The relationship between guarding, pain, and emotion

Advanced cancer perineural invasion induces profound peripheral neuronal plasticity, pain, and somatosensory mechanical deactivation, unmitigated by the lack of TNFR1. Part. 1: Behavior and single-cell in vivo electrophysiology

Patients with cancer perineural invasion (PNI) report greater spontaneous pain and mechanical allodynia. Here, we examine the impact of the disease on the peripheral sensory system, the excitability changes induced by PNI at the dorsal root ganglia, and the potential protective role of the absence of Tumor Necrosis Factor-α Receptor 1 (TNFR1). To study these effects, we use a murine model generated by injecting mouse oral cancer squamous cell carcinoma (MOC2) into the sciatic nerve (MOC2-PNI) in both male and female mice. We found that MOC2-PNI induces a profound change in the somatosensory landscape by deactivating/blocking the peripheral inputs while modulating the afferent's sensibility (tactile desensitization with concurrent nociceptive sensitization) and demyelination without inducing spontaneous activity. All these changes caused by MOC2-PNI are unmitigated by the absence of TNFR1. We conclude that MOC2-PNI induces an aberrant neuronal excitability state and triggers extreme gender-specific neuronal plasticity. These data allow us to speculate on the role of such plasticity as a powerful defense mechanism to prevent terminal sensory dysfunction, the rise of chronic pain, and extend animals' survivability.

Is lower motor control on the trunk in patients with non-specific chronic low back pain linked to difficulties in working despite functional restoration programs?

INTRODUCTION

In the case of patients with Chronic Low Back Pain (cLBP), Functional Restoration Programs (FRP) can improve their condition. Chronicity may reoccur and lead to difficulties in the ability to work related to Fear-Avoidance Beliefs, which may depend on lower motor control.

RATIONALE OF THE STUDY

Whereas a limited clinical scale evaluates these beliefs, our study is justified by the search to define motor control parameters that can be used as quantified indicators of fear-avoidance beliefs associated with work activity.

AIM

The aim of this study is to explore whether difficulty in working one year after participating in the FRP was related to low motor control in patients with cLBP.

METHODS

Two groups were defined as: "the patients who could work one year after FRP" (called W-Group) and "the patients who could not work one year after FRP because of cLBP" (called NW-Group). The clinical analysis is based on the assessment of pain intensity and the Fear-Avoidance Belief Questionnaire (or FABQ). Gait stability and coefficients of attenuation on four back levels were considered.

RESULTS

The NW-Group had a significantly higher FABQ score than the W-Group one year after FRP (p = 0.02) without any difference regarding pain intensity (p = 0.31). The NW-Group (0.11 ± 0.02) presented significantly higher RMS values for the low back in the anteroposterior axis than the W-group (0.09 ± 0.01), showing lower gait stability in the NW-group.

DISCUSSION

Motor control parameters reveal significant differences between these groups.

CONCLUSIONS

Motor control and fear-avoidance beliefs are associated with work.

Guarding and flow in the movements of people with chronic pain: A qualitative study of physiotherapists' observations

BACKGROUND

Among the adaptations of movement consistently associated with disability in chronic pain, guarding is common. Based on previous work, we sought to understand better the constituents of guarding; we also used the concept of flow to explore the description of un/naturalness that emerged from physiotherapists' descriptions of movement in chronic pain. The aim was to inform the design of technical systems to support people with chronic pain in everyday activities.

METHODS

Sixteen physiotherapists, experts in chronic pain, were interviewed while repeatedly watching short video clips of people with chronic low back pain doing simple movements; physiotherapists described the movements, particularly in relation to guarding and flow. The transcribed interviews were analysed thematically to elaborate these constructs.

RESULTS

Moderate agreement emerged on the extent of guarding in the videos, with good agreement that guarding conveyed caution about movement, distinct from biomechanical variables of stiffness or slow speed. Physiotherapists' comments on flow showed slightly better agreement, and described the overall movement in terms of restriction (where there was no flow or only some flow), of tempo of the entire movement, and as naturalness (distinguished from normality of movement).

CONCLUSIONS

These qualities of movement may be useful in designing technical systems to support self-management of chronic pain.

