Sensory characteristics of chronic non-specific low back pain: A subgroup investigation

Quantitative sensory testing and exercise-induced hypoalgesia protocols in low back pain: A scoping review

A significant driver of pain in individuals with low back pain (LBP) is alterations to endogenous pain modulation (EPM). EPM can be measured using quantitative sensory testing (QST), however; there are inconsistencies in the way QST has been implemented across the low back pain literature. The objective of this scoping review was to summarize protocols used to assess EPM using QST (pain pressure threshold (PPT), temporal summation (TS), conditioned pain modulation (CPM)) or exercise-induced hypoalgesia (EIH) in LBP. Databases Medline, Embase, CINAHL and AMED were searched on June 15, 2023, for articles that used QST or EIH protocols in LBP populations. Data was extracted on participants, study design, setting and details on QST and EIH protocols. Of the 221 studies included in the review, 196 used PPT, 62 used TS and 60 used CPM; only 5 studies investigated EIH. For all QST, there was high variability in the type of equipment, timing, trials, and testing location with many studies not reporting this information. There were 4 testing modalities used for TS, and 7 different test stimuli, and 3 different conditioning stimuli used across the studies for CPM. For CPM and EIH, PPT was the most common testing modality. There were 4 types of exercises used across the 5 EIH studies. This scoping review provides a summary of QST and EIH protocols in LBP that may be used as a guide for assessment in future studies. These results demonstrate a need for the development of standardized protocols and reporting guidelines. PERSPECTIVE: This article presents a summary of measures used to assess EPM in LBP. The results show the wide variability of protocols used in the literature. Future research should focus on creating standardized protocols, reporting guidelines and providing more guidance for researchers in selecting appropriate tests for their research questions.

Words matter: Effects of instructional cues on pressure pain threshold values in healthy people

BACKGROUND

Pressure pain threshold (PPT) measurements require standardised verbal instructional cues to ensure that the increasing pressure is stopped at the correct time consistently. This study aimed to compare how PPT values and their test-retest reliability were affected by different instructional cues.

METHODS

At two separate sessions, two PPT measurements were taken at the anterior knee for each of four different instructional cues: the cue of the German Neuropathic Research Network instructions ('DFNS'), the point where pressure first feels uncomfortable ('Uncomfortable'), 3/10 on the numerical pain rating scale ('3NPRS'), and where pain relates to an image from the pictorial-enhanced NPRS scale ('Pictorial'). Linear mixed modeling was used to quantify differences between pairs of instructional cues. Test-retest reliability was estimated using intraclass correlation coefficients (ICC[2,1] and ICC[2,k]).

RESULTS

Twenty participants were recruited. The cue resulting in greatest PPT value was DFNS (394.32 kPa, 95%CI [286.32 to 543.06]), followed by Pictorial (342.49 kPa, 95%CI [248.68 to 471.68]), then Uncomfortable (311.85 kPa, 95%CI [226.43 to 429.48]), and lastly 3NPRS (289.78 kPa, 95%CI [210.41 to 399.09]). Five of six pairwise contrasts were statistically significant. Regardless of the cues, the point estimates of ICC (2,1) ranged from 0.80 to 0.86, and the ICC (2,k) values ranged from 0.89 to 0.93. No statistically significant differences were found between any pairwise contrasts of reliability indices.

CONCLUSION

Words matter when instructing people when to stop testing in pressure algometry. Clinicians should use the same instructional cue when assessing pain thresholds to ensure reliability.

Sensorimotor Integration in Chronic Low Back Pain

OBJECTIVE

Chronic low back pain (CLBP) impacts on spine movement. Altered sensorimotor integration can be involved. Afferents from the lumbo-pelvic area might be processed differently in CLBP and impact on descending motor control. This study aimed to determine whether afferents influence the corticomotor control of paravertebral muscles in CLBP. Fourteen individuals with CLBP (11 females) and 13 pain-free controls (8 females) were tested with transcranial magnetic stimulation (TMS) to measure the motor-evoked potential [MEP] amplitude of paravertebral muscles. Noxious and non-noxious electrical stimulation, and magnetic stimulation in the lumbo-sacral area were used as afferent stimuli and triggered 20 to 200 ms prior to TMS. EMG modulation elicited by afferent stimulation alone was measured to control net motoneuron excitability. MEP/EMG ratio was used as a measure of corticospinal excitability with control of net motoneuron excitability. MEP/EMG ratio was larger at 60, 80 and 100-ms intervals in CLBP compared to controls, and afferent stimulations alone reduced EMG amplitude greater in CLBP than controls at 100 ms. Our results suggest alteration in sensorimotor integration in CLBP highlighted by a greater facilitation of the descending corticospinal input to paravertebral muscles. Our results can help to optimise interventions by better targeting mechanisms.

Reference intervals and sources of variation of pressure pain threshold for quantitative sensory testing in a Japanese population

Quantitative sensory testing (QST) is useful when analysing musculoskeletal pain disorders. A handheld algometer is most commonly used for pressure pain threshold (PPT) tests. However, reference intervals for PPTs are not elucidated. We assessed reference intervals of PPTs for QST in 158 healthy adult Japanese with no history of musculoskeletal or neurological problems. A handheld algometer was used to record PPT at five different assessment sites on the body: lumbar paravertebral muscle, musculus gluteus maximus, quadriceps, tibialis anterior muscle, and anterior talofibular ligament. Multiple regression analysis was performed to explore sources of variation of PPT according to sex, age, body mass index, UCLA Activity Level Rating, and Tegner Activity Score. Reference intervals were determined parametrically by Gaussian transformation of PPT values using the two-parameter Box-Cox formula. Results of multiple regression analysis revealed that age was significantly associated with PPT of lumbar paravertebral muscle and musculus gluteus maximus. In females, body mass index showed significant positive correlation with PPT of anterior talofibular ligament, and UCLA Activity Level Rating also showed significant positive association with tibialis anterior muscle and anterior talofibular ligament. Site-specific reference intervals of PPTs for Japanese are of practical relevance in fields of pain research using a handheld algometer.

Physiotherapists' perceptions on using a multidimensional clinical reasoning form during psychologically informed training for low back pain

PURPOSE

Building clinical reasoning skills is important to effectively implement psychologically informed practice. We developed a multidimensional clinical reasoning form (CRF) to be used by physiotherapists in a psychologically informed practice training programme for low back pain. In this paper we describe the development of the CRF, how the CRF was used in the training, and present an evaluation of physiotherapists' perceptions of the CRF.

METHODS

Qualitative semi-structured interviews were conducted with ten physiotherapists purposively sampled in primary care. Data were gathered through pre, and post training focus group interviews and a secondary analysis of individual physiotherapist interviews conducted after the training. Thematic analysis was used to analyse the data and capture the emergent themes.

RESULTS

Two main themes emerged before the training: (1) the CRF 'needs formal training' and (2) 'lacked instruction'. Three main themes emerged after the training (1) it provided 'a helpful framework for multidimensional clinical reasoning' (2) the CRF, and accompanying operational definitions, helped physiotherapists 'elicit information, with 'question prompts' helpful in facilitating patient disclosure (3) 'Utility' - although the CRF was not formally used by the physiotherapists it provided a conceptual reasoning framework to work from with more challenging patients.

CONCLUSION

The CRF was not designed to be used in isolation by clinicians without training. However, when used as a training adjunct it appears to be valued by physiotherapists to help develop their critical thinking and better characterise patients' presentations in order to personalise care from a bio-psychosocial perspective.

Nociceptive withdrawal reflexes of the trunk muscles in chronic low back pain

Individuals with chronic low back pain (CLBP) move their spine differently. Changes in brain motor areas have been observed and suggested as a mechanism underlying spine movement alteration. Nociceptive withdrawal reflex (NWR) might be used to test spinal networks involved in trunk protection and to highlight reorganization. This study aimed to determine whether the organization and excitability of the trunk NWR are modified in CLBP. We hypothesized that individuals with CLBP would have modified NWR patterns and lower NWR thresholds. Noxious electrical stimuli were delivered over S1, L3 and T12, and the 8th Rib to elicit NWR in 12 individuals with and 13 individuals without CLBP. EMG amplitude and occurrence of lumbar multifidus (LM), thoracic erector spinae, rectus abdominus, obliquus internus and obliquus externus motor responses were recorded using surface electrodes. Two different patterns of responses to noxious stimuli were identified in CLBP compared to controls: (i) abdominal muscle NWR responses were generally more frequent following 8th rib stimulation and (ii) occurrence of erector spinae NWR was less frequent. In addition, we observed a subgroup of participants with very high NWR threshold in conjunction with the larger abdominal muscle responses. These results suggest sensitization of NWR is not present in all individuals with CLBP, and a modified organization in the spinal networks controlling the trunk muscles that might explain some changes in spine motor control observed in CLBP.

