLBP episodes and severe/disabling CLBP by 67% (95% confidence interval [CI]: 1.12-2.47) and 70% (95% CI: 1.14-2.53), respectively. High overcommitment increased the incidence of CLBP by 23% (95% CI: 1.01-1.50) and the chances of multiple CLBP episodes and severe/disabling CLBP by 67% (95% CI: 1.11-2.50) and 57% (95% CI: 1.05-2.34), respectively. These results indicate that exposure to job stress is associated with a higher incidence, a greater number of episodes, and increased severity of CLBP over a 4-year period. If this association is causal, measures aimed at reducing exposure to job stress are likely to alleviate the burden of CLBP.

Efficacy of radiofrequency in lumbar facet joint pain: a systematic review and meta-analysis of placebo-controlled randomized controlled trials

BACKGROUND

Lumbar facet joint pain (LFJP) is one of the main causes of chronic low back pain (LBP) and can be treated using radiofrequency (RF) sensory denervation. The aim of this work is to analyze the efficacy of RF in LFJP through a systematic review and meta-analysis of randomized controlled trials (RCTs) with placebo control.

MATERIALS AND METHODS

A systematic search was conducted in the Medline (PubMed), Scopus, Web of Science databases, and the Cochrane Central Register of Controlled Trials (CENTRAL). The variables of interest were pain, functional status, quality of life (QoL), and global perceived effect (GPE) measured at different time intervals: short (< 3 months), medium (> 3 and < 12 months), and long term (> 12 months).

RESULTS

Eight RCTs with placebo control were included. RF showed significant benefits over placebo in pain relief in the short (MD - 1.01; 95% CI - 1.98 to -0.04; p = 0.04), medium (MD - 1.42; 95% CI - 2.41 to - 0.43; p = 0.005), and long term (MD - 1.12; 95% CI - 1.57 to - 0.68; p < 0.001), as well as improvement in functional disability in the short (SMD - 0.94; 95% CI - 1.73 to - 0.14; p = 0.02) and long term (SMD - 0.74; 95% CI - 1.09 to - 0.39; p < 0.001). No statistically significant differences were observed in QoL or quantitative GPE, but benefits for RF were observed in dichotomous GPE in the medium (OR 0.19; 95% CI 0.07-0.52; p = 0.001) and long term (OR 0.22; 95% CI 0.06-0.78; p = 0.02). Subgroup analyses showed more benefits for RF in LBP < 1 year in the short term and in RCTs that did not require performing an MRI for patient selection.

CONCLUSIONS

RF demonstrated significant improvement in pain and functionality, but the benefits in terms of QoL and GPE are inconclusive. Future clinical trials should investigate the long-term effects of RF, its impact on quality of life, and define appropriate criteria for patient selection.

Ocular surface information seen from the somatosensory thalamus and cortex

Ocular Surface (OS) somatosensory innervation detects external stimuli producing perceptions, such as pain or dryness, the most relevant symptoms in many OS pathologies. Nevertheless, little is known about the central nervous system circuits involved in these perceptions, and how they integrate multimodal inputs in general. Here, we aim to describe the thalamic and cortical activity in response to OS stimulation of different modalities. Electrophysiological extracellular recordings in anaesthetized rats were used to record neural activity, while saline drops at different temperatures were applied to stimulate the OS. Neurons were recorded in the ophthalmic branch of the trigeminal ganglion (TG, 49 units), the thalamic VPM-POm nuclei representing the face (Th, 69 units) and the primary somatosensory cortex (S1, 101 units). The precise locations for Th and S1 neurons receiving OS information are reported here for the first time. Interestingly, all recorded nuclei encode modality both at the single neuron and population levels, with noxious stimulation producing a qualitatively different activity profile from other modalities. Moreover, neurons responding to new combinations of stimulus modalities not present in the peripheral TG subsequently appear in Th and S1, being organized in space through the formation of clusters. Besides, neurons that present higher multimodality display higher spontaneous activity. These results constitute the first anatomical and functional characterization of the thalamocortical representation of the OS. Furthermore, they provide insight into how information from different modalities gets integrated from the peripheral nervous system into the complex cortical networks of the brain. KEY POINTS: Anatomical location of thalamic and cortical ocular surface representation. Thalamic and cortical neuronal responses to multimodal stimulation of the ocular surface. Increasing functional complexity along trigeminal neuroaxis. Proposal of a new perspective on how peripheral activity shapes central nervous system function.

Dorsal root ganglion-pulsed neuromodulation radiofrequency treatment has significant clinical efficacy in chronic spinal-origin pain, bringing noticeable improvement in symptoms and sleep quality for patients

BACKGROUND

Chronic spinal-origin pain poses a substantial clinical challenge, prompting the investigation of novel treatment modalities. This study aims to evaluate the potential application of spinal nerve dorsal root ganglion (DRG) radiofrequency treatment in addressing chronic spinal-origin pain.

METHODS

The study encompassed patients undergoing treatment for chronic spinal-origin pain, with a particular focus on those experiencing pain localized in specific regions. Inclusion criteria comprised patients with conditions such as a herniated intervertebral disc or foraminal stenosis leading to compression of descending or exiting nerve roots, accompanied by reported radicular pain in the lower limb.

RESULTS

There was no significant difference in comparability between the two groups (p > 0.05). The clinical effective rate in the study group was significantly higher than that in the control group (p < 0.05). The VAS scores of the study group at 2 weeks and 1 month after treatment were significantly lower than those of the control group (p < 0.05). The PSQI index of the study group after treatment was significantly lower than that of the control group (p < 0.05). There was no significant difference in the incidence of complications between the two groups (p > 0.05).

CONCLUSION

Spinal nerve DRG radiofrequency treatment has significant clinical efficacy in chronic spinal-origin pain, bringing noticeable improvement in symptoms and sleep quality for patients. The occurrence of complications is relatively low, and it can be reduced through strict operational standards and preoperative and postoperative management. However, caution should be exercised in its widespread application, but it is worthy of broad clinical use.

Unveiling the Efficacy of Physiotherapy Strategies in Alleviating Low Back Pain: A Comprehensive Review of Interventions and Outcomes

Low back pain (LBP) presents a significant burden globally, affecting individuals of all ages, but it is more common in adults aged 30-60 years old and demographics including race, ethnicity, and socioeconomic status. Physiotherapy interventions are commonly employed to manage LBP due to their non-invasive nature and potential for addressing underlying biomechanical dysfunctions. This comprehensive review aims to evaluate the efficacy of various physiotherapy strategies in alleviating LBP, considering a range of interventions and their associated outcomes. Through a thorough examination of existing literature from January 2017 to October 2023, this review synthesises evidence on the effectiveness of interventions such as manual therapy, exercise therapy, electrotherapy modalities, and education-based approaches. The review also scrutinizes the comparative effectiveness of different physiotherapy modalities and their suitability for specific patient populations, considering factors such as chronicity, severity, and underlying pathology. By critically evaluating the evidence base, this review aims to provide insights into the most effective physiotherapy strategies for alleviating LBP, chronic low back pain (CLBP) and chronic nonspecific low back pain (CNLBP) and guiding clinical practice toward evidence-based interventions. The Visual Analogue Scale and Numerical Pain Rating Scale for pain, Oswestry Disability Index and Roland-Morris Disability Questionnaire for disability, Modified-Modified Schober Test for measurement of lumbar flexion and extension and static and dynamic balance for assessing postural stability and balance were among the measures used to foresee enhancements in pain, disability, balance, and LBP symptoms. Twenty-one studies that fulfilled the criteria for inclusion (aged 20 to 50 years and of both genders) were added to the review. Exercises for core stability, strengthening, orthosis (a medical device designed to support, align, stabilise, or correct musculoskeletal structures and functions), transcutaneous electrical nerve stimulation, heat massage therapy, interferential current (a form of electrical stimulation used in physical therapy), Mulligan's mobilization (a manual therapy technique), low-level laser therapy, and McGill stabilization exercises (core exercises) were among the therapeutic strategies. The McKenzie method (back exercises), ultrasound, sensory-motor training, Swiss ball exercises, and other techniques reduced pain and enhanced strength, balance, and ease of daily activities. Every therapeutic approach has an impact on recovery rates ranging from minimal to maximal. Conventional physical therapy is less effective than most recent advanced techniques like mobilisation and exercises. In summary, the integration of manual techniques, orthoses and alternative intervention strategies with conservative therapeutic approaches can effectively alleviate pain, enhance function and yield better overall outcomes. To get more information about the optimal dosage, therapeutic modalities and long-term effects of these treatments, more admirable research is required. This paper aims to expand the scientific discourse by exploring non-traditional physiotherapy interventions and assessing their efficacy in light of the rigorous standards set forth by the latest WHO guidelines.

