Interhemispheric Inhibition Between Primary Motor Cortices is Not Altered in Individuals With Chronic Lateral Epicondylalgia.

Lateral epicondylalgia (LE), commonly referred to as tennis elbow, is a musculoskeletal condition characterized by pain and sensorimotor dysfunction. In some individuals with chronic unilateral LE, sensorimotor symptoms develop on the unaffected side despite no evidence of tissue damage. Altered interhemispheric inhibition (IHI) is one mechanism that could underpin this phenomenon. The aim of this cross-sectional study was to examine IHI between the primary motor cortices (M1) in individuals with chronic LE and healthy controls. In 20 individuals with chronic LE and 20 healthy participants, transcranial magnetic stimulation was used to assess 1) short and long-latency IHI from the affected (corresponding to the injured side) to the unaffected M1 and 2) corticomotor excitability of the affected and unaffected M1. Sensorimotor function was evaluated bilaterally at the extensor carpi radialis brevis muscle using pressure pain threshold, grip strength, 2-point discrimination, and temporal summation tests. Short- and long-latency IHI from the affected to the unaffected M1 and corticomotor excitability of the affected and unaffected M1 were not altered in individuals with LE compared with healthy participants. No differences in sensorimotor function were observed for the affected or unaffected extensor carpi radialis brevis muscles when individuals with LE were compared with healthy participants. IHI is not altered in individuals with chronic LE. Further studies are required to determine the mechanisms that underpin the development of bilateral sensorimotor symptoms in unilateral LE. PERSPECTIVE: IHI is unaltered from the affected M1 (corresponding to the painful muscle) to unaffected M1 in individuals with LE compared to healthy controls. The absence of bilateral sensorimotor dysfunction and low pain severity in this cohort of individuals with LE may explain this finding.

Cortical function and sensorimotor plasticity are prognostic factors associated with future low back pain after an acute episode: the Understanding persistent Pain Where it ResiDes prospective cohort study.

ABSTRACT: Predicting the development of chronic low back pain (LBP) at the time of an acute episode remains challenging. The Understanding persistent Pain Where it ResiDes study aimed to identify neurobiological and psychological risk factors for chronic LBP. Individuals with acute LBP (N = 120) participated in a prospective cohort study with 6-month follow-up. Candidate predictors were selected from the neurobiological (eg, sensorimotor cortical excitability assessed by sensory and motor-evoked potentials and brain-derived neurotrophic factor genotype), psychological (eg, depression and anxiety), symptom-related (eg, LBP history), and demographic domains. Analyses involved multivariable linear regression models with pain intensity or disability degree as continuous variables. Secondary analyses involved a multivariable logistic model with the presence of LBP at 6 months (thresholding pain intensity and disability degree) as a dichotomous variable. Lower sensory cortex and corticomotor excitability, higher baseline pain intensity, higher depression, stress, and pain catastrophizing were the strongest predictors ( R2 = 0.47) of pain intensity at 6 months. Older age and higher pain catastrophizing were the strongest predictors ( R2 = 0.30) of disability at 6 months. When the LBP outcome was dichotomised, sensory cortex and corticomotor excitability, brain-derived neurotrophic factor genotype, depression and anxiety, LBP history and baseline pain intensity, discriminated between those who did and did not report LBP at 6 months (C-statistic 0.91). This study identifies novel risk factors for the development of future LBP. Neurobiological risk factors, when added to a multivariable linear regression model, explained a further 15% of the variance in the 6-month pain intensity.

Interhemispheric Inhibition Between Primary Sensory Cortices is not Influenced by Acute Muscle Pain.