Pressure Pain Threshold Protocols With Pressure Algometer in Patients With Low Back Pain: A Systematic Review With Meta-Analysis

OBJECTIVE

The pressure pain threshold is commonly employed to assess pain in various conditions. Despite its widespread use, the measurement of pressure pain thresholds is not consistently described across studies. Therefore, this review aimed to systematically examine the evidence regarding the assessment of pressure pain thresholds in patients with low back pain, including the protocols and body sites employed.

METHODS

Six databases were systematically screened from their earliest records to May 2023 to identify studies utilizing pressure pain thresholds. Eligibility screening was conducted for the identified studies, and the included studies underwent appraisal using the appropriate tool corresponding to their study design.

RESULTS

Upon categorizing based on the type of pain, we included 5 studies involving acute low back pain and 43 studies with chronic pain. The meta-analysis was conducted to compare subjects with and without pain, revealing no significant difference for the paraspinal region (SMD = -4.19, 95%CI = -11.7 to 3.32, z = -1.09, p = .27), piriformis (SMD = -1.24, 95%CI = -4.25 to 1.76, z = -0.81, p = .42) and quadratus lumborum musculature (SMD = -0.37, 95%CI = -1.35 to 0.60, z = -0.75, p = .45).

CONCLUSION

The paraspinal and gluteal musculature are the most frequently evaluated. Concerning the protocols for assessment, no consensus was identified. However, studies that assessed chronic low back pain typically adhered to a similar approach regarding the number of measures and a constant increase in pressure.

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.

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.

Pain-related interference and pain-related psychosocial factors of three different subgroups of patients with chronic low back pain

BACKGROUND

Low back pain (LBP) subgroup identification and management are a research priority. The clarification of subgroup differences could assist clinicians in clinical decisions contributing to a tailored treatment.

OBJECTIVES

To compare pain-related interference and pain-related psychosocial factors among subgroups of chronic low back pain (localised low back pain, peripheral neuropathic back pain, and widespread pain).

DESIGN

Cross-sectional study.

METHODS

A cross-sectional study was conducted on 444 participants with chronic low back pain. Pain-related interference was investigated by the Brief Pain Inventory and Patient-Specific Functional Scale. Pain-related psychosocial factors assessment included psychosocial factors from Brief Screening Questions and maladaptive beliefs from Back Beliefs Questionnaire, self-efficacy, and expectation questions. Participants' characteristics, pain-related interference, and pain-related psychosocial factors were compared among the three groups.

RESULTS

A one-way ANCOVA presented statistically significant differences among the groups for current pain intensity [F(2,441) = 6.77, p = 0.001], pain duration [F(2,425) = 9.83, p < 0.001], pain-related interference by Brief Pain Inventory [F(2,441) = 11.97, p < 0.001], and pain-related psychosocial factors regarding symptoms of anxiety [F(2,441) = 3.85, p = 0.022], symptoms of depression [F(2,441) = 6.74, p = 0.001], social isolation [F(2,441) = 6.54, p = 0.002], catastrophising [F(2,441) = 9.72, p < 0.001], perceived stress [F(2,441) = 3.93, p = 0.020], maladaptive beliefs [F(2,441) = 6.89, p = 0.001], and expectation [F(2,441) = 6.66, p = 0.001].

CONCLUSION

Participants with widespread pain presented higher pain-related interference and pain-related psychosocial factors compared to the localised low back pain group. Participants with peripheral neuropathic back pain and widespread pain presented with similar characteristics.

An Exploration of the Influence of Non-Biomechanical Factors on Lifting-Related LBP

Objective: The primary objective was to compare non-biomechanical factors between manual workers with and without a history of LBP related to lifting. A secondary objective was to investigate associations between the change in pain intensity during repeated lifting (termed pain ramp) and non-biomechanical factors tested in the LBP group. Methods: Manual workers currently in lifting occupations with and without a history of lifting-related LBP were recruited (21 LBP and 20 noLBP) and took part in a repeated (100) lift task. A series of non-biomechanical factors, including psychological, work-related, lifestyle, whole health and psychophysical factors, were collected. Psychophysical factors (pressure pain thresholds (PPTs) and fatigue) were also measured at different time points. Associations between pain ramp during lifting and non-biomechanical factors were investigated with linear regression. Results: The LBP group reported worse perceived sleep quality, more musculoskeletal pain sites other than LBP and greater symptoms related to gastrointestinal complaints and pseudo-neurology compared to the group with no history of LBP. The group with LBP were also slightly more worried about the lifting task and felt more fatigued at the end of the lifting task. The feeling of fatigue during lifting was positively associated with pain ramp in the LBP group. Anxiety and gastrointestinal complaints were weakly negatively associated with pain ramp during lifting. Conclusions: The group differences of poorer perceived sleep, greater non-specific health complaints, slightly more worry about the lifting task and more perceived fatigue in the LBP group highlight the complex and multi-factorial nature of LBP related to lifting. The feeling of fatigue was positively associated with pain ramp in the LBP group, suggesting a close relationship with pain and fatigue during lifting that requires further exploration.

Inter-individual variability in mechanical pain sensation in patients with cervicogenic headache: an explorative study

Currently, evidence for effective physiotherapy interventions in patients with cervicogenic headache (CeH) is inconsistent. Although inter-individual variability in pain response is predictive for successful physiotherapy interventions, it was never explored in patients with CeH. Therefore the objective of the current study was to explore inter-individual variability in mechanical pain sensation, and its association with biopsychosocial-lifestyle (BPSL) characteristics in patients with CeH. A cross-sectional explorative analysis of inter-individual variability in mechanical pain sensation in 18 participants with CeH (29-51 years) was conducted. Inter-individual variability in mechanical pain sensation (standard deviations (SDs), F-statistics, Measurement System Analysis) was deducted from bilateral pressure pain thresholds of the suboccipitals, erector spine, tibialis anterior. BPSL-characteristics depression, anxiety, stress (Depression Anxiety Stress Scale-21), quality of life (Headache Impact Test-6), sleep-quality (Pittsburgh Sleep Quality Index), and sedentary time (hours/week) were questioned. Inter-individual variability in mechanical pain sensation explained 69.2% (suboccipital left), 86.8% (suboccipital right), 94.6% (erector spine left), 93.2% (erector spine right), 91.7% (tibialis anterior left), and 82% (tibialis anterior right) of the total variability in patients with CeH. The significant p-values and large F-statistic values indicate inter-individual differences in SDs. Significant associations between (1) lower quality of life and lower SDs of the suboccipital left PPT (p .005), and (2) longer sedentary time and higher SDs of the suboccipital left PPT (p .001) were observed. Results from our explorative study could suggest inter-individual variability in mechanical pain sensation at the left suboccipitals which associates with quality of life and sedentary time. These novel findings should be considered when phenotyping patients and 'individually' match interventions.

Associated Risk Factors with Low Back Pain in White-Collar Workers-A Cross-Sectional Study

Objective: The purpose of the study was to compare the pressure pain threshold (PPT) of soft tissue and the curvatures of the spine in a sitting position and to estimate associated physical risk factors with low back pain (LBP) in young adults. Subjects: White-collar workers (n= 139), both women (n = 51) and men (n = 88) were separated into a control group (n = 82) and a low-intensity LBP (NRS < 3) (n = 57). Methods: The PPTs were tested utilizing the Wagner algometer. The curvatures of the spine were measured employing the photogrammetric method. In the logistic regression model, the odds ratio (OR) was estimated with ±95% confidence interval (CI) indicating the probability of the reported LBP. Results: The PPTs of soft tissue (OR = 1.1; CI = 1.02−1.19; p < 0.05) and the angle of the thoracolumbar spine in the everyday, habitual sitting position (OR = 1.19; CI = 1.05−1.34; p < 0.05) were associated with low-intensity LBP in female subjects. Additionally, the low intensity LBP were associated with the angles of the torso (OR = 1.14; CI = 1.01−1.29; p < 0.05) and the lumbosacral spine in the corrected sitting position (OR = 1.06; CI = 0.98−1.15; p > 0.05) and BMI (OR = 1.56; CI = 0.84−2.90; p > 0.05) in male subjects. Conclusion: Individual risk factors were associated with the low-intensity LBP only in females utilizing the PPT and the thoracolumbar angle in the habitual sitting position study factors. Men from the LBP group did not effectively correct the lumbosacral angle. Therefore, re-educated, self-corrected posture with specific postural training would be expected to improve proprioception in postural control capacity and result in decreasing pain.

Taking the strain: An examination of upper back musculoskeletal tissue sensitivity in relation to upper back pain and breast size. A cross-sectional study

BACKGROUND

The physiological basis for upper back pain experienced by women with large breasts is unclear but could relate to sensitivity of musculoskeletal tissues strained from the postural adaptations to large breasts. The aim of this cross-sectional study was to examine if upper back pain and breast size were associated with greater localised sensitivity of upper back musculoskeletal tissues.