Whole Body Cryostimulation: A New Adjuvant Treatment in Central Sensitization Syndromes? An Expert Opinion

Central sensitisation is defined as a multifactorial etiopathogenetic condition involving an increase in the reactivity of nociceptive neurons and alterations in pain transmission and perception in the central nervous system. Patients may present with widespread chronic pain, fatigue, sleep disturbance, dizziness, psychological (e.g., depression, anxiety, and anger) and social impairment. Pain can be spontaneous in onset and persistence, characterised by an exaggerated response and spread beyond the site of origin, and sometimes triggered by a non-painful stimulus. Whole-body cryostimulation (WBC) could be an adjuvant therapy in the management of this type of pain because of its global anti-inflammatory effect, changes in cytokines and hormone secretion, reduction in nerve conduction velocity, autonomic modulation, and release of neurotransmitters involved in the pain pathway. In several conditions (e.g., fibromyalgia, rheumatoid arthritis, and chronic musculoskeletal pain), WBC affects physical performance, pain perception, and psychological aspects. Given its multiple targets and effects at different organs and levels, WBC appears to be a versatile adjuvant treatment for a wide range of conditions of rehabilitation interest. Further research is needed to fully understand the mechanisms of analgesic effect and potential actions on pain pathways, as well as to study long-term effects and potential uses in other chronic pain conditions.

Proinflammatory Dietary Intake Relates to Pain Sensitivity in Chronic Nonspecific Low Back Pain: A Case-Control Study

Nonspecific chronic low back pain (nCLBP) has been associated with nutrition. Yet, it is not clear how nutritional factors and nCLBP relate to one another. Therefore, the aim of the present study was to investigate differences in diet quality and dietary intake levels between nCLBP patients and healthy controls (HCs) and explore the association between nutritional factors and pain sensitivity in nCLBP. In this case-control study, 106 participants (ie, n = 53 nCLBP and n = 53 HCs) were recruited and completed a 3-day food diary to assess their dietary intake, which allowed to generate individual diet quality scores (ie, the Healthy Eating Index-2015 and Dietary Inflammatory Index). Additionally, each participant underwent an experimental pain assessment (quantitative sensory testing) and filled out self-reported pain questionnaires. Compared to HCs, the nCLBP group showed significantly lower diet quality, higher inflammatory scores, and a lower intake of total protein, total fat, dietary fiber, omega-3 fatty acids, vitamin B6, vitamin A, beta-carotene, vitamin E, and magnesium. Pain sensitivity mainly showed a negative correlation with nutritional intakes known for anti-inflammatory properties (ie, vitamins E, D, A, B6, B12, and zinc). Interestingly, total fat, cholesterol, saturated, and monounsaturated fat intakes were found to be inversely associated with pain sensitivity. Overall, patients with nCLBP have a lower diet quality, eat more proinflammatory, have less intake of nutrients known for their anti-inflammatory and antioxidative properties, and drink less water compared to HCs. Accordingly, pain sensitivity was mainly found to be positively associated with proinflammatory dietary intake. PERSPECTIVE: This study emphasizes the association between a proinflammatory diet and nCLBP. Among nCLBP patients, positive association between increased pain sensitivity and the proinflammatory potential of a diet, highlighting the potential for individualized pain management strategies and leading to the development of novel therapeutic methods.

Relationship between Fear-Avoidance Beliefs and Reaction Time Changes Prior to and following Exercise-Induced Muscle Fatigue in Chronic Low Back Pain

Background

Reaction time is a reliable indicator of the velocity and efficiency of neuromuscular control and may be associated with fear-avoidance beliefs. However, the effect of exercise-induced muscle fatigue on reaction time in chronic low back pain (cLBP) and its relationship with fear-avoidance beliefs remains poorly understood.

Objectives

This study aimed to reveal the relationship between fear-avoidance beliefs and reaction time changes before and after exercise-induced muscle fatigue in cLBP.

Methods

Twenty-five patients with cLBP were tested by the Biering-Sorensen test (BST) to induce exhaustive muscle fatigue. Total reaction time (TRT), premotor time (PMT), and electromechanical delay (EMD) of dominated deltoid muscle were recorded by surface electromyography during the arm-raising task with visual cues before and after muscle fatigue. The mean difference (MD) of TRT (MDTRT), PMT (MDPMT), and EMD (MDEMD) was calculated from the changes before and after muscle fatigue. Fear-avoidance beliefs questionnaire (FABQ) was applied to evaluate fear-avoidance beliefs before muscle fatigue. In addition, the duration time of BST was recorded for each subject.

Results

TRT and PMT of dominated deltoid muscle were prolonged after exercise-induced muscle fatigue (Z = 3.511, p < 0.001; t = 3.431, p = 0.001), while there was no statistical difference in EMD (Z = 1.029, p = 0.304). Correlation analysis showed that both the MDTRT and MDPMT were positively correlated with FABQ (r = 0.418, p = 0.042; r = 0.422, p = 0.040).

Conclusions

These findings suggested that we should pay attention to both muscle fatigue-induced reaction time delay in cLBP management and the possible psychological mechanism involved in it. Furthermore, this study implied that FABQ-based psychotherapy might serve as a potential approach for cLBP treatment by improving reaction time delay. This trial is registered with ChiCTR2300074348.

Transcranial Direct Current Stimulation for Orthopedic Pain: A Systematic Review with Meta-Analysis

(1) Background: Transcranial direct current stimulation (tDCS) appears to alleviate chronic pain via a brain-down mechanism. Although several review studies have examined the effects of tDCS on patients with chronic pain, no systematic review or meta-analysis has comprehensively analyzed the effects of tDCS on chronic orthopedic joint pain in one study. We aim to evaluate the effectiveness of tDCS for pain reduction in chronic orthopedic patients; (2) Methods: A comprehensive search of five electronic databases (Medline, Embase, Web of Science, CINAHL, and Cochrane) was performed. Only randomized controlled trials that compared tDCS with a control intervention were included. Eighteen studies met our inclusion criteria. We identified four categories of chronic orthopedic pain: knee (k = 8), lower back (k = 7), shoulder (k = 2), and orofacial pain (k = 1). Random effect models were utilized, and a sensitivity analysis was conducted in the presence of significant heterogeneity. Studies within each pain condition were further classified according to the number of treatment sessions: 1-5 sessions, 6-10 sessions, and >10 sessions.; (3) Results: Significant reductions in chronic orthopedic joint pain were observed following tDCS compared to controls for knee (g = 0.59, p = 0.005), lower back (g = 1.14, p = 0.005), and shoulder (g = 1.17, p = 0.020). Subgroup analyses showed pain reductions after 6-10 tDCS sessions for knee pain and after 1-5 and >10 sessions for lower back pain; (4) Conclusions: tDCS could be considered a potential stand-alone or supplemental therapy for chronic knee and lower back pain. The effectiveness of tDCS treatment varies depending on the number of treatment sessions. Our findings suggest the importance of implementing individualized treatment plans when considering tDCS for chronic pain conditions.

Effects of sleep quality on pain, cognitive factors, central sensitization, and quality of life in patients with chronic low back pain

BACKGROUND

Sleep quality in patients with chronic low back pain (CLBP) may affect quality of life (QoL), possibly due to worsening pain, central sensitization (CS), and cognitive factors. However, causal relationship among the factors has not been confirmed yet.

OBJECTIVE

The purpose of this study was to test the hypothesis that sleep quality in patients with CLBP is attributable to pain, cognitive factors, and CS, and influences QoL, by structural covariance analysis.

METHODS

This is a cross-sectional study. Participants were recruited from six health care facilities and 101 patients with CLBP were included. Structural covariance analysis assessed the fit of data to the model using goodness of fit index (GFI), adjusted goodness of fit index (AGFI), comparative fit index (CFI), and mean squared approximation error (RMSEA).

RESULTS

The structural covariance analysis showed that the goodness-of-fit indices were high (GFI = 0.993, AGFI = 0.964, CFI = 1.00, RMSEA < 0.01). Sleep quality was not directly influenced by QoL but rather by CS and cognitive factors.

CONCLUSION

This study suggests that sleep quality in patients with CLBP is indirectly mediated through multiple pathways, including cognitive factors and CS, which may influence QoL.

Effects of transcranial direct current stimulation combined with Pilates-based exercises in the treatment of chronic low back pain in outpatient rehabilitation service in Brazil: double-blind randomised controlled trial protocol

INTRODUCTION

Chronic low back pain may be associated with pathoanatomical, neurophysiological, physical, psychological and social factors; thus, treatments to reduce symptoms are important to improve the quality of life of this population. We aimed to evaluate the effects of transcranial direct current stimulation (tDCS) combined with Pilates-based exercises compared with sham stimulation on pain, quality of life and disability in patients with chronic non-specific low back pain.

