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.

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.

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.

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.

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.

Organisation and function of the primary motor cortex in chronic pain: protocol for a systematic review and meta-analysis.

INTRODUCTION: Primary motor cortical (M1) adaptation in the form of altered organisation and function is hypothesised to underpin motor dysfunction observed in chronic pain. The aim of this review is to assess the evidence for altered M1 organisation and function in chronic pain. METHODS AND ANALYSIS: Systematic review and meta-analysis. We will search electronic databases with predetermined search terms to identify relevant studies and evaluate the studies for inclusion and risks of bias. Two independent reviewers will extract data. Any disagreement will be resolved through a third reviewer. Cross-sectional or prospective studies published in English before May 2015 that investigate M1 organisation and function in chronic pain will be included if they meet the eligibility criteria. Primary outcomes will include M1 cortical excitability, spatial cortical representation, the function of inhibitory and facilitatory intracortical networks, cortical reactivity and cortical glucose metabolism. Clinical measures such as pain and disability will be included where the correlation with the primary outcomes of M1 organisation and function were investigated in the included studies. ETHICS AND DISSEMINATION: This systematic review does not require ethical approval. The results of this review will be submitted for peer-reviewed publication regardless of outcome and will be presented at relevant conferences. TRIAL REGISTRATION NUMBER: Our systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO; registration number CRD42015014823).

Combined exercise and transcranial direct current stimulation intervention for knee osteoarthritis: protocol for a pilot randomised controlled trial.

INTRODUCTION: Osteoarthritis (OA) is a major health problem and a leading cause of disability. The knee joint is commonly affected, resulting in pain and physical dysfunction. Exercise is considered the cornerstone of conservative management, yet meta-analyses indicate, at best, moderate effect sizes. Treatments that bolster the effects of exercise, such as transcranial direct current stimulation (tDCS), may improve outcomes in knee OA. The aims of this pilot study are to (1) determine the feasibility, safety and perceived patient response to a combined tDCS and exercise intervention in knee OA, 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-blind and participant-blind, sham-controlled trial. 20 individuals with knee OA who report a pain score of 40 or more on a 100 mm visual analogue scale on walking, and meet a priori selection criteria will be randomly allocated to receive either: (1) active tDCS plus exercise, or (2) sham tDCS plus exercise. All participants will receive 20 min of either active or sham tDCS immediately prior to 30 min of supervised muscle strengthening exercise twice a week for 8 weeks. Participants in both groups will also complete unsupervised home exercises twice per week. Outcome measures of feasibility, safety, pain, disability and pain system function will be assessed immediately before and after the 8-week intervention. Analyses of feasibility and safety will be performed using descriptive statistics. Statistical analyses will be used to determine trends of effectiveness and will be based on intention-to-treat as well as per protocol. ETHICS AND DISSEMINATION: This study was approved by the institutional ethics committee (H10184). Written informed consent will be obtained from all participants. The results of this study will be submitted for peer-reviewed publication. TRIAL REGISTRATION NUMBER: ANZCTR365331.

Feasibility and effect of supplementing a modified OTAGO intervention with multisensory balance exercises in older people who fall: a pilot randomized controlled trial.

OBJECTIVE: To investigate the feasibility and comparative effect of supplementing a modified OTAGO falls rehabilitation programme with multisensory balance exercises and informed sample size calculation for a definitive trial. DESIGN: Single-blinded randomized controlled trial with pre/postcomparisons using a per-protocol analysis. SETTING: Secondary care-based falls clinic, London, UK. SUBJECTS: Community-dwelling older people (n = 21) experiencing ≥2 non-syncopal falls during previous 12 months. INTERVENTION: Modified OTAGO exercise classes supplemented with supervised home-based rehabilitation consisting of multisensory balance or stretching exercises. Group classes and home sessions each occurred twice-weekly for eight weeks. MEASUREMENTS: A computerised randomization was used for group allocation. A rater, blinded to intervention, performed the assessment including the Functional Gait Assessment (primary outcome), Physiological Profile Assessment, and questionnaires relating to symptoms, balance confidence, and psychological state (secondary outcomes). RESULTS: Significant within-group improvements were noted for the Functional Gait (p < 0.01, r = -0.63) and Physiological Profile Assessments (p < 0.05, r = -0.63) in the OTAGO+multisensory rehabilitation group only and for balance confidence scores in the OTAGO+stretching group (p < 0.01, r = -0.63). Between-group differences were noted for the Functional Gait (p < 0.01, r = -0.71) and Physiological Profile (p < 0.05, r = -0.54) assessments with the OTAGO+multisensory group showing significantly greater improvement. The drop-out rate was similar for both groups (~30%). No serious adverse events were reported. CONCLUSIONS: Supplementing the OTAGO programme with multisensory balance exercises is feasible in older people who fall and may have a beneficial effect on falls risk as measured using the Functional Gait and Short-form Physiological Profile Assessments. An adequately powered randomized controlled trial would require 36 participants to detect an effect size of 1.35 on the Functional Gait Assessment.

Postural prioritization is differentially altered in healthy older compared to younger adults during visual and auditory coded spatial multitasking.

Many daily activities require appropriate allocation of attention between postural and cognitive tasks (i.e. dual-tasking) to be carried out effectively. Processing multiple streams of spatial information is important for everyday tasks such as road crossing. Fifteen community-dwelling healthy older (mean age=78.3, male=1) and twenty younger adults (mean age=25.3, male=6) completed a novel bimodal spatial multi-task test providing contextually similar spatial information via separate sensory modalities to investigate effects on postural prioritization. Two tasks, a temporally random visually coded spatial step navigation task (VS) and a regular auditory-coded spatial congruency task (AS) were performed independently (single task) and in combination (multi-task). Response time, accuracy and dual-task costs (% change in multi-task condition) were determined. Results showed a significant 3-way interaction between task type (VS vs. AS), complexity (single vs. multi) and age group for both response time (p ≤ 0.01) and response accuracy (p ≤ 0.05) with older adults performing significantly worse than younger adults. Dual-task costs were significantly greater for older compared to younger adults in the VS step task for both response time (p ≤ 0.01) and accuracy (p ≤ 0.05) indicating prioritization of the AS over the VS stepping task in older adults. Younger adults display greater AS task response time dual task costs compared to older adults (p ≤ 0.05) indicating VS task prioritization in agreement with the posture first strategy. Findings suggest that novel dual modality spatial testing may lead to adoption of postural strategies that deviate from posture first, particularly in older people. Adoption of previously unreported postural prioritization strategies may influence balance control in older people.