A Subgroup of Chronic Low Back Pain Patients With Central Sensitization

Biopsychosocial contributors to irritability in individuals with shoulder or low back pain

OBJECTIVES

Irritability is a foundational clinical reasoning concept in rehabilitation to evaluate reactivity of the examination and treatment. While originally theorized to reflect tissue damage, a large body of evidence supports pain is a biopsychosocial experience impacted by pain sensitivity and psychological factors. Therefore, the purpose of this study was to examine biopsychosocial contributors to irritability.

METHODS

40 patients with shoulder (n = 20) and low back (n = 20) pain underwent Quantitative Sensory Testing (QST) (Pressure Pain Threshold, Heat Pain Threshold, Conditioned Pain Modulation, Temporal Summation), completed pain-related psychological questionnaires, an Exercise-Induced Hypoalgesia protocol, and standardized irritability assessment based on Clinical Practice Guidelines. Participants were then categorized as irritable or not irritable based on Maitland's criteria and by irritability level based on Clinical Practice Guidelines. An independent samples t-test examined for differences in QST and psychological factors by irritability category. A MANOVA examined for differences in QST and psychological factors by irritability level (high, moderate, low).

RESULTS

Significantly lower heat and pressure pain thresholds at multiple locations (p < 0.05), as well as less efficient conditioned pain modulation (p = 0.02), were demonstrated in individuals categorized as irritable. Heat and pressure pain thresholds were also significantly lower in patients with high irritability compared to other levels. Significantly higher depression and anger, as well as lower self-efficacy, were reported in individuals with an irritable presentation.

DISCUSSION/CONCLUSION

Biopsychosocial factors, including widespread hyperalgesia and elevated psychological factors, may contribute to an irritable presentation.

Nociplastic Pain and Pain-Motivated Drinking in Alcohol Use Disorder

Heavy chronic alcohol use may produce pain amplification through neurochemical and neuroplastic changes at multiple levels of the nervous system. Similar changes are thought to underlie nociplastic pain. The American College of Rheumatology Fibromyalgia Survey has been used as a surrogate for nociplastic pain, including among individuals with alcohol use disorder (AUD). However, studies linking nociplastic pain to pain-motivated drinking are lacking. The present study aimed to determine if nociplastic pain is associated with pain-motivated drinking in AUD. To achieve this aim, a new scale-the Pain-Motivated Drinking Scale (PMDS)-was developed to measure how often participants were motivated by pain to drink alcohol. Measurement properties of this new scale were determined, including its factor structure, internal consistency reliability, and construct validity. In this cross-sectional observational study, participants with AUD (n = 138) were consecutively recruited from the patient pool at an academic addiction treatment facility. Seventy-two percent (95, 72.0%) reported they drank alcohol "to get relief from physical pain" at least some of the time, and over forty-two percent (56, 42.4%) reported pain relief motivated their drinking at least half of the time. PMDS had a single-factor structure, strong internal consistency reliability, and construct validity. A multiple hierarchical linear regression was run to determine if nociplastic pain was associated with pain-motivated drinking. Nociplastic pain was associated with PMDS even after controlling for potential confounders and pain severity. These findings suggest nociplastic pain is uniquely associated with pain-motivated drinking in AUD. PERSPECTIVE: Nociplastic pain is independently associated with pain-motivated drinking in alcohol use disorder (AUD). The Pain-Motivated Drinking Scale (PMDS) is a new scale to measure how often people drink to cope with pain. PMDS has promising psychometric properties. Nociplastic pain may be uniquely associated with pain-motivated drinking in AUD.

Cognition is selectively impaired in males with spinal pain: A retrospective analysis of data from the Longitudinal Study of Ageing Danish Twins

Cognitive decline and spinal pain (back pain [BP] and neck pain [NP]) represent a major public health challenge, yet the potential relationship between them remains elusive. A retrospective analysis of the Longitudinal Study of Ageing Danish Twins was performed to determine any potential relationships between BP/NP and cognitive function adjusting for age, sex, educational and socioeconomic status. A total of 4731 adults (2788 females/1943 males) aged 78 ± 6 (SD) years were included in the analysis. We observed a 1-month prevalence of 25% with BP, 21% with NP and 11% for combined BP/NP. While there were no differences in cognition scores for males and females reporting combined BP/NP, compared to those without combined BP/NP (34.38 points [95% confidence interval (CI) = 31.88, 36.88] vs. 35.72 points [95% CI = 35.19, 36.26]; P = 0.180; and 35.72 points [95% CI = 35.19, 36.26] vs. 35.85 points [95% CI = 35.39, 36.31]; P = 0.327; for male and females, respectively), an adjusted analysis revealed that males with combined BP/NP presented with lower cognitive scores compared to males without combined BP/NP (81.26 points [95% CI = 73.80, 88.72] vs. 79.48 points [95% CI = 70.31, 88.66]; P = 0.043). The findings of this hypothesis-generating study may highlight a potential sex-specific association between spinal pain and later-life neurodegeneration.

Sensory profiles and their role in the persistence of central sensitization symptoms in low back pain. A prospective cohort study

INTRODUCTION

Acute lower back pain can lead to neuroplastic changes in the central nervous system, and symptoms of central sensitization after 12 weeks. While sensory sensitivity has been shown to predict symptoms of central sensitization, trait sensory profiles may be prognostic in the persistence of central sensitization symptoms in low back pain over time.

OBJECTIVE

To examine sensory profiles as prognostic symptoms of central sensitization in people with acute low back pain.

METHODS

A longitudinal type 2 prognostic factor research study was performed according to the PROGRESS framework. Baseline and 12-week follow-up measures were taken using the Adolescent/Adult Sensory Profile and the Central Sensitization Inventory measures. Study participants were consecutively included from primary care physiotherapy practices. Univariable, and multivariable regression analyses were performed to adjust sensory profiles based on previous history of low back pain, baseline Central Sensitization Inventory scores, level of pain, disability, age, and duration of low back pain.

RESULTS

After adjustment, the sensory profiles of Low Registration B = 0.44, 95%CI (0.18, 0.70), Sensation Seeking B = 0.38, 95%CI (0.19, 0.57), Sensory Sensitive B = 0.49, 95%CI (0.25, 0.74), Sensation Avoiding B = 0.40, 95% CI (0.15, 0.65) was significantly associated with the persistence of central sensitization symptoms (N = 103).

CONCLUSION

Sensory profiles may predict symptoms of central sensitization after 12 weeks in people with acute low back pain.

Paraspinal muscle oxygenation and mechanical efficiency are reduced in individuals with chronic low back pain

This study aimed to compare the systemic and local metabolic responses during a 5-min trunk extension exercise in individuals with chronic low back pain (CLBP) and in healthy individuals. Thirteen active participants with CLBP paired with 13 healthy participants performed a standardised 5-min trunk extension exercise on an isokinetic dynamometer set in continuous passive motion mode. During exercise, we used near-infrared spectroscopy to measure tissue oxygenation (TOI) and total haemoglobin-myoglobin (THb). We used a gas exchange analyser to measure breath-by-breath oxygen consumption (V̇O2) and carbon dioxide produced (V̇CO2). We also calculated mechanical efficiency. We assessed the intensity of low back pain sensation before and after exercise by using a visual analogue scale. In participants with CLBP, low back pain increased following exercise (+ 1.5 units; p < 0.001) and THb decreased during exercise (- 4.0 units; p = 0.043). Paraspinal muscle oxygenation (65.0 and 71.0%, respectively; p = 0.009) and mechanical efficiency (4.7 and 5.3%, respectively; p = 0.034) were both lower in participants with CLBP compared with healthy participants. The increase in pain sensation was related to the decrease in tissue oxygenation (R2 = - 0.420; p = 0.036). Decreases in total haemoglobin-myoglobin and mechanical efficiency could involve fatigability in exercise-soliciting paraspinal muscles and, therefore, exacerbate inabilities in daily life. Given the positive correlation between tissue oxygenation and exercise-induced pain exacerbation, muscle oxygenation may be related to persisting and crippling low back pain.

Reduction of Chronic Primary Low Back Pain by Spinal Manipulative Therapy is Accompanied by Decreases in Segmental Mechanical Hyperalgesia and Pain Catastrophizing: A Randomized Placebo-controlled Dual-blind Mixed Experimental Trial

Chronic primary low back pain (CPLBP) refers to low back pain that persists over 3 months, that cannot be explained by another chronic condition, and that is associated with emotional distress and disability. Previous studies have shown that spinal manipulative therapy (SMT) is effective in relieving CPLBP, but the underlying mechanisms remain elusive. This randomized placebo-controlled dual-blind mixed experimental trial (NCT05162924) aimed to investigate the efficacy of SMT to improve CPLBP and its underlying mechanisms. Ninety-eight individuals with CPLBP and 49 controls were recruited. Individuals with CPLBP received SMT (n = 49) or a control intervention (n = 49), 12 times over 4 weeks. The primary outcomes were CPLBP intensity (0-100 on a numerical rating scale) and disability (Oswestry Disability Index). Secondary outcomes included pressure pain thresholds in 4 body regions, pain catastrophizing, Central Sensitization Inventory, depressive symptoms, and anxiety scores. Individuals with CPLBP showed widespread mechanical hyperalgesia (P < .001) and higher scores for all questionnaires (P < .001). SMT reduced pain intensity compared with the control intervention (mean difference: -11.7 [95% confidence interval, -11.0 to -12.5], P = .01), but not disability (P = .5). Similar mild to moderate adverse events were reported in both groups. Mechanical hyperalgesia at the manipulated segment was reduced after SMT compared with the control intervention (P < .05). Pain catastrophizing was reduced after SMT compared with the control intervention (P < .05), but this effect was not significant after accounting for changes in clinical pain. Although the reduction of segmental mechanical hyperalgesia likely contributes to the clinical benefits of SMT, the role of pain catastrophizing remains to be clarified. PERSPECTIVE: This randomized controlled trial found that 12 sessions of SMT yield greater relief of CPLBP than a control intervention. These clinical effects were independent of expectations, and accompanied by an attenuation of hyperalgesia in the targeted segment and a modulation of pain catastrophizing.