SIGNIFICANCE

Drawing on the descriptions of movements of people with chronic low back pain provided by expert physiotherapists to standard stimuli, two key concepts were elaborated. Guarding was distinguished from stiffness (a physical limitation) or slowness as motivated by fear or worry about movement. Flow served to describe harmonious and continuous movement, even when adapted around restrictions of pain. Movement behaviours associated with pain are better understood in terms of their particular function than aggregated without reference to function.

Association between chronic pain classes and cognitive function in older adults: A cross-sectional study based on latent class analysis

The purpose of this study was to identify latent classes of chronic pain in older adults based on perceptual, cognitive, behavioral, emotional and social factors, and to explore the associations between each class of chronic pain and different cognitive domains. A total of 629 participants were included. Three classes of chronic pain were identified: "episodic recurrent mild pain with good psychosocial state" (class 1), "episodic recurrent moderate pain with general psychosocial state" (class 2) and "continuous multilocational severe pain with attacks accompanied by poor psychosocial state and avoidance of activity" (class 3). After adjusting for relevant confounders, chronic pain presenting as class 1 was associated with worse memory; class 2 was associated with worse global cognitive function, memory, information processing speed, and executive function; and class 3 was additionally associated with worse attention compared to class 2. The findings contribute to the development of targeted programs for treating pain and improving cognitive functioning.

Association Between Chronic Back Pain and Protective Behaviors is Subjective and Context Dependent

Chronic lower back (CLB) pain limits patients' day-to-day activities, increases their missed days of work, and causes emotional distress. Developing adequate and individual-tailored treatment for CLB patients requires a better understanding of pain and protective behaviors, and how these behaviors are modulated or altered by context and subjectivity. In this work, we conducted experiments to investigate 1) the relationship between pain and protective behaviors in patients with CLB pain, 2) whether individual differences and context are relevant factors in the relationship, and 3) the impact of this relationship and its factors on the performance of current automated models for pain and protective behavior perception. Our results show 1) significant association (p - value < 0.05) between pain and protective behaviors in patients with CLB pain and 2) subjectivity and context are influential factors in this association. Further, our results show that considering this association along with its factors significantly (p-value < 0.05) improves the performance of automated pain and protective behaviors perception. These findings highlight the role of this association on pain and protective behaviors perception and raise several questions about the robustness of existing automated models that do not take this association into account.

The association between foot posture, single leg balance and running biomechanics of the foot

OBJECTIVES

A mal-aligned foot posture (high-arched and flat feet) and poor single leg balance ability have been separately associated with foot injuries during running. Therefore, clinicians assess these routinely. However, the extent to which foot posture and single-leg balance ability affect actual foot biomechanics during running is not known. This study aims to investigate the association of foot posture, single-leg balance ability, and foot biomechanics during running.

METHOD

This is a cross sectional study of sixty-nine participants who had their foot postures and single-leg balance ability assessed. The Foot Posture Index and Balance Error Scoring System were used. Their foot kinetics was measured as they ran on an instrumented treadmill and foot kinematics was processed using a 3D motion capture system. Multiple-regression was used to analyse the variance of foot biomechanics explained by foot posture and single-leg balance ability.

RESULTS

Foot posture and single-leg balance ability were found to account significantly for the variance in rearfoot eversion (24%) and forefoot dorsiflexion (7%). Two regression equations were derived, where rearfoot eversion and forefoot dorsiflexion during running may be predicted.

CONCLUSION

Foot posture and single-leg balance ability can predict rearfoot eversion and forefoot dorsiflexion only during running. Based on the regression equations, individuals with the same foot posture but different single-leg balance ability may exhibit different foot kinematics. However, the angular differences are small. The equations may be useful for clinicians working in places where running gait analysis equipment are not readily accessible. Further studies with larger sample sizes are required to validate these equations. In addition, further studies are necessary to investigate the effect of these two variables under different running conditions e.g. with footwear and with orthoses.

Coping and Beliefs as Predictors of Functioning and Psychological Adjustment in Fibromyalgia Subgroups

Objectives

Research has pointed to two profiles of persons with fibromyalgia according to differences in functionality, thus distinguishing between functional and dysfunctional patients. The role of psychological factors underlying such clusters is unclear. This study aims to explore the contribution of pain beliefs and coping on fibromyalgia clustering.

