Nociception affects motor output: a review on sensory-motor interaction with focus on clinical implications

Effects of Chronic Pain on Static and Dynamic Postural Control in Chronic Ankle Instability

OBJECTIVE

To identify the effects of chronic pain levels on static and dynamic postural (DP) control in individuals with chronic ankle instability (CAI).

DESIGN

Cross-sectional study.

SETTING

Controlled laboratory.

PARTICIPANTS

Sixty participants were divided into the following 3 groups: 20 high pain individuals with CAI (high pain), 20 low pain individuals with CAI (low pain), and 20 healthy controls (control).

INDEPENDENT VARIABLES

Groups (CAI with high pain, CAI with low pain, and control) and visual conditions (eyes open and closed) for single-leg stance.

MAIN OUTCOME MEASURES

Participants performed single-leg stance with eyes open and closed, the star excursion balance test, and single-leg hop to stabilization.

RESULTS

The high pain group experienced worse self-reported outcomes, including Foot and Ankle Ability Measure activities of daily living and sports, than the low pain and control groups. Regardless of visual condition, both the high and low pain groups exhibited decreased static postural control in mediolateral (ML) compared with the control group. Specifically, the high pain group showed decreased static postural control in ML under closed eyes compared with the low pain and the control groups. The high pain group showed less reach distance than the control group and increased DP control in vertical and overall DP stability index compared with the low and control groups.

CONCLUSIONS

Chronic pain can significantly affect both static and DP control in individuals with CAI. Therefore, clinicians should consider chronic pain as one of the factors affecting postural control in individuals with CAI.

Aberrant Functional Connectivity of the Salience Network in Adult Patients with Tic Disorders: A Resting-State fMRI Study

Tic disorders (TD) are characterized by the presence of motor and/or vocal tics. Common neurophysiological frameworks suggest dysregulations of the cortico-striatal-thalamo-cortical (CSTC) brain circuit that controls movement execution. Besides common tics, there are other "non-tic" symptoms that are primarily related to sensory perception, sensorimotor integration, attention, and social cognition. The existence of these symptoms, the sensory tic triggers, and the modifying effect of attention and cognitive control mechanisms on tics may indicate the salience network's (SN) involvement in the neurophysiology of TD. Resting-state functional MRI measurements were performed in 26 participants with TD and 25 healthy controls (HC). The group differences in resting-state functional connectivity patterns were measured based on seed-to-voxel connectivity analyses. Compared to HC, patients with TD exhibited altered connectivity between the core regions of the SN (insula, anterior cingulate cortex, and temporoparietal junction) and sensory, associative, and motor-related cortices. Furthermore, connectivity changes were observed in relation to the severity of tics in the TD group. The SN, particularly the insula, is likely to be an important site of dysregulation in TD. Our results provide evidence for large-scale neural deviations in TD beyond the CSTC pathologies. These findings may be relevant for developing treatment targets.

Relationship between pain and proprioception among individuals with rotator cuff-related shoulder pain

BACKGROUND

Individuals with rotator cuff-related shoulder pain (RCRSP) have altered proprioception. The relationship between shoulder pain and proprioception is not well understood.

PURPOSE

This study aimed to investigate the relationship between shoulder pain and proprioception.

STUDY DESIGN

This was a cross-sectional comparative study.

METHODS

Twenty-two participants with RCRSP (mean age 27.6 ± 4.8 years) and 22 matched pain-free participants (23.4 ± 2.5 years) performed two upper limb active joint position sense tests: (1) the Upper Limb Proprioception Reaching Test (PRO-Reach; reaching toward seven targets) in centimeters and (2) Biodex System at 90% of maximum internal rotation in degrees. Participants performed three memorization and three reproduction trials blindfolded. The proprioception error (PE) is the difference between the memorized and estimation trials. Pain levels were captured pre- and post-evaluation (11-point Likert Numerical Pain Rating Scale). Relationships between PE and pain were investigated using independent t-tests and Spearman rank correlations.

RESULTS

Overall, 22.7% RCRSP participants indicated an increase in pain following the PRO-Reach (X̅ increase of 1.4 ± 1.5 points), while 59% did so with the Biodex (X̅ increase of 2.3 ± 1.8 points), reflecting a clinically important increase in pain. Weak-to-moderate correlations between pain and PEs were found with the Biodex (r = 0.39-0.53) and weak correlations with the PRO-Reach (r = -0.26 to 0.38). Concerning PEs, no significant differences were found between groups with the Biodex (p = 0.32, effect size d = -0.31 [-0.90 to 0.29]). The RCRSP participants demonstrated lower PEs with the PRO-Reach in elevation compared to pain-free participants (global X̅ = 4.6 ± 1.2 cm vs 5.5 ± 1.5 cm; superior 3.8 ± 2.1 cm vs 5.7 ± 2.9 cm; superior-lateral nondominant targets 4.3 ± 2.2 cm vs 6.1 ± 2.8 cm; p = 0.02-0.05, effect size d = 0.72-0.74 [0.12-1.3]).

CONCLUSIONS

Individuals with RCRSP demonstrated better upper limb proprioception in elevation, suggesting a change to interoception (sensory reweighting) in the presence of pain.

Self-Massage Acute Effects on Pressure Pain Threshold, Muscular Electrical Activity, and Muscle Force Production: A Systematic Review and Meta-Analysis

ABSTRACT

Furlan, MR, Machado, E, Petter, GdN, Barbosa, IM, Geremia, JM, and Glänzel, MH. Self-massage acute effects on pressure pain threshold, muscular electrical activity, and muscle force production: a systematic review and meta-analysis. J Strength Cond Res 38(3): 620-635, 2024-Self-massage (SM) is often used in physiotherapy and sports training programs. However, the SM acute effects on pressure pain threshold (PPT), muscle electrical activity (MEA), and muscle force production remain unclear. A meta-analytical review was performed to verify the SM acute effects on neuromuscular responses in healthy adults or athletes. The review (CRD42021254656) was performed in the PubMed, Web of Science, and Embase databases. A synthesis of the included studies was performed, and both the risk of bias and the evidence certainty level were assessed through the PEDro scale and Grading of Recommendations Assessment, Development, and Evaluation approach, respectively. Nineteen studies were included, 5 evaluated the PPT, 7 the thigh muscles' MEA, and 15 the lower-limb strength. The SM application induces moderate increases in quadriceps' PPT (5 studies; standardized mean difference [SMD]: 0.487; 95% CI 0.251-0.723; p < 0.001; I2 = 0%). We found no SM effects on the hamstrings and plantar flexors' MEA. Also, we observed small increases in knee extensors' concentric torque (2 studies; SMD: 0.288; 95% CI 0.088-0.489; p = 0.005; I2 = 0%), without effects in isometric muscle strength, eccentric torque, and rate of force development. Grading of recommendations assessment, development, and evaluation analysis showed high and low certainty levels for the SM effects on quadriceps' PPT and muscle strength, respectively. Self-massage pressure-volume application seems to be a determining factor in inducing changes in these parameters, and it may vary among the treated muscles, where a higher pressure-volume application is required for increasing knee flexors and plantar flexors' PPT and strength. Thus, new studies with better methodological quality should be performed to strengthen this evidence.

Experimentally Induced Pain Results in Reduced Activity of the Rotator Cuff Muscles in Healthy Subjects

Shoulder pain is a complex, prevalent problem that is multifactorial in nature. While there are many potential causes, one common suspect is the rotator cuff musculature. The purpose of the present study was to induce pain in the supraspinatus muscle of healthy subjects and observe the resulting changes in muscle activity. Eight muscles on 23 subjects were assessed using electromyography: anterior, middle, and posterior deltoid; pectoralis major; upper trapezius; latissimus dorsi; serratus anterior; supraspinatus; and infraspinatus. It was hypothesized that the rotator cuff muscles would display reduced activity during pain, and that reductions in activity would remain after the pain had dissipated. Both of the rotator cuff muscles measured did indeed display reduced activity in a majority of the dynamic, isometric, and maximal contractions. Many of those reductions remained after the pain had subsided.

Motor Imagery and Pain Processing in Patients With Entrapment Neuropathies: A Cross-sectional Study

OBJECTIVES

(1) To assess the ability to generate both kinesthetic and visual motor imagery in participants with carpal tunnel syndrome (CTS), compared with asymptomatic participants. (2) To assess the influence of psychophysiological and functional variables in the motor imagery process.

