[Adaptation to physical activity and mental stress in the context of pain : Psychobiological aspects]

Training intervention effects on cognitive performance and neuronal plasticity—A pilot study

Studies suggest that people suffering from chronic pain may have altered brain plasticity, along with altered functional connectivity between pain-processing brain regions. These may be related to decreased mood and cognitive performance. There is some debate as to whether physical activity combined with behavioral therapy (e.g. cognitive distraction, body scan) may counteract these changes. However, underlying neuronal mechanisms are unclear. The aim of the current pilot study with a 3-armed randomized controlled trial design was to examine the effects of sensorimotor training for nonspecific chronic low back pain on (1) cognitive performance; (2) fMRI activity co-fluctuations (functional connectivity) between pain-related brain regions; and (3) the relationship between functional connectivity and subjective variables (pain and depression). Six hundred and sixty two volunteers with non-specific chronic low back pain were randomly allocated to a unimodal (sensorimotor training), multidisciplinary (sensorimotor training and behavioral therapy) intervention, or to a control group within a multicenter study. A subsample of patients (n = 21) from one study center participated in the pilot study presented here. Measurements were at baseline, during (3 weeks, M2) and after intervention (12 weeks, M4 and 24 weeks, M5). Cognitive performance was measured by the Trail Making Test and functional connectivity by MRI. Pain perception and depression were assessed by the Von Korff questionnaire and the Hospital and Anxiety. Group differences were calculated by univariate and repeated ANOVA measures and Bayesian statistics; correlations by Pearson's r. Change and correlation of functional connection were analyzed within a pooled intervention group (uni-, multidisciplinary group). Results revealed that participants with increased pain intensity at baseline showed higher functional connectivity between pain-related brain areas used as ROIs in this study. Though small sample sizes limit generalization, cognitive performance increased in the multimodal group. Increased functional connectivity was observed in participants with increased pain ratings. Pain ratings and connectivity in pain-related brain regions decreased after the intervention. The results provide preliminary indication that intervention effects can potentially be achieved on the cognitive and neuronal level. The intervention may be suitable for therapy and prevention of non-specific chronic low back pain.

Effect of transcutaneous electrical nerve stimulation on jaw movement-evoked pain in patients with TMJ disc displacement without reduction and healthy controls

Objective: Transcutaneous electrical nerve stimulation (TENS) may serve as non-invasive intervention for painful temporomandibular disorders (TMD) to improve jaw motor function, but its efficacy is still debated. This parallel study evaluated the effect of TENS on pain and movement patterns after repeated jaw movements in patients with painful temporomandibular joints (TMJ) and disc displacement without reduction (DDwoR), and compared with healthy controls.Material and Methods: 20 patients with TMJ pain and DDwoR and 20 age- and gender-matched healthy volunteers were randomly assigned to TENS/sham TENS (sTENS) intervention groups in a block design (10 in each group). Participants performed 20 repeated jaw movements (4 x 5 sessions), and reported pain intensity on a 0-10 Numerical Rating Scale (NRS) subsequently both before and after the intervention. Data were tested by repeated measures analysis of variance (ANOVA).Results: Significant increase of pain intensity and reduction of opening range were shown within repeated jaw movements in TMJ pain patients in contrast to healthy participants (p ≤ .001). Pain was significantly reduced during repeated open-close (p = .007), fast open-close (p = .016) and horizontal movements (p = .023), accompanied with increased opening range (p = .033) and open-close velocity (p = .019) with TENS intervention when compared with sTENS group (p > .05) in TMJ pain patients.Conclusions: This study indicated that movement-evoked pain was reduced either spontaneously or by sTENS in TMJ pain patients with DDwoR, and interestingly, that TENS could attenuate movement-evoked pain and improve jaw motor function during repeated jaw movements. The findings may have implications for TENS treatment in TMJ pain patients with DDwoR.