METHODS AND ANALYSIS

This is a protocol for a double-blind randomised controlled trial with participants, outcome assessor and statistician blinded. We will include 36 individuals with a history of non-specific chronic low back pain for more than 12 weeks and minimum pain intensity of 3 points on the Numerical Pain Rating Scale. Individuals will be randomised into two groups: (1) active tDCS combined with Pilates-based exercises and (2) sham tDCS combined with Pilates-based exercises. Three weekly sessions of the protocol will be provided for 4 weeks, and individuals will be submitted to three assessments: the first (T0) will be performed before the intervention protocol, the second (T1) immediately after the intervention protocol and the third (T2) will be a follow-up 1 month after the end of the intervention. We will assess pain, disability, central sensitisation, quality of life, pressure pain threshold, global impression of change, adverse events and medication use. The Numerical Pain Rating Scale and the Roland-Morris Disability Questionnaire will be used at T1 to assess pain and disability, respectively, as primary outcome measures.

ETHICS AND DISSEMINATION

This trial was prospectively registered in ClinicalTrials.gov website and ethically approved by the Ethics and Research Committee of the Faculty of Health Sciences of Trairi (report number: 5.411.244) before data collection. We will publish the results in a peer-reviewed medical journal and on institution websites.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov (NCT05467566).

Sensory phenotypes in complex regional pain syndrome and chronic low back pain-indication of common underlying pathomechanisms

Introduction

First-line pain treatment is unsatisfactory in more than 50% of chronic pain patients, likely because of the heterogeneity of mechanisms underlying pain chronification.

Objectives

This cross-sectional study aimed to better understand pathomechanisms across different chronic pain cohorts, regardless of their diagnoses, by identifying distinct sensory phenotypes through a cluster analysis.

Methods

We recruited 81 chronic pain patients and 63 age-matched and sex-matched healthy controls (HC). Two distinct chronic pain cohorts were recruited, ie, complex regional pain syndrome (N = 20) and low back pain (N = 61). Quantitative sensory testing (QST) was performed in the most painful body area to investigate somatosensory changes related to clinical pain. Furthermore, QST was conducted in a pain-free area to identify remote sensory alterations, indicating more widespread changes in somatosensory processing.

Results

Two clusters were identified based on the QST measures in the painful area, which did not represent the 2 distinct pain diagnoses but contained patients from both cohorts. Cluster 1 showed increased pain sensitivities in the painful and control area, indicating central sensitization as a potential pathomechanism. Cluster 2 showed a similar sensory profile as HC in both tested areas. Hence, either QST was not sensitive enough and more objective measures are needed to detect sensitization within the nociceptive neuraxis or cluster 2 may not have pain primarily because of sensitization, but other factors such as psychosocial ones are involved.

Conclusion

These findings support the notion of shared pathomechanisms irrespective of the pain diagnosis. Conversely, different mechanisms might contribute to the pain of patients with the same diagnosis.

Neural correlates of central pain sensitization in chronic low back pain: a resting-state fMRI study

PURPOSE

The objective of this study is to explore the neural correlates of pain sensitization in patients with chronic low back pain (cLBP). While the association between cLBP and pain sensitization has been widely reported, the underlying brain mechanism responsible for this relationship requires further investigation.

METHODS

Our study included 56 cLBP patients and 56 healthy controls (HC). Functional magnetic resonance imaging data were obtained, and the voxel-wise amplitude of low-frequency fluctuation (ALFF) was calculated to identify brain alterations in cLBP patients compared to HC groups. Pearson correlation coefficients were computed to explore the association between clinical data and brain alterations. Furthermore, mediation analyses were performed to investigate the path association between brain alterations and pain-related behaviors.

RESULTS

Our findings revealed that patients with cLBP exhibited higher sensitivity, attention, and catastrophizing tendencies towards pain compared to HC. Furthermore, cLBP patients displayed significantly higher ALFF in various brain regions within the "pain matrix" and the default mode network when compared to HC. The altered precuneus ALFF was positively correlated with pain intensity (R = 0.51, P<0.001) and was negatively correlated with pain sensitivity (R = -0.43, P<0.001) in cLBP patients. Importantly, the effect of altered precuneus ALFF on pain intensity was mediated by pain threshold in these patients.

CONCLUSION

Our study suggests that altered neural activity in the precuneus may contribute to pain hypersensitivity, which further exacerbating pain in cLBP patients.

Association of central sensitization, visceral fat, and surgical outcomes in lumbar spinal stenosis

BACKGROUND

Controversy remains regarding predictors of surgical outcomes for patients with lumbar spinal stenosis (LSS). Pain sensitization may be an underlying mechanism contributing to LSS surgical outcomes. Further, obesity is associated with dissatisfaction and poorer outcomes after surgery for LSS. Therefore, this study aimed to examine the relationship between central sensitization (CS), visceral fat, and surgical outcomes in LSS.

METHODS

Patients with LSS were categorized based on their central sensitization inventory (CSI) scores into low- (CSI < 40) and high- (CSI ≥ 40) CSI subgroups. The participants completed clinical outcome assessments preoperatively and 12 months postoperatively.

RESULTS

Overall, 60 patients were enrolled in the study (28 men, 32 women; mean age: 62.1 ± 2.8 years). The high-CSI group had significantly higher mean low back pain (LBP), leg pain, and leg numbness visual analogue scale (VAS) scores than the low-CSI group (p < 0.01). The high-CSI group had a significantly higher mean visceral fat area than the low-CSI group (p < 0.01). Postoperatively, LBP VAS score was significantly worse in the high-CSI group. Relative to preoperatively, postoperative leg pain and leg numbness improved significantly in both groups.

CONCLUSIONS

We believe that neuro decompression can be effective for LSS surgical outcomes in patients with CS; nonetheless, it should be approached with caution owing to the potential for worsening LBP. Additionally, visceral fat is an important indicator suggesting the involvement of CS.

Impact of central sensitization on pain, disability and psychological distress in patients with knee osteoarthritis and chronic low back pain

BACKGROUND

Central sensitization (CS) is becoming increasingly recognized as a significant factor in many chronic pain conditions, including knee osteoarthritis (KOA) and chronic low back pain (CLBP). Yet it presently remains unclear how strong is the involvement of CS in KOA and CLBP and which factors are involved in CS in these two chronic disabling diseases.

METHODS

This is a cross-sectional study in which included a total of 178 patients with KOA and 118 patients with CLBP. Inclusion criteria for eligible participants for the KOA group were a confirmed diagnosis of KOA according to the American College of Rheumatology criteria, and for the CLBP group a chronic low back pain for more than 3 months. Subjects were excluded if they presented with a diagnosed psychiatric disorder or if they lacked the capacity to provide informed consent, understand study questionnaires or perform physical performance tests. In each group, were assessed; CS-related symptoms using the Central Sentization Inventory (CSI); demographic and clinical characteristics such as disease duration, pain intensity on a visual analog scale, self-reported function using the Lequesne index for KOA patients and the Oswestry Disability index for CLBP patients, and physical performance with the 6 minutes' walk test; as well as psychosocial risk factors using the Patient Health Questionnaire for depression (PHQ-9), the Generalized Anxiety Disorder (GAD-7) and the Pain Catastrophizing Scale (PCS).

RESULTS

CSI scores significantly correlated with pain intensity and disability in KOA and CLBP patients, and were highly correlated with self-reported symptoms of depression, anxiety and pain catastrophizing. Depression significantly predicted the CSI score in both groups.

CONCLUSION

These findings provide further evidence for the impact of CS on pain, function and physical performance in KOA and CLBP patients. Psychosocial symptoms such as pain catastrophizing, anxiety and depression should also be considered as they are also associated with CS.

Are Sexual Assaults Related to Functional Somatic Disorders? A Cross-Sectional Study

An increasing number of sexual assaults (SAs) are being reported. This study investigated associations between SA and FSD, conceptualized as bodily distress syndrome (BDS), and five functional somatic syndromes (FSSs): chronic widespread pain (CWP), irritable bowel (IB), chronic fatigue (CF), multiple chemical sensitivity (MCS), and whiplash-associated disorder (WAD). Participants (n = 7493) from the population-based cohort Danish Study of Functional Disorders (DanFunD) completed questionnaires on FSD, emotional distress, SA, and sociodemographics. Risk ratios (RRs) for each FSD and emotional distress were calculated in nine models with SA as the primary exposure using generalized linear models with binomial family and log link and were adjusted for other potential risk factors. The results showed that SA was associated with single-organ FSD (RR = 1.51; 95% CI = 1.22-1.87), multi-organ FSD (RR = 3.51; 95% CI = 1.89-6.49), CWP (RR = 1.28; 95% CI = 0.83-1.98), IB (RR = 2.00; 95% CI = 1.30-3.07), CF (RR = 1.81; 95% CI = 1.42-2.32), WAD (RR = 2.62; 95% CI = 1.37-5.03), MCS (RR = 3.04; 95% CI = 1.79-5.17), emotional distress (RR = 1.75; 95% CI = 1.21-2.54), and health anxiety (RR = 1.65; 95% CI = 1.10-2.46). Overall, SA victims experienced significantly more somatic symptoms than individuals not exposed to SA. Adjusting for physical and emotional abuse did not change the observed associations. Our results suggest a large impact of SA on the overall somatic and mental health of SA victims. Due to the cross-sectional study design, further studies are required.