METHODS

Twenty patients with unilateral CTS and 18 pain-free individuals were recruited. An observational case-control study with a nonprobability sample was conducted to assess visual and kinesthetic movement imagery ability and psychophysiological variables in patients with CTS compared with asymptomatic participants in a control group. The trial was conducted in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology statement.

RESULTS

CTS patients have more difficulties in generating visual motor images compared with asymptomatic individuals ( t =-2.099; P <0.05; d=0.70). They need more time to complete the mental tasks (visual t =-2.424; P <0.05 and kinesthetic t =-2.200; P <0.05). A negative correlation was found between the ability to imagine and functional deficits ( r =-0.569; P =0.021) for the kinesthetic subscale and temporal summation ( r =-0.515; P <0.5). A positive correlation was found between pain pressure threshold homolateral (homolateral) and time to generate the visual mental images ( r =0.537; P <0.05).

DISCUSSION

CTS patients have greater difficulty generating motor images than asymptomatic individuals. Patients also spend more time during mental tasks. CTS patients present a relationship between temporal summation and the capacity to generate kinesthetic images. In addition, the CST patients presented a correlation between chronometry mental tasking and mechanical hyperalgesia.

Analysis of Postural Stability Following the Application of Myofascial Release Techniques for Low Back Pain-A Randomized-Controlled Trial

INTRODUCTION

Low back pain (LBP) is one of the most frequently observed disorders of the musculoskeletal system in the modern population. It is suggested that myofascial disorders in the highly innervated thoracolumbar fascia (TLF), reported in patients with LBP, may be an underlying cause of the ailment. Research also confirms that patients with LBP demonstrate poorer postural stability compared with individuals without the condition. Myofascial release techniques (MFR) are additional therapeutic options that complement existing therapies and help provide a more holistic treatment for chronic LBP (CLBP).

OBJECTIVE

Evaluation of changes in postural stability following one MFR intervention applied to CLBP subjects immediately after manual therapy and after a month. It was hypothesized that postural stability is going to aggravate immediately after the MFR intervention and improve one month after treatment compared with the baseline results before the treatment.

METHODS

113 patients with CLBP participated in a randomized-controlled trial. The experimental group (n = 59) received one MFR intervention, whereas the control group (n = 54) did not receive any therapeutic intervention. Posturography was performed to determine experimental group's immediate response to the therapy and to evaluate the experimental and control groups' responses to the therapy one month after the intervention.

RESULTS

Only 2 out of 12 comparisons of stabilometric parameters demonstrated reliable effects that are in line with our research hypotheses. Even though both comparisons were observed for therapy outcomes within the experimental group, no reliable differences between the groups were found.

CONCLUSIONS

A single MFR treatment in the TLF did not affect postural stability in CLBP patients in the experimental group. Further studies are needed to extend the findings by performing a series of holistic MFR treatments applied to a larger area of the body surface that would induce more general tissue changes and thus having a greater impact on postural stability.

Case report: Individualized pulsed electromagnetic field therapy in a Long COVID patient using the Adaptive Force as biomarker

The increasing prevalence of Long COVID is an imminent public health disaster, and established approaches have not provided adequate diagnostics or treatments. Recently, anesthetic blockade of the stellate ganglion was reported to improve Long COVID symptoms in a small case series, purportedly by "rebooting" the autonomic nervous system. Here, we present a novel diagnostic approach based on the Adaptive Force (AF), and report sustained positive outcome for one severely affected Long COVID patient using individualized pulsed electromagnetic field (PEMF) at the area C7/T1. AF reflects the capacity of the neuromuscular system to adapt adequately to external forces in an isometric holding manner. In case, maximal isometric AF (AFisomax) is exceeded, the muscle merges into eccentric muscle action. Thereby, the force usually increases further until maximal AF (AFmax) is reached. In case adaptation is optimal, AFisomax is ~99-100% of AFmax. This holding capacity (AFisomax) was found to be vulnerable to disruption by unpleasant stimulus and, hence, was regarded as functional parameter. AF was assessed by an objectified manual muscle test using a handheld device. Prior to treatment, AFisomax was considerably lower than AFmax for hip flexors (62 N = ~28% AFmax) and elbow flexors (71 N = ~44% AFmax); i.e., maximal holding capacity was significantly reduced, indicating dysfunctional motor control. We tested PEMF at C7/T1, identified a frequency that improved neuromuscular function, and applied it for ~15 min. Immediately post-treatment, AFisomax increased to ~210 N (~100% AFmax) at hip and 184 N (~100% AFmax) at elbow. Subjective Long COVID symptoms resolved the following day. At 4 weeks post-treatment, maximal holding capacity was still on a similarly high level as for immediately post-treatment (~100% AFmax) and patient was symptom-free. At 6 months the patient's Long COVID symptoms have not returned. This case report suggests (1) AF could be a promising diagnostic for post-infectious illness, (2) AF can be used to test effective treatments for post-infectious illness, and (3) individualized PEMF may resolve post-infectious symptoms.

Limited evidence of altered gait parameters in people with chronic nonspecific low back pain

BACKGROUND

Differences in gait parameters have been shown between people with and without low back pain (LBP). However, previous studies did not well control factors such as sex, age, height and walking speed known to influence gait parameters.

RESEARCH QUESTION

Is gait altered in people with LBP when sex, age, height and walking speed are controlled?

METHODS

A series of gait parameters were measured in 16 participants with LBP and 16 age, sex and height matched healthy controls while walking on an instrumented treadmill. LBP group walked at a comfortable speed whilst control group walked at their own comfortable speed and at the comfortable speed of their matched participants with LBP. Pain and disability were measured for the LBP group. The between-group differences in mean, standard deviation (SD) and coefficient of variation (CV) of gait parameters were tested using paired samples t-test, Wilcoxon signed-rank test or two-factor repeated measures analyses of variance.

RESULTS

The median (interquartile range) of pain intensity was 2 (1, 3.5). From 102 tests of between-group difference in mean, SD and CV of 17 gait parameters at both comfortable speed and matched speed walking, only the mean of stride length (p = 0.037) during matched speed walking and SD of single support phase (p = 0.040) during comfortable speed walking showed significant between-group differences. There was no significant between-group difference in the rest means (comfortable walking: p ≥ 0.116; matched speed walking: p ≥ 0.069), SDs (comfortable walking: p ≥ 0.066; matched speed walking: p ≥ 0.098) and CVs of gait parameters (comfortable walking: p ≥ 0.110; matched speed walking: p ≥ 0.121).

SIGNIFICANCE

The lack of significant between-group difference in gait parameters may suggest that the gait of people with low level of LBP were not altered when sex, age and height were controlled.

Transcranial magnetic stimulation maps the neurophysiology of chronic noncancer pain: A scoping review

BACKGROUND

Chronic noncancer pain is a global public health challenge. It is imperative to identify biological markers ("biomarkers") to understand the mechanisms underlying chronic pain and to monitor pain over time and after interventions. Transcranial magnetic stimulation (TMS) is a promising method for this purpose.

OBJECTIVES

To examine differences in TMS-based outcomes between persons with chronic pain and healthy controls (HCs) and/or before versus after pain-modulating interventions and relationships between pain measures and TMS outcomes; To summarize the neurophysiological mechanisms underlying chronic pain as identified by TMS.

METHODS

We searched the PubMed database for literature from January 1, 1985, to June 9, 2020, with the keywords "pain" and "transcranial magnetic stimulation." Eligible items included original studies of adult human participants with pain lasting for ≥ 6 months. We completed a narrative synthesis of the study findings stratified by chronic pain etiology (primary pain, neuropathic pain, and secondary musculoskeletal pain).

RESULTS

The search yielded 1265 records. The final 12 articles included 244 patients with chronic pain (192 females, aged 35-65 years) and 169 HCs (89 females, aged 28-59 years). Abnormalities in TMS outcomes that reflect GABAergic and glutamatergic activities were associated with many of the disorders studied and were distinct for each pain etiology. Chronic primary pain is characterized by reduced intracortical inhibition and corticospinal excitability, chronic neuropathic pain shows evidence of increased excitation and disinhibition, and chronic secondary musculoskeletal pain involves low corticospinal excitability.