Bilateral deficits in sensorimotor function have been observed in unilateral musculoskeletal pain conditions. Altered interhemispheric inhibition (IHI) between primary sensory cortices (S1s) is one mechanism that could explain this phenomenon. However, IHI between S1s in response to acute muscle pain, and the relationship between IHI and pressure pain sensitivity in the unaffected limb have not been examined. In 21 healthy individuals, IHI was assessed using somatosensory evoked potentials in response to paired median nerve electrical stimulation at: 1) baseline; 2) immediately following pain resolution; and 3) at 30-minutes follow-up. Acute muscle pain was induced by injection of hypertonic saline into the right abductor pollicis brevis (APB) muscle. Pressure pain thresholds were assessed at the right and left APB muscles before and 30-minutes after pain resolution. Compared to baseline, IHI from the affected to unaffected S1 was unaltered in response to acute muscle pain immediately following pain resolution, or at 30-minutes follow-up. Pressure pain thresholds were reduced over the right (P = .001) and left (P = .001) APB muscles at 30-minutes follow-up. These findings suggest IHI between S1s is unaffected by acute, short-lasting muscle pain, despite the development of increased sensitivity to pressure in the unaffected APB muscle. PERSPECTIVE: IHI from the affected S1 (contralateral to the side of pain) to unaffected S1 is unaltered following the resolution of acute muscle pain. This finding suggests that IHI between S1s may not be relevant in the development of bilateral sensorimotor symptoms in unilateral pain conditions.

Dancing Against falls iN Community-dwElling older adults (DANCE): a study protocol of a stratified, block-randomised trial.

BACKGROUND: Unintentional falls among older adults are of primary importance due to their impact on quality of life. Falling accounts for 95% of hip fractures, leading to an approximately six times increased risk of death within the first 3 months. Furthermore, physical and cognitive parameters are risk factors for falls. The purpose of this study is to examine the effect of a 6-month salsa dance training intervention, compared with regular fitness circuit training and a control group. METHODS: This study will include 180 older adults: 90 healthy patients and 90 patients with osteoporosis. Participants will be allocated randomly in either of the groups, stratified according to age. Training groups will receive 2 weekly 1-hour training sessions, continuously through 6 months. Participants will be tested at baseline and 6 and 18 months post baseline. Primary outcome will be number of falls and secondary outcomes include bone mineral density, body composition, pain evaluation, weekly physical activity, single-task and dual-task gait patterns, balance, Fullerton Functional Fitness Test and assessment of the mini-BESTest. DISCUSSION: This study will investigate the effects of a specially designed dance training programme (Dancing Against falls iN Community-dwElling older adults (DANCE)) to reduce the risk of falling among older adults. The study will investigate the effect against an active and passive comparator, resulting in the possibility to state, if DANCE training should be an alternative to traditional training. TRIAL REGISTRATION NUMBER: NCT03683849.

Low Somatosensory Cortex Excitability in the Acute Stage of Low Back Pain Causes Chronic Pain.

Determining the mechanistic causes of complex biopsychosocial health conditions such as low back pain (LBP) is challenging, and research is scarce. Cross-sectional studies demonstrate altered excitability and organization of the somatosensory and motor cortex in people with acute and chronic LBP, however, no study has explored these mechanisms longitudinally or attempted to draw causal inferences. Using sensory evoked potential area measurements and transcranial magnetic stimulation derived map volume we analyzed somatosensory and motor cortex excitability in 120 adults experiencing acute LBP. Following multivariable regression modelling with adjustment for confounding, we identified lower primary (OR = 2.08, 95% CI = 1.22-3.57) and secondary (OR = 2.56, 95% CI = 1.37-4.76) somatosensory cortex excitability significantly increased the odds of developing chronic pain at 6-month follow-up. Corticomotor excitability in the acute stage of LBP was associated with higher pain intensity at 6-month follow-up (B = -0.15, 95% CI: -0.28 to -0.02) but this association did not remain after confounder adjustment. These data provide evidence that low somatosensory cortex excitability in the acute stage of LBP is a cause of chronic pain. PERSPECTIVE: This prospective longitudinal cohort study design identified low sensorimotor cortex excitability during the acute stage of LBP in people who developed chronic pain. Interventions that target this proposed mechanism may be relevant to the prevention of chronic pain.

Investigating the feasibility and acceptability of the HOLOBalance system compared with standard care in older adults at risk for falls: study protocol for an assessor blinded pilot randomised controlled study.