Preliminary investigation of the interactive role of physiological arousal and insomnia complaints in gray matter volume alterations in chronic widespread pain

STUDY OBJECTIVES

Brain regions involved in insomnia and chronic pain are overlapping and diffuse. The interactive role of physiological arousal in associations between insomnia symptoms and neural regions is unknown. This preliminary study examined whether arousal interacted with sleep in associations with gray matter volume of frontal (dorsolateral prefrontal cortex, anterior cingulate cortex) and temporal (right/left hippocampus) regions in adults with chronic widespread pain and insomnia complaints.

METHODS

Forty-seven adults with chronic widespread pain and insomnia (mean age = 46.00, standard deviation = 13.88, 89% women) completed 14 daily diaries measuring sleep onset latency (SOL), wake time after sleep onset, and total sleep time (TST), as well as Holter monitor assessments of heart rate variability (measuring physiological arousal), and magnetic resonance imaging. Multiple regressions examined whether average SOL, wake time after sleep onset, or TST were independently or interactively (with arousal/heart rate variability) associated with dorsolateral prefrontal cortex, anterior cingulate cortex, and left/right hippocampus gray matter volumes.

RESULTS

Shorter TST was associated with lower right hippocampus volume. TST also interacted with arousal in its association with right hippocampal volume, Specifically, shorter TST was associated with lower volume at highest and average arousal levels. SOL interacted with arousal in its association with anterior cingulate cortex volume, such that, among individuals with lowest arousal, longer SOL was associated with lower volume.

CONCLUSIONS

Preliminary findings highlight the interactive roles of physiological arousal and insomnia symptoms in associations with neural structure in chronic widespread pain and insomnia. Individuals with the highest physiological arousal may be particularly vulnerable to the impact of shorter TST on hippocampal volume loss. Reducing SOL may only impact anterior cingulate cortex volume in those with lower physiological arousal.

CITATION

Curtis AF, Nair N, Hayse B, et al. Preliminary investigation of the interactive role of physiological arousal and insomnia complaints in gray matter volume alterations in chronic widespread pain. J Clin Sleep Med. 2024;20(2):293-302.

Presence of endometriosis and chronic overlapping pain conditions negatively impacts the pain experience in women with chronic pelvic-abdominal pain: A cross-sectional survey

BACKGROUND

Evidence of overlap between endometriosis and chronic pain conditions is emerging; however, little is known about how the pain experience differs based on the presence or absence of endometriosis.

OBJECTIVES

In a sample of women reporting chronic pelvic-abdominal pain (CPP), the aim of this study was to characterize differences in pain symptomatology between women with and without endometriosis and to examine the influence of chronic overlapping pain conditions (COPCs) on pain among these two groups.

DESIGN

This was a cross-sectional study, based on an online survey.

METHODS

Participants (aged 18+ years) completed a survey collecting pain diagnoses and symptoms assessing pelvic pain severity, pain interference, and pain impact. Independent sample t-tests, chi-square, and multiple linear regression models were employed to analyze group differences in pain symptomatology and COPCs.

RESULTS

Of the 525 respondents with CPP, 25% (n = 133) reported having endometriosis. Women with endometriosis were younger at the onset of pelvic pain, relative to women without endometriosis (p = 0.04). There were no differences in age, race, ethnicity, or duration of pelvic pain between women with and without endometriosis. Women with endometriosis reported higher pelvic pain severity (+0.8, 95% CI = 0.4-1.1), pain interference (+5.9, 95% CI = 2.4-9.3), and pain impact (+1.9, 95% CI = 0.8-2.9). Endometriosis was associated with a higher number of COPCs (p = 0.003), with 25% (n = 33) of women reporting ⩾3 overlapping pain conditions compared with 12% (n = 45) of those without endometriosis. Women with endometriosis had a higher frequency of fibromyalgia (p < 0.001), chronic fatigue syndrome (p < 0.001), and temporomandibular disorder (p = 0.001). The number of COPCs was associated with higher pain severity, interference, and impact, independently of endometriosis.

CONCLUSION

Women with endometriosis experienced higher levels of pain-related burden and COPCs compared with those without endometriosis. Pain intensity, interference, and impact increased with a higher number of pain conditions regardless of endometriosis presence.

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).

Lifestyle factors and psychological factors are associated with central pain processing in service members with persistent low-back pain: A cross-sectional exploratory study

Persistent low-back pain (LBP) is highly prevalent in the military. Altered central pain processing is one of the mechanisms found to underlie persistent LBP. Our aim was to explore which factors are associated with altered pain processing in Dutch service members with persistent LBP. This knowledge may guide clinicians in what factors to address in the treatment of dysfunctional pain processing in service members with persistent LBP. Twenty-one service members with persistent LBP (mean age 34.0 years, 18 males) were included in this cross-sectional exploratory study. Participants completed questionnaires regarding lifestyle and psychological factors. Altered central pain processing was measured by temporal summation of pain to examine the function of the pain facilitatory system and by conditioned pain modulation to examine the pain inhibitory function. Univariable and multivariable linear regression analyses were performed. A higher local temporal summation of pain was associated with a longer sitting time, a higher level of physical activity and a higher level of pain catastrophizing. A higher local conditioned pain modulation was associated with a higher level of pain catastrophizing, anxiety and depression symptoms, and with a lower sleep quality. A higher remote conditioned pain modulation effect was associated with a higher level of physical activity, a higher body mass index and a shorter sitting time. This study succeeded in identifying lifestyle and psychological factors associated with altered pain processing in service members with persistent LBP. Prospective studies are needed to examine causality in these relationships.

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.

Low-dose naltrexone's utility for non-cancer centralized pain conditions: a scoping review

BACKGROUND

At low doses, naltrexone (LDN) has been shown to modulate inflammation through the interruption of microglial cell activation within the central nervous system. One of the most likely contributors to centralized pain is changes in microglial cell processing. Therefore, it has been postulated that LDN can be used to manage patients with pain resulting from central sensitization due to this relationship. This scoping review aims to synthesize the relevant study data for LDN as a novel treatment strategy for various centralized pain conditions.

METHODS

A comprehensive literature search was conducted in PubMed, Embase, and Google Scholar, guided by the Scale for Assessment of Narrative Review Articles (SANRA) criteria.

RESULTS

Forty-seven studies related to centralized pain conditions were identified. Many of the studies were case reports/series and narrative reviews, but a few randomized control trials have been conducted. Overall, the body of evidence revealed improvement in patient-reported pain severity and in outcomes related to hyperalgesia, physical function, quality of life, and sleep. Variability in dosing paradigms and the time to patient response was present in the reviewed studies.

CONCLUSIONS

Evidence synthesized for this scoping review supports the ongoing use of LDN for the treatment of refractory pain in various centralized chronic pain conditions. Upon review of the currently available published studies, it is apparent that further high-quality, well-powered randomized control trials need to be conducted to establish efficacy, standardization for dosing, and response times. In summary, LDN continues to offer promising results in the management of pain and other distressing symptoms in patients with chronic centralized pain conditions.

Adaptation and psychometric evaluation of the Thai version of the modified STarT Back Screening Tool in individuals with neck pain

BACKGROUND

The modified STarT Back Screening Tool (mSBST) can be used to classify individuals with neck pain (NP) into low, medium, and high risk for chronicity. However, the mSBST-Thai version (mSBST-TH) for NP does not exist.

OBJECTIVES

The aims of this study were to adapt the SBST-TH into the mSBST-TH and evaluate its psychometric properties.

METHODS

The adaptation process committee included one researcher, one musculoskeletal physical therapist, and one Thai linguistic expert. A total of 261 participants (aged 20-70 years) with NP in Phitsanulok Province were invited to complete the mSBST-TH, visual analogue scale, neck disability index, fear-avoidance beliefs questionnaire (FABQ), pain catastrophizing scale, EuroQol five-dimensions five-levels questionnaire (EQ5D-5L), and EQ5D-5L-visual analogue scale (EQ5D-5L-VAS). Fifty participants completed the mSBST-TH twice, with an interval of 48 hours to perform test-retest reliability.