Composite Biomarkers, Behavioral Symptoms, and Comorbidities in Axial Low Back Pain: A Systematic Review

PURPOSE

Proinflammatory cytokines play a critical role in chronic inflammation and pain and contribute to behavioral symptoms (depressive symptoms, anxiety, fatigue, sleep disturbance) and comorbidities (diabetes, cardiac diseases, cancer). Evidence is lacking on the specific proinflammatory cytokines associated with these behavioral symptoms/comorbidities co-occurring with axial low back pain (aLBP). This review aimed to systematically analyze the following: (1) specific proinflammatory cytokines associated with aLBP in adults, (2) associations among proinflammatory cytokines and behavioral symptoms in aLBP, and (3) relationships among proinflammatory cytokines and comorbidities in aLBP, to develop a new clinical framework for future diagnostic and intervention targets for patients with aLBP.

METHODS

Electronic databases, including PubMed/MEDLINE, ProQuest Nursing & Allied Health Source, and CINAHL Complete (EBSCO) were searched for the period January 2012 to February 2023. Eligible studies included cross-sectional, case-control, longitudinal, and cohort studies in which proinflammatory cytokines were reported in adults above 18 years with aLBP. Intervention studies and randomized controlled trails were excluded. The Joanna Briggs Institute (JBI) criteria were used for quality evaluation.

RESULTS

Findings from 11 studies showed 3 proinflammatory cytokines associated with pain intensity in adult patients with aLBP: C-Reactive Protein (CRP), Tumor Necrosis Factor (TNF-α), and Interleukin (IL-6). Some studies assessed associations between proinflammatory cytokines and depressive symptoms; none explored the association of proinflammatory cytokines with fatigue, anxiety, sleep disturbance, or comorbidities (diabetes, cardiac diseases, and cancer) in aLBP.

CONCLUSIONS

Proinflammatory cytokines in aLBP can serve as composite biomarkers for pain, associated symptoms, and comorbidities and may serve as a target for future interventions. There is need for well-designed studies assessing associations among chronic inflammation, behavioral symptoms, and comorbidities.

Multimodal non-invasive non-pharmacological therapies for chronic pain: mechanisms and progress

BACKGROUND

Chronic pain conditions impose significant burdens worldwide. Pharmacological treatments like opioids have limitations. Non-invasive non-pharmacological therapies (NINPT) encompass diverse interventions including physical, psychological, complementary and alternative approaches, and other innovative techniques that provide analgesic options for chronic pain without medications.

MAIN BODY

This review elucidates the mechanisms of major NINPT modalities and synthesizes evidence for their clinical potential across chronic pain populations. NINPT leverages peripheral, spinal, and supraspinal mechanisms to restore normal pain processing and limit central sensitization. However, heterogeneity in treatment protocols and individual responses warrants optimization through precision medicine approaches.

CONCLUSION

Future adoption of NINPT requires addressing limitations in standardization and accessibility as well as synergistic combination with emerging therapies. Overall, this review highlights the promise of NINPT as a valuable complementary option ready for integration into contemporary pain medicine paradigms to improve patient care and outcomes.

Evaluation of Central Sensitization Inventory in Patients Undergoing Elective Spine Surgery in a Multicenter Study

STUDY DESIGN

This study is a retrospective review.

OBJECTIVE

Central sensitization (CS) is a neurological phenomenon that involves hypersensitivity of the central nervous system. The central sensitization inventory (CSI) was developed as a screening tool to assess CS-related symptoms. The purpose of this study was to evaluate the association of preoperative CSI scores with patient-reported outcome measures (PROMs) including neurological symptoms for patients who underwent spine surgeries in a multicenter study.

METHODS

A consecutive 673 patients who underwent spine surgery at 8 different institutions were included in this study. Preoperative CSI scores were assessed for all subjects. The participants completed the following PROMs: the Oswestry Disability Index (ODI), the Japanese Orthopaedic Association (JOA) back pain evaluation questionnaire (JOABPEQ) for lumbar spinal diseases, and the JOA cervical myelopathy evaluation questionnaire (JOACMEQ) for cervical spinal diseases. The association of CSI scores with PROMs was statistically evaluated.

RESULTS

The average CSI score for the total subjects was 23.6 ± 13.5. The subjects with CS-related symptoms (CSI ≥ 40) were 13.2% (n = 89). The CSI score showed a significant and weak-to-moderate correlation with the PROMs including neurological symptoms that included all the domains of the JOACMEQ for cervical spinal diseases, and JOABPEQ and ODI for lumbar spinal diseases. Among these, psychological factors had the most influence on the correlation with CSI score.

CONCLUSION

Central sensitization evaluated by the CSI is related to neurological symptoms and health-related quality of life in patients undergoing elective spine surgery.

The importance of inflammatory biomarkers in non-specific acute and chronic low back pain: a systematic review

OBJECTIVE

The purpose of this study was to systematically review the evidence on inflammatory biomarkers as analytic predictors of non-specific low back pain (NsLBP). Low back pain (LBP) is the number one cause of disability globally, posing a major health problem that causes an enormous social and economic burden, and there is an increasing interest on the importance of biomarkers in quantifying and even emerge as potential therapeutic tools to LBP.

METHODS

A systematic search was conducted on July 2022 in Cochrane Library, MEDLINE and Web of Science for all the available literature. Cross-sectional, longitudinal cohort or case-control studies that evaluated the relationship between inflammatory biomarkers collected from blood samples and low back pain in humans were considered eligible for inclusion, as well as prospective and retrospective studies.

RESULTS

The systematic database search resulted in a total of 4016 records, of which 15 articles were included for synthesis. Sample size comprised a total of 14,555 patients with LBP (acute LBP (n = 2073); chronic LBP (n = 12482)) and 494 controls. Most studies found a positive correlation between classic pro-inflammatory biomarkers and NsLBP, namely C-reactive protein (CRP), interleukin 1 (IL-1) and IL-1β, interleukin 6 (IL-6) and tumour necrosis factor α (TNF-α). On the other hand, anti-inflammatory biomarker interleukin 10 (IL-10) demonstrated a negative association with NsLBP. Four studies have made direct comparisons between ALBP and CLBP groups regarding their inflammatory biomarkers profile.

CONCLUSIONS

This systematic review found evidence of increased levels of pro-inflammatory biomarkers CRP, IL-6 and TNF-α and decreased levels of anti-inflammatory biomarker IL-10 in patients with LBP. Hs-CRP was not correlated with LBP. There is insufficient evidence to associate these findings with the degree of pain severity or the activity status of the lumbar pain over time.

Effect of a Behavioral Therapy-Based Virtual Reality Application on Quality of Life in Chronic Low Back Pain

OBJECTIVES

Low back pain is the leading cause of years lived with disability with a large impact on quality of life and resistance to a broad array of current treatments. This study aimed to investigate the effect of a novel self-administered behavioral therapy-based virtual reality (VR) application on the quality of life of patients with nonspecific chronic low back pain (CLBP).

METHODS

A pilot randomized controlled trial was conducted in adults with nonspecific CLBP with moderate to severe pain, waiting for treatment in a teaching hospital-based pain clinic. The intervention group used a self-administered behavioral therapy-based VR application for at least 10 minutes daily for 4 weeks. The control group received standard care. The primary outcome was quality of life at 4 weeks measured by the short form-12 physical and mental scores. Secondary outcomes were daily worst and least pain, pain coping strategies, activities of daily living, positive health, anxiety, and depression. Discontinuation of therapy and adverse events were analyzed as well.

RESULTS

Forty-one patients were included. One patient withdrew due to personal reasons. No significant treatment effect was found for the short form-12 physical score (mean difference: 2.6 points; 95% CI: -5.60 to 0.48) and mental score (-1.75; -6.04 to 2.53) at 4 weeks. There was a significant treatment effect for daily "worst pain score" ( F [1, 91.425] = 33.3, P < 0.001) and "least pain score" ( F [1, 30.069] = 11.5, P = 0.002). Three patients reported mild and temporary dizziness.