DISCUSSION

TMS could be a useful tool for delineating the neurophysiological underpinnings of chronic pain syndromes.

Emotional Imagery Influences the Adaptive Force in Young Women: Unpleasant Imagery Reduces Instantaneously the Muscular Holding Capacity

The link between emotions and motor function has been known for decades but is still not clarified. The Adaptive Force (AF) describes the neuromuscular capability to adapt to increasing forces and was suggested to be especially vulnerable to interfering inputs. This study investigated the influence of pleasant and unpleasant food imagery on the manually assessed AF of elbow and hip flexors objectified by a handheld device in 12 healthy women. The maximal isometric AF was significantly reduced during unpleasant vs. pleasant imagery and baseline (p < 0.001, dz = 0.98−1.61). During unpleasant imagery, muscle lengthening started at 59.00 ± 22.50% of maximal AF, in contrast to baseline and pleasant imagery, during which the isometric position could be maintained mostly during the entire force increase up to ~97.90 ± 5.00% of maximal AF. Healthy participants showed an immediately impaired holding function triggered by unpleasant imagery, presumably related to negative emotions. Hence, AF seems to be suitable to test instantaneously the effect of emotions on motor function. Since musculoskeletal complaints can result from muscular instability, the findings provide insights into the understanding of the causal chain of linked musculoskeletal pain and mental stress. A case example (current stress vs. positive imagery) suggests that the approach presented in this study might have future implications for psychomotor diagnostics and therapeutics.

Limb Laterality Discrimination, Evoked Sensations and Somatosensory Behavior in Fibromyalgia Syndrome: A Cross-Sectional Study

The main objective of this study was to assess the status of body schema using limb laterality discrimination tasks and pain measurement variables of patients with FMS compared to healthy subjects. The secondary aim was to analyze the relationships between laterality discrimination with respect to somatosensory variables. Thirty female patients with FMS (with a mean age of 52.43 ± 11.82 years) and thirty healthy women (with a mean age of 47.93 ± 5.92 years) were recruited. The main outcome measures were laterality discrimination, referral of evoked sensations, pressure pain threshold and conditioned pain modulation. The main analysis showed that patients with FMS have a longer reaction time for laterality discrimination in hands (hands—20 images, t = 4.044, p < 0.0001, d = 1.04; hands—50 images t = 4.012, p < 0.0001, d = 1.31; feet—20 images t = 2.982, p < 0.01, d = 0.76; feet—50 images, t = 2.159, p < 0.05, d = 0.55). With regard the secondary analysis, patients with FM have higher mechanical hyperalgesia (t = −9.550; p < 0.0001, d = 2.51) and decreased response to conditioned pain modulation compared with healthy subjects (t = 15.519; p < 0.0001, d = 4.17). A positive correlation was found in patients with FMS between greater laterality discrimination ability and better function of conditioned pain modulation (hands r = 0.676, p < 0.0001; feet r = 0.485, p < 0.01). In conclusion, patients with FMS have a longer reaction time and lower accuracy for laterality discrimination, increased mechanical hyperalgesia and decreased conditioned pain modulation compared to healthy subjects. Finally, it seems that there is a positive correlation between greater laterality discrimination ability and better conditioned pain modulation function.

Unsupervised Machine Learning on Motion Capture Data Uncovers Movement Strategies in Low Back Pain

Chronic low back pain (LBP) is a leading cause of disability and opioid prescriptions worldwide, representing a significant medical and socioeconomic problem. Clinical heterogeneity of LBP limits accurate diagnosis and precise treatment planning, culminating in poor patient outcomes. A current priority of LBP research is the development of objective, multidimensional assessment tools that subgroup LBP patients based on neurobiological pain mechanisms, to facilitate matching patients with the optimal therapies. Using unsupervised machine learning on full body biomechanics, including kinematics, dynamics, and muscle forces, captured with a marker-less depth camera, this study identified a forward-leaning sit-to-stand strategy (STS) as a discriminating movement biomarker for LBP subjects. A forward-leaning STS strategy, as opposed to a vertical rise strategy seen in the control participants, is less efficient and results in increased spinal loads. Inefficient STS with the subsequent higher spinal loading may be a biomarker of poor motor control in LBP patients as well as a potential source of the ongoing symptomology.

Linking Pain and Motor Control: Conceptualization of Movement Deficits in Patients With Painful Conditions

When people experience or expect pain, they move differently. Pain-altered movement strategies, collectively described here as pain-related movement dysfunction (PRMD), may persist well after pain resolves and, ultimately, may result in altered kinematics and kinetics, future reinjury, and disability. Although PRMD may manifest as abnormal movements that are often evident in clinical assessment, the underlying mechanisms are complex, engaging sensory-perceptual, cognitive, psychological, and motor processes. Motor control theories provide a conceptual framework to determine, assess, and target processes that contribute to normal and abnormal movement and thus are important for physical therapy and rehabilitation practice. Contemporary understanding of motor control has evolved from reflex-based understanding to a more complex task-dependent interaction between cognitive and motor systems, each with distinct neuroanatomic substrates. Though experts have recognized the importance of motor control in the management of painful conditions, there is no comprehensive framework that explicates the processes engaged in the control of goal-directed actions, particularly in the presence of pain. This Perspective outlines sensory-perceptual, cognitive, psychological, and motor processes in the contemporary model of motor control, describing the neural substrates underlying each process and highlighting how pain and anticipation of pain influence motor control processes and consequently contribute to PRMD. Finally, potential lines of future inquiry-grounded in the contemporary model of motor control-are outlined to advance understanding and improve the assessment and treatment of PRMD.

IMPACT

This Perspective proposes that approaching PRMD from a contemporary motor control perspective will uncover key mechanisms, identify treatment targets, inform assessments, and innovate treatments across sensory-perceptual, cognitive, and motor domains, all of which have the potential to improve movement and functional outcomes in patients with painful conditions.

Motor alterations in the kinetic chain in individuals with chronic shoulder pain

BACKGROUND

Shoulder pain may be related to biomechanical dysfunctions in the kinetic chain.

OBJECTIVE

To compare the mobility and muscular endurance of thoracolumbar spine and hip, and the neuromuscular control of the lower extremity of individuals with and without shoulder pain and to determine the discriminative capacity between groups of these variables.

DESIGN

A cross-sectional study.

METHOD

One hundred and two individuals with and without shoulder pain were evaluated to range of motion (ROM) of the thoracolumbar spine and hips, the muscular endurance time of the thoracolumbar spine and hips muscles, and the neuromuscular control of the lower extremity, by the Star Excursion Balance Test (SEBT).

RESULTS

Individuals with shoulder pain presented lower ROM and muscular endurance time in all tests evaluated (p < 0.01-p = 0.03), greater perception of pain during all ROM and muscle endurance (p < 0.01-p = 0.04) evaluations, and less neuromuscular control of the lower extremity in the compound reach (p < 0.01-p = 0.01), anterior and posteromedial (p < 0.01-p = 0.04) directions of the SEBT on both sides. The anterior reach direction of the SEBT of the contralateral limb to the shoulder pain (AUC=0.80, cut-off point=47.7%) presented excellent capacity to discriminate individuals with shoulder pain, while the other variables showed between acceptable and small capacity (AUC=0.58-0.76).

CONCLUSION

Individuals with chronic shoulder pain presented alterations in joint mobility, muscular endurance time of the thoracolumbar spine and hips and neuromuscular control of the lower extremity. The anterior reach of the SEBT of the contralateral limb showed excellent discriminative capacity.