RESULTS

The Cronbach's alpha coefficient of the mSBST-TH total score was 0.73. Factor analysis revealed two components, psychosocial and physical. The intraclass correlation coefficient of test-retest reliability was found to be 0.81 for the total score. Moderate correlations were found between the mSBST-TH and all questionnaires, except for the FABQ-work. The discriminative validity was excellent between the mSBST-TH total score and the EQ5D-5L-VAS. The standard error of measurement and minimal detectable change of the mSBST-TH total score were 0.56 and 1.56, respectively. No significant floor and ceiling effects were found.

CONCLUSION

The mSBST-TH was successfully adapted with no ambiguity reported. Furthermore, the mSBST-TH has presented acceptable psychometric evaluation.

Identifying chronic low back pain phenotypic domains and characteristics accounting for individual variation: a systematic review

ABSTRACT

Interpatient variability is frequently observed among individuals with chronic low back pain (cLBP). This review aimed at identifying phenotypic domains and characteristics that account for interpatient variability in cLBP. We searched MEDLINE ALL (through Ovid), Embase Classic and EMBASE (through Ovid), Scopus, and CINAHL Complete (through EBSCOhost) databases. Studies that aimed to identify or predict cLBP different phenotypes were included. We excluded studies that focused on specific treatments. The methodological quality was assessed using an adaptation of the Downs and Black tool. Forty-three studies were included. Although the patient and pain-related characteristics used to identify phenotypes varied considerably across studies, the following were among the most identified phenotypic domains and characteristics that account for interpatient variability in cLBP: pain-related characteristics (including location, severity, qualities, and duration) and pain impact (including disability, sleep, and fatigue), psychological domains (including anxiety and depression), behavioral domains (including coping, somatization, fear avoidance, and catastrophizing), social domains (including employment and social support), and sensory profiling (including pain sensitivity and sensitization). Despite these findings, our review showed that the evidence on pain phenotyping still requires further investigation. The assessment of the methodological quality revealed several limitations. We recommend adopting a standard methodology to enhance the generalizability of the results and the implementation of a comprehensive and feasible assessment framework to facilitate personalized treatments in clinical settings.

The Association Between the Patient Self-Report Survey for the Assessment of Fibromyalgia with Pain Sensitivity and Psychological Factors in Individuals with Musculoskeletal Pain

Purpose

The Patient Self-Report Survey for the Assessment of Fibromyalgia may potentially be a method for subgrouping patients with musculoskeletal pain who have a nociplastic pain presentation. Limited research has explored the convergent validity of this questionnaire against psychophysical measures of pain sensitivity and psychological factors in individuals with musculoskeletal pain. Therefore, the purpose of this study is to examine the strength of the association between total scores on the Patient Self-Report Survey for the Assessment of Fibromyalgia with clinical, pain sensitivity, and psychological factors.

Patients and Methods

As a secondary analysis of a cross-sectional study, participants with shoulder (n = 20) or low back pain (n = 20) completed Quantitative Sensory Testing (QST), pain-related psychological questionnaires, and the Patient Self-Report Survey for the Assessment of Fibromyalgia. A Spearman correlation determined the association between total scores on the Patient Self Report Survey for the Assessment of Fibromyalgia with psychological factors and pain sensitivity behaviorally assessed with QST.

Results

Negative psychological factors demonstrate moderate to strong positive associations with the Patient Self-Report Survey for the Assessment of Fibromyalgia (rho range = 0.36-0.80), suggesting greater negative psychological factors were observed in patients with higher severity of fibromyalgia symptoms. Pain sensitivity factors demonstrated weak to moderate negative associations with The Patient Self-Report Survey for the Assessment of Fibromyalgia (PPT rho range=-0.36- -0.41), suggesting that elevated pain sensitivity was observed in individuals with higher severity of nociplastic pain symptoms.

Conclusion

Collectively, this supports the convergent validity of the Patient Self-Report Survey for the Assessment of Fibromyalgia with psychological and pain sensitivity factors in patients with musculoskeletal pain.

Assessment of Prevalence and Risk Factors for Central Sensitization Related to Shoulder Osteoarthritis and Rotator Cuff Tears Using the Central Sensitization Inventory: A Cross-Sectional Study in Shoulder Surgery Patients

Shoulder disorders occasionally cause intractable pain. Central sensitization (CS) may be involved in such pain. Identifying risk factors associated with CS is crucial for effective pain control. This study aimed to determine the effects of shoulder osteoarthritis and rotator cuff tears (RCT) on CS and associated factors. This study included patients evaluated for CS using the Central Sensitization Inventory (CSI) before surgery for shoulder osteoarthritis, RCT, or cuff tear arthropathy. Patients with a CSI score of 40 or higher were defined as having CS. The relationships between glenohumeral osteoarthritis (GHOA), RCT size, and CS were statistically analyzed. Multiple regression analysis was performed to examine the factors affecting CSI scores. Subjects included 167 patients: 131 patients had RCT without GHOA, 23 had GHOA with RCT, and 13 had GHOA without RCT. The GHOA group had a significantly higher CSI score (27.5 [10.8-40.5] vs. 18.0 [10.0-27.5]) and CS prevalence (27.8% vs. 8.4%) than the RCT without GHOA group. There was no significant correlation between RCT size and CSI scores. Multiple regression analysis showed that female sex, severe pain, and long pain duration were associated with higher CSI scores. Considering the risk factors for CS might be helpful in shoulder treatment.

Patients with neuropathic pain from lumbosacral radiculopathy demonstrate similar pressure pain thresholds and conditioned pain modulation to those with fibromyalgia

OBJECTIVE

The purpose of the study was to evaluate pain thresholds, impairment of the endogenous pain modulatory system, and self-reported cognitive-emotional and central sensitization-related symptoms among three subject groups: a rarely studied patient cohort with neuropathic pain from lumbosacral radiculopathy (NPLSR), patients with fibromyalgia (FM) and healthy controls (HC).

METHODS

Patient-reported pain-related symptomology was evaluated with psychometricallyvalidated questionnaires. Pressure pain threshold (PPT), heat pain threshold (HPT), and cold pain threshold (CPT) were assessed in the low back and contralateral forearm. Conditioned pain modulation (CPM) was evaluated with a recently introduced methodology that accounts for a standard error of measurement.

RESULTS

Compared to the HC subjects, the FM and NPLSR subjects had significantly lower pain thresholds and more CPM impairment. No significant differences in PPT and CPM were observed between the FM and NPLSR groups. Significant group differences were found in self-reported symptoms of depression, anxiety, stress, and central sensitization. Self-reported symptom severity increased in a stair-step fashion, with the HC group scoring lowest and FM group scoring highest.

CONCLUSION

The NPLSR group manifested CPM dysfunction and pressure hyperalgesia at similar levels to the FM group, indicating that these two chronic pain syndromes, likely based on different pathophysiological mechanisms, in fact share some common pain processing features. However, though both patient groups demonstrated similarities in pain processing, self-reported cognitive-emotional and central sensitization-related symptom severity was significantly higher in the FM cohort, which distinguished them from the chronic NPLSR cohort.

The Neurophysiological Lesion: A Scoping Review

Objective

The purpose of this study was to examine the extent of the literature on the neurophysiological lesion as referenced in functional neurology.

Methods

A literature search was performed within the period from 2010 to March 2021. Search terms included central sensitization, central sensitivity syndrome, nociplastic pain, cold hyperalgesia, heat hyperalgesia, mechanical hyperalgesia, dynamic mechanical allodynia, temporal summation, spatial summation, and descending inhibition. A qualitative synthesis summarized the research findings, including clinical conditions and effect of spinal manipulation.

Results

There were 30 studies, which included 7 high-level studies (meta-analysis or systematic reviews), 22 randomized controlled studies, and 1 scoping review. The findings suggest the existence of the changes in the central integrated state of a population of neurons with various disorders, experimentally induced stimulation, and treatment. The current literature suggests plasticity of the central integrative state (CIS) with the onset of pathologies and the changes in the CIS with different conservative nonpharmacologic treatments.

Conclusions

This review suggests changes in the resting state of the CIS of a population of neurons that exist in the physiologic lesion may change in response to various therapies, including manipulative therapy. The findings from this review provide support of the hypothesis that nonpharmacologic conservative care may affect the neurophysiological lesion. However, studies were heterogeneous and evidence was lacking in the translation of targeting the therapies to distinct neuronal areas for clinical outcomes to treat specific disease states.

Group differences and associations between patient-reported outcomes and physical characteristics in chronic low back pain patients and healthy controls

BACKGROUND

Patients with chronic low back pain can exhibit altered slower gait, poor balance, and lower strength/power, and psychological dysfunctions such as pain catastrophizing and fear of movement. Few studies have investigated the relationships between physical and psychological dysfunctions. This study examined associations between patient-reported outcomes (pain interference, physical function, central sensitization, and kinesiophobia) and physical characteristics (gait, balance, and trunk sensorimotor characteristics).