DISCUSSION

Four weeks of self-administered VR for CLBP does not improve quality of life, however, it may positively affect daily pain experience.

High intensity training improves symptoms of central sensitization at six-month follow-up in persons with chronic nonspecific low back pain: Secondary analysis of a randomized controlled trial

BACKGROUND

High intensity training (HIT) improves disability and physical fitness in persons with chronic nonspecific low back pain (CNSLBP). However, it remains unclear if HIT affects pain processing and psychosocial factors.

OBJECTIVE

To evaluate 1) the effects of HIT on symptoms of central sensitization and perceived stress and 2) the relationship of symptoms of central sensitization and perceived stress with therapy success, at six-month follow-up, in persons with CNSLBP.

METHODS

This is a secondary analysis of a previously published randomized controlled trial. Persons with CNSLBP (n = 51, age=43.6y) completed the Central Sensitization Inventory (CSI) and Perceived Stress Scale (PSS) at baseline (PRE) and six months after 12-week of HIT consisting of concurrent exercise therapy (FU). Two groups were formed based on CSI scores (low-CSI/high-CSI). First, linear mixed models were fitted for each outcome, with time and groups as covariates. Multiple comparisons were executed to evaluate group (baseline), time (within-group), and interaction (between-group) effects. Second, correlation and regression analyses were performed to evaluate if baseline and changes in CSI/PSS scores were related to therapy success, operationalized as improvements on disability (Modified Oswestry Disability Index), and pain intensity (Numeric Pain Rating Scale).

RESULTS

Total sample analyses showed a decrease in both CSI and PSS. Within-group analyses showed a decrease of CSI only in the high-CSI group and a decrease of PSS only in the low-CSI group. Between-group analyses showed a pronounced decrease favouring high-CSI (mean difference: 7.9; 95%CI: 2.1, 12.7) and no differences in PSS (mean difference: 0.1; 95%CI: -3.0, 3.2). CSI, but not PSS, was weakly related to therapy success.

CONCLUSION

HIT improves symptoms of central sensitization in persons with CNSLBP. This effect is the largest in persons with clinically relevant baseline CSI scores. HIT also decreases perceived stress.

Transcranial direct current stimulation combined with peripheral stimulation in chronic pain: a systematic review and meta-analysis

INTRODUCTION

The combination of Transcranial Direct Current Stimulation (tDCS) with peripheral stimulation may optimize their effects and bring positive results in treatment of people with chronic pain.

AREAS COVERED

A systematic review with meta-analysis of randomized and non-randomized trials was performed to investigate the combination of tDCS with peripheral stimulation in adults with chronic pain. The primary outcome was pain intensity. Six studies were included in this review (sample of 228 participants), which investigated the combination of tDCS and transcutaneous electrical nerve stimulation, peripheral electrical stimulation, breathing-controlled electrical stimulation and intramuscular electrical stimulation. The conditions studied were knee osteoarthritis, spinal cord injury, chronic low back pain, and neurogenic pain of the arms. Pain intensity, measured by visual analog scale or numerical rating scale, was reduced in all included studies when at least one of the interventions was active, regardless they were combined or alone, with or without tDCS. However, meta-analysis showed superiority of tDCS used in combination with peripheral stimulation.

EXPERT OPINION

This systematic review and meta-analysis suggests positive effects of tDCS combined with peripheral stimulation in chronic pain conditions. However, the evidence of the primary outcome was classified as low quality due to the limited number of studies.

Aloe Vera-Containing Matrix in Transdermal Fentanyl Therapy Improves Adhesion, Skin Tolerance and Quality of Life: Results of a German Multicenter Study with a New Fentanyl Patch

BACKGROUND

Chronic pain represents a significant and costly healthcare problem especially in the older patient. Transdermal opioid therapy is easy to apply and ensures constant supply of active ingredients. However, skin irritation, poor adhesion and systemic side effects complicate transdermal pain therapy.

METHODS

In the Relief study, comprising 54 centers, all in Germany, 252 patients were recruited and data about the general care situation as well as the characteristics, effects and side effects of the Aloe vera fentanyl patch were collected. 92 patients had a prior treatment with fentanyl patch without Aloe vera, allowing a comparative analysis.

RESULTS

Compared to patches without Aloe vera, the new fentanyl patch showed better adhesion. Systemic and local tolerance and pain reduction were also significantly better. Patients also reported improvements in side effects and central parameters of quality of life. The data regarding the care situation in Germany showed remarkably low use of coanalgetics and laxatives in pain patients.

DISCUSSION

Aloe vera in transdermal pain treatment improves adhesion and local tolerance of the patch. Pain control and quality of life were also improved. Regional care data concerning cotreatment in pain therapy from this study indicate a lack of penetration of existing guidelines in general practitioners' pain therapy.

Multisensory sensitivity differentiates between multiple chronic pain conditions and pain-free individuals

ABSTRACT

Multisensory sensitivity (MSS) to nonpainful stimuli has been identified as a risk factor for the presence of coexisting chronic pain conditions. However, it remains unclear whether MSS can differentiate pain phenotypes involving different levels of central sensitivity. Both pain-free and those with chronic pain, particularly fibromyalgia (FM), migraine, or low back pain (LBP) were recruited, with pain comorbidities assessed. MSS was highest in FM, followed by migraine, then LBP, and lowest in pain-free individuals (adjusted between condition Cohen d = 0.32-1.2, P ≤ 0.0007). However, when secondly grouping patients by the total number of pain comorbidities reported, those with a single pain condition (but not FM) did not have significantly elevated MSS vs pain-free individuals (adj d= 0.17, P = 0.18). Elevated MSS scores produced increased odds of having 2 or more pain comorbidities; OR [95% CI] =2.0 [1.15, 3.42], without, and 5.6 [2.74, 11.28], with FM ( P ≤ 0.0001). Furthermore, those with low MSS levels were 55% to 87% less likely to have ≥ 2 pain comorbidities with or without FM (OR 0.45 [0.22, 0.88]-0.13 [0.05, 0.39]; P ≤ 0.0001). Our findings support that MSS can differentiate between pain phenotypes with different degrees of expected central mechanism involvement and also serve as a risk and resilience marker for total coexisting chronic pain conditions. This supports the use of MSS as a marker of heightened central nervous system processing and thus may serve as a clinically feasible assessment to better profile pain phenotypes with the goal of improving personalized treatment.

Acupuncture for treating chronic spinal pain: A systematic review and meta-analysis protocol

BACKGROUND

Chronic spinal pain is one of the most leading causes of disability among adults worldwide and is associated with significant health care use. The effect of acupuncture on chronic spinal pain seems controversial based on evidence-based perspective. Thus, we performed a protocol for systematic review and meta-analysis to evaluate the effectiveness of acupuncture for treatment of chronic spinal pain.

METHODS

This systematic review has been registered in PROSPERO (CRD42019120665), which will be conducted in accordance with preferred reporting items for systematic review and meta-analysis protocols 2015 statement. We will search 7 electronic databases to identify relevant studies from inception to November, 2022, which includes PubMed, MEDLINE, Embase, Cochrane Clinical Trials Database, Web of Science, China National Knowledge Infrastructure, and Chinese Biomedical Literature Database. Cochrane "bias risk" tool is used to assess the bias risk of the quality of the included literature. RevMan V.5.3 software will be used to analyze all data.

RESULTS

A synthesis of current evidence of acupuncture for treating chronic spinal pain will be provided in this protocol.

CONCLUSION

This review will provide directions and recommendations for future research and clinical practices of acupuncture for treating chronic spinal pain.

Preoperative duration of pain is associated with chronic opioid use after adult spinal deformity surgery

PURPOSE

Few studies have explored the association between preoperative patient-reported measures and chronic opioid use following adult spinal deformity (ASD) surgery. We sought to explore the association between preoperative duration of pain, as well as other patient-reported factors, and chronic opioid use after ASD surgery.

METHODS

We retrospectively reviewed our U.S. academic tertiary care hospital's database of ASD patients. We included patients 18 years or older who underwent arthrodesis of four or more spinal levels from January 2008 to February 2018, with 2-year follow-up. The primary outcome variable was chronic opioid use, defined as opioid use at both 1 and 2 years postoperatively. We analyzed patient characteristics; duration of preoperative pain (<4 years or ≥4 years); radiculopathy; preoperative Scoliosis Research Society-22r (SRS-22r) score; Oswestry Disability Index (ODI) value; and surgical characteristics.