METHODS

119 healthy postmenopausal women (mean age 61 years) had their upper back pain (numerical rating scale), breast size (breast size score), and upper back tissue sensitivity (pressure pain thresholds (digital algometry, kPa)) assessed. The pressure pain thresholds of six skeletal sites (T2, T4, T6, T8, T10 and T12) and six muscular sites (pectoralis major, levator scapulae, sternocleidomastoid, and upper, middle, and lower trapezius muscles) were examined. Linear mixed models with random subject effects were used to evaluate differences in sensitivity at each anatomical site between participants grouped by upper back pain (nil-mild, moderate-severe) and breast size (small, large).

FINDINGS

For most sites, the differences in sensitivity between upper back pain groups were highly significant (P < 0.002) with significantly lower pressure pain thresholds (Mean difference (MD): 74.6 to 151.1 kPa) recorded for participants with moderate-severe upper back pain. There were no differences in sensitivity between breast size groups.

INTERPRETATION

Increased upper back musculoskeletal sensitivity is related to perceived upper back pain but not to breast size. It remains unclear if and how structural or mechanical factors related to breast size contribute to upper back pain in women with large breasts.

Do psychological factors relate to movement-evoked pain in people with musculoskeletal pain? A systematic review and meta-analysis

BACKGROUND

A growing body of evidence has demonstrated the importance of implementing movement-evoked pain in conventional pain assessments, with a significant role for psychological factors being suggested. Whether or not to include these factors in the assessment of movement-evoked pain has not yet been determined.

OBJECTIVES

The aim of this systematic review is to explore the association between psychological factors and movement-evoked pain scores in people with musculoskeletal pain.

METHODS

For this systematic review with meta-analysis, four electronic databases (PubMed, Medline, WOS, and Scopus) were searched. Cross-sectional studies, longitudinal cohort studies, and randomized controlled trials investigating the association between movement-evoked pain and psychological factors in adults with musculoskeletal pain were considered. Meta-analysis was conducted for outcomes with homogeneous data from at least 2 studies. Fischer-Z transformations were used as the measure of effect. Quality of evidence was assessed using the National Institutes of Health's Quality assessment tool for observational cohort and cross-sectional studies and Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework.

RESULTS

Meta-analyses and grading the quality of evidence revealed moderate evidence for a relation between movement-evoked pain and depressive symptoms (Fisher-z=0.27; 95%CI: 0.17, 0.36; 5 studies (n=440)), pain-related fear (Fisher-z=0.35; 95%CI: 0.26, 0.44; 6 studies (n=492)), and pain catastrophizing (Fisher-z=0.47; 95%CI: 0.36, 0.58; 4 studies (n=312)) in people with musculoskeletal pain.

CONCLUSIONS

Movement-evoked pain is weakly to moderately associated to depressive symptoms, pain-related fear, and pain catastrophizing in people with musculoskeletal pain.

Relative contributions of the nervous system, spinal tissue and psychosocial health to non-specific low back pain: Multivariate meta-analysis

BACKGROUND AND OBJECTIVES

Nervous system, psychosocial and spinal tissue biomarkers are associated with non-specific low back pain (nsLBP), though relative contributions are unclear.

DATABASES AND DATA TREATMENT

MEDLINE, EMBASE, CINAHL, PsycINFO and SPORTDiscus were searched up to 25 March 2020. Related reviews and reference lists were also screened. Observational studies examining structural and functional nervous system biomarkers (e.g. quantitative sensory tests, structural and functional brain measures), psychosocial factors (e.g. mental health, catastrophizing) and structural spinal imaging biomarkers (e.g. intervertebral disc degeneration, paraspinal muscle size) between nsLBP and pain-free controls were included. For multivariate meta-analysis, two of three domains were required in each study. Random-effects pairwise and multivariate meta-analyses were performed. GRADE approach assessed evidence certainty. Newcastle-Ottawa scale assessed risk of bias. Main outcomes were the effect size difference of domains between nsLBP and pain-free controls.

RESULTS

Of 4519 unique records identified, 33 studies (LBP = 1552, referents = 1322) were meta-analysed. Psychosocial state (Hedges' g [95%CI]: 0.90 [0.69-1.10], p < 0.001) in nsLBP showed larger effect sizes than nervous system (0.31 [0.13-0.49], p < 0.001; difference: 0.61 [0.36-0.86], p < 0.001) and spine imaging biomarkers (0.55 [0.37-0.73], p < 0.001; difference: 0.36 [0.04-0.67], p = 0.027). The relationship between domains changes depending on if pain duration is acute or chronic.

CONCLUSIONS

Psychosocial effect sizes in nsLBP are greater than that for spinal imaging and nervous system biomarkers. Limitations include cross-sectional design of studies included and inference of causality. Future research should investigate the clinical relevance of these effect size differences in relation to pain intensity and disability.

STUDY REGISTRATION

PROSPERO-CRD42020159188.

SIGNIFICANCE

Spinal imaging (e.g. intervertebral disc degeneration), psychosocial (e.g. depression) and nervous system (e.g. quantitative sensory tests, structural and functional brain measures) biomarkers contribute to non-specific low back pain. However, psychosocial factors may be more compromised than nervous system and spinal imaging biomarkers. This relationship depends on if the pain is acute or chronic. These findings underscore that the 'non-specific' label in back pain should be reconsidered, and more specific multidimensional categories evaluated to guide patient management.

Exploring multidimensional characteristics in cervicogenic headache: Relations between pain processing, lifestyle, and psychosocial factors

OBJECTIVE

Although multidimensional interventions including physiotherapy, psychology, and education are generally recommended in managing headache, and to prevent chronification, such approach is lacking in cervicogenic headache (CeH). Therefore, exploring CeH within a biopsychosocial framework is deemed an essential first step.

METHODS

Non-randomized cross-sectional design to compare pain processing, lifestyle, and psychosocial characteristics between 18 participants with CeH (CeH group) (40.2 ± 10.9 years) and 18 matched controls (control group) (39.2 ± 13.1 years). Pain processing characteristics included degree of central sensitization (Central Sensitization Inventory), and (extra)-cephalic pressure pain thresholds (kPa/cm²/s). Lifestyle characteristics included sleep quality (Pittsburgh Sleep Quality Index), physical activity, screen time, and sedentary time (hours a week). Psychosocial characteristics included degree of depression, anxiety and stress (Depression Anxiety Stress Scale-21), and quality of life (Headache Impact Test-6).

RESULTS

Pain processing characteristics: More (p = .04) participants in the CeH group showed higher degrees of central sensitization compared to the control group. Lower (p < .05) (extra)-cephalic pressure pain thresholds were revealed in the CeH group compared to the control group for each muscle. Lifestyle and psychosocial characteristics: Compared to the control group, sleep quality and headache-related quality of life were worse (p < .0001) in the CeH group. Severe to extreme stress was experienced by more participants in the CeH group (p = .02). Further, significant relations between pain processing and (1) lifestyle characteristics and (2) psychosocial characteristics were seen in the CeH group.

CONCLUSION

Exploring multidimensional characteristics in CeH exposed relations between pain processing, lifestyle, and psychosocial characteristics. These novel findings fill a gap in the current scientific literature, and highlight the need for outcome research targeting lifestyle and psychosocial factors.

Contribution of COMT and BDNF Genotype and Expression to the Risk of Transition From Acute to Chronic Low Back Pain

OBJECTIVES

A number of factors, including heritability and the environment, contribute to risk of transition from acute low back pain to chronic low back pain (CLBP). The aim of this study was to (1) compare somatosensory function and pain ratings at low back pain (LBP) onset between the acute low back pain and CLBP conditions and (2) evaluate associations between BDNF and COMT polymorphisms and expression levels at LBP onset to acute and chronic pain burden and risk for transition to the chronic pain state.

METHODS

In this longitudinal study, 220 participants were enrolled following recent onset of LBP and data were collected until the LBP resolved or until the end of the study at 6 months. Forty-two participants' pain resolved before 6 weeks from onset and 42 participants continued to have pain at 6 months. Patient-reported pain burden, somatosensory function (quantitative sensory testing), and blood samples were collected at each study visit.

RESULTS

CLBP is associated with greater pain burden and somatosensory hypersensitivity at the time of LBP onset. COMT rs4680 genotype (GG) was associated with acute cold pain sensitivity and with the risk for transition to CLBP while COMT expression was independently associated with risk for transition.

DISCUSSION

CLBP was characterized by higher reported pain burden and augmented hypersensitivity at LBP onset. COMT expression and genotype were associated with acute pain burden and likelihood of transition to CLBP.