METHODS

Laboratory testing included a 4-m walk, balance, and trunk sensorimotor testing with 18 patients and 15 controls. Gait and balance were collected with inertial measurement units. Isokinetic dynamometry measured trunk sensorimotor characteristics. Patient-reported outcomes included PROMIS Pain Interference / Physical Function, Central Sensitization Inventory, and Tampa Scale of Kinesiophobia. Independent t-tests or Mann-Whitney U tests were used to compare between groups. Additionally, Spearman's rank correlation coefficient (r_s) established associations between physical and psychological domains, and Fisher z-tests compared correlation coefficient values between groups (significance P < 0.05).

FINDINGS

The patient group had worse tandem balance and all patient-reported outcomes (P < 0.05) while no group differences were observed in gait and trunk sensorimotor characteristics. There were significant correlations between worse central sensitization and poor tandem balance (r_s = 0.446-0.619, P < 0.05) and lower peak force and rate of force development (r_s = -0.429-0.702, P < 0.05).

INTERPRETATION

Observed group differences in tandem balance agree with previous studies, indicating impaired proprioception. The current findings provide preliminary evidence that balance and trunk sensorimotor characteristics were significantly associated with patient-reported outcomes in patients. Early and period screening could help clinicians further categorize patients and develop objective treatment plans.

Soft-Tissue Mobilization and Pain Neuroscience Education for Chronic Nonspecific Low Back Pain with Central Sensitization: A Prospective Randomized Single-Blind Controlled Trial

This study was conducted to demonstrate the therapeutic effect of soft-tissue mobilization (STM) combined with pain neuroscience education (PNE) for patients with chronic nonspecific low back pain with central sensitization. A total of 28 participants were recruited and randomly allocated to either the STM group (SMG) (n = 14) or the STM plus PNE group (BG; blended group) (n = 14). STM was applied twice a week for four weeks, with a total of eight sessions, and PNE was applied within four weeks, for a total of two sessions. The primary outcome was pain intensity, and the secondary outcomes were central sensitization, pressure pain, pain cognition, and disability. Measurements were made at baseline, after the test, and at 2-week and 4-week follow-ups. The BG showed significant improvement in pain intensity (p < 0.001), pressure pain (p < 0.001), disability (p < 0.001), and pain cognition (p < 0.001) compared to the SMG. This study demonstrated that STM plus PNE is more effective for all measured outcomes compared to STM alone. This finding suggests that the combination of PNE and manual therapy has a positive effect on pain, disability index, and psychological factors in the short term.

Human assumed central sensitization in people with acute non-specific low back pain: A cross-sectional study of the association with brain-derived neurotrophic factor, clinical, psychological and demographic factors

BACKGROUND

Early evidence suggests human assumed central sensitization (HACS) is present in some people with acute low back pain (LBP). Factors influencing individual variation in HACS during acute LBP have not been fully explored. We aimed to examine the evidence for HACS in acute LBP and the contribution of brain-derived neurotrophic factor (BDNF), clinical, psychological and demographic factors to HACS.

METHODS

Participants with acute LBP (<6 weeks after pain onset, N = 118) and pain-free controls (N = 57) from a longitudinal trial were included. Quantitative sensory testing including pressure and heat pain thresholds and conditioned pain modulation, BDNF serum concentration and genotype and questionnaires were assessed.

RESULTS

There were no signs of HACS during acute LBP at group level when compared with controls. Sensory measures did not differ when compared between controls and LBP participants with different BDNF genotypes. Two LBP subgroups with distinct sensory profiles were identified. Although one subgroup (N = 60) demonstrated features of HACS including pressure/heat pain hypersensitivity at a remote site and deficient conditioned pain modulation, pain severity and disability did not differ between the two subgroups. Variation in sensory measures (~33%) was partially explained by BDNF genotype, sex, age and psychological factors.

CONCLUSIONS

This study confirms that HACS is present in some people with acute LBP, but this was not associated with pain or disability. Further, no relationship was observed between BDNF and HACS in acute LBP. More research is needed to understand factors contributing to individual variation in sensory measures in LBP.

SIGNIFICANCE

Human assumed central sensitization (HACS) is present in acute low back pain (LBP) but factors contributing to individual variation are not fully explored. This study investigated the relationship between factors such as brain derived neurotrophic factor (BDNF) and HACS in acute LBP. Our findings indicate that HACS was present in specific LBP subgroups but BDNF was unrelated to HACS. Combinations of BDNF genotype, demographic and psychological factors explained a small proportion of the variation in sensory measures during acute LBP.

Pressure Pain Thresholds and Central Sensitization in Relation to Psychosocial Predictors of Chronicity in Low Back Pain

(1) Background: Peripheral, as well as central, sensitization have been described in chronic low back pain (cLBP). The purpose of this study is to investigate the influence of psychosocial factors on the development of central sensitization. (2) Methods: This prospective study investigated local and peripheral pressure pain thresholds and their dependence on psychosocial risk factors in patients with cLBP receiving inpatient multimodal pain therapy. Psychosocial factors were assessed using the Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ). (3) Results: A total of 90 patients were included in the study, 61 (75.4% women, 24.6% men) of whom had significant psychosocial risk factors. The control group consisted of 29 patients (62.1% women, 37.9% men). At baseline, patients with psychosocial risk factors showed significantly lower local and peripheral pressure pain thresholds, suggesting central sensitization, compared to the control group. Sleep quality, measured by the Pittsburgh Sleep Quality Index (PSQI), was also correlated with altered PPTs. After multimodal therapy, all participants reported increased local pain thresholds compared to at admission, independent of psychosocial chronification factors. (4) Conclusions: Psychosocial chronicity factors measured using the ÖMPSQ have a significant influence on pain sensitization in cLBP. A 14-day multimodal pain therapy increased local, but not peripheral, pressure pain thresholds.

Pain phenotyping and investigation of outcomes in physical therapy: An exploratory study in patients with low back pain

Phenotypes have been proposed as a method of characterizing subgroups based on biopsychosocial factors to identify responders to analgesic treatments. This study aimed to, first, confirm phenotypes in patients with low back pain receiving physical therapy based on an a priori set of factors used to derive subgroups in other pain populations. Second, an exploratory analysis examined if phenotypes differentiated pain and disability outcomes at four weeks of physical therapy. Fifty-five participants completed psychological questionnaires and pressure pain threshold (PPT). Somatization, anxiety, and depression domains of the Symptom-Checklist-90-Revised, and PPT, were entered into a hierarchical agglomerative cluster analysis with Ward's method to identify phenotypes. Repeated measures ANOVAs assessed pain ratings and disability by phenotype at four weeks. Three clusters emerged: 1) high emotional distress and pain sensitivity (n = 10), 2) low emotional distress (n = 34), 3) low pain sensitivity (n = 11). As an exploratory study, clusters did not differentiate pain ratings or disability after four weeks of physical therapy (p's>0.05). However, trends were observed as magnitude of change for pain varied by phenotype. This supports the characterization of homogenous subgroups based on a protocol conducted in the clinical setting with varying effect sizes noted by phenotype for short-term changes in pain. As an exploratory study, future studies should aim to repeat this trial in a larger sample of patients.

Mechanisms of chiropractic spinal manipulative therapy for patients with chronic primary low back pain: protocol for a mechanistic randomised placebo-controlled trial

INTRODUCTION

Chronic low back pain (CLBP) is a highly prevalent and disabling condition. Identifying subgroups of patients afflicted with CLBP is a current research priority, for which a classification system based on pain mechanisms was proposed. Spinal manipulative therapy (SMT) is recommended for the management of CLBP. Yet, little data are available regarding its mechanisms of action, making it difficult to match this intervention to the patients who may benefit the most. It was suggested that SMT may influence mechanisms associated with central sensitisation. Therefore, classifying patients with CLBP according to central sensitisation mechanisms may help predict their response to SMT.

METHODS AND ANALYSIS

This protocol describes a randomised placebo-controlled trial aiming to examine which variables linked to central sensitisation may help predict the clinical response to SMT in a cohort of patients with CLBP. One hundred patients with chronic primary low back pain will be randomised to receive 12 sessions of SMT or placebo SMT over a 4-week period. Pain intensity and disability will be assessed as primary outcomes after completing the 4-week treatment (primary endpoint), and at 4-week and 12-week follow-ups. Baseline values of two pain questionnaires, lumbar pressure pain thresholds, concentrations of an inflammatory cytokine and expectations of pain relief will be entered as predictors of the response to SMT in a multiple regression model. Changes in these variables after treatment will be used in a second multiple regression model. The reference values of these predictors will be measured from 50 age and sex-matched healthy controls to allow interpretation of values in patients. Mixed analyses of variance will also be conducted to compare the primary outcomes and the predictors between groups (SMT vs placebo) over time (baseline vs post-treatment).

ETHICS AND DISSEMINATION

Ethical approval was granted by the Fundación Jiménez Díaz Clinical Research Ethics Committee.

TRIAL REGISTRATION NUMBER

NCT05162924.

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.