INTRODUCTION: Approximately one in three of all older adults fall each year, with wide ranging physical, psychosocial and healthcare-related consequences. Exercise-based interventions are the cornerstone for falls prevention programmes, yet these are not consistently provided, do not routinely address all components of the balance system and are often not well attended. The HOLOBalance system provides an evidence-based balance training programme delivered to patients in their home environment using a novel technological approach including an augmented reality virtual physiotherapist, exergames and a remote monitoring system. The aims of this proof-of-concept study are to (1) determine the safety, acceptability and feasibility of providing HOLOBalance to community dwelling older adults at risk for falls and (2) provide data to support sample size estimates for a future trial. METHODS: A single (assessor) blinded pilot randomised controlled proof of concept study. 120 participants will be randomised to receive an 8-week home exercise programme consisting of either: (1) HOLOBalance or (2) The OTAGO Home Exercise Programme. Participants will be required to complete their exercise programme independently under the supervision of a physiotherapist. Participants will have weekly telephone contact with their physiotherapist, and will receive home visits at weeks 0, 3 and 6. Outcome measures of safety, acceptability and feasibility, clinical measures of balance function, disability, balance confidence and cognitive function will be assessed before and immediately after the 8 week intervention. Acceptability and feasibility will be explored using descriptive statistics, and trends for effectiveness will be explored using general linear model analysis of variance. ETHICS AND DISSEMINATION: This study has received institutional ethical approvals in Germany (reference: 265/19), Greece (reference: 9769/24-6-2019) and the UK (reference: 19/LO/1908). Findings from this study will be submitted for peer-reviewed publications. TRIAL REGISTRATION NUMBER: NCT04053829. PROTOCOL VERSION: V.2, 20 January 2020.

Does attention switching between multiple tasks affect gait stability and task performance differently between younger and older adults?

Gait stability and secondary task performance are affected by the need to share attention when dual-tasking. Further decrements may result from the need to switch attention between multiple secondary tasks. The aim of the current study was to determine the effects of attention switching upon gait stability and task performance in healthy younger and older adults. Ten healthy younger and ten healthy older adults walked on a treadmill at their preferred speed during three trials including: (1) baseline walking; (2) non-switching task walking, requiring response to an auditory-spatial or visual-spatial cue presented in an expected order; and (3) switching task walking, which required response to an auditory-spatial or visual-spatial cue presented in an unexpected order. Response time and accuracy, the margin of stability in the frontal (MoSML) and sagittal planes (MoSA: anterior, MoSP: posterior), step width and step length were calculated for non-switching and switching tasks. The MoSML, MoSA, MoSP, step width and step length during non-switching and switching tasks were normalized to baseline walking. Older adults took significantly longer to respond to cues and made more errors during the switching task compared to younger adults. Younger adults took narrower steps (p < 0.01) and displayed a reduction in MoSML (p < 0.01) during the switching task compared with the non-switching task. Conversely, older adults displayed no differences in MoSML between tasks. These findings suggest that attention switching results in different task prioritization strategies in younger and older adults during walking.

A Dynamic Bayesian Network Approach to Behavioral Modelling of Elderly People during a Home-based Augmented Reality Balance Physiotherapy Programme.

In this study, we propose a dynamic Bayesian network (DBN)-based approach to behavioral modelling of community dwelling older adults at risk for falls during the daily sessions of a hologram-enabled vestibular rehabilitation therapy programme. The component of human behavior being modelled is the level of frustration experienced by the user at each exercise, as it is assessed by the NASA Task Load Index. Herein, we present the topology of the DBN and test its inference performance on real-patient data.Clinical Relevance- Precise behavioral modelling will provide an indicator for tailoring the rehabilitation programme to each individual's personal psychological needs.

Does surface slope affect dual task performance and gait? An exploratory study in younger and older adults.