Spinal postural variability relates to biopsychosocial variables in patients with cervicogenic headache

Patients with cervicogenic headache (CeH) showed lower spinal postural variability (SPV). In a next step, the complex character of such SPV needs to be analysed. Therefore, variables influencing SPV need to be explored. A non-randomized repeated-measure design was applied to analyse relations between biopsychosocial variables and SPV within a CeH-group (n = 18), 29–51 years, and matched control-group (n = 18), 26–52 years. Spinal postural variability, expressed by standard deviations, was deducted from 3D-Vicon motion analysis of habitual spinal postures (degrees). Interactions between SPV and pain processing, lifestyle, psychosocial characteristics were analysed. Pain processing characteristics included symptoms of central sensitization (Central Sensitization Inventory), (extra)-cephalic pressure pain thresholds (kPa/cm²/s). Lifestyle characteristics included sleep quality (Pittsburgh Sleep Quality Index), physical activity, screen-time, sedentary-time (hours a week), position (cm) and inclination (degrees) of the laptop (= desk-setup). Psychosocial characteristics included degree of depression, anxiety and stress (Depression Anxiety Stress Scale-21), impact of headache on quality of life (Headache Impact Test-6). Spinal postural variability related significantly to intrinsic (stress, anxiety, extra-cephalic pressure pain thresholds, sleep-duration) and extrinsic (desk-setup, screen-time) variables in the CeH-group. In the control-group, SPV related significantly to extra-cephalic pressure pain thresholds. Spinal postural variability related to diverse variables in the CeH-group compared to the control-group. More research is needed into a possible causal relationship and its clinical implication.

Methods to discriminate between mechanism-based categories of pain experienced in the musculoskeletal system: a systematic review

ABSTRACT

Mechanism-based classification of pain has been advocated widely to aid tailoring of interventions for individuals experiencing persistent musculoskeletal pain. Three pain mechanism categories (PMCs) are defined by the International Association for the Study of Pain: nociceptive, neuropathic, and nociplastic pain. Discrimination between them remains challenging. This study aimed to build on a framework developed to converge the diverse literature of PMCs to systematically review methods purported to discriminate between them; synthesise and thematically analyse these methods to identify the convergence and divergence of opinion; and report validation, psychometric properties, and strengths/weaknesses of these methods. The search strategy identified articles discussing methods to discriminate between mechanism-based categories of pain experienced in the musculoskeletal system. Studies that assessed the validity of methods to discriminate between categories were assessed for quality. Extraction and thematic analysis were undertaken on 184 articles. Data synthesis identified 200 methods in 5 themes: clinical examination, quantitative sensory testing, imaging, diagnostic and laboratory testing, and pain-type questionnaires. Few methods have been validated for discrimination between PMCs. There was general convergence but some disagreement regarding findings that discriminate between PMCs. A combination of features and methods, rather than a single method, was generally recommended to discriminate between PMCs. Two major limitations were identified: an overlap of findings of methods between categories due to mixed presentations and many methods considered discrimination between 2 PMCs but not others. The results of this review provide a foundation to refine methods to differentiate mechanisms for musculoskeletal pain.

Masterclass: A pragmatic approach to pain sensitivity in people with musculoskeletal disorders and implications for clinical management for musculoskeletal clinicians

INTRODUCTION

Research on musculoskeletal disorders indicates that pain sensitivity can be an important consideration for musculoskeletal clinicians in the holistic view of a patient presentation. However, diversity in research findings in this field can make this a difficult concept for clinicians to navigate. Limited integration of the concept of pain sensitivity into clinical practice for musculoskeletal clinicians has been noted.

PURPOSE

The purpose of this masterclass is to provide a framework for the consideration of pain sensitivity as a contributing factor in the presentation of people with musculoskeletal pain. It provides pragmatic synthesis of the literature related to pain sensitivity through a lens of how this information can inform clinical practice for musculoskeletal clinicians. Guidance is provided in a 'how to' format for integration of this knowledge into the clinical encounter to facilitate personalised care.

IMPLICATIONS

The relationship of pain sensitivity with pain and disability is not clear or linear. The real importance of pain sensitivity in a clinical presentation may be: (1) the potential for pain sensitivity to modify the effect of common treatments utilised by musculoskeletal clinicians, or (2) the effect of pain sensitivity on the prognosis/course of a disorder. Screening tools and subjective features have been highlighted to indicate when physical assessment of pain sensitivity should be prioritised in the physical examination. A pragmatic blueprint for specific assessment related to pain sensitivity has been outlined. A framework for integrating assessment findings into clinical reasoning to formulate management plans for the pain sensitive patient is provided.

Correlation Between Central Sensitization and Remote Muscle Performance in Individuals With Chronic Low Back Pain

OBJECTIVE

The purpose of this study was to examine associations between the degree of central sensitization (CS) and remote muscle performance in people with chronic low back pain (CLBP).

METHODS

The 2011 fibromyalgia (FM) criteria and severity scales (2011 FM survey) were used as a surrogate measure of CS to divide the participants into 2 groups: FM-positive CLBP and FM-negative CLBP. Measures related to central sensitization included the 2011 FM survey and pressure pain threshold of the thumbnail. Measures related to muscle performance included neck flexor muscle strength and endurance and plantar flexor muscle strength. Between-groups and correlation analyses were performed.

RESULTS

Sixty people with CLBP were enrolled (30 FM-positive, 30 FM-negative). There was no significant difference between the subgroups in age, sex, or pain duration (P > .05). The FM-positive CLBP group showed poorer neck flexor muscle endurance (P = .01) and plantar flexor muscle strength (P = .002) than the FM-negative CLBP group, whereas neck flexor muscle strength was not different between the groups (P = .175). Scores for FM and values for pressure pain thresholds of the thumbnail were associated with neck flexor muscle strength (respectively, r = -0.320, P = .013, and r = 0.467, P < .001), endurance (r = -0.242, P < .001, and r = 0.335, P = .009), and plantar flexor muscle strength (r = -0.469, P < .001, and r = 0.500, P < .001).

CONCLUSION

We found associations between the degree of CS and remote muscle strength and endurance, suggesting that poor remote muscle performance is possibly a clinical sign of CS in people with CLBP.

Simulation-based learning for enhanced gynecologic brachytherapy training among radiation oncology residents

PURPOSE

Brachytherapy is an irreplaceable component of gynecologic cancer treatment. Resident training has declined, and procedural exposure is variable. We evaluated whether simulation-based gynecologic brachytherapy training among radiation oncology residents could improve knowledge, confidence, and interest.

METHODS AND MATERIALS

Before a brachytherapy workshop, radiation oncology residents without prior gynecologic brachytherapy experience completed a survey on brachytherapy knowledge, procedural confidence, plan evaluation, and quality/safety. Residents then participated in a gynecologic brachytherapy workshop. Lectures covered brachytherapy imaging and physics principles/quality assurance, followed by hands-on and individualized feedback regarding applicator selection and placement, target segmentation, and physics quality assurance. Afterward, preworkshop questions were recollected. Descriptive statistics and Fisher's exact tests were used for data analysis.

RESULTS

After the workshop, resident responses regarding the learning environment and baseline knowledge questions improved overall. There was a 30% improvement in favorable responses to the learning environment statement "My residency has a formal process/curriculum to teach brachytherapy" and for baseline knowledge the greatest improvement was seen for "I am familiar with the anatomy and placement of the applicators in relation to the anatomy". "Lack of didactic or procedural training exposure" was identified as the main reason for declining brachytherapy use. Initially, 1/8 residents correctly completed the knowledge questions, and after the workshop, 6/7 (p < 0.001) residents correctly completed the questions.

CONCLUSIONS

Domain-specific knowledge, procedural confidence, and brachytherapy interest improved after a gynecologic brachytherapy workshop. Integrated didactic and simulation-based brachytherapy training may serve as a valuable learning tool to augment resident knowledge, introduce practical skills, and spark resident interest in brachytherapy.

Meta-Analysis of Integrated Therapeutic Methods in Noninvasive Lower Back Pain Therapy (LBP): The Role of Interdisciplinary Functional Diagnostics

Introduction. Lower back pain (LBP) is almost a problem of civilizations. Quite often, it is a consequence of many years of disturbed distribution of tension within the human body caused by local conditions (injuries, hernias, stenoses, spondylolisthesis, cancer, etc.), global factors (postural defects, structural integration disorders, lifestyle, type of activity, etc.), or systemic diseases (connective tissue, inflammation, tumours, abdominal aneurysm, and kidney diseases, including urolithiasis, endometriosis, and prostatitis). Therefore, LBP rehabilitation requires the use of integrated therapeutic methods, combining the competences of interdisciplinary teams, both in the process of diagnosis and treatment. Aim of the Study. Given the above, the authors of the article conducted meta-analysis of the literature in terms of integrated therapeutic methods, indicating the techniques focused on a holistic approach to the patient. The aim of the article is to provide the reader with comprehensive knowledge about treating LBP using noninterventional methods. Material and Methods. An extensive search for the materials was conducted online using PubMed, the Cochrane database, and Embase. The most common noninterventional methods have been described, as well as the most relevantly updated and previously referenced treatment of LBP. The authors also proposed noninvasive (measurable) diagnostic procedures for the functional assessment of the musculoskeletal system, including initial, systematic, and cross-sectional control. All figures and images have been prepared by the authors and are their property.