Methods

A cluster analysis was performed to classify 238 women with fibromyalgia using the Fibromyalgia Impact Questionnaire and the Beck Depression Inventory as clustering variables. Cluster differences in physical functioning, depression, pain beliefs, coping, and age were then calculated (Student's t-test). Finally, a binary logistic regression was conducted to study the unique contribution of age, beliefs, and coping on cluster classification.

Results

Two clusters were revealed. Cluster 1 had a poor adaptation to fibromyalgia regarding physical functioning and depression. They generally embraced less adaptive beliefs (i.e., disability, harm, emotion, and requests) and coping strategies (i.e., guarding, resting, and asking for assistance). Cluster 2 showed a better adaptation to fibromyalgia and adopted more favorable beliefs (i.e., control) and coping strategies (i.e., exercise and task persistence). Cluster differences in age were significant but small. The backward binary logistic regression suggested a final model with six predictors (guarding, task persistence, harm, emotion, solicitude, and age) that explained 31% of the variance of group membership. Discussion. These results suggest that only a subset of psychological variables uniquely and independently contribute to functional/dysfunctional group membership. The results support the need to address psychological components in the management of fibromyalgia and point to a subset of preferred target beliefs and coping strategies.

Pain among Individuals with Chronic Respiratory Diseases Attending Pulmonary Rehabilitation

Purpose: This study reports on the prevalence and impact of pain in individuals with different chronic respiratory diseases attending pulmonary rehabilitation (PR). Method: A retrospective review of medical records data was conducted for 488 participants who had attended a PR programme over a 2-year period. Data on pain and medication history taken from multidisciplinary medical records, together with participant demographics and PR outcomes, were extracted. We compared pain among participants with different types of chronic respiratory disease. Results: The overall prevalence of pain was 77%, with a significantly higher prevalence among individuals with obstructive lung diseases (80%) compared with restrictive lung diseases (69%; p = 0.04). Some participants (17%) who took pain medications did not discuss pain with their clinicians. The presence of pain and different reporting of pain did not have a negative impact on the PR programme completion rate (p = 0.74), improvements in exercise capacity (p = 0.51), or health-related quality of life (all four chronic respiratory disease questionnaire domains, p>0.05). Conclusions: The prevalence of pain is high among individuals with chronic respiratory disease attending PR. The presence or absence of pain was not negatively associated with the programme completion rate or PR outcomes; therefore, pain should not deter clinicians from referring patients to PR.

Automated Assessment of Pain: Prospects, Progress, and a Path Forward

Advances in the understanding and control of pain require methods for measuring its presence, intensity, and other qualities. Shortcomings of the main method for evaluating pain-verbal report-have motivated the pursuit of other measures. Measurement of observable pain-related behaviors, such as facial expressions, has provided an alternative, but has seen limited application because available techniques are burdensome. Computer vision and machine learning techniques have been successfully applied to the assessment of painrelated facial expression, suggesting that automated assessment may be feasible. Further development is necessary before such techniques can have more widespread implementation in pain science and clinical practice. Suggestions are made for the dimensions that need to be addressed to facilitate such developments.

Investigating the Role of Ly6G+ Neutrophils in Incisional and Inflammatory Pain by Multidimensional Pain-Related Behavioral Assessments: Bridging the Translational Gap