An increased risk of falling is associated with changes in gait while dual-tasking. The degree to which gait stability is altered during walking is influenced by an individual's cognitive and postural capacity, and the difficulty of the presented tasks. However, it is unknown how greater walking task difficulty affects gait stability in younger and older adults when dual-tasking. The purpose of the current study was to determine the effect of walking task difficulty on gait stability in younger and older adults while performing a difficult audiospatial task. Ten younger [mean (SD) age 30.8 (6.6) years; 5 women] and 10 older [66.8 (5.7) years; 6 women] healthy adults walked on a treadmill at their preferred walking speed [younger 4.8 (0.4) ms-1, older 4.5 (0.5) ms-1) on either a level, or downhill slope both with and without responding to an audiospatial task. Step width, step width SD and mediolateral centre of mass displacement were calculated to determine changes in gait, and response time and accuracy were calculated to determine secondary task performance. Results indicated that older adults displayed a consistently greater step width (p ≤ 0.015) and maintained their mediolateral centre of mass displacement (p > 0.05) while walking downhill and responding to the audiospatial task, compared to downhill walking only. In contrast, younger adults maintained a regular step width during both level and downhill dual-tasking compared to level and downhill walking only (p > 0.05), however displayed a lower mediolateral centre of mass displacement during level dual-task walking compared to level walking only (p = 0.013). When the difficulty of the walking task was greater, older adults increased their step width, which increased their stability.

Evaluating the Performance of Balance Physiotherapy Exercises Using a Sensory Platform: The Basis for a Persuasive Balance Rehabilitation Virtual Coaching System.

Rehabilitation programs play an important role in improving the quality of life of patients with balance disorders. Such programs are usually executed in a home environment, due to lack of resources. This procedure usually results in poorly performed exercises or even complete drop outs from the programs, as the patients lack guidance and motivation. This paper introduces a novel system for managing balance disorders in a home environment using a virtual coach for guidance, instruction, and inducement. The proposed system comprises sensing devices, augmented reality technology, and intelligent inference agents, which capture, recognize, and evaluate a patient's performance during the execution of exercises. More specifically, this work presents a home-based motion capture and assessment module, which utilizes a sensory platform to recognize an exercise performed by a patient and assess it. The sensory platform comprises IMU sensors (Mbientlab MMR© 9axis), pressure insoles (Moticon©), and a depth RGB camera (Intel D415©). This module is designed to deliver messages both during the performance of the exercise, delivering personalized notifications and alerts to the patient, and after the end of the exercise, scoring the overall performance of the patient. A set of proof of concept validation studies has been deployed, aiming to assess the accuracy of the different components for the sub-modules of the motion capture and assessment module. More specifically, Euler angle calculation algorithm in 2D (R 2 = 0.99) and in 3D (R 2 = 0.82 in yaw plane and R 2 = 0.91 for the pitch plane), as well as head turns speed (R 2 = 0.96), showed good correlation between the calculated and ground truth values provided by experts' annotations. The posture assessment algorithm resulted to accuracy = 0.83, while the gait metrics were validated against two well-established gait analysis systems (R 2 = 0.78 for double support, R 2 = 0.71 for single support, R 2 = 0.80 for step time, R 2 = 0.75 for stride time (WinTrack©), R 2 = 0.82 for cadence, and R 2 = 0.79 for stride time (RehaGait©). Validation results provided evidence that the proposed system can accurately capture and assess a physiotherapy exercise within the balance disorders context, thus providing a robust basis for the virtual coaching ecosystem and thereby improve a patient's commitment to rehabilitation programs while enhancing the quality of the performed exercises. In summary, virtual coaching can improve the quality of the home-based rehabilitation programs as long as it is combined with accurate motion capture and assessment modules, which provides to the virtual coach the capacity to tailor the interaction with the patient and deliver personalized experience.

Is the 10 metre walk test on sloped surfaces associated with age and physical activity in healthy adults?