RESULTS

Of 119 patients who met the inclusion criteria, 93 (78%) were women, and mean ± standard deviation age was 59 ± 13. Sixty patients (50%) reported preoperative opioid use, and 35 (29%) reported chronic opioid use. Preoperative opioid use was associated with higher odds of chronic use (adjusted odds ratio, 5.9; 95% confidence interval 1.6-21), as was preoperative pain duration of ≥4 years (adjusted odds ratio, 3.3; 95% confidence interval 1.1-9.8). Patient characteristics, surgical variables, ODI value, and SRS-22r score were not significantly associated with chronic postoperative opioid use.

CONCLUSION

Preoperative opioid use and duration of pain of ≥4 years were associated with higher odds of chronic opioid use after ASD surgery.

LEVEL OF EVIDENCE

III.

Combined effects of lifestyle and psychosocial factors on central sensitization in patients with chronic low back pain: A cross-sectional study

BACKGROUND

Central sensitization is one cause of chronic low back pain. Lifestyle and psychosocial factors are involved in the exacerbation of central sensitization. However, the combined effects of these factors on central sensitization in patients with chronic low back pain are unclear. The objective of this study was to investigate the combined effects of lifestyle and psychosocial factors on central sensitization in patients with chronic low back pain.

METHODS

This was a cross-sectional study. The participants were recruited from three orthopedic clinics for a total of 70 patients with chronic low back pain. Data were analyzed using hierarchical multiple regression analysis. In Model 1, lifestyle factors such as sleep quality, physical activity, sitting time, and perceived stress were included. Model 2 included psychosocial factors (pain catastrophizing, anxiety, and depression).

RESULTS

The data showed that sleep (b = 0.30) and perceived stress (b = 0.47) were significantly correlated in Model 1, and anxiety (b = 0.41) and perceived stress (b = 0.27) were significantly correlated in Model 2. Furthermore, contributions from sleep (b = 0.14) decreased, and no significant correlations were observed. The coefficient of determination increased significantly from Model 1 to Model 2 (ΔR ² = 0.12, p < 0.05).

CONCLUSIONS

In this study, we clarified that perceived stress and anxiety were correlated with central sensitization in patients with chronic low back pain. In addition, sleep quality mediates anxiety and may be associated with central sensitization.

Pain Management and Rehabilitation for Central Sensitization in Temporomandibular Disorders: A Comprehensive Review

Temporomandibular disorders (TMD) are a group of musculoskeletal diseases affecting masticatory muscles and temporomandibular joints (TMJ). In this context, the chronic TMD could be considered as a condition with chronic primary orofacial pain, presenting as myofascial TMD pain or TMJ arthralgia. In this context, myogenous TMD may present overlapping features with other disorders, such as fibromyalgia and primary headaches, characterized by chronic primary pain related to dysfunction of the central nervous system (CNS), probably through the central sensitization. This phenomenon could be defined as an amplified response of the CNS to sensory stimuli and peripheral nociceptive, characterized by hyperexcitability in the dorsal horn neurons in the spinal cord, which ascend through the spinothalamic tract. The main objectives of the management of TMD patients are: decreasing pain, increasing TMJ function, and reducing the reflex masticatory muscle spasm/pain. The first-line treatments are physical therapy, pharmacological drugs, occlusal splints, laser therapy, extracorporeal shockwave therapy, transcutaneous electrical nerve stimulation, and oxygen–ozone therapy. Although all these therapeutic approaches were shown to have a positive impact on the central sensitization of TMD pain, there is still no agreement on this topic in the scientific literature. Thus, in this comprehensive review, we aimed at evaluating the evidence on pain management and rehabilitation for the central sensitization in TMD patients.

Associations between visceral fat chronic low back pain and central sensitization in patients with lumbar spinal stenosis

BACKGROUND

Pain sensitization may be one of the mechanisms contributing to chronic low back pain (CLBP).

OBJECTIVE

To evaluate the association between visceral fat, CLBP, and central sensitization (CS); describe the relationship between low back pain (LBP) intensity and CS; and identify possible correlation between visceral fat and LBP intensity.

METHODS

Patients with CLBP were divided using their CS inventory (CSI) scores into low- (CSI < 40) and high-CSI (CSI ⩾ 40) subgroups. We compared computed tomography (CT) measurements and scores for association with pain according to the visual analogue scale (VAS) between the two groups.

RESULTS

The low-CSI and the high-CSI groups had 47 patients (67.1%; 21 men, 26 women) and 23 patients (32.9%; 11 men and 12 women), respectively. The high-CSI group had a significantly higher mean VAS score (p< 0.01) and estimated mean visceral fat area (p< 0.05) than the low-CSI group. There was a moderate positive correlation between VAS score and visceral fat (standardised partial regression coefficient: 0.659, p< 0.01) in the high-CSI group according to multiple linear regression analysis adjusted for age and sex.

CONCLUSIONS

Visceral fat is associated with CLBP, regardless of sex or age, and may be a potential therapeutic target for CLBP with CS.

Immune-inflammatory and hypothalamic-pituitary-adrenal axis biomarkers are altered in patients with non-specific low back pain: A systematic review

This systematic review aimed to investigate immune-inflammatory and hypothalamic-pituitary-adrenal (HPA) axis biomarkers in individuals with non-specific low back pain (NSLBP) compared to healthy control. The search was performed in five databases until 4 November 2021. Two reviewers independently conducted screenings, data extraction, risk of bias, and methodological quality assessment of 14 unique studies. All studies reported the source of the fluid analyzed: nine studies used serum, two used plasma, one used serum and plasma, and two studies used salivary cortisol. We found preliminary and limited evidence (only one study for each biomarker) of increased levels in growth differentiation factor 15 (GDF-15), interleukin-23 (IL-23), transforming growth factor–beta (TGF-β), and soluble tumor necrosis factor receptor 1 (sTNF-R1) in NSLBP. Inconsistent and limited evidence was identified for interleukin-10 (IL-10). Although C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor–alpha (TNF-α) levels appear to increase in NSLBP, only one study per each biomarker reported statistically significant differences. Interleukin-1 beta (IL-1β), interleukin-17 (IL-17), interferon gamma (IFN-γ), and high-sensitivity CRP (hsCRP) showed no significant differences. Regarding cortisol, one study showed a significant increase and another a significant decrease. More robust evidence between GDF-15, IL-23, TGF-β, and sTNF-R1 with NSLBP is needed. Moreover, contrary to the findings reported in previous studies, when comparing results exclusively with healthy control, insufficient robust evidence for IL-6, TNF-α, and CRP was found in NSLBP. In addition, cortisol response (HPA-related biomarker) showed a dysregulated functioning in NSLBP, with incongruent evidence regarding its directionality. Therefore, our effort is to find adjusted evidence to conclude which immune-inflammatory and HPA axis biomarkers are altered in NSLBP and how much their levels are affected.

Chiropractic Care and Quality of Life Among Office Workers With Nonspecific Pain: A Cross-Sectional Study

Objective

The aim of this study was to evaluate the quality of life by a self-administered World Health Organization Quality of Life short version survey (WHOQoL-BREF) among office workers with nonspecific pain receiving chiropractic care in Istanbul, Turkey.

Methods

This cross-sectional study included 77 office workers (age interval, 18-65) with nonspecific neck, thoracic, back and/or extremity pain who underwent chiropractic care. Two weeks later, the quality of life was evaluated by a self-administered WHOQoL-BREF. The Numeric Pain Scale to evaluate the perceived pain was administered to all of the participants in the beginning and at the end of the study. Group-level changes on WHOQoL-BREF total score and subdimensions were compared according to descriptive data of office workers. The significance level was set at P ≤ .05.

Results

WHOQoL-BREF scale scores after chiropractic care (mean ± standard deviation) were 71.21% ± 7.91% (total score), 81.49% ± 14.43% (general health), 80.38% ± 10.49% (physical health), 73.16% ± 11.68% (psychological), 70.41% ± 12.43% (social), and 65.58% ± 10.91% (environment). Numeric Pain Scale scores decreased in a statistically significant way when compared with baseline (P ≤ .05). The descriptive statistical analysis of WHOQoL-BREF dimensions revealed that women had significantly higher scores than men, the 18-to-35 age group had higher scores compared with the 50-to-65 age group, and those married had significantly higher scores than those who were not married (P ≤ .05).

Conclusion

The findings of our study suggest that chiropractic care had positive effects on the quality of life of office workers.

Preoperative dynamic quantitative sensory testing in remote pain-free areas is associated with axial pain after posterior cervical spinal surgeries

BACKGROUND

Postoperative axial pain (PAP), characterized by pain and/or stiffness around the posterior neck, periscapular areas and/or shoulder region, is a vexing complication affecting 5-60% of patients undergoing posterior cervical decompression. Given its relatively high frequency and negative impact on patients' physical and mental status, efforts preoperatively to confirm patients at risk of developing PAP to offer more efficient pain management to minimize this complication have a high priority. The aim of this study is to investigate the role of preoperative dynamic quantitative sensory testing (QST) in predicting the PAP after posterior cervical decompression.