Personalized Treatment Suggestions: The Validity and Applicability of the Risk-Prevention-Index Social in Low Back Pain Exercise Treatments

Background: The back pain screening tool Risk-Prevention-Index Social (RPI-S) identifies the individual psychosocial risk for low back pain chronification and supports the allocation of patients at risk in additional multidisciplinary treatments. The study objectives were to evaluate (1) the prognostic validity of the RPI-S for a 6-month time frame and (2) the clinical benefit of the RPI-S. Methods: In a multicenter single-blind 3-armed randomized controlled trial, n = 660 persons (age 18–65 years) were randomly assigned to a twelve-week uni- or multidisciplinary exercise intervention or control group. Psychosocial risk was assessed by the RPI-S domain social environment (RPI-S_SE) and the outcome pain by the Chronic Pain Grade Questionnaire (baseline M1, 12-weeks M4, 24-weeks M5). Prognostic validity was quantified by the root mean squared error (RMSE) within the control group. The clinical benefit of RPI-S_SE was calculated by repeated measures ANOVA in intervention groups. Results: A subsample of n = 274 participants (mean = 38.0 years, SD 13.1) was analyzed, of which 30% were classified at risk in their psychosocial profile. The half-year prognostic validity was good (RMSE for disability of 9.04 at M4 and of 9.73 at M5; RMSE for pain intensity of 12.45 at M4 and of 14.49 at M5). People at risk showed significantly stronger reduction in pain disability and intensity at M4/M5, if participating in a multidisciplinary exercise treatment. Subjects at no risk showed a smaller reduction in pain disability in both interventions and no group differences for pain intensity. Regarding disability due to pain, around 41% of the sample would gain an unfitted treatment without the back pain screening. Conclusion: The RPI-S_SE prognostic validity demonstrated good applicability and a clinical benefit confirmed by a clear advantage of an individualized treatment possibility.

[What influence do increased physical performance, age, sex and training frequency have on the effectiveness of back training?]

BACKGROUND

Active exercising can effectively reduce low back pain but the mechanisms of action are still unclear.

OBJECTIVE

What are the influences of training frequency, increased physical performance, age and gender on the effectiveness of a multimodal back training?

MATERIAL AND METHODS

A total of 1395 persons with back pain (mean age 46.9 ± 12.3 years, 65% female) took part in a multimodal back training over 24 months in the context of a multicenter study (39 locations). Back pain, physical capacity of strength, mobility and bilateral strength ratio of the spine stabilizing muscles were measured at the beginning of the training and after 6, 12 and 18 months.

RESULTS AND DISCUSSION

The participants trained on average for 41.0 (SD ± 17.8) 60-min training units. This resulted in an increase of strength (28.1%), mobility (14.7%) and strength ratio (6.5%) compared to an age and gender-matched cohort without back pain. Back pain was reduced by 37.5%. The reduction in back pain can be ascribed to the training frequency by 70% and to increased physical performance by 30%. Age only marginally influenced the effect of training, while gender had no significant effect.

CONCLUSION

Increases in physical performance have positive effects on the reduction of back pain but the number of training sessions was shown to be more relevant in the reduction of low back pain.

Psychosoziale Risikofaktoren in der Entstehung von chronisch unspezifischen Rückenschmerzen