BACKGROUND: Preferred walking speed is considered an important indicator of health in older adults and is measured on level ground. However, this may not represent the complex demands of community ambulation such as walking on sloped surfaces. Performing a 10 m walk test on a sloped surface is a novel test, and may be a more sensitive measure of walking capacity which may better discriminate age or health-related changes in gait speed compared to a traditional level 10 m walk test. The purpose of this investigation was to determine healthy adults' performance in the 10 m walk test across various inclines and speeds, and which version of the 10 m walk test would be best at discriminating age-related changes in walking speed. Further, this study aimed to determine whether measures of general health and physical activity are associated with the performance of each test. METHODS: Healthy Adults (n = 181) aged 20-80 years completed the 10 m walk test on level, downhill and uphill surfaces (8° inclination) at fastest and preferred speeds. Descriptive statistics were calculated for walking speed for males and females across each decade of life. Repeated measures ANOVA was performed to discriminate age-related changes in gait speed by decade, for the 10 m walk test at each speed and slope. Multiple linear regression analyses were conducted to examine the association between waist to height ratio, resting heart rate, age and self-reported physical activity upon preferred and fastest walking speeds at each incline (level/downhill/uphill). RESULTS: The 10 m walk test best discriminated age-related changes in gait speed when performed at fastest speeds on each slope, or at a preferred speed on an uphill slope. Waist to height ratio, age and the physical activity index were all significantly associated with fastest walking speeds over each incline and preferred uphill speed. Only waist to height ratio was associated with preferred walking speed on level and downhill surfaces. CONCLUSIONS: The 10 m walk test has the greatest ability to discriminate age- and health-related changes in gait speed when it is performed at a fastest speed on any slope, or uphill at a preferred speed. The normative data reported in this study may be used to compare the performance of the 10 m walk test to that of healthy adults at preferred and fastest speeds on sloped surfaces.

Do sensorimotor cortex activity, an individual's capacity for neuroplasticity, and psychological features during an episode of acute low back pain predict outcome at 6 months: a protocol for an Australian, multisite prospective, longitudinal cohort study.

INTRODUCTION: Low back pain (LBP) is the leading cause of disability worldwide, with prevalence doubling in the past 14 years. To date, prognostic screening tools display poor discrimination and offer no net benefit of screening over and above a 'treat all' approach. Characteristics of the primary sensory (S1) and motor (M1) cortices may predict the development of chronic LBP, yet the prognostic potential of these variables remains unknown. The Understanding persistent Pain Where it ResiDes (UPWaRD) study aims to determine whether sensorimotor cortex activity, an individual's capacity for plasticity and psychosocial factors in the acute stage of pain, predict LBP outcome at 6 months. This paper describes the methods and analysis plan for the development of the prediction model. METHODS AND ANALYSIS: The study uses a multicentre prospective longitudinal cohort design with 6-month follow-up. 120 participants, aged 18 years or older, experiencing an acute episode of LBP (less than 6 weeks duration) will be included. Primary outcomes are pain and disability. ETHICS AND DISSEMINATION: Ethical approval has been obtained from Western Sydney University Human Research Ethics Committee (H10465) and from Neuroscience Research Australia (SSA: 16/002). Dissemination will occur through presentations at national and international conferences and publications in international peer-reviewed journals. TRIAL REGISTRATION NUMBER: ACTRN12619000002189; Pre-results.

Interhemispheric Inhibition Is Reduced in Response to Acute Muscle Pain: A Cross-Sectional Study Using Transcranial Magnetic Stimulation.