Characteristics and Outcomes of Patients Receiving Physical Therapy for Low Back Pain with a Nociplastic Pain Presentation: A Secondary Analysis

Introduction

Individuals with low back pain (LBP) may be classified based on mechanistic descriptors, such as a nociplastic pain presentation (NPP). The purpose of this secondary analysis was to examine the frequency and characteristics of patients with a NPP referred to physical therapy with LBP. Additionally, we characterized patients with LBP meeting the criteria for NPP by demographic, clinical, psychological, and pain sensitivity variables. Finally, we examined short- and long-term clinical outcomes in patients with a NPP compared to those without a NPP.

Materials and Methods

Patients referred to physical therapy for LBP completed the Patient Self-report Survey for the Assessment of Fibromyalgia. Participants were categorized as "LBP with NPP" or "LBP without NPP" based on the threshold established in this measure. A rank sum test examined for differences in pain-related psychological factors and pressure-pain threshold between groups. Next, a Friedman test examined if LBP intensity and disability trajectories differed by groups at one and six months after initiation of physical therapy.

Results

22.2% of patients referred to physical therapy for LBP met the criteria for a NPP. Patients with a NPP reported significantly greater disability, pain catastrophizing, depression, anxiety, and somatization compared to individuals without a NPP (p < 0.05). Pressure-pain threshold did not differ between groups (p > 0.05). Individuals with LBP with a NPP demonstrated nonsignificant, small to medium reductions in pain and disability at one and six months. Individuals experiencing LBP without a NPP demonstrated significant reductions in pain and disability in the short- and long term.

Conclusion

Patients with LBP with a NPP displayed greater negative pain-related psychological factors but similar pain sensitivity compared to LBP without NPP.

Predictors of disability in patients with chronic low back pain

INTRODUCTION

Chronic low back pain (CLBP) is a common and disabling health problem. In this study, we aimed to assess the relationship between pain intensity, the components of catastrophizing, depression and disability in patients with chronic low back pain.

MATERIAL AND METHODS

Seventy-six patients diagnosed with CLBP (age range 25-77 years; 73.7% female) participated in the study. Participants' socio-demographic data were collected: age, gender, height, weight, and work status (employed or retired). All participants were asked to complete the Pain Catastrophizing Scale (PCS), the visual analogue scale (VAS), the Oswestry Disability Questionnaire (ODQ), and the Beck Depression Inventory (BDI).

RESULTS

The mean group scores revealed moderate CLBP complaints (VAS - 4 [3-6]), mild depression (BDI - 10 [5-16]), a moderate level of catastrophizing (PCS total score 20.5 [10-34]) and moderate disability (Oswestry Disability Index [ODI] - 31 [14-38]). Positive significant correlations were found between ODI and age, residence, work status, VAS, PCS-rumination, PCS-magnification, PCS-helplessness and BDI, and also between PCS subscales and VAS. Our multivariate linear regression analysis showed that age, pain intensity, PCS-helplessness and depression can predict disability in patients with CLBP, explaining 84% of the variance of disability (R² = 0.851, adjusted R² = 0.843).

CONCLUSIONS

A multidisciplinary approach is needed for patients with CLBP and should include physical, mental and social evaluation in order to offer an optimal treatment.

Factors Associated with Low Inter-Session Reliability of Conditioned Pain Modulation in Older People with or Without Chronic Musculoskeletal Pain

Purpose

Conditioned pain modulation (CPM) is a measurement of the descending pain pathways that inhibit or facilitate afferent noxious stimuli. The reliability of CPM in older individuals with or without chronic musculoskeletal pain has not been sufficiently reported. This study aimed to examine the inter-session reliability of CPM in these cohorts and the factors in CPM reliability.

Patients and Methods

Individuals aged 65 or older were recruited in Narita, Japan. The measurements were performed on separate days 2 weeks apart (sessions 1 and 2). Each participant's hand was immersed in cold water, and we measured pressure pain threshold (PPT) before and after the immersion. The ratio before and after PPT measurements was presented as CPM index. The autonomic activities (heart rate variability, heart rate, and blood pressure) were simultaneously measured. An absolute reliability of CPM index was analyzed by the adjusted two-way analysis of variance (ANOVA) and the Bland Altman plot, and relative reliability was analyzed by intraclass correlation coefficient (ICC). Spearman's rho correlation and the adjusted multivariate regression analysis were utilized for examining the CPM reliability factors.

Results

Thirty-two participants were divided into two groups: chronic pain (n=19) and non-chronic pain (n=13) groups. The mean difference between session 1 and 2 in CPM index showed a systematic error in the chronic pain group at 17.3 (confidence interval, CI: 15.0 to 19.7), but none in the non-chronic pain group at 3.7 (CI: -0.02 to 7.4). The adjusted two-way ANOVA for CPM index did not identify any differences. ICC was not significant at p=-0.247 in the non-chronic and 0.167 in chronic pain. Multivariate regression analysis revealed total power and low/high frequencies as significant factors for CPM index.

Conclusion

This study identified low inter-session reliability in older adults with chronic musculoskeletal pain and autonomic nervous system activities as factors in CPM reliability.

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.

Triad Multisystem Phenotype with High-risk for Developing Temporomandibular Disorders- Characteristics and Potential Pathophysiology Results from the OPPERA Dataset

ABSTRACT

A multisystem phenotype with the Triad of bodily pain, psychological distress, and sleep disturbance was found to have high risk for developing initial onset of painful temporomandibular disorders (TMDs) in the multicenter Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) dataset. In this study, we systemically examined phenotypic characteristics and explored potential pathophysiology in quantitative sensory testing (QST) and autonomic nervous system (ANS) domains in this multisystem Triad phenotype. Secondary analysis was performed on 1199 non-Triad and 154 Triad TMD-free OPPERA enrollees at baseline. Results indicate that prior to developing TMDs, the Triad phenotype demonstrated both orofacial and systemic signs and symptoms that can only be captured through multisystem assessment. In addition, we found significantly lower resting heart rate variability and higher resting heart rate in the Triad phenotype as compared to the non-Triad group. However, pain sensitivity measured by QST was not different between groups. These findings highlight the importance of whole-person multisystem assessment at the stage prior to developing complex pain conditions such as TMDs, and suggest that, in addition to a "tissue damage monitor", pain should be considered in a broader context, such as a component within a "distress monitoring system" at the whole-person level when multisystem issues co-present. Therefore, the presence or absence of multisystem issues may carry critical information when searching for disease mechanisms and developing mechanism-based intervention and prevention strategies for TMDs and related pain conditions. Cardiovascular autonomic function should be further researched when multisystem issues co-present prior to developing TMDs.

Correlation of Fibromyalgia Survey Questionnaire and Quantitative Sensory Testing Among Patients With Active Rheumatoid Arthritis

OBJECTIVE

Patients with rheumatoid arthritis (RA) commonly demonstrate disordered pain processing associated with high pain sensitization. Pain sensitization is often assessed using quantitative sensory testing (QST), which is burdensome to patients. The self-administered Fibromyalgia Survey Questionnaire (FSQ) has been proposed as a low-burden, surrogate measure of central pain sensitization. We examined the correlation between FSQ and QST in patients with active RA.

METHODS

Participants in the Central Pain in Rheumatoid Arthritis (CPIRA) cohort underwent FSQ and QST evaluation at enrollment. QST measures included pressure pain threshold (PPT) at the thumb, trapezius, wrist, and knee; temporal summation (TS) at the wrist and arm; and conditioned pain modulation (CPM). Partial Spearman correlation between FSQ and each QST measure was assessed, adjusted for demographic factors, study site, disease characteristics, and pain catastrophizing. Sensitivity analyses included (1) stratified analysis by sex and (2) evaluation of how each component of FSQ associates with the QST measures.

RESULTS

Among 285 participants with active RA, FSQ was weakly but statistically significantly correlated with PPT (r range = -0.31 to -0.21), and TS (r range = 0.13-0.15) at all sites in unadjusted analyses. After adjustment, statistically significant correlations persisted for TS at the wrist and PPT at all sites (except the thumb). Sensitivity analyses did not identify differences in association based on sex or with individual FSQ components.

CONCLUSION

FSQ and QST were correlated among participants with active RA, but the strength of association was weak. QST and FSQ are not interchangeable measures of pain sensitization.

Central sensitization in opioid use disorder: a novel application of the American College of Rheumatology Fibromyalgia Survey Criteria

Central sensitization may be an underlying mechanism linking chronic pain and opioid use disorder associated with opioid use disorder onset, maintenance, escalation, treatment delay, and relapse.

Introduction:

Central sensitization (CS) involves dysfunctional central nervous system pain modulation resulting in heightened pain perception. Central sensitization is not commonly assessed among patients with opioid use disorder (OUD), despite the fact that pain has been implicated in the development, maintenance, and relapse of OUD and chronic opioid use may produce opioid-induced hyperalgesia. Central sensitization is a plausibly important mechanism underlying the complex relationship between OUD and chronic pain. However, this premise is largely untested.

Methods:

Participants with OUD (n = 141) were recruited from an academic addiction treatment center in Columbus, Ohio. An established surrogate measure of CS, the American College of Rheumatology 2011 Fibromyalgia Survey Criteria, was administered using electronic survey. Participants also responded to questions about pain interference (Brief Pain Inventory), quality of life (RAND-36), and items regarding pain beliefs and expectations of pain and addiction treatment. Descriptive analyses, Spearman rho correlations, and Mann–Whitney U tests were performed.