In recent years, preclinical pain research has failed to develop genuinely new analgesics for clinical use. This fact is reflected by a high number of patients, limited drug efficacy accompanied by side effects, and a long-term opioid intake. Two main aspects have been addressed, which hinder translation: the use of non-relevant pain models and a mismatch between pain-related outcomes in preclinical and clinical studies. Conversely, disease-specific pain models that mirror more closely the clinical situation and multidimensional behavioral outcome measures that objectively and reproducibly assess relevant pain-related symptoms in a preclinical setting could improve translation. Mechanistically, a matter of debate is the role of Ly6G⁺ neutrophil granulocytes (NGs) for pain. NGs are essential to eliminate pathogens and promote the wound healing process. For this purpose, there is a need to release various pro- and anti-inflammatory mediators, some of which could ameliorate or enhance pain. However, the contribution of NGs to different pain entities is contradictory for reflex-based tests, and completely unknown in the context of non-evoked pain (NEP) and movement-evoked pain (MEP). First, we combined withdrawal reflex-based assays with novel video-based assessments for NEP- and MEP-related behavior in two mouse pain models. The pain models utilized in this study were incision (INC) and pathogen/adjuvant-induced inflammation (CFA), translating well to postsurgical and inflammatory pain entities. Second, we depleted NGs and applied a set of behavioral assessments to investigate the role of NG migration in different pain modalities. Our comprehensive behavioral approach identified pain-related behaviors in mice that resemble (NEP) or differentiate (MEP) behavioral trajectories in comparison to mechanical and heat hypersensitivity, thereby indicating modality-dependent mechanisms. Further, we show that injury-induced accumulation of NGs minimally affects pain-related behaviors in both pain models. In conclusion, we report a novel assessment to detect NEP in mice after unilateral injuries using a more unbiased approach. Additionally, we are capable of detecting an antalgic gait for both pain entities with unique trajectories. The different trajectories between MEP and other pain modalities suggest that the underlying mechanisms differ. We further conclude that NGs play a subordinate role in pain-related behaviors in incisional and inflammatory pain.

Massage for Combat Injuries in Veteran with Undisclosed PTSD: a Retrospective Case Report

INTRODUCTION

Massage has shown promise in reducing symptoms related to dissociation and anxiety that can exacerbate chronic pain and suffering. The combat wounded, veteran population is increasing and requires a multidisciplinary approach for comprehensive treatment. This case study examines massage therapy use to improve veteran combat injury rehabilitation and recovery experience through purposive, retrospective, and comprehensive SOAP note review.

METHODS

A 31-year-old White male received seven, 60-min, full body massages for combat related shoulder injury complications incurred approximately six years before presentation. The right shoulder sustained a broken humeral head and complete dislocation during a defensive maneuver in a life-threatening attack. This case study utilized data from three different assessments: goniometric measurements for shoulder range of motion, observation and documentation for environmental comfort behaviors, and client self-report for treatment goal attainment. Six weekly, full body, 60-min massages were completed sequentially. A follow-up 60-min treatment was completed at Week 8. Treatment to the injured area included focused trigger point therapy, myofascial release, and proprioceptive neuromuscular facilitation to the neck, shoulder, and chest.

RESULTS

Total percent change for active flexion, extension, abduction, adduction, internal rotation, and external rotation were 12.5, 150, 40, 167, 14.3, and 0%, respectively. Total percent change for passive flexion, extension, abduction, adduction, internal rotation, and external rotation were 63.6, 350, 66.7, 450, 133, and 77.8%, respectively. Environmental comfort behaviors were reduced. Client treatment goals were attained.

CONCLUSIONS

Massage therapy provided meaningful benefit to a combat injury for a veteran with PTSD.

Does Movement Change When Low Back Pain Changes? A Systematic Review

OBJECTIVE

To investigate the relationship between changes in volitional spinal movement (including muscle activity) and changes in pain or activity limitation at the individual level in people with nonspecific low back pain.

DESIGN

Etiology systematic review.

LITERATURE SEARCH

MEDLINE, Embase, CINAHL, and AMED were searched from inception to January 2020.

STUDY SELECTION CRITERIA

The study included peer-reviewed articles that reported the relationship between changes in volitional spinal movement and changes in pain or activity limitation at the individual level in people with nonspecific low back pain.

DATA SYNTHESIS

The data were descriptively synthesized to identify a relationship between change in movement and improved pain or activity limitation.

RESULTS

We included 27 studies involving 2739 participants. There was low-quality evidence of a relationship between change in movement and change in pain or activity limitation at the individual level 31% of the time (20 of the 65 times investigated within the 27 studies). Increases in spinal range of motion, velocity, and flexion relaxation of the back extensors were consistently related to improved pain or activity limitation (93%, 18.5/20 relationships observed).