Bilateral deficits in sensorimotor function have been observed in unilateral musculoskeletal pain conditions. Evidence suggests a reduction in interhemispheric inhibition (IHI) from the "affected" (contralateral to the side of pain) to the "unaffected" primary motor cortex (M1) could contribute. However, the effect of short-lasting acute muscle pain on IHI, and whether any changes are related to early sensorimotor changes in the unaffected limb, is unknown. Using a cross-sectional study design, IHI was investigated in 20 healthy individuals before, immediately after, and 30 minutes after the induction of acute muscle pain in the right first dorsal interosseous muscle via a bolus injection of hypertonic saline. Transcranial magnetic stimulation was used to assess corticomotor excitability and short and long latency IHI. Pain intensity and quality were recorded using an 11-point numerical rating scale and the McGill Pain Questionnaire. Pressure pain thresholds were assessed in the affected and unaffected first dorsal interosseous and both tibialis anterior muscles. Participants reported an average pain intensity of 4.8 points (standard deviation = 1.3 points). Compared with baseline, corticomotor excitability was decreased at all time points in the affected but not the unaffected M1. IHI was decreased at all time points from the affected to the unaffected M1. Pressure pain thresholds were decreased over both first dorsal interosseous muscles at 30 minutes of follow-up. These findings suggest a decrease in IHI from the affected to the unaffected M1 that occurs rapidly after the onset of acute pain and could contribute to the development of bilateral symptoms. PERSPECTIVE: The affected M1 (contralateral to the side of pain) releases inhibition over the unaffected M1 within minutes after the onset of acute muscle pain. This finding could have relevance for the development of bilateral sensorimotor symptoms in unilateral pain conditions.

The Role of Perceived Stress and Life Stressors in the Development of Chronic Musculoskeletal Pain Disorders: A Systematic Review.

The etiologic role of work-related psychological stress in the development of musculoskeletal pain disorders (MDs) has been systematically investigated. Less clear, however, is the role of perceived stress and life stressors. This review aimed to assess the evidence for an etiologic role of perceived stress and life stressors in the development of chronic MDs. Database searches were conducted to identify prospective longitudinal studies that assessed perceived stress and life stressors in individuals without, or in the first 6 weeks of, musculoskeletal pain. The primary outcome was the development of a chronic MD. Methodologic quality was investigated using an adapted version of the Quality Assessment Tool for Observational Cohort studies and Cross-Sectional studies, and the strength of evidence using the Grading of Recommendations Assessment, Development and Evaluation approach. Seven studies were included representing data from 6 independent cohorts. There was some evidence to support the etiologic role of perceived stress and life stressors in the development of arthritis (low quality) and chronic spinal pain (low quality). The limited number of studies, the poor quality of the evidence, and the heterogeneity of stress measures used across studies suggest that further high quality prospective studies are required to clarify the role of perceived stress and life stressors in the development of chronic MDs. PROSPERO: CRD42017059949 PERSPECTIVE: This review summarizes and critically appraises the evidence for the etiologic role of perceived stress and life stressors in the development of chronic MDs. The limited number of studies, the low quality of the evidence, and the heterogeneity across studies suggest that further research is needed on perceived stress and life stressors in MDs.

Sensorimotor Cortical Activity in Acute Low Back Pain: A Cross-Sectional Study.

Sensorimotor cortical activity is altered in both the immediate acute and chronic stages of musculoskeletal pain. However, these changes are opposite, with decreased cortical activity reported in experimentally induced acute pain (lasting minutes to hours), and increased cortical activity in chronic, clinical pain (lasting >6 months). It is unknown whether sensorimotor cortical activity is altered in acute, clinical musculoskeletal pain (lasting <4 weeks). In 36 individuals with acute, nonspecific, clinical low back pain (LBP) and 36 age- and sex-matched, pain-free controls, we investigated the processing of non-noxious afferent inputs using sensory evoked potentials (SEPs), as well as corticomotor excitability and organization of the primary motor cortex using transcranial magnetic stimulation. Processing of non-noxious sensory inputs was lower (smaller area of the N80-N150-P260 SEP complex) in acute LBP (F1,70 = 45.28, P < .01). The examination of specific SEP components revealed a smaller area of the N150 and P260 SEP components in acute LBP, although interindividual variability was high. Motor cortical map volume was lower in acute LBP (F1,70 = 5.61, P = .02). These findings demonstrate that acute LBP is characterized by lower sensorimotor cortical activity at the group level. However, individual variation was high, suggesting individual adaptation of cortical plasticity in acute pain. PERSPECTIVE: This is the first study to examine sensorimotor cortical activity in the acute stage of clinical LBP. This information is critical for understanding the neurophysiology of acute LBP.