Results:

Hypothesized relationships were confirmed between degree of CS, pain interference, and health-related quality of life. Degree of CS was also positively correlated with greater endorsement of pain as a reason for the onset, maintenance, and escalation of OUD; treatment delay; and OUD relapse. Participants with the American College of Rheumatology 2011 Fibromyalgia Survey Criteria ≥13 had significantly greater endorsement of pain as a reason for delaying OUD treatment, continuing and increasing opioid use, and precipitating OUD relapse.

Conclusions:

This study provides early evidence CS may underlie previously observed connections between clinically salient features of chronic pain and OUD, potentially informing future mechanistic research and precision treatment.

Advances in the management of fibromyalgia: what is the state of the art?

INTRODUCTION

Fibromyalgia (FM) is a chronic pain syndrome associated with fatigue, insomnia, dyscognition, and emotional distress. Critical illness mechanisms include central sensitization to nociceptive and non-nociceptive stimuli often resulting in hypersensitivity to all sensory input.

AREAS COVERED

The clinical presentation of FM can vary widely and therefore requires therapies tailored to each patient's set of symptoms. This manuscript examines currently prescribed therapeutic approaches supported by empirical evidence as well as promising novel treatments. Although pharmacological therapy until now has been only moderately effective for FM symptoms, it represents a critical component of every treatment plan.

EXPERT OPINION

Currently approved pharmacological therapies for FM symptoms have limited but proven effectiveness. Novel therapies with cannabinoids and naltrexone appear promising. Recent functional imaging studies of FM have discovered multiple brain network abnormalities that may provide novel targets for mechanism-based therapies. Future treatment approaches, however, need to improve more than clinical pain but also other FM domains like fatigue, insomnia, and distress.

Association of lumbar disc degeneration with low back pain in middle age in the Northern Finland Birth Cohort 1966

Background

Although it has been suggested that lumbar disc degeneration (LDD) is a significant risk factor for low back pain (LBP), its role remains uncertain. Our objective was to clarify the association between LDD and LBP and whether mental distress modifies the association.

Methods

Participants of a birth cohort underwent 1.5-T lumbar magnetic resonance imaging at the age of 47. The association between the sum score of LDD (Pfirrmann classification, range 0–15) and LBP (categorized into “no pain”, “mild-to-moderate pain”, “bothersome-and-frequent pain”) was assessed using logistic regression analysis, with sex, smoking, body mass index, physical activity, occupational exposure, education, and presence of Modic changes and disc herniations as confounders. The modifying role of mental distress (according to the Hopkins Symptom Check List-25 [HSCL-25], the Beck Depression Inventory and the Generalized Anxiety Disorder Scale) in the association was analyzed using linear regression.

Results

Of the study population (n = 1505), 15.2% had bothersome and frequent LBP, and 29.0% had no LBP. A higher LDD sum score increased the odds of belonging to the “mild-to-moderate pain” category (adjusted OR corresponding to an increase of one point in the LDD sum score 1.11, 95% CI 1.04–1.18, P = 0.003) and the “bothersome-and-frequent pain” category (adjusted OR 1.20, 95% CI 1.10–1.31, P < 0.001), relative to the “no pain” category. Mental distress significantly modified the association between LDD and LBP, as a linear positive association was consistently observed among individuals without mental distress according to HSCL-25 (adjusted B 0.16, 95% CI 0.07–0.26, P < 0.001), but not among individuals with higher mental distress.

Conclusions

LDD was significantly associated with both mild-to-moderate and bothersome-and-frequent LBP. However, the co-occurrence of mental distress diminished the association between LDD and LBP bothersomeness. Our results strongly suggest that mental symptoms affect the pain experience.

Epigenome-wide DNA methylation profiling of conditioned pain modulation in individuals with non-specific chronic low back pain

BACKGROUND

The pathoanatomic cause of chronic low back pain (cLBP) cannot be identified for up to 90% of individuals. However, dysfunctional processing of endogenous nociceptive input, measured as conditioned pain modulation (CPM), has been associated with cLBP and may involve changes in neuronal gene expression. Epigenetic-induced changes such as DNA methylation (DNAm) have been associated with cLBP.

METHODS

In the present study, the relationship between CPM and DNAm changes in a sample of community-dwelling adults with nonspecific cLBP (n = 48) and pain-free controls (PFC; n = 50) was examined using reduced representation bisulfite sequencing. Gene ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were applied to identify key pathways involved in efficient versus deficient CPM.

RESULTS

Based on CPM efficiency, we identified 6006 and 18,305 differentially methylated CpG sites (DMCs) with q values < 0.01 among individuals with cLBP and PFCs, respectively. Most of the DMCs were hypomethylated and annotated to genes of relevance to pain, including OPRM1, ADRB2, CACNA2D3, GNA12, LPL, NAXD, and ASPHD1. In both cLBP and PFC groups, the DMCs annotated genes enriched many GO terms relevant to pain processing, including transcription regulation by RNA polymerase II, nervous system development, generation of neurons, neuron differentiation, and neurogenesis. Both groups also enriched the pathways involved in Rap1-signaling, cancer, and dopaminergic neurogenesis. However, MAPK-Ras signaling pathways were enriched in the cLBP, not the PFC group.

CONCLUSIONS

This is the first study to investigate the genome-scale DNA methylation profiles of CPM phenotype in adults with cLBP and PFCs. Based on CPM efficiency, fewer DMC enrichment pathways were unique to the cLBP than the PFCs group. Our results suggest that epigenetically induced modification of neuronal development/differentiation pathways may affect CPM efficiency, suggesting novel potential therapeutic targets for central sensitization. However, CPM efficiency and the experience of nonspecific cLBP may be independent. Further mechanistic studies are required to confirm the relationship between CPM, central sensitization, and nonspecific cLBP.

Neurophysiological and transcriptomic predictors of chronic low back pain: Study protocol for a longitudinal inception cohort study

Chronic low back pain is one of the most common, costly, and debilitating pain conditions worldwide. Increased mechanistic understanding of the transition from acute to chronic low back and identification of predictive biomarkers could enhance the clinical assessment performed by healthcare providers and enable the development of targeted treatment to prevent and/or better manage chronic low back pain. This study protocol was designed to identify the neurological and transcriptomic biomarkers predictive of chronic low back pain at low back pain onset. This is a prospective descriptive longitudinal inception cohort study that will follow 340 individuals with acute low back pain and 40 healthy controls over 2 years. To analyze the neurophysiological and transcriptomic biomarkers of low back pain, the protocol includes psychological and pain-related survey data that will be collected beginning within 6 weeks of low back pain onset (baseline, 6, 12, 24, 52 weeks, and 2 years) and remotely at five additional time points (8, 10, 16, 20 weeks, and 18 months). Quantitative sensory testing and collection of blood samples for RNA sequencing will occur during the six in-person visits. The study results will describe variations in the neurophysiological and transcriptomic profiles of healthy pain-free controls and individuals with low back pain who either recover to pain-free status or develop chronic low back pain.

Cultural Validation of the Chinese Central Sensitization Inventory in Patients with Chronic Pain and its Predictive Ability of Comorbid Central Sensitivity Syndromes

Background

Central sensitization (CS) is frequently reported in chronic pain, and the central sensitization inventory (CSI) is popularly used to assess CS. However, a validated Chinese CSI is lacking and its predictive ability for the comorbidity of central sensitivity syndromes (CSSs) remains unclear. Hence, this study aimed to generate the Chinese CSI (CSI-C) with cultural adaptation and examine its psychometric properties.

Methods

The CSI-C was formulated through forward and backward translation, panel review and piloting and then validated among patients with chronic pain (n = 235). Its internal consistency, test–retest reliability, and concurrent validity were measured. An exploratory factor analysis (EFA) was performed for the construct validity. Receiver operating characteristic (ROC) analysis was employed to determine the discriminative ability in the presence of comorbidity of CSSs.

Results

About 70% of the participants in the study experienced at least mild CS symptoms. CSI-C demonstrates a high internal consistency (Cronbach’s alpha = 0.896) and excellent test–retest reliability (ICC = 0.932). CSI-C scoring was significantly correlated with pain intensity (r = 0.188), EQ-5D index (r = −0.375), anxiety (r=0.525), and depression (r = 0.467). The EFA generated a 5-factor model, including physical symptoms, emotional distress, hypersensitivity syndromes and so on. An CSI cutoff of 42 had a sensitivity of 71.4% and a specificity of 70% for identifying chronic pain patients with ≥2 CSSs.

Conclusion

The CS manifestations are prevalent in those with persistent pain. CSI-C is a reliable and valid instrument for measuring CS. A CSI score ≥42 may predict the comorbidity of 2 or above CSSs in patients with chronic pain.