Neonatal anoxia increases nociceptive response in rats: Sex differences and lumbar spinal cord and insula alterations

Neonatal anoxia is a well-known world health problem that results in neurodevelopmental deficits, such as sensory alterations that are observed in patients with cerebral palsy and autism disorder, for which oxygen deprivation is a risk factor. Nociceptive response, as part of the sensory system, has been reported as altered in these patients. To determine whether neonatal oxygen deprivation alters nociceptive sensitivity and promotes medium- and long-term inflammatory feedback in the central nervous system, Wistar rats of around 30 h old were submitted to anoxia (100% nitrogen flux for 25 min) and evaluated on PND23 (postpartum day) and PND90. The nociceptive response was assessed by mechanical, thermal, and tactile tests in the early postnatal and adulthood periods. The lumbar spinal cord (SC, L4-L6) motor neurons (MNs) and the posterior insular cortex neurons were counted and compared with their respective controls after anoxia. In addition, we evaluated the possible effect of anoxia on the expression of astrocytes in the SC at adulthood. The results showed increased nociceptive responses in both males and females submitted to anoxia, although these responses were different according to the nociceptive stimulus. A decrease in MNs in adult anoxiated females and an upregulation of GFAP expression in the SC were observed. In the insular cortex, a decrease in the number of cells of anoxiated males was observed in the neonatal period. Our findings suggest that oxygen-deprived nervous systems in rats may affect their response at the sensorimotor pathways and respective controlling centers with sex differences, which were related to the used stimulus.

Adaptive Force and emotionally related imaginations - preliminary results suggest a reduction of the maximal holding capacity as reaction to disgusting food imagination

The link between emotions and motor control has been discussed for years. The measurement of the Adaptive Force (AF) provides the possibility to get insights into the adaptive control of the neuromuscular system in reaction to external forces. It was hypothesized that the holding isometric AF is especially vulnerable to disturbing inputs. Here, the behavior of the AF under the influence of positive (tasty) vs. negative (disgusting) food imaginations was investigated. The AF was examined in n = 12 cases using an objectified manual muscle test of the hip flexors, elbow flexors or pectoralis major muscle, performed by one of two experienced testers while the participants imagined their most tasty or most disgusting food. The reaction force and the limb position were measured by a handheld device. While the slope of force rises and the maximal AF did not differ significantly between tasty and disgusting imaginations (p > 0.05), the maximal isometric AF was significantly lower and the AF at the onset of oscillations was significantly higher under disgusting vs. tasty imaginations (both p = 0.001). A proper length tension control of muscles seems to be a crucial functional parameter of the neuromuscular system which can be impaired instantaneously by emotionally related negative imaginations. This might be a potential approach to evaluate somatic reactions to emotions.

Assessment of the Adaptive Force of Elbow Extensors in Healthy Subjects Quantified by a Novel Pneumatically Driven Measurement System with Considerations of Its Quality Criteria

Adaptive Force (AF) reflects the capability of the neuromuscular system to adapt adequately to external forces with the intention of maintaining a position or motion. One specific approach to assessing AF is to measure force and limb position during a pneumatically applied increasing external force. Through this method, the highest (AF_max), the maximal isometric (AFiso_max) and the maximal eccentric Adaptive Force (AFecc_max) can be determined. The main question of the study was whether the AFiso_max is a specific and independent parameter of muscle function compared to other maximal forces. In 13 healthy subjects (9 male and 4 female), the maximal voluntary isometric contraction (pre- and post-MVIC), the three AF parameters and the MVIC with a prior concentric contraction (MVICpri-con) of the elbow extensors were measured 4 times on two days. Arithmetic mean (M) and maximal (Max) torques of all force types were analyzed. Regarding the reliability of the AF parameters between days, the mean changes were 0.31–1.98 Nm (0.61%–5.47%, p = 0.175–0.552), the standard errors of measurements (SEM) were 1.29–5.68 Nm (2.53%–15.70%) and the ICCs(3,1) = 0.896–0.996. M and Max of AFiso_max, AF_max and pre-MVIC correlated highly (r = 0.85–0.98). The M and Max of AFiso_max were significantly lower (6.12–14.93 Nm; p ≤ 0.001–0.009) and more variable between trials (coefficient of variation (CVs) ≥ 21.95%) compared to those of pre-MVIC and AF_max (CVs ≤ 5.4%). The results suggest the novel measuring procedure is suitable to reliably quantify the AF, whereby the presented measurement errors should be taken into consideration. The AFiso_max seems to reflect its own strength capacity and should be detected separately. It is suggested its normalization to the MVIC or AF_max could serve as an indicator of a neuromuscular function.

Intramuscular Electrical Stimulation Combined with Therapeutic Exercises in Patients with Shoulder Adhesive Capsulitis: A Randomised Controlled Trial

Background:

Myofascial trigger points (MTrPs) precipitate the shoulder pain severity and disability in patients with shoulder adhesive capsulitis (SAC). This study aims to compare the effectiveness of intramuscular electrical stimulation (IMES) combined with therapeutic exercises versus dry needling (DN) combined with therapeutic exercises in improving the clinical outcomes in patients with SAC.

Methods and Materials:

In this randomized controlled trial, IMES (n = 45) and DN (43) groups had received respectively IMES, and DN twice weekly for three consecutive weeks. Both groups received therapeutic exercises 1520 minutes, five days in a week during the second and third week. Pain, disability, kinesiophobia, number of active and latent MTrPs, shoulder abduction and external rotation range of motion were assessed at baseline, week-1, week-2, week-3 and follow-up at 3 months. A repeated measures ANOVA performed to find out the significant differences in the clinical outcomes between the groups.

Results:

The results of repeated measures of ANOVA shows that the post intervention timelines assessment scores of VAS, DASH, shoulder abduction and external rotation ROM, number of active and latent MTrPs and kinesiophobia were significantly (p. < 0.05) improved in both groups. However, IMES group had achieved a greater improvement over DN group (p. < 0.05) on the shoulder pain severity and disability, shoulder range of motion, number of active and latent MTrPs and kinesiophobia. Despite the significant statistical differences between the groups, IMES group did not achieve the minimal clinically important differences of 1.5cm and 11-points respectively for the VAS and DASH scores. No serious adverse effects occurred during the three weeks of treatment.

Conclusion:

IMES combined with therapeutic exercises is an effective treatment to reduce the shoulder pain severity and upper limb disability by deactivating the active and latent MTrPs and improving the shoulder abduction and external rotation range of motion in patients with SAC.

Correlating cognition and cortical excitability with pain in fibromyalgia: a case control study

BACKGROUND

Fibromyalgia is a chronic pain disorder characterized by widespread musculoskeletal symptoms, primarily attributed to sensitization of somatosensory system carrying pain. Few reports have investigated the impact of fibromyalgia symptoms on cognition, corticomotor excitability, sleepiness, and the sleep quality - all of which can deteriorate the quality of life in fibromyalgia. However, the existing reports are underpowered and have conflicting directions of findings, limiting their generalizability. Therefore, the present study was designed to compare measures of cognition, corticomotor excitability, sleepiness, and sleep quality using standardized instruments in the recruited patients of fibromyalgia with pain-free controls.

METHODS

Diagnosed cases of fibromyalgia were recruited from the Rheumatology department for the cross-sectional, case-control study. Cognition (Mini-Mental State Examination, Stroop color-word task), corticomotor excitability (Resting motor threshold, Motor evoked potential amplitude), daytime sleepiness (Epworth sleepiness scale), and sleep quality (Pittsburgh sleep quality index) were studied according to the standard procedure.

RESULTS

Thirty-four patients of fibromyalgia and 30 pain-free controls were recruited for the study. Patients of fibromyalgia showed decreased cognitive scores (p = 0.05), lowered accuracy in Stroop color-word task (for color: 0.02, for word: 0.01), and prolonged reaction time (< 0.01, < 0.01). Excessive daytime sleepiness in patients were found (< 0.01) and worsened sleep quality (< 0.01) were found. Parameters of corticomotor excitability were comparable between patients of fibromyalgia and pain-free controls.

CONCLUSIONS

Patients of fibromyalgia made more errors, had significantly increased reaction time for cognitive tasks, marked daytime sleepiness, and impaired quality of sleep. Future treatment strategies may include cognitive deficits and sleep disturbances as an integral part of fibromyalgia management.

Acute experimentally-induced pain replicates the distribution but not the quality or behaviour of clinical appendicular musculoskeletal pain. A systematic review

OBJECTIVES

Experimental pain is a commonly used method to draw conclusions about the motor response to clinical musculoskeletal pain. A systematic review was performed to determine if current models of acute experimental pain validly replicate the clinical experience of appendicular musculoskeletal pain with respect to the distribution and quality of pain and the pain response to provocation testing.