Results

This review article goes beyond combining a detailed description of each procedure with full references, as well as a comprehensive discussion of this very complex and troublesome problem.

Conclusions

Lower back pain is a serious health problem, and this review article will help educate physicians and physiotherapists dealing with LBP in the options of evidence-based treatment. Ultimately, the article introduces and postulates the need to systematize therapeutic procedures in LBP therapy, with a long-term perspective.

Relationships Between Psychological, Social, Physical Activity, and Sleep Measures and Somatosensory Function in Individuals With Spinal Pain: A Systematic Review and Meta-analysis

OBJECTIVE

Somatosensory abnormalities are linked to clinical pain outcomes in individuals with spinal pain. However, a range of factors might confound the relationship between altered somatosensory function and clinical pain outcomes. This systematic review aimed to evaluate the literature to assess the level of evidence of associations between psychological, social, physical activity, and sleep measures and somatosensory function (assessed via sensory psychophysical testing) among individuals with spinal pain.

METHODS

A comprehensive literature search was performed in 6 electronic databases from their inception to June 2018. Two reviewers independently assessed the methodological quality using a modified Quality in Prognostic Studies (QUIPS) tool and supplemented with recommendations from the Critical Appraisal and Data Extraction for the Systematic Review of Prediction Modelling Studies (CHARMS) checklist and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. The level of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) system. Data were pooled to evaluate the strength of the relationships of interest.

RESULTS

Among the 17 factors identified in the included studies, pain catastrophizing, depression, and pain-related fear have significant negative (small to fair) associations with pain thresholds. A "very low" to "moderate" quality of evidence was found for all the investigated factors. Subgroup analysis showed a smaller effect size for pain catastrophizing/fear of movement and pain thresholds in individuals with low back pain.

CONCLUSIONS

Psychological factors are associated negatively with pain thresholds and they need to be adjusted when establishing predictive relationships between somatosensory function and pain outcomes in individuals with spinal pain.

A Subgroup of Chronic Low Back Pain Patients With Central Sensitization

BACKGROUND

Our knowledge of central sensitization (CS) in chronic low back pain (CLBP) is limited. 2011 fibromyalgia criteria and severity scales (2011 FM survey) have been used to determine FM positive as a surrogate of CS. The major features of CS including widespread hyperalgesia and dysfunction of the descending inhibitory pathways can be identified by pressure pain threshold (PPT) and conditioned pain modulation (CPM) tests. The purpose of the study was to examine neurophysiological characteristics and psychosocial symptoms in a subgroup of FM-positive CLBP compared with FM-negative CLBP patients.

METHODS

A total of 46 participants with CLBP and 22 pain-free controls completed outcome measures of the 2011 FM survey, PPT and CPM tests, and psychosocial questionnaires. Differences between FM-positive and FM-negative CLBP participants on these measures and correlations were analyzed.

RESULTS

The 2011 FM survey identified 22 (48%) participants with CLBP as FM positive. FM-positive CLBP participants showed lower PPT values of the thumbnail (P=0.011) and lower back (P=0.003), lower CPM values of the thumbnail (P=0.002), and more severe pain catastrophizing, anxiety, and depression symptoms (P<0.05) than FM-negative CLBP participants. The 2011 FM scores were significantly correlated with the PPT and CPM values of the thumbnail and with psychosocial symptoms (P<0.001).

DISCUSSION

Our findings suggest a subgroup of CLBP patients exhibiting with signs and symptoms of CS. Associations between subjective and objective CS measures indicate that the 2011 FM survey can be utilized to identify the presence of CS in CLBP in clinical practice.

Pain Mechanisms in Low Back Pain: A Systematic Review With Meta-analysis of Mechanical Quantitative Sensory Testing Outcomes in People With Nonspecific Low Back Pain

BACKGROUND

Mechanical quantitative sensory testing (QST) assesses sensory functioning and detects functional changes in (central) nociceptive processing. It has been hypothesized that these functional changes might be apparent in people with nonspecific low back pain (LBP), although the results are mixed.

OBJECTIVE

The aim of this systematic review was to examine whether sensory function, measured with QST, was altered in people with nonspecific LBP.

METHODS

This systematic review was conducted according to PRISMA guidelines. Six databases were searched for relevant literature. Studies comparing mechanical QST measures involving people with subacute and chronic LBP and healthy controls were included if (1) pressure pain thresholds (PPTs), (2) temporal summation, or (3) conditioned pain modulation were reported. Risk of bias was assessed using the Newcastle-Ottawa scale. When possible, the results from different studies were pooled.

RESULTS

Twenty-four studies were included. Scores on the Newcastle-Ottawa scale varied between 1 and 6 points. People with nonspecific LBP, compared to healthy controls, had significantly lower PPTs at remote sites and increased temporal summation at the lower back. The PPTs measured at the scapula were significantly lower in patients with nonspecific LBP than in healthy controls (pooled mean difference, 119.2 kPa; 95% confidence interval: 91.8, 146.6 kPa; P<.001).

CONCLUSION

The PPT measurements at remote body parts were significantly lower in people with nonspecific LBP compared with healthy controls. Temporal summation and conditioned pain modulation measurements had mixed outcomes.

LEVEL OF EVIDENCE

Therapy, level 3a. J Orthop Sports Phys Ther 2019;49(10):698-715. Epub 23 Aug 2019. doi:10.2519/jospt.2019.8876.

Preclinical Signs of a Temporomandibular Disorder in Female Patients With Episodic Cervicogenic Headache Versus Asymptomatic Controls: A Cross-Sectional Study

BACKGROUND

The International Classification of Headache Disorders, 3rd Edition, accepted "headache attributed to temporomandibular disorders" as a valid headache. The neurophysiologic interplay between cervical structures and the temporomandibular joint, however, might also suggest that a temporomandibular disorder could develop in patients with cervicogenic headache.

OBJECTIVE

To compare the presence of preclinical temporomandibular signs between female patients with episodic cervicogenic headache and a control group.

DESIGN

Case-controlled cross-sectional design.

SETTING

Institutional setting: Hasselt University.

PARTICIPANTS

Twenty-two women (mean age ± SD: 20.7 ± 2.5 years) with episodic cervicogenic headache, without temporomandibular signs and 22 matched (gender, age, level of education, occupation) asymptomatic controls (21 ± 2.3 years).

METHODS

(Un)assisted temporomandibular range of motion, pressure pain thresholds, painful palpations were examined and the level of perceived stress was measured.

MAIN OUTCOME MEASUREMENTS

Temporomandibular range of motion (mm), pressure pain thresholds (kPa/cm²), painful palpations (yes/no), and level of perceived stress (Perceived Stress Scale).

RESULTS

Maximal mouth-opening was significantly smaller in the headache group (P <.05; effect size [ES] -0.45). Palpation of the masseter resulted in significantly more positive pain responses in the headache group at the left (P = .009; ES ∞) and right (P = .002;ES 17.5) origin, left (P = .004; ES 14.54) and right (P = .03; ES 5.71) body and left (P < .001; ES 12) insertion. Significantly lower pressure pain thresholds on the left and right anterior (P = .03; ES -0.33 resp. P = .02; ES -0.35), central (P = .003; ES 1.02 resp. P = .02; ES 0.79) and right posterior (P = .03; ES 0.62) temporalis and right tibialis anterior (P = .03; ES -0.33) were measured in the headache group. The level of perceived stress was significantly higher (P = .02) in the headache group.

CONCLUSIONS

Patients with episodic cervicogenic headache present with signs of a preclinical temporomandibular disorder and sensitization. The smaller range of motion, lower pressure pain thresholds, and higher levels of stress accentuate the multidimensionality of the problem.

LEVEL OF EVIDENCE

IV.

Development of a topical menthol stimulus to evaluate cold hyperalgesia

PURPOSE

Cold hyperalgesia is an indicator of widespread pain sensitivity and is associated with poor clinical outcomes. Menthol activates TRPM8, a cold-sensing receptor channel. This research evaluated topical menthol as a potential stimulus to be used in the clinical evaluation of cold hyperalgesia.

METHODS

Participants were 59 pain free volunteers (17 male: 42 female). A blinded, repeated measures design was used. Participants received applications of menthol at different concentrations in a liquid (study 1) or gel (study 2) formulation with a 24-h interval between each application. Each menthol concentration was applied for 15 min and participants were asked to rate the sensation produced using a series of visual analogue scales and by selecting words from a descriptor list derived from the McGill pain questionnaire (MPQ). The menthol was applied to a site on the volar forearm. Participants also had their cold pain thresholds (CPT) evaluated at the same site using a contact thermode.

RESULTS

There were significant concentration-dependent effects for intensity of cold, unpleasantness and pain VAS: cold F_(2,62) = 8.67, p < 0.001; unpleasantness χ²(₂) = 14.14, p < 0.001; χ²(₂) = 11.74, p = 0.003, with moderate effect sizes for unpleasantness and pain. There were also significant concentration dependent effects for descriptor indices, pain rating index (PRI) F_(2,62) = 26.33, p < 0.001; number of words chosen (NWC) F_(2,62) = 19.62, p < 0.001, with large effect sizes for 10-20% and 10-30% comparisons. Significant correlations were seen between measures of unpleasantness, pain, PRI, NWC and CPT dependent on menthol concentration.