Proprioceptive acuity is core for back awareness in chronic low back pain: Further analysis of the content validity of the Spanish version of the Fremantle Back Awareness Questionnaire

Treatments aimed at increasing self-perception may improve chronic low back pain (CLBP) symptomatology and present novel management approaches. Consequently, it is important to have valid, complete, and reliable tools for its assessment, and to understand which variables influence altered back awareness. We aimed to evaluate the face/content validity of the Spanish version of the Fremantle Back Awareness Questionnaire (FreBAQ-S) among people with and without CLBP, and to explore additional variables suggested to be involved in back awareness. A total of 264 individuals with CLBP and 128 healthy controls (HC) answered an online survey, including the FreBAQ-S, and questions regarding the completeness, comprehensibility, time-to-complete adequacy, and time spent completing it. If participants declared a lack of completeness, they had to report which aspects would be incorporated into the questionnaire to explore additional back-awareness-related variables. A statistically significant difference in completeness emerged between groups (p < 0.01). The questionnaire was comprehensible for more than 85% of participants, regardless of the group (p = 0.45). CLBP participants spent significantly more time in completing the questionnaire than controls (p < 0.01), but no differences were found between groups regarding the time-to-complete adequacy (p = 0.49). Regarding the back-awareness-related variables, 77 suggestions from CLBP group and seven from the HC were received. Most of them were related to proprioceptive acuity such as posture, weight, or movement patterns, among others. The FreBAQ-S demonstrated adequate face/content validity, completeness, comprehensibility, and adequate time of response. The feedback provided will help improve currently available assessment tools.

The Definition, Assessment, and Prevalence of (Human Assumed) Central Sensitisation in Patients with Chronic Low Back Pain: A Systematic Review

Central sensitisation is assumed to be one of the underlying mechanisms for chronic low back pain. Because central sensitisation is not directly assessable in humans, the term 'human assumed central sensitisation' (HACS) is suggested. The objectives were to investigate what definitions for HACS have been used, to evaluate the methods to assess HACS, to assess the validity of those methods, and to estimate the prevalence of HACS. Database search resulted in 34 included studies. Forty different definition references were used to define HACS. This review uncovered twenty quantitative methods to assess HACS, including four questionnaires and sixteen quantitative sensory testing measures. The prevalence of HACS in patients with chronic low back pain was estimated in three studies. The current systematic review highlights that multiple definitions, assessment methods, and prevalence estimates are stated in the literature regarding HACS in patients with chronic low back pain. Most of the assessment methods of HACS are not validated but have been tested for reliability and repeatability. Given the lack of a gold standard to assess HACS, an initial grading system is proposed to standardize clinical and research assessments of HACS in patients with a chronic low back.

Denying the Truth Does Not Change the Facts: A Systematic Analysis of Pseudoscientific Denial of Complex Regional Pain Syndrome

Purpose

Several articles have claimed that complex regional pain syndrome (CRPS) does not exist. Although a minority view, it is important to understand the arguments presented in these articles. We conducted a systematic literature search to evaluate the methodological quality of articles that claim CRPS does not exist. We then examined and refuted the arguments supporting this claim using up-to-date scientific literature on CRPS.

Methods

A systematic search was conducted in MEDLINE, EMBASE and Cochrane CENTRAL databases. Inclusion criteria for articles were (a) a claim made that CRPS does not exist or that CRPS is not a distinct diagnostic entity and (b) support of these claims with subsequent argument(s). The methodological quality of articles was assessed if possible.

Results

Nine articles were included for analysis: 4 narrative reviews, 2 personal views, 1 letter, 1 editorial and 1 case report. Seven points of controversy were used in these articles to argue that CRPS does not exist: 1) disagreement with the label “CRPS”; 2) the “unclear” pathophysiology; 3) the validity of the diagnostic criteria; 4) CRPS as a normal consequence of immobilization; 5) the role of psychological factors; 6) other identifiable causes for CRPS symptoms; and 7) the methodological quality of CRPS research.

Conclusion

The level of evidence for the claim that CRPS does not exist is very weak. Published accounts concluding that CRPS does not exist, in the absence of primary evidence to underpin them, can harm patients by encouraging dismissal of patients’ signs and symptoms.

Adaptive body awareness predicts fewer central sensitization-related symptoms and explains relationship between central sensitization-related symptoms and pain intensity: A cross-sectional study among individuals with chronic pain

BACKGROUND

Central sensitization (CS), defined as the amplification of neural signaling within the CNS that elicits pain hypersensitivity, is thought be a characteristic of several chronic pain conditions. Maladaptive body awareness is thought to contribute and maintain CS. Less is known about the relationship between CS and adaptive body awareness.

PURPOSE

This cross-sectional study investigated relationships among self-reported adaptive body awareness (Multidimensional Interoceptive Awareness Scale-2; MAIA-2), CS-related symptoms (Central Sensitization Inventory; CSI), and pain intensity and further delineate potential direct and indirect links among these constructs.

METHODS

Online surveys were administered to 280 individuals with chronic pain reporting elevated CSI scores. Strategic sampling targeted respondents to reflect the 2010 census. Pearson's correlations characterized overall relationship between variables. Multiple regression analyses investigated potential direct links. A path analysis assessed mediational effects of CS-related symptoms on the relationship between adaptive body awareness and pain intensity.

RESULTS

CSI demonstrated strong, inverse correlations with some MAIA-2 subscales, but positive correlations with others. Higher CSI scores predicted greater pain intensity (b = 0.049, p ≤ 0.001). Two MAIA-2 subscales, Not-Distracting (b = -0.56, p ≤ 0.001) and Not-Worrying (b = -1.17, p ≤ 0.001) were unique predictors of lower CSI. Not-Distracting (b = -0.05, p = 0.003) and Not-Worrying (b = -0.06, p = 0.007) uniquely predicted lower pain intensity. CSI completely mediated the relationship between adaptive body awareness and pain intensity [point estimate = -0.04; 95% bootstrap confident intervals (CI) = -0.05 to -0.02].

CONCLUSIONS

Findings also support future research to explore causal relationships of variables. Findings suggest that frequency of attention to bodily sensations is distinct from cognitive-affective appraisal of bodily sensation, and the two distinct higher order processes may have divergent influences on perceived pain and CS-related symptoms. Results also support future research to explore causal relationships of variables.

Functional and structural neuroplastic changes related to sensitization proxies in patients with Osteoarthritis: a systematic review

OBJECTIVE

Several reports in literature have identified sensitization as a possible basis for the enhanced pain reactions associated with Osteoarthritis (OA). The aim of this current systematic review is to summarize functional and structural brain changes associated with surrogate sensitization parameters assessed in patients with OA-related pain.

DESIGN

Systematic review.

SUBJECTS

Patients with OA related pain.

METHODS

A literature search was conducted systematically in MEDLINE, CINAHL, EMBASE databases for human studies up to December 2019. Articles were included if they assessed brain imaging and senzitisation parameters (quantitative sensory testing and questionnaires) in adults with OA related pain. Methodological quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS) score.

RESULTS

Five studies reporting on 138 patients were included in this review. The MINORS scale yielded mean scores of 8.5/16 and 12.3/24, for the cohort and case-control studies respectively. Four low-quality studies suggest a greater pain matrix activation associated with clinical measures of sensitization in patients with OA, while another study underlined the presence of structural changes (reduced gray matter volume) in the cortical areas involved in the nociceptive processing possible also related to sensitization.

CONCLUSION

This review shows conflicting evidence for structural and functional neuroplastic brain changes related to sensitization proxies in patients with OA.

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.

Insulin Resistance is Associated with Central Pain in Patients with Fibromyalgia

BACKGROUND

Insulin resistance (IR) is a pathological condition in which cells fail to respond normally to insulin. IR has been associated with multiple conditions, including chronic pain. Fibromyalgia (FM) is one of the common generalized chronic painful conditions with an incidence rate affecting 3% to 6% of the population. Substantial interest and investigation into FM continue to generate  many hypotheses.The relationship between IR and FM has not been explored. IR is known to cause abnormalities in the cerebral microvasculature, leading to focal hypoperfusion. IR also has been shown to cause cognitive impairment in FM patients, as in parkinsonism. As demonstrated by advanced imaging methods, similar brain perfusion abnormalities occur in the brain of patients with FM as with IR.

OBJECTIVES

To determine the potential association between FM and IR.

SETTING

Subspecialty pain medicine clinics.

STUDY DESIGN

Observational cross-sectional study.

METHODS

Laboratory data was extracted through a retrospective review of medical records from patients who had met the American College of Rheumatology (ACR) criteria for FM. The Hemoglobin A1c (HbA1c) values from 33 patients with FM were compared with the means of the glycated HbA1c levels of 2 control populations. In addition, established indices of IR [Quantitative Insulin Sensitivity Check Index (QUICKI) and the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR)] were calculated in a subgroup of patients in whom the analytes necessary for these calculations were available. To assess for confounding factors, the associations between HbA1c, QUICKI, HOMA-IR, fasting insulin levels, and glucose, after controlling for age, were explored by multiple analyses of variance with relation to gender and ethnicity.