METHODS

This longitudinal observational study included 122 patients with degenerative cervical myelopathy undergoing laminoplasty or laminectomy. Preoperatively, all patients underwent the assessment of pressure pain thresholds (PPTs) at local and remote pain-free areas and both temporal summation (TS) and conditioned pain modulation (CPM) at remote pain free-areas. These patients underwent further pain-related, psychosocial and clinical function assessments before and/or after operation.

RESULTS

In the present study, 21 patients (21/122, 17.2%) developed PAP, and the 6-month postoperative follow-up demonstrated that 8 of these 21 patients developed chronic PAP (CPAP). All preoperative covariates with significant differences between the PAP and non-PAP groups were subjected to multivariate logistic regression, and the presence of preoperative axial pain, surgical plan including C2 decompression, total international physical activity questionnaire score (cutoff value [CV]: 2205.5, sensitivity: 82.4%; specificity: 61.1%) and TS value (CV: 2.5, sensitivity: 42.9%; specificity: 83.2%) were independently associated with PAP (P < 0.05). Logistic regression further revealed that the presence of preoperative axial pain, TS value (CV: 2.5, sensitivity: 62.5%; specificity: 83.2%) and CPM value (CV: 0.65, sensitivity: 87.5%; specificity: 61.4%) were significant predictors of CPAP (P < 0.05).

CONCLUSIONS

The findings of this study support the hypothesis that preoperative endogenous pain modulation efficiency may be associated with axial pain after posterior cervical decompression. Clinically, preoperative estimation of both TS and CPM in remote pain-free areas may provide additional useful information for identifying patients who may be at risk of developing both PAP and CPAP, which may be beneficial in enabling stratification in the perioperative period of patients based on individual vulnerabilities to avoid/reduce this complication.

Central sensitization and adult attention deficit hyperactivity disorder in medical students with chronic back pain: a cross-sectional study

Background

Chronic back pain is a common health complaint among university students. A subset of chronic back pain patients suffer from increased pain sensitivity, a process termed central sensitization. Chronic pain is also associated with cognitive dysfunction, involving attention, memory, and learning. Those are key features of adult attention deficit hyperactivity disorder. This study aimed to assess the associations between adult attention deficit hyperactivity disorder and central sensitization in students with chronic back pain.

Results

Two hundred twenty-seven students completed the survey, and 90 (39.6%) had back pain for more than 3 months. Students with back pain had significantly higher central sensitization (P<0.01) and higher attention deficit scores (P=0.05). Significant positive correlations were found between scores of the two questionnaires (r= 0.55, P<0.01). Regression analysis adjusted for age and gender showed that higher attention deficit scores were associated with back pain (odd’s ratio:1.025, P=0.05). The odd’s ratio was attenuated after adding central sensitization to the model (odd’s ratio: 0.99, P=0.70).

Conclusions

The findings of this study suggest that attention deficit hyperactivity disorder is associated with elevated central sensitization in patients with chronic back pain. Our results support the hypothesis that central sensitization mediates the effect of attention deficit on back pain.

Using quantitative sensory testing to predict attrition in an interdisciplinary pain management program: a pilot study

Aim: To determine the extent to which quantitative sensory testing (QST) predicted attrition in an interdisciplinary pain program (IPP). Patients & methods: Participants (n = 53) enrolled in an IPP completed pretreatment assessments of QST and the PROMIS-29 quality of life survey. Results & conclusion: Compared with completers, non-completers (24.5%) reported significantly higher pain intensity (7.1, 95% CI [5.8, 8.4] versus 5.4, 95% CI [4.8, 6.1]) and cold hyperalgesia (14.6°C, 95% CI [8.8, 20.4] versus 7.5°C, 95% CI [4.8, 6.1]), with both variables also predicting attrition. This finding highlights a potentially novel and clinically significant use of QST. Higher overall pain intensity and the presence of remote cold hyperalgesia may identify patients at risk for dropping out of an IPP.

[Therapeutic injections and manual medicine in low-back pain : Bimodal synergies between evidence and empiricism]

Hintergrund

Angelehnt an die zielorientierte Therapieplanung und -führung in der Versorgung chronisch Rheumakranker, plädiert der Autor bei Patienten mit (chronischem) degenerativem tiefem Rückenschmerz (TRS), orientiert an den differenzialtherapeutischen Grundsätzen der Manuellen Medizin (MM), und unter Kenntnis von Techniken und Evidenzen therapeutischer Lokalinfiltrationen (TLI), für die Etablierung eines strukturierten mechanismenbasierten Therapiekonzeptes im Sinne des „treat to target“ (T2T) im ambulanten schmerztherapeutischen Versorgungsbereich.

Diagnostik

Dies setzt eine konsequente (Primär‑)Diagnostik mit Schmerzanalyse unter der Prämisse, dass TRS, wenn strukturell-funktionell bedingt, immer spezifisch ist, voraus. Eine breite biopsychosoziale Anamnese und strukturbezogene klinisch-bildgebende (Ausschluss‑)Diagnostik mit funktioneller Differenzierung nach MM-Grundsätzen und ggf. interventionelle Blocks, sollten am Ende zur Formulierung einer 3‑Ebenen-Diagnose als Voraussetzung zu einer mechanismenbasiert-zielorientiert-hierarchischen Stufentherapie bei TRS führen. Diese wird in diesem Artikel pragmatisch fallorientiert, unter Implementierung von Techniken und Evidenzen der TLI und MM, vorgestellt.

Mechanical Needling with Sterile Water versus Steroids Injection for Facet Joint Syndrome: A Retrospective Observational Study

Objective. This present study aimed to explore the clinical effects of ultrasound-guided (USG) mechanical needling with sterile water injection for lumbar facet joint syndrome. Methods. This was a retrospective cohort study that assessed the clinical outcome of ageing patients who received USG mechanical needling with sterile water injection. In addition, the clinical outcome of age- and gender-matched patients randomly selected from patients who received mechanical needling with sterile water was compared to the patients injected with steroids in a 2 : 1 ratio. The data were extracted from the medical records of ageing patients with facet joint syndrome who received USG injection at the lumbosacral spine by the first author. Low back pain or axial pain, and leg pain or radicular pain were assessed by the visual analogue scale (VAS), and gait ability with walking distance was obtained at 6 different time points. Results. A total of 4,276 medical records were examined. Four thousand two hundred twenty-eight ageing patients received needling with sterile water injection and found that the efficacy lasted up to 6 months. Ninety-six patients were compared with 48 patients who received steroid injection. Those who received steroids had less back and leg pain at 1 week after injection; however, pain returned at 3 months and 6 months after injection. Conclusions. USG mechanical needling with sterile water could help relieve axial and radicular pain for at least 6 months. Reduced sensitization and removal of calcification and fibrosis were all possible mechanisms.Keywords: Mechanical needling, Sterile water, Ultrasound guided (USG) injection, Facet joint syndrome, Pain

Neuropathic Pain in Multiple Sclerosis and Its Animal Models: Focus on Mechanisms, Knowledge Gaps and Future Directions

Multiple sclerosis (MS) is a multifaceted, complex and chronic neurological disease that leads to motor, sensory and cognitive deficits. MS symptoms are unpredictable and exceedingly variable. Pain is a frequent symptom of MS and manifests as nociceptive or neuropathic pain, even at early disease stages. Neuropathic pain is one of the most debilitating symptoms that reduces quality of life and interferes with daily activities, particularly because conventional pharmacotherapies do not adequately alleviate neuropathic pain. Despite advances, the mechanisms underlying neuropathic pain in MS remain elusive. The majority of the studies investigating the pathophysiology of MS-associated neuropathic pain have been performed in animal models that replicate some of the clinical and neuropathological features of MS. Experimental autoimmune encephalomyelitis (EAE) is one of the best-characterized and most commonly used animal models of MS. As in the case of individuals with MS, rodents affected by EAE manifest increased sensitivity to pain which can be assessed by well-established assays. Investigations on EAE provided valuable insights into the pathophysiology of neuropathic pain. Nevertheless, additional investigations are warranted to better understand the events that lead to the onset and maintenance of neuropathic pain in order to identify targets that can facilitate the development of more effective therapeutic interventions. The goal of the present review is to provide an overview of several mechanisms implicated in neuropathic pain in EAE by summarizing published reports. We discuss current knowledge gaps and future research directions, especially based on information obtained by use of other animal models of neuropathic pain such as nerve injury.

Association between temporal summation and conditioned pain modulation in chronic low back pain: baseline results from 2 clinical trials

Introduction

Temporal summation (TS) and conditioned pain modulation (CPM) represent different aspects of central pain processing. Their relationship and differential performance within distinct body locations are not well understood.