METHODS

A structured search of Medline, Scopus and Embase databases was conducted from database inception to August 2020 using the following key terms: "experimental muscle pain" OR "experimental pain" OR "pain induced" OR "induced pain" OR "muscle hyperalgesia" OR ("Pain model" AND "muscle"). Studies in English were included if investigators induced experimental musculoskeletal pain into a limb (including the sacroiliac joint) in humans, and if they measured and reported the distribution of pain, quality of pain or response to a provocation manoeuvre performed passively or actively. Studies were excluded if they involved prolonged or delayed experimental pain, if temporomandibular, orofacial, lumbar, thoracic or cervical spine pain were investigated, if a full text of the study was not available or if they were systematic reviews. Two investigators independently screened each title and abstract and each full text paper to determine inclusion in the review. Disagreements were resolved by consensus with a third investigator.

RESULTS

Data from 57 experimental pain studies were included in this review. Forty-six of these studies reported pain distribution, 41 reported pain quality and six detailed the pain response to provocation testing. Hypertonic saline injection was the most common mechanism used to induce pain with 43 studies employing this method. The next most common methods were capsaicin injection (5 studies) and electrical stimulation, injection of acidic solution and ischaemia with three studies each. The distribution of experimental pain was similar to the area of pain reported in clinical appendicular musculoskeletal conditions. The quality of appendicular musculoskeletal pain was not replicated with the affective component of the McGill Pain Questionnaire consistently lower than that typically reported by musculoskeletal pain patients. The response to provocation testing was rarely investigated following experimental pain induction. Based on the limited available data, the increase in pain experienced in clinical populations during provocative maneuvers was not consistently replicated.

CONCLUSIONS

Current acute experimental pain models replicate the distribution but not the quality of chronic clinical appendicular musculoskeletal pain. Limited evidence also indicates that experimentally induced acute pain does not consistently increase with tests known to provoke pain in patients with appendicular musculoskeletal pain. The results of this review question the validity of conclusions drawn from acute experimental pain studies regarding changes in muscle behaviour in response to pain in the clinical setting.

Reduction of Knee Pain in a 45-Year-Old Woman After Pelvic Manipulation and Kinesiology Taping: A Case Report

Objective

The purpose of this case report is to describe the chiropractic management of a patient with knee pain stemming from pelvic imbalance.

Clinical Features

A female patient presented to a chiropractic clinic with ongoing anteromedial knee pain whenever she walks. The patient reported being unable to walk a half mile without her knee feeling like it would "give out."

Intervention and Outcome

The patient received 5 treatments focusing on the pelvic imbalance and reduced muscle strength discovered in the patient's initial evaluation. Chiropractic manipulation of the sacroiliac joint, kinesiology taping, and gluteus medius exercises were administered. The Verbal Rating Scale, muscle strength assessment, and orthopedic evaluation measured the patient's progress. After 5 treatments the Verbal Rating Scale went from 8 to 1 and gluteus medius strength scored 5 of 5.

Conclusion

The patient in this case reported resolution of her knee pain after 5 treatments over the course of 10 days. The patient reported no pain while walking nor while performing other activities of daily living. Although this is one case, correcting pelvic balance via conservative measures resolved the knee pain. Implementing therapy proximal to the complaint may be a viable option for patients with knee pain.

Deep Friction Massage in the Management of Patellar Tendinopathy in Athletes: Short-Term Clinical Outcomes

CONTEXT

Deep friction massage (DFM) is often used in the treatment of tendinopathies; however, the pressure applied may vary and interfere with the obtained results.

OBJECTIVE

To assess whether the immediate effects of DFM on pain (pain intensity and time to onset of analgesia) and muscle strength are dependent on the pressure applied during the DFM application in athletes with patellar tendinopathy.

DESIGN

Randomized, controlled, cross-over trial.

SETTING

University research laboratory (institutional).

PARTICIPANTS

Ten athletes with diagnosis of unilateral patellar tendinopathy (age 27.90 [5.24] y).

INTERVENTIONS

All participants attended 4 sessions, 3 treatment sessions with DFM applied with different pressures (the mean pressure-previously determined for each participant-and the mean pressure ± 25%) and a control session, each of which was separated by 48 hours.

MAIN OUTCOME MEASURES

Pain (intensity upon palpation and time to onset of analgesia), and muscle strength of knee extensors were assessed before and immediately after each session.

RESULTS

Pain intensity changed significantly over time (F1,9 = 52.364; P < .001; ηp2=.853) and among sessions (F3,27 = 82.588; P < .001; ηp2=.902), with a significant interaction for group × time (F3,27 = 19.841; P < .001; ηp2=.688). The knee extensors strength did not change significantly over time (F1,9 = 2.240; P = .17; ηp2=.199), nor a significant interaction for session × time was observed (F3,27 = 3.276; P = .07; ηp2=.267). Regardless of the pressure applied, the time to onset of analgesia was not significantly different (F2,18 = 1.026; P > .05; ηp2=.102).

CONCLUSION

It was shown that DFM induces an immediate reduction in pain intensity upon palpation, regardless of the pressure performed. Notwithstanding, the reader should take into account the small sample size and the caution needed in the results' interpretation.

Does Motor Cortex Engagement During Movement Preparation Differentially Inhibit Nociceptive Processing in Patients with Chronic Whiplash Associated Disorders, Chronic Fatigue Syndrome and Healthy Controls? An Experimental Study

BACKGROUND

Patients with chronic fatigue syndrome (CFS) and chronic whiplash associated disorders (cWAD) present a reduced ability to activate central descending nociceptive inhibition after exercise, compared to measurements before exercise. It was hypothesised that a dysfunctional motor-induced inhibition of nociception partly explains this dysfunctional exercise-induced hypoalgesia. This study investigates if engagement of the motor system during movement preparation inhibits nociception-evoked brain responses in these patients as compared to healthy controls (HC).

METHODS

The experiment used laser-evoked potentials (LEPs) during three conditions (no task, mental task, movement preparation) while recording brain activity with a 32-channel electroencephalogram in 21 patients with cWAD, 20 patients with CFS and 18 HC. Two-factor mixed design Analysis of variance were used to evaluate differences in LEP amplitudes and latencies.

RESULTS

No differences in N1, N2, N2P2, and P2 LEP amplitudes were found between the HC, CFS, and cWAD groups. After nociceptive stimulation, N1, N2 (only at hand location), N2P2, and P2 LEP amplitudes significantly decreased during movement preparation compared to no task (within group differences).

CONCLUSION

Movement preparation induces a similar attenuation of LEPs in patients with CFS, patients with cWAD and HC. These findings do not support reduced motor-induced nociceptive inhibition in these patients.

Perception of verticality is altered in people with severe chronic low back pain compared to healthy controls: A cross-sectional study

BACKGROUND

People with chronic low back pain (CLBP) have abnormal lumbar proprioception, which increases their reliance on visual input to maintain body verticality. Maintaining verticality is important for spatial orientation, balance and movement coordination. It is unknown if these patients also have altered perception of verticality.

OBJECTIVE

To compare whether the perception of verticality is different between people with and without CLBP.

DESIGN

Cross-sectional.

METHODS

Two comparisons of perception of verticality were done between a group of people with CLBP (n = 25) and healthy people (n = 25); and between a subgroup of people with severe CLBP (n = 14) and healthy people (n = 25). In a dark room, the subjective visual vertical test was performed under 3 conditions: rod, rod-and-frame, and rod-and-disc. In each condition, the rod was tilted 40° clockwise and counterclockwise, and the participants were asked to bring it back to vertical 0° position. The rod deviation from verticality was recorded in degrees.

RESULTS

When considering the CLBP group, analysis of variance showed that deviation from verticality had no significant group interaction with condition (p = 0.2), or group main effect (p = 0.2). However, deviation from verticality was significantly different between the conditions (p < 0.001). When considering the severe CLBP subgroup, the interaction effect was significant (p = 0.046). Simple main effects showed that the severe CLBP subgroup had larger deviations from verticality (7.5 ± 0.9 deg) compared to the healthy group (4.2 ± 0.7 deg) specifically on the rod-and-frame condition (p = 0.007).

CONCLUSION

People with severe CLBP appear to have larger deviations in judging verticality compared to the healthy group.