CONCLUSION

Topical menthol has potential as a stimulus to evaluate cold hyperalgesia.

Is the Organization of the Primary Motor Cortex in Low Back Pain Related to Pain, Movement, and/or Sensation?

AIM/BACKGROUND

Primary motor cortex (M1) organization differs between individuals with and without chronic low back pain (CLBP), in parallel with motor and sensory impairments. This study investigated whether movement behaviour and tactile/pain sensation are related to M1 organisation in CLBP.

METHODS

Transcranial magnetic stimulation (TMS) was used to map the M1 representation of the erector spinae and multifidus muscles in 20 participants with and without CLBP. Cortical organisation was quantified by: map volume; center of gravity (CoG); number of peaks; and primary and secondary peak location. Movement behaviour was assessed as the ability to dissociate lumbar from thorax motion and sensory function as two-point discrimination, pressure pain thresholds, and pain intensity (visual analogue scale).

RESULTS

People with CLBP showed more anterior location of the CoG than controls. Map peaks were more numerous in CLBP participants who performed the movement task good than those with poor performance. In CLBP, smaller map volume correlated with greater pain during the movement task. Movement behaviour was not linearly correlated with M1 features.

CONCLUSIONS

This study confirms that M1 maps differ between people with and without CLBP, but these changes are variable within the CLBP group and are not related to motor and sensory features in a simple manner.

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

BACKGROUND AND AIMS

Some low back pain (LBP) patients recover after every pain episode whereas others develop chronicity. Research indicates that the amount of atrophy and fat infiltration differs between patients with LBP. Also enhanced pain sensitivity is present only in a subgroup of LBP patients. The relationship between pain sensitivity and muscular deformations in LBP, is however unexplored. This study examined the association between pressure pain sensitivity and the structural characteristics of the lumbar muscles in three different groups of non-specific LBP patients.

METHODS

This cross-sectional study examined the total cross-sectional area (CSA), fat CSA, muscle CSA and muscle fat index (MFI) of the lumbar multifidus (MF) and erector spinae (ES) at level L4 by magnetic resonance imaging in 54 patients with non-specific LBP (23 recurrent LBP, 15 non-continuous chronic LBP and 16 continuous chronic LBP). Pressure pain thresholds were measured at four locations (lower back, neck, hand and leg) by a manual pressure algometer and combined into one "pain sensitivity" variable. As a primary outcome measure, the association between pain sensitivity and muscle structure characteristics was investigated by multiple independent general linear regression models. Secondly, the influence of body mass index (BMI) and age on muscle characteristics was examined.

RESULTS

A positive association was found between pain sensitivity and the total CSA of the MF (p=0.006) and ES (p=0.001), and the muscle CSA of the MF (p=0.003) and ES (p=0.001), irrespective of the LBP group. No association was found between pain sensitivity and fat CSA or MFI (p>0.01). Furthermore, a positive association was found between BMI and the fat CSA of the MF (p=0.004) and ES (p=0.006), and the MFI of the MF (p<0.01) and ES (p=0.003). Finally, a positive association was found between age with the fat CSA of the MF (p=0.008) but not with the fat CSA of the ES (p>0.01), nor the MFI of the MF (p>0.01) and ES (p>0.01).

CONCLUSIONS

A higher pain sensitivity is associated with a smaller total and muscle CSA in the lumbar MF and ES, and vice versa, but results are independent from the LBP subgroup. On the other hand, the amount of fat infiltration in the lumbar muscles is not associated with pain sensitivity. Instead, a higher BMI is associated with more lumbar fat infiltration. Finally, older patients with LBP are associated with higher fat infiltration in the MF but not in the ES muscle.

IMPLICATIONS

These results imply that reconditioning muscular tissues might possibly decrease the pain sensitivity of LBP patients. Vice versa, therapy focusing on enhancement of pain sensitivity might also positively influence the CSA and that way contribute to the recovery of LBP. Furthermore, the amount of lumbar muscle fat seems not susceptible to pain sensitivity or vice versa, but instead a decrease in BMI might decrease the fat infiltration in the lumbar muscles and therefore improve the muscle structure quality in LBP. These hypothesis apply for all non-specific LBP patients, despite the type of LBP.

Hypothalamic-pituitary-adrenal axis feedback sensitivity in different states of back pain

Pain normally signals a threat to bodily integrity and causes emotional distress. Acute pain serves a protective function, yet, when pain turns chronic, the protective function is lost. A chain of psychophysiological alterations including changes in the stress regulation system, apparent in dysfunctional activity and responsivity of the hypothalamic-pituitary-adrenal (HPA) axis, might be an important factor in this context. Moreover, maladaptive responses may be complicated by affective comorbid symptoms such as anxiety and depression, and alter nociceptive processing. However, the relationship among pain chronicity, stress regulation, and contributing components of comorbid symptomatology as well as somatosensory profiles has rarely been examined. In the present study, we obtained diurnal cortisol profiles at baseline and feedback regulation (following a dexamethasone suppression test (DST)) in subacute (SABP) and chronic (CBP) back pain patients and healthy control individuals (HC). We also assessed anxiety, depression and chronic stress levels and used quantitative sensory testing (QST) to detect sensory abnormalities. We found a hyper-suppression of cortisol following DST and thus enhanced negative stress feedback sensitivity in SABP compared to both CBP and HC. In SABP, DST-related cortisol levels were negatively associated with pain intensity, mediated by cold pain thresholds and anxiety. These data support a stress model of pain chronicity and suggest that stress responses might be indicators of individual vulnerability in the transition period of subacute pain.

Clinical assessments can discriminate altered body perception in patients with unilateral chronic low back pain, but not differences between affected and unaffected side

Chronic pain disorders appear to be associated with altered body perception. The clinical tools of two-point discrimination (TPD), left/right judgment task (LRJ) and body image drawing (BID) can all be used to assess altered body perception in people with chronic low back pain (CLBP). The aim of this observational study was to examine whether values from TPD, LRJ and BID can determine altered body perception between unilateral CLBP patients' painful and pain-free trunk sides, through the evaluation of some of the underlying mechanisms of body perception. Twenty-seven eligible participants completed all tasks. Inclusion criteria were: unilateral CLBP with duration of over 12 weeks; pain level higher than two out of ten on the numeric rating scale; a minimum score of four points on the Roland Morris Disability Questionnaire (RMDQ). Findings from TPD and BID tests showed an alteration in body awareness. However, no significant interaction effects were found between the affected sides and their measurements (TPD p = 0.310, LRJ response time p = 0.571, LRJ accuracy p = 0.190, BID p = 0.751). The profiling of people with high levels of distorted body perception for other factors known to contribute to CLBP may be a useful direction for further investigation.

No immediate analgesic effect of diadynamic current in patients with nonspecific low back pain in comparison to TENS

BACKGROUND AND DESIGN

Chronic nonspecific low back pain (CNSLBP) has major socioeconomic as well as personal impact in many industrialized and developing countries. Physiotherapy is a common intervention for this group of patients and using anti-pain physical modalities is a common part of the physical therapy. In a randomized controlled trial we investigated the immediate effect of the Diadynamic current in comparison to TENS on reducing the pain in patients suffering from non specific chronic low back pain.

METHODS

Thirty patients were randomized into the Diadynamic current and TENS groups. Electrical stimulation was applied for 10 min in the Diadynamic group and for 15 min in the TENS group for one session. Pain, on a 100 mm Visual Analog Scale, and Pressure Pain Threshold (PPT), using an Algometer, was measured before the treatment, after the current application, 20 min later and after 48 h.

RESULTS

Pain was decreased significantly after 20 min following the current application only in the TENS group, with no improvement at all measurement points in the group receiving Diadynamic current. PPT was increased immediately after current application in both groups but did not last until later measurements.

CONCLUSION

Diadynamic current had no positive effect on prompt relief of pain in patients suffering from recurrent CNSLBP.

Evidence of generalised mechanical hyperalgesia in patients with advanced knee osteoarthritis undergoing total knee arthroplasty

BACKGROUND AND OBJECTIVE

Persistent pain is reported in up to 34% of patients following total knee arthroplasty (TKA) for management of knee osteoarthritis (KOA). Persistent pain in this group is thought to be at least partly reflective of pain sensory hypersensitivity. The objective of this study was to evaluate sensory hypersensitivity, using mechanical and thermal quantitative sensory testing, in patients about to undergo TKA.

DESIGN AND METHODS

Pressure pain thresholds (PPT) and cold pain thresholds (CPT) were recorded from 30 participants prior to their TKA, and compared with recordings taken from 30 healthy control participants of similar age and gender. Thresholds were recorded locally and remotely (other knee, deltoid) to the operative knee. Group comparisons (KOA, control, groups) were made using a general linear mixed models approach with age, gender, and body mass index (BMI) included as covariates. Pairwise comparisons were conducted with Bonferonni correction for multiple comparisons.