Is there a causal relationship between acute stage sensorimotor cortex activity and the development of chronic low back pain? a protocol and statistical analysis plan.

INTRODUCTION: Why some people develop chronic pain following an acute episode of low back pain is unknown. Recent cross-sectional studies have suggested a relationship between aberrant sensorimotor cortex activity and pain persistence. The UPWaRD (Understanding persistent Pain Where it ResiDes) cohort study is the first prospective, longitudinal investigation of sensorimotor cortex activity in low back pain. This paper describes the development of a causal model and statistical analysis plan for investigating the causal effect of sensorimotor cortex activity on the development of chronic low back pain. METHODS AND ANALYSIS: Sensorimotor cortex activity was assessed within 6 weeks of low back pain onset using somatosensory evoked potentials and transcranial magnetic stimulation mapping techniques. Chronic low back pain is defined as ongoing pain (Numerical Rating score ≥1) or disability (Roland Morris Disability Questionnaire score ≥3) at 6 months follow-up. Variables that could confound the relationship between sensorimotor cortex activity and chronic low back pain were identified using a directed acyclic graph and content expertise was used to specify known causal paths. The statistical model was developed 'a priori' to control for confounding variables identified in the directed acyclic graph, allowing an unbiased estimate of the causal effect of sensorimotor activity in acute low back pain on the development of chronic pain. The statistical analysis plan was finalised prior to follow-up of all participants and initiation of analysis. ETHICS AND DISSEMINATION: Ethical approval has been obtained from Western Sydney University Human Research Ethics Committee (H10465) and from Neuroscience Research Australia (SSA: 16/002). Dissemination will occur through presentations at national and international conferences and publications in international peer-reviewed journals. TRIAL REGISTRATION NUMBER: ACTRN12619000002189 (retrospectively registered).

Altered Primary Motor Cortex Structure, Organization, and Function in Chronic Pain: A Systematic Review and Meta-Analysis.

Chronic pain can be associated with movement abnormalities. The primary motor cortex (M1) has an essential role in the formulation and execution of movement. A number of changes in M1 function have been reported in studies of people with chronic pain. This review systematically evaluated the evidence for altered M1 structure, organization, and function in people with chronic pain of neuropathic and non-neuropathic origin. Database searches were conducted and a modified STrengthening the Reporting of OBservational studies in Epidemiology checklist was used to assess the methodological quality of included studies. Meta-analyses, including preplanned subgroup analyses on the basis of condition were performed where possible. Sixty-seven studies (2,290 participants) using various neurophysiological measures were included. There is conflicting evidence of altered M1 structure, organization, and function for neuropathic and non-neuropathic pain conditions. Meta-analyses provided evidence of increased M1 long-interval intracortical inhibition in chronic pain populations. For most measures, the evidence of M1 changes in chronic pain populations is inconclusive. PERSPECTIVE: This review synthesizes the evidence of altered M1 structure, organization, and function in chronic pain populations. For most measures, M1 changes are inconsistent between studies and more research with larger samples and rigorous methodology is required to elucidate M1 changes in chronic pain populations.

The role of psychosocial stress in the development of chronic musculoskeletal pain disorders: protocol for a systematic review and meta-analysis.

BACKGROUND: Psychosocial factors play an important role in chronic musculoskeletal pain disorders. Although psychosocial stress is likely to contribute to the development of chronic musculoskeletal pain, investigations are limited to work-related stress or examination of specific conditions such as upper limb pain. The purpose of this review is to assess the evidence for an aetiological role of psychological stress in chronic musculoskeletal pain disorders. METHODS: A systematic review and meta-analysis will be conducted. Electronic databases will be searched using predefined search terms to identify relevant studies. Data will be extracted by two independent reviewers, and disagreement will be resolved by a third reviewer. Only prospective longitudinal studies that assess psychosocial stress at baseline will be included. The population of interest will be inception cohorts or cohorts of people who have not yet developed chronic musculoskeletal pain disorders. The primary outcome measure will be the onset of chronic musculoskeletal pain. DISCUSSION: To our knowledge, this review will be the first to systematically explore the available evidence on the aetiological role of psychosocial stress for the development of chronic musculoskeletal pain disorders. This review has the capacity to inform clinical practice on the importance of an early identification and, consequently, treatment of individuals who present with acute musculoskeletal disorders accompanied by a high level of stress. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42017059949.