Effects of Vibration Rolling with and without Dynamic Muscle Contraction on Ankle Range of Motion, Proprioception, Muscle Strength and Agility in Young Adults: A Crossover Study

Vibration rolling (VR) has emerged as a self-myofascial release (SMR) tool to aid exercise performance when warming up. However, the benefits of VR on exercise performance when combined with dynamic muscle contraction are unclear. The purpose of this study was to investigate the immediate effects of the combination of VR with dynamic muscle contraction (DVR), VR, and static stretching (SS) during warm-up on range of motion (ROM), proprioception, muscle strength of the ankle, and agility in young adults. In this crossover design study, 20 recreationally active adults without musculoskeletal disorders completed three test sessions in a randomized order, with 48 h of rest between each session. Participants completed one warm-up intervention and its measurements on the same day; different warm-up interventions and measurements were performed on each of the three days. The measurements included ankle dorsiflexion and plantarflexion ROM, ankle joint proprioception, muscle strength, and agility. After DVR and VR intervention, ankle dorsiflexion ROM (both DVR and VR, p < 0.001), plantarflexion ROM (both DVR and VR, p < 0.001), plantar flexor muscle strength (DVR, p = 0.007; VR, p < 0.001), and agility (DVR, p = 0.016; VR, p = 0.007) significantly improved; after SS intervention, ankle dorsiflexion and plantar flexion ROM (dorsiflexion, p < 0.001; plantar flexion, p = 0.009) significantly improved, but muscle strength and agility were not enhanced. Compared with SS, DVR and VR significantly improved ankle plantar flexor muscle strength (p = 0.008 and p = 0.001, respectively). Furthermore, DVR significantly improved ankle dorsiflexion compared with VR (p < 0.001) and SS (p < 0.001). In conclusion, either DVR, VR, or SS increased ankle ROM, but only DVR and VR increased muscle strength and agility. In addition, DVR produced considerable increases in ankle dorsiflexion. These findings may have implications for warm-up prescription and implementation in both rehabilitative and athletic practice settings.

Low Back Pain: The Potential Contribution of Supraspinal Motor Control and Proprioception

Motor control, which relies on constant communication between motor and sensory systems, is crucial for spine posture, stability and movement. Adaptions of motor control occur in low back pain (LBP) while different motor adaption strategies exist across individuals, probably to reduce LBP and risk of injury. However, in some individuals with LBP, adapted motor control strategies might have long-term consequences, such as increased spinal loading that has been linked with degeneration of intervertebral discs and other tissues, potentially maintaining recurrent or chronic LBP. Factors contributing to motor control adaptations in LBP have been extensively studied on the motor output side, but less attention has been paid to changes in sensory input, specifically proprioception. Furthermore, motor cortex reorganization has been linked with chronic and recurrent LBP, but underlying factors are poorly understood. Here, we review current research on behavioral and neural effects of motor control adaptions in LBP. We conclude that back pain-induced disrupted or reduced proprioceptive signaling likely plays a pivotal role in driving long-term changes in the top-down control of the motor system via motor and sensory cortical reorganization. In the outlook of this review, we explore whether motor control adaptations are also important for other (musculoskeletal) pain conditions.

The Role of Sensorimotor Processes in Pain Empathy

Pain is a salient, aversive sensation which motivates avoidance, but also has a strong social signaling function. Numerous studies have shown that regions of the nervous system active in association with first-hand pain are also active in response to the pain of others. When witnessing somatic pain, such as seeing bodies in painful situations, significant activations occur not only in areas related to the processing of negative emotions, but also in neuronal structures engaged in somatosensation and the control of skeletal muscles. These empathy-related sensorimotor activations are selectively reviewed in this article, with a focus on studies using electrophysiological methods and paradigms investigating responses to somatic pain. Convergent evidence from these studies shows that these activations (1) occur at multiple levels of the nervous system, from the spinal cord up to the cerebral cortex, (2) are best conceptualized as activations of a defensive system, in line with the role of pain to protect body from injury, and (3) contribute to establishing a matching of psychological states between the sufferer and the observer, which ultimately supports empathic understanding and motivate prosocial action. Future research should thus focus on how these sensorimotor responses are related to higher-order empathic responses, including affective sharing and emotion regulation, and how this motivates approach-related prosocial behaviors aimed at alleviating the pain and suffering of others.

Foam Rolling of Quadriceps Decreases Biceps Femoris Activation

Cavanaugh, MT, Aboodarda, SJ, Hodgson, DD, and Behm, DG. Foam rolling of quadriceps decreases biceps femoris activation. J Strength Cond Res 31(8): 2238-2245, 2017-Foam rolling has been shown to increase range of motion without subsequent performance impairments of the rolled muscle, however, there are no studies examining rolling effects on antagonist muscles. The objective of this study was to determine whether foam rolling the hamstrings and/or quadriceps would affect hamstrings and quadriceps activation in men and women. Recreationally, active men (n = 10, 25 ± 4.6 years, 180.1 ± 4.4 cm, 86.5 ± 15.7 kg) and women (n = 8, 21.75 ± 3.2 years, 166.4 ± 8.8 cm, 58.9 ± 7.9 kg) had surface electromyographic activity analyzed in the dominant vastus lateralis (VL), vastus medialis (VM), and biceps femoris (BF) muscles on a single leg landing from a hurdle jump under 4 conditions. Conditions included rolling of the hamstrings, quadriceps, both muscle groups, and a control session. Biceps femoris activation significantly decreased after quadriceps foam rolling (F(1,16) = 7.45, p = 0.015, -8.9%). There were no significant changes in quadriceps activation after hamstrings foam rolling. This might be attributed to the significantly greater levels of perceived pain with quadriceps rolling applications (F(1,18) = 39.067, p < 0.001, 98.2%). There were no sex-based changes in activation after foam rolling for VL (F(6,30) = 1.31, p = 0.283), VM (F(6,30) = 1.203, p = 0.332), or BF (F(6,36) = 1.703, p = 0.199). Antagonist muscle activation may be altered after agonist foam rolling, however, it can be suggested that any changes in activation are likely a result of reciprocal inhibition due to increased agonist pain perception.

[Relationship between perineal characteristics and symptoms and pelvic girdle pain: A literature review]

INTRODUCTION

Pelvic girdle pain (PGP) is characterized by the presence of pain in the posterior pelvic area, distally and laterally to the fifth lumbar vertebra, and/or at the pubic symphysis. PGP is a very common pain condition in women, especially during pregnancy and postpartum. After delivery, pain prevalence decreases to 7 % in the first three months. The current literature describes an association between pelvic girdle pain and different perineal characteristics and symptoms.

OBJECTIVES

A better understanding of perineal structures influence on PGP could assist towards the management of this condition. The aim of this review is to describe the peer-reviewed literature about perineal function in patients with PGP.

METHODS

A bibliographic search on PubMed was conducted. The key words used were: pelvic girdle pain, pregnacy-related low back pain, lumbopelvic pain, posterior pelvic pain, peripartum pelvic pain, pelvic girdle relaxation, pelvic joint instability, peripartum pelvic pain, sacroiliac joint pain, sacroiliac joint dysfunction, sacroiliac-joint related pelvic pain and pelvic floor. Two hundred and twenty-one (221) articles were identified. Out of them, a total of nine articles were selected. The level of evidence was determined using Oxford's scale.

RESULTS

Patients with PGP showed increased activity of the pelvic floor muscles (P=0.05) (LE3), decreased urogenital hiatus area (PGP 12.4 cm²±2.7, control 13.7 cm²±2.8, P=0.015) (LE3), shorter endurance time (PGP 17.8 s; control 54.0 s, P=0.00) (LE3), significantly later onset time during affected side leg elevation (PGP 25ms, control -129ms, P=0.01) (LE3), levator ani and obturator internus tenderness (PGP 25/26; control 5/25, P<0.001) (LE3) and a higher prevalence of vesico-sphincteric disorders compared to asymptomatic subjects (LE3).

CONCLUSION

This review confirms that subjects suffering PGP present particular perineal characteristics regarding morphology and biomechanics. It would be interesting to develop clinical research concerning pelvic floor release effect in PGP.