RESULTS

Significantly lower PPTs were at all measured sites in the KOA group compared to the control group (P<0.001 at all sites, except the deltoid P=0.004). Males demonstrated higher pain threshold compared to females, averaged over all sites, P=0.02. There were no observed between-group differences in CPT (P=0.122).

CONCLUSIONS

This study suggested that some individuals about to undergo TKA for their advanced KOA demonstrated widespread mechanical sensory hypersensitivity. These findings have potentially important clinical implications regarding perioperative and longer-term pain management in these patients.

Cognitive Functional Therapy: An Integrated Behavioral Approach for the Targeted Management of Disabling Low Back Pain

Biomedical approaches for diagnosing and managing disabling low back pain (LBP) have failed to arrest the exponential increase in health care costs, with a concurrent increase in disability and chronicity. Health messages regarding the vulnerability of the spine and a failure to target the interplay among multiple factors that contribute to pain and disability may partly explain this situation. Although many approaches and subgrouping systems for disabling LBP have been proposed in an attempt to deal with this complexity, they have been criticized for being unidimensional and reductionist and for not improving outcomes. Cognitive functional therapy was developed as a flexible integrated behavioral approach for individualizing the management of disabling LBP. This approach has evolved from an integration of foundational behavioral psychology and neuroscience within physical therapist practice. It is underpinned by a multidimensional clinical reasoning framework in order to identify the modifiable and nonmodifiable factors associated with an individual's disabling LBP. This article illustrates the application of cognitive functional therapy to provide care that can be adapted to an individual with disabling LBP.

Cold Pain Threshold Identifies a Subgroup of Individuals With Knee Osteoarthritis That Present With Multimodality Hyperalgesia and Elevated Pain Levels

OBJECTIVES

Cold hyperalgesia has been established as an important marker of pain severity in a number of conditions. This study aimed to establish the extent to which patients with knee osteoarthritis (OA) demonstrate widespread cold, heat, and pressure hyperalgesia. OA participants with widespread cold hyperalgesia were compared with the remaining OA cohort to determine whether they could be distinguished in terms of hyperalgesia, pain report, pain quality, and physical function.

METHODS

A total of 80 participants with knee OA and 40 matched healthy, pain-free controls participated. OA participants completed a washout of their usual medication. Quantitative sensory testing was completed at 3 sites using standard methods. Cold pain threshold (CPT) and heat pain thresholds (HPT) were tested using a Peltier thermode and pressure pain thresholds (PPT) using a digital algometer. All participants completed the short-form health survey questionnaire and OA participants completed the PainDETECT, Western Ontario and McMaster Universities Osteoarthritis Index of the Knee (WOMAC), and pain quality assessment scale questionnaires.

RESULTS

OA participants demonstrated widespread cold hyperalgesia (P<0.0001), had lower PPT at the index knee (P<0.0001) compared with controls and reported decreased physical health on the SF-36 (P=0.01). The OA subcohort with high global CPT (≥12.25°C) exhibited multimodality sensitization compared with the remaining OA cohort (PPT P<0.0001; CPT P<0.0001; HPT P=0.021 index knee). This group also reported increased pain, decreased function, and more features of neuropathic pain.

DISCUSSION

This study identified a specific subgroup of patients with knee OA who exhibited widespread, multimodality hyperalgesia, more pain, more features of neuropathic pain, and greater functional impairment. Identification of patients with this pain phenotype may permit more targeted and effective pain management.

Individual Variation in Pain Sensitivity and Conditioned Pain Modulation in Acute Low Back Pain: Effect of Stimulus Type, Sleep, and Psychological and Lifestyle Factors

Generalized hyperalgesia and impaired pain modulation are reported in chronic low back pain (LBP). Few studies have tested whether these features are present in the acute phase. This study aimed to test for differences in pain presentation in early-acute LBP and evaluate the potential contribution of other factors to variation in sensitivity. Individuals within 2 weeks of onset of acute LBP (n = 126) and pain-free controls (n = 74) completed questionnaires related to their pain, disability, behavior, and psychological status before undergoing conditioned pain modulation (CPM) and pain threshold (heat, cold, and pressure) testing at the back and forearm/thumb. LBP participants were more sensitive to heat and cold at both sites and pressure at the back than controls, without differences in CPM. Only those with high-pain (numeric rating scale ≥4) were more sensitive to heat at the forearm and pressure at the back. Four subgroups with distinct features were identified: "high sensitivity," "low CPM efficacy," "high sensitivity/low CPM efficacy," and "low sensitivity/high CPM efficacy." Various factors such as sleep and alcohol were associated with each pain measure. Results provide evidence for generalized hyperalgesia in many, but not all, individuals during acute LBP, with variation accounted for by several factors. Specific pain phenotypes provide candidate features to test in longitudinal studies of LBP outcome.

PERSPECTIVE

Sensory changes indicative of increased/decreased central processing of pain and nociceptive input presented differently between individuals with acute LBP and were related to factors such as sleep and alcohol. This may underlie variation in outcome and suggest potential for early identification of individuals with poor long-term outcome.

ISSLS PRIZE IN CLINICAL SCIENCE 2018: longitudinal analysis of inflammatory, psychological, and sleep-related factors following an acute low back pain episode-the good, the bad, and the ugly

STUDY DESIGN

Prospective longitudinal study.

OBJECTIVE

To determine whether systemic cytokines and C-reactive protein (CRP) during an acute episode of low back pain (LBP) differ between individuals who did and did not recover by 6 months and to identify sub-groups based on patterns of inflammatory, psychological, and sleep features associated with recovery/non-recovery. Systemic inflammation is observed in chronic LBP and may contribute to the transition from acute to persistent LBP. Longitudinal studies are required to determine whether changes present early or develop over time. Psychological and/or sleep-related factors may be related.

METHODS

Individuals within 2 weeks of onset of acute LBP (N = 109) and pain-free controls (N = 55) provided blood for assessment of CRP, tumor necrosis factor (TNF), interleukin-6 (IL-6) and interleukin-1β, and completed questionnaires related to pain, disability, sleep, and psychological status. LBP participants repeated measurements at 6 months. Biomarkers were compared between LBP and control participants at baseline, and in longitudinal (baseline/6 months) analysis, between unrecovered (≥pain and disability), partially recovered (reduced pain and/or disability) and recovered (no pain and disability) participants at 6 months. We assessed baseline patterns of inflammatory, psychological, sleep, and pain data using hierarchical clustering and related the clusters to recovery (% change in pain) at 6 months.

RESULTS

CRP was higher in acute LBP than controls at baseline. In LBP, baseline CRP was higher in the recovered than non-recovered groups. Conversely, TNF was higher at both time-points in the non-recovered than recovered groups. Two sub-groups were identified that associated with more ("inflammatory/poor sleep") or less ("high TNF/depression") recovery.

CONCLUSIONS

This is the first evidence of a relationship between an "acute-phase" systemic inflammatory response and recovery at 6 months. High inflammation (CRP/IL-6) was associated with good recovery, but specific elevation of TNF, along with depressive symptoms, was associated with bad recovery. Depression and TNF may have a two-way relationship. These slides can be retrieved under Electronic Supplementary Material.

Process of Change in Pain-Related Fear: Clinical Insights From a Single Case Report of Persistent Back Pain Managed With Cognitive Functional Therapy

Study Design Single case report with repeated measures over 18 months. Background Management of persistent low back pain (PLBP) associated with high pain-related fear is complex. This case report aims to provide clinicians with insight into the process of change in a person with PLBP and high bending-related fear, who was managed with an individualized behavioral approach of cognitive functional therapy. Case Description A retired manual worker with PLBP believed that his spine was degenerating, that bending would hurt him, and that avoidance was the only form of pain control. At baseline, he presented high levels of pain-related fear on the Tampa Scale of Kinesiophobia (score, 47/68) and a high-risk profile on the Örebro Musculoskeletal Pain Questionnaire (score, 61/100). Unhelpful beliefs and behaviors led to a vicious cycle of fear and disengagement from valued life activities. Guided behavioral experiments were used to challenge his thoughts and protective responses, indicating that his behavior was modifiable and the pain controllable. Using a multidimensional clinical-reasoning framework, cognitive functional therapy management was tailored to target key drivers of PLBP and delivered over 6 sessions in a 3-month period. Outcomes Over an 18-month clinical journey, he demonstrated improvements in bending-related fear, pain expectancy, and pain experience, and substantial changes in pain-related fear (Tampa Scale of Kinesiophobia: 33/68; change, -14 points) and risk profile (Örebro Musculoskeletal Pain Questionnaire: 36/100; change, -25 points). Clinical interviews at 6 and 18 months revealed positive changes in mindset, understanding of pain, perceived pain control, and behavioral responses to pain. Discussion This case report provides clinicians with an insight to using a multidimensional clinical-reasoning framework to identify and target the key drivers of the disorder, and to using cognitive functional therapy to address unhelpful psychological and behavioral responses to pain in a person with PLBP and high pain-related fear. Level of Evidence Therapy, level 5. J Orthop Sports Phys Ther 2017;47(9):637-651. Epub 13 Jul 2017. doi:10.2519/jospt.2017.7371.