Objectives

To examine the association between TS and CPM in chronic low back pain and the influence of testing location on this relationship.

Methods

We analyzed baseline data from 2 clinical trials on participants with chronic low back pain (n = 264; 47.3% female; mean age = 41 years, SD = 12; mean pain = 5.3/10, SD = 1.4). Measures used included questionnaires assessing pain and negative affect, phasic thermal TS at the hand (thenar) and the lower back (lumbar), followed by CPM that included a thermal testing stimulus (Heat-6, the temperature where pain rating is 6/10) and a cold-pressor conditioning stimulus. Nonparametric, proportional odds logistic regression was used to model thenar, and separately, lumbar TS, using CPM, Heat-6, negative affect, and demographics.

Results

Our models revealed a small association (βs = 0.17, P = 0.01) between reduced CPM and heightened TS at both testing sites, regardless of demographics or negative affect.

Conclusion

Results suggest a modest association between TS and CPM, irrespective of anatomical testing location, demographics, and negative affect. These findings will help improve the methodology and interpretation of TS and CPM measurement in clinical pain populations.

Do patients with low back pain and central sensitization have differences in physical fitness?

INTRODUCTION

Low back pain is one of the main musculoskeletal complaints, and may be associated with central sensitization (CS). The physical capacity of patients with low back pain and CS is not very clear.

METHODS

A cross-sectional study, with 92 patients divided into two groups according to their risk of CS. The patient's physical capacity ability was assessed using 6-min walking test (6MWT); timed up and go test (TUG); sit-to-stand test (STS); and trunk flexor, extensor and side-bridge endurance tests. In addition, participants completed questionnaires regarding disability, kinesiophobia, catastrophization and quality of life.

RESULTS

The group with a higher risk of CS had worst performance in the 6MWT (U = 1248; p < 0.001), STS (t(83) = 3.63; p < 0.001) and TUG (t(83) = -4.46; p < 0.001). Similarly, endurance in the right (U = 1453,5; p = 0,002) and left (U = 1467; p = 0,003) side-bridge tests, and the trunk extensor test (U = 1546; p = 0,003) was worse. Disability (U = 1272; p < 0.001), physical capacity kinesiophobia (t(83) = -2.21; p = 0.03) work kinesiophobia (U = 1452; p < 0.001), and pain catastrophization (t(77.57) = -5.03; p < 0.001), were also higher in the group with a higher risk of CS. Quality of life indicators were worse in the higher risk group for all domains of the EQ-5D-3L: Mobility (X²(1) = 12.92; p < 0.001), self-care (X²(1) = 16,3; p = 0,012), usual activities (X²(2) = 14.14; p = 0.001), pain (X²(2) = 27.79; p < 0.001), anxiety and depression (X²(2) = 15.05; p = 0.001).

CONCLUSION

Patients with low back pain and higher risks of CS appear to show lower performance in physical capacity tests, higher rates of disability, kinesiophobia, pain catastrophization, and lower quality of life compared to those with lower risks of CS.

Potential Nociceptive Role of the Thoracolumbar Fascia: A Scope Review Involving In Vivo and Ex Vivo Studies

Nociceptive innervation of the thoracolumbar fascia (TLF) has been investigated over the past few decades; however, these studies have not been compiled or collectively appraised. The purpose of this scoping review was to assess current knowledge regarding nociceptive innervation of the TLF to better inform future mechanistic and clinical TLF research targeting lower back pain (LBP) treatment. PubMed, ScienceDirect, Cochrane, and Embase databases were searched in January 2021 using relevant descriptors encompassing fascia and pain. Eligible studies satisfied the following: (a) published in English; (b) preclinical and clinical (in vivo and ex vivo) studies; (c) original data; (d) included quantification of at least one TLF nociceptive component. Two-phase screening procedures were conducted by a pair of independent reviewers, after which data were extracted and summarized from eligible studies. The search resulted in 257 articles of which 10 met the inclusion criteria. Studies showed histological evidence of nociceptive nerve fibers terminating in lower back fascia, suggesting a TLF contribution to LBP. Noxious chemical injection or electrical stimulation into fascia resulted in longer pain duration and higher pain intensities than injections into subcutaneous tissue or muscle. Pre-clinical and clinical research provides histological and functional evidence of nociceptive innervation of TLF. Additional knowledge of fascial neurological components could impact LBP treatment.

Central sensitisation in primary Sjögren Syndrome and its effect on sleep quality

OBJECTIVE

The aim of the present study is to evaluate the presence and frequency of central sensitisation (CS) in primary Sjögren Syndrome (pSS) and to determine the effect of CS on sleep quality.

MATERIALS AND METHODS

In this cross-sectional study, 50 patients diagnosed with pSS between the ages of 18 and 75 were included. The healthy control group was composed of 43 healthcare workers. Each participant underwent a physical examination, and demographic data and the medications they used were recorded. Central sensitisation inventory and Pittsburgh Sleep Quality Index questionnaires were filled in to garner data on CS and sleep quality, respectively, from all participants.

RESULTS

While central sensitisation inventory  >40 was detected in 74% of pSS patients, it was 25.6% in healthy controls, and there is a statistically significant difference between the groups (p < .05). A correlation analysis of the central sensitisation inventory and Pittsburgh Sleep Quality Index values of all participants revealed a statistically significant correlation between all parameters other than the duration of sleep (p < .05).

CONCLUSIONS

CS was found to have a negative effect on sleep quality in patients with pSS. We suggest that the cause of widespread pain seen in patients with pSS as the possible development of CS should be considered.

Brain Circuits Involved in the Development of Chronic Musculoskeletal Pain: Evidence From Non-invasive Brain Stimulation

It has been well-documented that the brain changes in states of chronic pain. Less is known about changes in the brain that predict the transition from acute to chronic pain. Evidence from neuroimaging studies suggests a shift from brain regions involved in nociceptive processing to corticostriatal brain regions that are instrumental in the processing of reward and emotional learning in the transition to the chronic state. In addition, dysfunction in descending pain modulatory circuits encompassing the periaqueductal gray and the rostral anterior cingulate cortex may also be a key risk factor for pain chronicity. Although longitudinal imaging studies have revealed potential predictors of pain chronicity, their causal role has not yet been determined. Here we review evidence from studies that involve non-invasive brain stimulation to elucidate to what extent they may help to elucidate the brain circuits involved in pain chronicity. Especially, we focus on studies using non-invasive brain stimulation techniques [e.g., transcranial magnetic stimulation (TMS), particularly its repetitive form (rTMS), transcranial alternating current stimulation (tACS), and transcranial direct current stimulation (tDCS)] in the context of musculoskeletal pain chronicity. We focus on the role of the motor cortex because of its known contribution to sensory components of pain via thalamic inhibition, and the role of the dorsolateral prefrontal cortex because of its role on cognitive and affective processing of pain. We will also discuss findings from studies using experimentally induced prolonged pain and studies implicating the DLPFC, which may shed light on the earliest transition phase to chronicity. We propose that combined brain stimulation and imaging studies might further advance mechanistic models of the chronicity process and involved brain circuits. Implications and challenges for translating the research on mechanistic models of the development of chronic pain to clinical practice will also be addressed.

Systematic Literature Review of Spinal Cord Stimulation in Patients With Chronic Back Pain Without Prior Spine Surgery

OBJECTIVE

Low back pain is the leading cause of disability worldwide and one of the most common reasons for seeking healthcare. Despite numerous care strategies, patients with low back pain continue to exhibit poor outcomes. Spinal cord stimulation (SCS) is an evidence-based therapeutic modality for patients with failed back surgery syndrome. For patients without a surgical lesion or history, minimally invasive interventions that provide long-term reduction of chronic back pain are needed. Therefore, we conducted a systematic review of the evidence on SCS therapy in patients with chronic back pain who have not undergone spinal surgery.

MATERIALS AND METHODS

A systematic literature search was performed to identify studies reporting outcomes for SCS in chronic back pain patients (with or without secondary radicular leg pain) without prior surgery using date limits from database inception to February 2021. Study results were analyzed and described qualitatively.

RESULTS

A total of ten primary studies (16 publications) were included. The included studies consistently demonstrated favorable outcomes in terms of pain reduction and functional improvement following SCS therapy. Improvements also occurred in quality of life scores; however, not all studies reported statistically significant findings. Additionally, the studies reported that SCS resulted in high patient satisfaction, reductions in opioid use, and an acceptable safety profile, although these data were more limited.

CONCLUSION

Findings suggest that SCS is a promising, safe, minimally invasive, and reversible alternative option for managing chronic back pain in patients who have not undergone spinal surgery.