The sensory side of post-stroke motor rehabilitation

Contemporary strategies to promote motor recovery following stroke focus on repetitive voluntary movements. Although successful movement relies on efficient sensorimotor integration, functional outcomes often bias motor therapy toward motor-related impairments such as weakness, spasticity and synergies; sensory therapy and reintegration is implied, but seldom targeted. However, the planning and execution of voluntary movement requires that the brain extracts sensory information regarding body position and predicts future positions, by integrating a variety of sensory inputs with ongoing and planned motor activity. Neurological patients who have lost one or more of their senses may show profoundly affected motor functions, even if muscle strength remains unaffected. Following stroke, motor recovery can be dictated by the degree of sensory disruption. Consequently, a thorough account of sensory function might be both prognostic and prescriptive in neurorehabilitation. This review outlines the key sensory components of human voluntary movement, describes how sensory disruption can influence prognosis and expected outcomes in stroke patients, reports on current sensory-based approaches in post-stroke motor rehabilitation, and makes recommendations for optimizing rehabilitation programs based on sensory stimulation.

Sensory Disturbances, but Not Motor Disturbances, Induced by Sensorimotor Conflicts Are Increased in the Presence of Acute Pain

Incongruence between our motor intention and the sensory feedback of the action (sensorimotor conflict) induces abnormalities in sensory perception in various chronic pain populations, and to a lesser extent in pain-free individuals. The aim of this study was to simultaneously investigate sensory and motor disturbances evoked by sensorimotor conflicts, as well as to assess how they are influenced by the presence of acute pain. It was hypothesized that both sensory and motor disturbances would be increased in presence of pain, which would suggest that pain makes body representations less robust. Thirty healthy participants realized cyclic asymmetric movements of flexion-extension with both upper limbs in a robotized system combined to a 2D virtual environment. The virtual environment provided a visual feedback (VF) about movements that was either congruent or incongruent, while the robotized system precisely measured motor performance (characterized by bilateral amplitude asymmetry and medio-lateral drift). Changes in sensory perception were assessed with a questionnaire after each trial. The effect of pain (induced with capsaicin) was compared to three control conditions (no somatosensory stimulation, tactile distraction and proprioceptive masking). Results showed that while both sensory and motor disturbances were induced by sensorimotor conflicts, only sensory disturbances were enhanced during pain condition comparatively to the three control conditions. This increase did not statistically differ across VF conditions (congruent or incongruent). Interestingly however, the types of sensations evoked by the conflict in the presence of pain (changes in intensity of pain or discomfort, changes in temperature or impression of a missing limb) were different than those evoked by the conflict alone (loss of control, peculiarity and the perception of having an extra limb). Finally, results showed no relationship between the amount of motor and sensory disturbances evoked in a given individual. Contrary to what was hypothesized, acute pain does not appear to make people more sensitive to the conflict itself, but rather impacts on the type and amount of sensory disturbances that they experienced in response to that conflict. Moreover, the results suggest that some sensorimotor integration processes remain intact in presence of acute pain, allowing us to maintain adaptive motor behavior.

Applying contemporary neuroscience in exercise interventions for chronic spinal pain: treatment protocol

BACKGROUND

Nonspecific chronic spinal pain is a common problem within the chronic pain population and is characterized by high social, economic and personal impact. To date, therapists are still struggling in adequately treating these types of patients, as seen in the small and short-term benefits of frequently applied primary care treatments. It is remarkable that despite the well-documented presence of abnormalities in central nociceptive processing in nonspecific chronic spinal pain patients, the implementation of this knowledge in clinical practice is still nearly non-existent.

METHODS

This paper provides the treatment protocol used in a large randomized controlled trial that aimed to assess the effectiveness of a modern neuroscience approach compared to usual care evidence-based physiotherapy. This comprehensive pain neuroscience treatment program combines pain neuroscience education and cognition-targeted exercise therapy.

CONCLUSION

Based on previous small-scaled studies, this treatment protocol is expected to normalize central alterations by addressing central nervous system dysfunctions, psychological factors, as well as peripheral dysfunctions in a broader biopsychosocially-driven framework.

Neurocognitive performance and physical function do not change with physical-cognitive-mindfulness training in female laboratory technicians with chronic musculoskeletal pain: Randomized controlled trial

BACKGROUND

Cognitive and physical performance can be negatively affected by chronic pain. This study evaluates the effect of combined physical-, cognitive-, and mindfulness training (PCMT) on cognitive and physical performance.

METHODS

From a large pharmaceutical company in Denmark we randomly allocated 112 female laboratory technicians with chronic upper limb pain to group-based PCMT at the worksite or a reference group for 10 weeks. Neurocognitive performance was measured by the computerized central nervous system vital signs neurocognitive assessment battery. Physical function was assessed in terms of shoulder external rotation strength and rate of force development in a custom-made dynamometer setup.

RESULTS

No between-group differences (least square means [95% confidence interval]) from baseline to follow-up could be detected in any of the neurocognitive domains as measured by the central nervous system vital signs neurocognitive assessment battery, for example, Psychomotoer Speed 1.9 (-1.0 to 4.7), Reaction Time -4.0 (-19.5 to 11.6), Complex Attention -0.3 (-1.9 to 1.4), and Executive Function -0.2 (-3.5 to 3.0). Similarly, we found no change in maximal voluntary isometric strength -0.63 (-4.8 to 3.6), or rate of force development 14.8 (-12.6 to 42.2) of the shoulder external rotators. Finally, test-retest reliability of maximal voluntary contraction and rate of force development shoulder external rotation showed high reliability at 0 to 30 ms, 0 to 50 ms, 0 to 100 ms, and 0 to 200 ms with ICCs at 0.95, 0.92, 0.93, 0.92, and 0.91, respectively.

CONCLUSION

Ten weeks of PCMT did not improve neurocognitive or physical performance.

Are There Abnormalities in Peripheral and Central Components of Somatosensory Evoked Potentials in Non-Specific Chronic Low Back Pain?

Chronic low back pain (CLBP) was shown to be associated with longer reflex response latencies of trunk muscles during external upper limb perturbations. One theoretical, but rarely investigated possibility for longer reflex latencies might be related to modulated somatosensory information processing. Therefore, the present study investigated somatosensory evoked potentials (SEPs) to median nerve stimulation in CLBP patients and healthy controls (HC). Latencies of the peripheral N9 SEP component were used as the primary outcome. In addition, latencies and amplitudes of the central N20 SEP component, sensory thresholds, motor thresholds and nerve conduction velocity were also analyzed in CLBP patients and HC. There is a trend for the CLBP patients to exhibit longer N9 latencies at the ipsilateral Erb’s point compared to HC. This trend is substantiated by significantly longer N9 latencies in CLBP patients compared to normative data. None of the other parameters showed any significant difference between CLBP patients and HC. Overall, our data indicate small differences of the peripheral N9 SEP component; however, these differences cannot explain the reflex delay observed in CLBP patients. While it was important to rule out the contribution of early somatosensory processing and to elucidate its contribution to the delayed reflex responses in CLBP patients, further research is needed to find the primary source(s) of time-delayed reflexes in CLBP.

The Influence of Centralization and Directional Preference on Spinal Control in Patients With Nonspecific Low Back Pain

STUDY DESIGN

Prospective cohort, test-retest design.

BACKGROUND

Directional preference (DP) with centralization (CEN) and DP without CEN are common pain-pattern responses assessed by Mechanical Diagnosis and Therapy (MDT). Although there is evidence that MDT can reduce pain and disability in the short term by treating the patient with direction-specific exercises concordant with the patient's DP, the mechanism responsible for this is unclear.

OBJECTIVE

To determine whether clinical signs of impaired spinal control improve immediately after eliciting a DP-with-CEN response or a DP-without-CEN response in patients with nonspecific low back pain.

METHODS

Participants underwent a standardized MDT assessment and were classified into the following pain-pattern subgroups: DP with CEN, DP without CEN, or no DP. Clinical signs of impaired spinal control were assessed pre-MDT assessment and post-MDT assessment by an independent examiner. Four spinal control tests were conducted: aberrant lumbar movements while bending forward, the active straight leg raise (ASLR) test, the Trendelenburg test, and the prone instability test. Differences in spinal control pre-MDT assessment and post-MDT assessment were calculated for the 3 pain-pattern subgroups and compared with chi-square tests. We hypothesized that a larger proportion of patients in the DP-with-CEN subgroup would exhibit improved spinal control than patients categorized as DP without CEN or no DP.