CONCLUSION

A relationship between changes in movement and changes in pain or activity limitation was infrequently observed at the individual level; however, a paucity of high-quality evidence precludes a definitive understanding of this relationship. J Orthop Sports Phys Ther 2020;50(12):664-680. Epub 28 Oct 2020. doi:10.2519/jospt.2020.9635.

Movement, posture and low back pain. How do they relate? A replicated single-case design in 12 people with persistent, disabling low back pain

BACKGROUND

Movement and posture are commonly believed to relate to non-specific low back pain (NSLBP). While people with NSLBP appear to move and posture themselves differently from those without NSLBP, changes in movement and posture infrequently relate to improvements in NSLBP when analysed at a group-level. Additionally, little is known about how movement or posture change when clinical outcome improves.

METHODS

Within-person relationships were investigated using a replicated, repeated measures, single-case design in 12 people with persistent, disabling NSLBP. Individually relevant movement and posture were captured using wearable sensors on up to 20 occasions over a 22-week period (5-week baseline, 12-week physiotherapy-led intervention, 5-week follow-up), while pain and activity limitation were collected concomitantly. A series of cross-correlation analyses estimated the presence, strength, and direction of relationships.

RESULTS

Many participants (n = 10/12) had strong (e.g. r = 0.91, p = <0.001) relationships between changes in movement or posture and changes in pain and activity limitation, while some showed no strong association. Where relationships were observed, clinical improvement predominantly (93% or 57/61 relationships) related to increased spinal movement range and velocity during forward bending and lifting, reduced lumbar muscle EMG activity at maximum voluntary flexion, and increased posterior-pelvic-tilt during sitting and standing.

CONCLUSION

Within-person changes to individually relevant movement and posture appear to often relate to clinical outcome, but not always. When changes were related, movement and posture appear to return towards being 'less protective', however causal directions remain unknown. Important activities, movements, and postural parameters varied across the participants, highlighting the potential importance of individualized management.

SIGNIFICANCE

Changes to individually relevant movement and posture appear to often relate to clinical outcome, but not always. Patient-specific activities, and movement or postural parameters that related to improved pain and activity limitation, varied across the 12 participants, highlighting the potential importance of individualised management. Where clinical improvements were related to changes in movement or posture, participants consistently returned towards being 'less protective' (increased range and speed of movement, increased posterior-pelvic-tilt during sitting and standing). Mechanisms and generalizability remain unclear.

A Review of the Theoretical Fascial Models: Biotensegrity, Fascintegrity, and Myofascial Chains

The fascial tissue includes solid and liquid fascia (body fluids such as blood and lymph). The fascia's nomenclature is the subject of debate in the academic world, as it is classified starting from different scientific perspectives. This disagreement is not a brake but is, in reality, the real wealth of research, the multidisciplinarity of thought and knowledge that leads to a deeper understanding of the topic. Another topic of discussion is the fascial model to conceptualize the human body, that is, how the fascial tissue fits into the living. Currently, there are some models: biotensegrity, fascintegrity, and myofascial chains. Biotensegrity is a mechanical model, which takes into consideration the solid fascia; fascintegrity considers the solid and the liquid fascia. Myofascial chains converge attention on the movement and transmission of force in the muscle continuum. The article is a reflection on fascial models and how these are theoretical-scientific visions that need to be further investigated.

Persistence of pain in humans and other mammals

Evolutionary models of chronic pain are relatively undeveloped, but mainly concern dysregulation of an efficient acute defence, or false alarm. Here, a third possibility, mismatch with the modern environment, is examined. In ancestral human and free-living animal environments, survival needs urge a return to activity during recovery, despite pain, but modern environments allow humans and domesticated animals prolonged inactivity after injury. This review uses the research literature to compare humans and other mammals, who share pain neurophysiology, on risk factors for pain persistence, behaviours associated with pain, and responses of conspecifics to behaviours. The mammal populations studied are mainly laboratory rodents in pain research, and farm and companion animals in veterinary research, with observations of captive and free-living primates. Beyond farm animals and rodent models, there is virtually no evidence of chronic pain in other mammals. Since evidence is sparse, it is hard to conclude that it does not occur, but its apparent absence is compatible with the mismatch hypothesis. This article is part of the Theo Murphy meeting issue 'Evolution of mechanisms and behaviour important for pain'.