RESULTS

We found an association between IR and FM that was independent of age, gender, and ethnicity. We found that patients with FM belong to a distinct population that can be segregated from the control groups by their HbA1c levels, a surrogate marker of IR. This was demonstrated by analyzing the data after introducing an age correction into a linear regression model. This strategy showed significant differences between patients with FM and control subjects (P < 0.0001 and P  = 0.0002, for 2 separate control populations, respectively). A subgroup analysis using the QUICKI and HOMA-IR showed that all patients with FM in this subgroup (100%) exhibited laboratory abnormalities pointing to IR.

LIMITATIONS

Small observational cross-sectional study. There are also intrinsic limitations that are attributed to cross-sectional studies.

CONCLUSION

The association demonstrated in this study warrant further investigation, including the pursuit of randomized, double-blind clinical trials to determine the effect of improving insulin sensitivity in FM related pain scores. Such studies could unveil a potential pathogenetic relationship between FM, central pain, and IR. Based on these initial findings, we present the hypothesis that IR may underlie pathological mechanisms leading to central pain. If confirmed, this may lead to a paradigm shift in the management of central pain.

Within-session test-retest reliability of pressure pain threshold and mechanical temporal summation in healthy subjects

Objective

To determine the absolute and relative intra-rater within-session test-retest reliability of pressure pain threshold (PPT) and mechanical temporal summation of pain (TSP) at the low back and the forearm in healthy participants and to test the influence of the number and sequence of measurements on reliability metrics.

Methods

In 24 participants, three PPT and TSP measures were assessed at four sites (2 at the low back, 2 at the forearm) in two blocks of measurements separated by 20 minutes. The standard error of measurement, the minimal detectable change (MDC) and the intraclass correlation coefficient (ICC) were investigated for five different sequences of measurements (e.g. measurement 1, 1–2, 1-2-3).

Results

The MDC for the group (MDC_gr) for PPT ranged from 28.71 to 50.56 kPa across the sites tested, whereas MDC_gr for TSP varied from 0.33 to 0.57 out of 10 (numeric scale). Almost all ICC showed an excellent relative reliability (between 0.80 and 0.97), except when only the first measurement was considered (moderate). Although minimal differences in absolute PPT reliability were present between the different sequences, in general, using only the first measurement increase measurement error. Three TSP measures reduced the measurement error.

Discussion

We established that two measurements of PPT and three of TSP reduced the measurement error and demonstrated an excellent relative reliability. Our results could be used in future pain research to confirm the presence of true hypo/hyperalgesia for paradigms such as conditioned pain modulation or exercise-induced hypoalgesia, indicated by a change exceeding the measurement variability.

Transcutaneous electrical nerve stimulation and heat to reduce pain in a chronic low back pain population: a randomized controlled clinical trial

BACKGROUND

Low back pain is the leading cause of disability worldwide. The therapeutic management of patients with chronic LBP is challenging.

OBJECTIVES

The aim of this study is to evaluate the effects of heat and transcutaneous electrical nerve stimulation combined on pain relief in participants with chronic low back pain.

METHODS

Fifty participants with chronic (≥3 months) low back pain were randomly assigned to two groups: HeatTens (n=25) and control group (n=25). Primary outcome was pain. Secondary outcomes were pressure pain thresholds, temporal summation, conditioned pain modulation, fear-avoidance and beliefs questionnaire, central sensitization inventory, quality of life, and medication use. The control group received no treatment and continued usual care. After four weeks of treatment, all measurements were repeated.

RESULTS

Fifty individuals participated in this study. Significant higher pressure pain threshold measures after both 30min and 4 weeks for the lower back region and the second plantar toe were found only in the experimental group.

CONCLUSION

The combination of heat and transcutaneous electrical nerve stimulation does not reduce pain scores in patients with chronic low back pain. Pressure pain threshold values significantly improved, showing beneficial effects of the experimental treatment. ClinicalTrials.gov: NCT03643731 (https://clinicaltrials.gov/ct2/show/NCT03643731).

One-Year Results of Prospective Research Study Using 10 kHz Spinal Cord Stimulation in Persistent Nonoperated Low Back Pain of Neuropathic Origin: Maiden Back Study

PURPOSE

Spinal cord stimulation (SCS) is a recommended treatment for chronic neuropathic pain. Persistent nonoperative low back pain of neuropathic origin has profound negative impacts on patient's lives. This prospective, open label, research study aimed to explore the use of SCS in patients with associated features of central sensitisation such as allodynia and hyperalgesia.

MATERIALS AND METHODS

Twenty-one patients with back pain and hyperalgesia or allodynia who had not had prior spinal surgery underwent a SCS trial followed by full implantation. SCS comprised administering electrical impulses epidurally at a frequency of 10 kHz and pulse width of 30 μsec. Patients attended follow-up visits after 6 and 12 months of SCS. Repeated measure ANOVAs/Friedman tests explored change after 6 and 12 months of 10 kHz SCS. Independent sample t-tests/Mann-Whitney U tests examined differences in response after 12 months of 10 kHz SCS.

RESULTS

Back and leg pain, quality of life (QoL), pain-related disability, and morphine equivalence significantly improved compared with baseline following 6 and 12 months of 10 kHz SCS. There were no increases in the consumption of opioids, amitriptyline, gabapentin or pregabalin in any patient. After 12 months of treatment, 52% encountered ≥50% improvement in back pain, 44% achieved remission (0-3 cm back pain VAS), 40% reported ODI scores between 0 and 40 and 60% experienced a reduction of at least 10 ODI points. Patients reporting ≥10-point improvement in ODI had significantly longer pain history durations and experienced significantly greater improvements in back pain, leg pain and QoL than those reporting <10-point improvement in ODI.

CONCLUSION

The 10 kHz SCS improved back and leg pain, QoL, pain-related disability and medication consumption in patients with nonoperative back pain of neuropathic origin. With further research incorporating a sham control arm, the efficacy of 10 kHz SCS in this patient cohort will become more established.

Quantitative Sensory Testing Discriminates Central Sensitization Inventory Scores in Participants with Chronic Musculoskeletal Pain: An Exploratory Study

BACKGROUND

The Central Sensitization Inventory (CSI) is often used in clinical settings to screen for the presence of central sensitization. However, various cutoff scores have been reported for this tool, and scores have not been consistently associated with widespread pain sensitivity as measured with quantitative sensory testing (QST). The purpose of this study was to compare QST profiles among asymptomatic controls and participants with chronic musculoskeletal pain (CMP), and to determine the association between self-report questionnaires and QST in participants with CMP.

METHODS

Twenty asymptomatic controls and 46 participants with CMP completed the CSI, PROMIS-29, and QST assessments of mechanical and thermal pain thresholds remote to the area of pain. Receiver Operating Characteristic analysis revealed a cutoff score of 33.5 for the CSI. PROMIS-29 Quality of Life (QOL) inventory and QST measures were compared between low and high CSI groups.

RESULTS

The high CSI group (n = 19) had significantly lower mechanical and thermal pain thresholds, and larger impairments in QOL measures, compared to the low CSI group (n = 27) and asymptomatic controls. Participants with CSI scores < 33.5 presented similarly to asymptomatic controls. Anxiety, pain interference, and CSI scores demonstrated the highest number of significant associations to QST measures.

CONCLUSION

A cutoff score of 33.5 on the CSI may be useful for discriminating widespread pain sensitivity and quality of life impairments in participants with CMP. Future studies should consider how the presence of high or low CSI may impact differential diagnosis, prognosis, and treatment responsiveness for patients with primary or secondary CMP.

Female Overrepresentation in Low Back-Related Leg Pain: A Retrospective Study of the Autonomic Response to a Minimally Invasive Procedure

Background

The newly proposed low back pain treatment requires case classification according to the pain mechanism (nociceptive, neuropathic or nociplastic) to determine the most effective therapeutic approach. However, there is a lack of objective tools for distinguishing these pain mechanisms. The aim of the study was to identify which symptoms, signs, and standard diagnostic parameters would allow predicting the nociplastic pain (NP) subtype among low back leg pain (LBLP) patients.

Methods

A retrospective analysis of an LBLP case–control study database was carried out. The presence of NP was assumed if the patient presented with myofascial pain syndrome (MPS) and developed a short-term intensive vasodilatation reaction in the perceived lower leg pain area after provocation by a minimally invasive procedure. Clinical data and standard LBLP diagnostic parameters were analyzed to classify patients as NP (+) vs NP (-). Next, to predict NP probability, logistic regression analysis and a diagnostic classification tree were constructed.

Results

NP was confirmed in 43.75% of LBLP patients. Women represented 95.24% of all NP (+) patients. The diagnostic classification tree indicated that NP was highly probable if the LBLP subject was female and the result of a positive straight leg raise (SLR) test was lower than 45 degrees. If the SLR test result was greater than or equal to 45 degrees, a negative result on the Bragard test would have diagnostic value. This classification tree was approved to a certain extent in the logistic regression model (deviance residuals, min: −1.8519; 1Q: −0.5551; median: −0.1907; 3Q: 0.6565 and max: 2.1058) but should be verified in a larger group of subjects.

Conclusion

Female sex, but not clinical data or standard diagnostic parameters, is indicative of nociplastic pain in LBLP patients. More sophisticated statistical methods, based on directly measurable parameters, should be proposed to distinguish NP involvement in LBLP.