RESULTS

Of 114 patients recruited, 51 patients (44.7%) were categorized as DP with CEN, 23 (20.2%) as DP without CEN, and 40 (35.1%) as no DP. Before MDT assessment, between 28.9% (Trendelenburg test) and 63.7% (ASLR test) of patients showed impaired spinal control. After MDT assessment, a larger proportion of patients in the DP-with-CEN subgroup (43%) showed improvement than those in the no-DP subgroup (7%) on aberrant lumbar movements (P = .02). Likewise, more patients in the DP-with-CEN subgroup (50%) improved on the ASLR test than those in the no-DP subgroup (8%, P<.01) or the DP-without-CEN subgroup (7%, P = .01). Changes in Trendelenburg test and prone instability test outcomes did not reach statistical significance.

CONCLUSION

Immediately following MDT assessment, a larger proportion of patients with a DP-with-CEN pain pattern showed improvement in clinical signs of spinal control compared to patients with a DP-without-CEN or no-DP pain pattern. The current study was registered in the Dutch trial registry at http://www.trialregister.nl/trialreg/index.asp (NTR4246).

LEVEL OF EVIDENCE

Therapy, level 2b.

Tendon neuroplastic training: changing the way we think about tendon rehabilitation: a narrative review

Tendinopathy can be resistant to treatment and often recurs, implying that current treatment approaches are suboptimal. Rehabilitation programmes that have been successful in terms of pain reduction and return to sport outcomes usually include strength training. Muscle activation can induce analgesia, improving self-efficacy associated with reducing one's own pain. Furthermore, strength training is beneficial for tendon matrix structure, muscle properties and limb biomechanics. However, current tendon rehabilitation may not adequately address the corticospinal control of the muscle, which may result in altered control of muscle recruitment and the consequent tendon load, and this may contribute to recalcitrance or symptom recurrence. Outcomes of interest include the effect of strength training on tendon pain, corticospinal excitability and short interval cortical inhibition. The aims of this concept paper are to: (1) review what is known about changes to the primary motor cortex and motor control in tendinopathy, (2) identify the parameters shown to induce neuroplasticity in strength training and (3) align these principles with tendon rehabilitation loading protocols to introduce a combination approach termed as tendon neuroplastic training. Strength training is a powerful modulator of the central nervous system. In particular, corticospinal inputs are essential for motor unit recruitment and activation; however, specific strength training parameters are important for neuroplasticity. Strength training that is externally paced and akin to a skilled movement task has been shown to not only reduce tendon pain, but modulate excitatory and inhibitory control of the muscle and therefore, potentially tendon load. An improved understanding of the methods that maximise the opportunity for neuroplasticity may be an important progression in how we prescribe exercise-based rehabilitation in tendinopathy for pain modulation and potentially restoration of the corticospinal control of the muscle-tendon complex.

Elevated corticospinal excitability in patellar tendinopathy compared with other anterior knee pain or no pain

Anterior knee pain (AKP) is a frequent clinical presentation in jumping athletes and may be aggravated by sustained sitting, stair use, and loading of the quadriceps. Corticospinal activation of the quadriceps in athletes with AKP has not yet been investigated, but is important in guiding efficacious treatment. This cross-sectional study assessed corticospinal excitability (CSE) of the quadriceps in jumping athletes using transcranial magnetic stimulation (TMS). Groups consisted of Control (no knee pain); patellar tendinopathy (PT) [localized inferior pole pain on single-leg decline squat (SLDS)]; and other AKP (nonlocalized pain around the patella). SLDS (numerical score of pain 0-10), Victorian Institute of Sport Assessment Patellar tendon (VISA-P), maximal voluntary isometric contraction (MVIC), active motor threshold (AMT), CSE, and Mmax were tested. Twenty nine athletes participated; control n = 8, PT n = 11, AKP n = 10. There were no group differences in age (P = 0.23), body mass index (P = 0.16), MVIC (P = 0.38) or weekly activity (P = 0.22). PT had elevated CSE compared with controls and other AKP (P < 0.001), but no differences were detected between AKP and controls (P = 0.47). CSE appears to be greater in PT than controls and other AKP. An improved understanding of the corticospinal responses in different sources of knee pain may direct better treatment approaches.

Persistent neuropathic pain influences persistence behavior in rats

AIMS

To determine whether self-regulation can be studied successfully in a rodent model and whether persistent facial pain influences self-regulatory behavior.

METHODS

Thirty male Sprague-Dawley rats, divided into two groups, (1) chronic constriction injury of the infraorbital nerve (CCI-ION) and (2) naïve, were used in a two-part behavioral paradigm of self-regulation. This paradigm consisted of both a cued go/no-go task (part one) and a persistence trial (part two). All animals were acclimated and trained for a period of 4 weeks prior to the experimental manipulation and then tested for a total of 5 weeks following experimental manipulation. Results were analyzed with t tests, one-way analysis of variance, and two-way, repeated measures analysis of variance.

RESULTS

CCI-ION surgery induced significant mechanical hypersensitivity of the ipsilateral whisker pad that began 3 weeks postsurgery and persisted through the duration of the experiment (P < .001). At weeks 4 and 5 post-experimental manipulation, naïve animals demonstrated a significant decrease in lever presses during the persistence task (P < .05) compared to baseline, whereas CCI-ION animals did not (P = .55).

CONCLUSION

These results suggest that persistent pain influences behavioral regulation and that animals experiencing persistent pain may have difficulty adapting to environmental demands.

The influence of somatosensory and muscular deficits on postural stabilization: Insights from an instrumented analysis of subjects affected by different types of Charcot-Marie-Tooth disease

•

We studied the role of sensory and muscular deficits in balance impairments in CMT.

•

Large sensory fibers and dorsi-flexor muscles affect the dynamic phase of stabilization.

•

Small sensory fibers and plantar-flexor muscles influence the static phase of balance.

•

Residual sensory and muscle functions must be evaluated for a proper rehabilitation.

Charcot–Marie–Tooth (CMT) disease is the most common hereditary neuromuscular disorder. CMT1 is primarily demyelinating, CMT2 is primarily axonal, and CMTX1 is characterized by both axonal and demyelinating abnormalities. We investigated the role of somatosensory and muscular deficits on quiet standing and postural stabilization in patients affected by different forms of CMT, comparing their performances with those of healthy subjects. Seventy-six CMT subjects (CMT1A, CMT2 and CMTX1) and 41 healthy controls were evaluated during a sit-to-stand transition and the subsequent quiet upright posture by means of a dynamometric platform. All CMT patients showed altered balance and postural stabilization compared to controls. Multivariate analysis showed that in CMT patients worsening of postural stabilization was related to vibration sense deficit and to dorsi-flexor's weakness, while quiet standing instability was related to the reduction of pinprick sensibility and to plantar-flexor's weakness. Our results show that specific sensory and muscular deficits play different roles in balance impairment of CMT patients, both during postural stabilization and in static posture. An accurate evaluation of residual sensory and muscular functions is therefore necessary to plan for the appropriate balance rehabilitation treatment for each patient, besides the CMT type.

Neck muscle vibration can improve sensorimotor function in patients with neck pain

BACKGROUND CONTEXT

People with neck pain display a diminished joint position sense and disturbed postural control, which is thought to be a result of impaired somatosensory afferent activity and/or integration. Afferent processing can be artificially manipulated by vibration and was shown to reduce motor performance in healthy subjects. However, the effect of vibration on sensorimotor function in neck pain patients is scarcely investigated.

PURPOSE

To assess the effect of neck muscle vibration on joint position sense and postural control in neck pain subjects and healthy controls.

STUDY DESIGN

Case control study.

PATIENT SAMPLE

Thirteen neck pain patients and 10 healthy controls participated in the present study.

OUTCOME MEASUREMENTS

Cervical joint position sense and dynamic and static postural stability.

METHODS

Short-term, targeted neck muscle vibration with 100 Hz was applied after baseline measurement.

RESULTS

Vibration had opposite effects in patients and healthy subjects. Patients showed improved joint position sense (p<.01) and reduced dynamic postural sway (p<.05) after vibration, whereas vibration resulted in reduced joint position sense acuity (p<.05) and a nonsignificant increase in postural sway in healthy controls.

CONCLUSIONS

This is the first study showing an improved motor performance after neck muscle vibration in patients with neck pain. Thus, vibration may be used to counteract sensorimotor impairment of the cervical spine. Potential underlying mechanisms are discussed.