Safety and feasibility of transcranial direct current stimulation (tDCS) combined with sensorimotor retraining in chronic low back pain: a protocol for a pilot randomised controlled trial.

INTRODUCTION: Chronic low back pain (LBP) is a common and costly health problem yet current treatments demonstrate at best, small effects. The concurrent application of treatments with synergistic clinical and mechanistic effects may improve outcomes in chronic LBP. This pilot trial aims to (1) determine the feasibility, safety and perceived patient response to a combined transcranial direct current stimulation (tDCS) and sensorimotor retraining intervention in chronic LBP and (2) provide data to support a sample size calculation for a fully powered trial should trends of effectiveness be present. METHODS AND ANALYSIS: A pilot randomised, assessor and participant-blind, sham-controlled trial will be conducted. Eighty participants with chronic LBP will be randomly allocated to receive either (1) active tDCS + sensorimotor retraining or (2) sham tDCS + sensorimotor retraining. tDCS (active or sham) will be applied to the primary motor cortex for 20 min immediately prior to 60 min of supervised sensorimotor retraining twice per week for 10 weeks. Participants in both groups will complete home exercises three times per week. Feasibility, safety, pain, disability and pain system function will be assessed immediately before and after the 10-week intervention. Analysis of feasibility and safety will be performed using descriptive statistics. Statistical analyses will be conducted based on intention-to-treat and per protocol and will be used to determine trends for effectiveness. ETHICS AND DISSEMINATION: Ethical approval has been gained from the institutional human research ethics committee (H10184). Written informed consent will be provided by all participants. Results from this pilot study will be submitted for publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ACTRN12616000624482.

Addition of transcranial direct current stimulation to quadriceps strengthening exercise in knee osteoarthritis: A pilot randomised controlled trial.

A randomised, assessor- and participant-blind, sham-controlled trial was conducted to assess the safety and feasibility of adding transcranial direct current stimulation (tDCS) to quadriceps strengthening exercise in knee osteoarthritis (OA), and provide data to inform a fully powered trial. Participants were randomised to receive active tDCS+exercise (AT+EX) or sham tDCS+exercise (ST+EX) twice weekly for 8 weeks whilst completing home exercises twice per week. Feasibility, safety, patient-perceived response, pain, function, pressure pain thresholds (PPTs) and conditioned pain modulation (CPM) were assessed before and after treatment. Fifty-seven people were screened for eligibility. Thirty (52%) entered randomisation and 25 (84%) completed the trial. One episode of headache in the AT+EX group was reported. Pain reduced in both groups following treatment (AT+EX: p<0.001, partial η2 = 0.55; ST+EX: p = 0.026, partial η2 = 0.18) but no between-group differences were observed (p = 0.18, partial η2 = 0.08). Function improved in the AT+EX (p = 0.01, partial η2 = 0.22), but not the ST+EX (p = 0.16, partial η2 = 0.08) group, between-group differences did not reach significance (p = 0.28, partial η2 = 0.052). AT+EX produced greater improvements in PPTs than ST+EX (p<0.05) (superolateral knee: partial η2 = 0.17; superior knee: partial η2 = 0.3; superomedial knee: partial η2 = 0.26). CPM only improved in the AT+EX group but no between-group difference was observed (p = 0.054, partial η2 = 0.158). This study provides the first feasibility and safety data for the addition of tDCS to quadriceps strengthening exercise in knee OA. Our data suggest AT+EX may improve pain, function and pain mechanisms beyond that of ST+EX, and provides support for progression to a fully powered randomised controlled trial.