Altered somatosensory profile according to quantitative sensory testing in patients with degenerative lumbar spine disorders scheduled for surgery

Background

Somatosensory profiling in affected and non-affected body regions can strengthen our insight regarding the underlying pain mechanisms, which can be valuable in treatment decision making and to improve outcomes, in patients with degenerative lumbar spine disorders pre-surgery. The aim was to describe somatosensory profiles in patients with degenerative lumbar spine disorders, to identify the proportion with altered somatosensory profile, and to analyze demographic characteristics, self-reported function, pain, and health pre- and 3 months post-surgery.

Methods

In this prospective cohort study in a Spine Clinic, 105 patients scheduled for surgery for spinal stenosis, disc herniation, degenerative disc disease, or spondylolisthesis were consecutively recruited. Exclusion criteria were; indication for acute surgery or previous surgery at the same spinal level or severe grade of pathology. Quantitative sensory testing (QST) and self-reported function, pain, and health was measured pre- and 3 months post-surgery. The somatosensory profile included cold detection threshold, warmth detection threshold, cold pain threshold, heat pain threshold and pressure pain threshold in affected and non-affected body regions.

Results

On a group level, the patients’ somatosensory profiles were within the 95% confidence interval (CI) from normative reference data means. On an individual level, an altered somatosensory profile was defined as having two or more body regions (including a non-affected region) with QST values outside of normal ranges for reference data. The 23 patients (22%) with altered somatosensory profiles, with mostly loss of function, were older (P = 0.031), more often female (P = 0.005), had higher back and leg pain (P = 0.016, 0.020), lower mental health component summary score (SF-36 MCS) (P = 0.004) and larger pain distribution (P = 0.047), compared to others in the cohort. Post-surgery there was a tendency to worse pain, function and health in the group with altered somatosensory profile pre-surgery.

Conclusions

On a group level, patients with degenerative lumbar spine disorders scheduled for surgery were within normal range for the QST measurements compared to reference values. On an individual level, an altered somatosensory profile outside of normal range in both affected and non-affected body regions occurred in 22% of patients, which may indicate disturbed somatosensory function. Those patients had mostly loss of sensory function and had worse self-reported outcome pre-surgery, compared to the rest of the cohort. Future prospective studies are needed to further examine whether these dimensions can be useful in predicting post-surgery outcome and guide need of additional treatments.

Pain provocation following sagittal plane repeated movements in people with chronic low back pain: Associations with pain sensitivity and psychological profiles

BACKGROUND AND AIMS

Provocative pain responses following standardised protocols of repeated sagittal plane spinal bending have not been reported in people with chronic low back pain (CLBP). Potential differing pain responses to movement likely reflect complex sensorimotor interactions influenced by physical, psychological and neurophysiological factors. To date, it is unknown whether provocative pain responses following repeated bending are associated with different pain sensitivity and psychological profiles. Therefore the first aim of this study was to determine whether data-driven subgroups with different, clinically-important pain responses following repeated movement exist in a large CLBP cohort, specifically using a standardised protocol of repeated sagittal plane spinal bending. The second aim was to determine if the resultant pain responses following repeated movement were associated with pain and disability, pain sensitivity and psychological factors.

METHODS

Clinically-important (≥2-points, 11-point numeric rating scale) changes in pain intensity following repeated forward/backward bending were examined. Participants with different provocative pain responses to forward and backward bending were profiled on age, sex, pain sensitivity, psychological variables, pain characteristics and disability.

RESULTS

Three groups with differing provocative pain responses following repeated movements were derived: (i) no clinically-important increased pain in either direction (n=144, 49.0%), (ii) increased pain with repeated bending in one direction only (unidirectional, n=112, 38.1%), (iii) increased pain with repeated bending in both directions (bidirectional, n=38, 12.9%). After adjusting for psychological profile, age and sex, for the group with bidirectional pain provocation responses following repeated spinal bending, higher pressure and thermal pain sensitivity were demonstrated, while for the group with no increase in pain, better cognitive and affective psychological questionnaire scores were evident. However, these associations between provocative pain responses following movement and pain sensitivity and psychological profiles were weak.

CONCLUSIONS

Provocative pain responses following repeated movements in people with CLBP appear heterogeneous, and are weakly associated with pain sensitivity and psychological profiles.

IMPLICATIONS

To date, suboptimal outcomes in studies examining exercise interventions targeting directional, movement-based subgroups in people with CLBP may reflect limited consideration of broader multidimensional clinical profiles associated with LBP. This article describes heterogeneous provocative pain responses following repeated spinal bending, and their associated pain sensitivity and psychological profiles, in people with CLBP. These findings may help facilitate targeted management. For people with no increase in pain, the lack of pain provocation following repeated spinal bending, in combination with a favourable psychological profile, suggests this subgroup may have fewer barriers to functional rehabilitation. In contrast, those with pain provoked by both forward and backward bending may require specific interventions targeting increased pain sensitivity and negative psychological cognitions and affect, as these may be may be important barriers to functional rehabilitation.

Pressure and cold pain threshold reference values in a large, young adult, pain-free population

Background and aims

Currently there is a lack of large population studies that have investigated pain sensitivity distributions in healthy pain free people. The aims of this study were: (1) to provide sex-specific reference values of pressure and cold pain thresholds in young pain-free adults; (2) to examine the association of potential correlates of pain sensitivity with pain threshold values.

Methods

This study investigated sex specific pressure and cold pain threshold estimates for young pain free adults aged 21–24 years. A cross-sectional design was utilised using participants (n =617) from the Western Australian Pregnancy Cohort (Raine) Study at the 22-year follow-up. The association of site, sex, height, weight, smoking, health related quality oflife, psychological measures and activity with pain threshold values was examined. Pressure pain threshold (lumbar spine, tibialis anterior, neck and dorsal wrist) and cold pain threshold (dorsal wrist) were assessed using standardised quantitative sensory testing protocols.

Results

Reference values for pressure pain threshold (four body sites) stratified by sex and site, and cold pain threshold (dorsal wrist) stratified by sex are provided. Statistically significant, independent correlates of increased pressure pain sensitivity measures were site (neck, dorsal wrist), sex (female), higher waist-hip ratio and poorer mental health. Statistically significant, independent correlates of increased cold pain sensitivity measures were, sex (female), poorer mental health and smoking.

Conclusions

These data provide the most comprehensive and robust sex specific reference values for pressure pain threshold specific to four body sites and cold pain threshold at the dorsal wrist for young adults aged 21–24 years. Establishing normative values in this young age group is important given that the transition from adolescence to adulthood is a critical temporal period during which trajectories for persistent pain can be established.

Implications

These data will provide an important research resource to enable more accurate profiling and interpretation of pain sensitivity in clinical pain disorders in young adults. The robust and comprehensive data can assist interpretation of future clinical pain studies and provide further insight into the complex associations of pain sensitivity that can be used in future research.

Heightened cold pain and pressure pain sensitivity in young female adults with moderate-to-severe menstrual pain

This study investigated the association between menstrual pain severity and psychophysical measures of cold and pressure pain sensitivity. A cross-sectional design was used with young women (n = 432) from the Western Australian Pregnancy Cohort (Raine) Study. Menstrual pain severity and oral contraception use was obtained from questionnaires at 20 and 22-year follow-ups. A visual analog scale (VAS; range from 0 [none] to 10 [unbearable]) was used to measure menstrual pain severity at both 20 and 22 years over the 3-year period, with 3 groups created: (1) no pain or mild pain (VAS 0-3), (2) at least moderate pain at a minimum of 1 of the 2 time points (hereafter named "mixed)", and (3) severe pain (VAS 8-10). Cold pain sensitivity (dorsal wrist) and pressure pain sensitivity (lumbar spine, upper trapezius, dorsal wrist, and tibialis anterior) were assessed using standardised quantitative sensory testing protocols. Confounding variables included number of musculoskeletal pain sites, oral contraceptive use, smoking, physical activity, body mass index, psychological distress, and sleep. Severe menstrual pain and mixed menstrual pain were positively associated with heightened cold pain sensitivity (distant from menstrual pain referral site) and pressure pain sensitivity (local to menstrual pain referral site). These associations remained significant after adjusting for potential confounding variables including multisite musculoskeletal pain. Our findings suggest peripheral and central neurophysiological mechanisms contributing to heightened pain sensitivity in young women with moderate and severe menstrual pain. These data highlight the need for innovative management approaches to attenuate the negative impact of severe menstrual pain in young women.