Zusammenfassung. Chronisch unspezifische Rückenschmerzen (CURS) gehören international zu den häufigsten Schmerzphänomenen und können für Athletinnen und Athleten karrierelimitierend sein. Knapp ein Drittel der jährlichen Trainingsausfallzeiten werden auf CURS zurückgeführt. In der Entstehung von chronischen Schmerzen ist ein multifaktorielles Ätiologiemodell mit einem signifikanten Einfluss psychosozialer Risikofaktoren evident. Obwohl dies in der Allgemeinbevölkerung bereits gut erforscht ist, gibt es in der Sportwissenschaft vergleichsweise wenige Arbeiten darüber. Dieses Thema wird daher in drei Multicenterstudien und zahlreichen Teilstudien des MiSpEx-Netzwerks ( Medicine in Spine-Exercise-Network, Förderzeitraum 2011 – 2018) aufgegriffen. Entsprechend der Empfehlung einer frühzeitigen Diagnostik von Chronifizierungsfaktoren in der „Nationalen Versorgungsleitlinie Kreuzschmerz“, beschäftigt sich das Netzwerk u. a. mit der Überprüfung, Entwicklung und Evaluation diagnostischer Möglichkeiten. Der vorliegende Beitrag beschreibt die Entwicklung einer Diagnostik von psychosozialen Risikofaktoren, die einerseits eine Einschätzung des Risikos der Entwicklung von CURS und andererseits eine individuelle Zuweisung zu (Trainings)Interventionen erlaubt. Es wird die Entwicklungsrationale beschrieben und dabei verschiedene methodische Herangehensweisen und Entscheidungssequenzen reflektiert.

Diagnosis of psychosocial risk factors in prevention of low back pain in athletes (MiSpEx)

Background

Low back pain (LBP) is a common pain syndrome in athletes, responsible for 28% of missed training days/year. Psychosocial factors contribute to chronic pain development. This study aims to investigate the transferability of psychosocial screening tools developed in the general population to athletes and to define athlete-specific thresholds.

Methods

Data from a prospective multicentre study on LBP were collected at baseline and 1-year follow-up (n=52 athletes, n=289 recreational athletes and n=246 non-athletes). Pain was assessed using the Chronic Pain Grade questionnaire. The psychosocial Risk Stratification Index (RSI) was used to obtain prognostic information regarding the risk of chronic LBP (CLBP). Individual psychosocial risk profile was gained with the Risk Prevention Index - Social (RPI-S). Differences between groups were calculated using general linear models and planned contrasts. Discrimination thresholds for athletes were defined with receiver operating characteristics (ROC) curves.

Results

Athletes and recreational athletes showed significantly lower psychosocial risk profiles and prognostic risk for CLBP than non-athletes. ROC curves suggested discrimination thresholds for athletes were different compared with non-athletes. Both screenings demonstrated very good sensitivity (RSI=100%; RPI-S: 75%-100%) and specificity (RSI: 76%-93%; RPI-S: 71%-93%). RSI revealed two risk classes for pain intensity (area under the curve (AUC) 0.92(95% CI 0.85 to 1.0)) and pain disability (AUC 0.88(95% CI 0.71 to 1.0)).

Conclusions

Both screening tools can be used for athletes. Athlete-specific thresholds will improve physicians' decision making and allow stratified treatment and prevention.

Development of a risk stratification and prevention index for stratified care in chronic low back pain. Focus: yellow flags (MiSpEx network)

Introduction

Chronic low back pain (LBP) is a major cause of disability; early diagnosis and stratification of care remain challenges.

Objectives

This article describes the development of a screening tool for the 1-year prognosis of patients with high chronic LBP risk (risk stratification index) and for treatment allocation according to treatment-modifiable yellow flag indicators (risk prevention indices, RPI-S).

Methods

Screening tools were derived from a multicentre longitudinal study (n = 1071, age >18, intermittent LBP). The greatest prognostic predictors of 4 flag domains ("pain," "distress," "social-environment," "medical care-environment") were determined using least absolute shrinkage and selection operator regression analysis. Internal validity and prognosis error were evaluated after 1-year follow-up. Receiver operating characteristic curves for discrimination (area under the curve) and cutoff values were determined.

Results

The risk stratification index identified persons with increased risk of chronic LBP and accurately estimated expected pain intensity and disability on the Pain Grade Questionnaire (0-100 points) up to 1 year later with an average prognosis error of 15 points. In addition, 3-risk classes were discerned with an accuracy of area under the curve = 0.74 (95% confidence interval 0.63-0.85). The RPI-S also distinguished persons with potentially modifiable prognostic indicators from 4 flag domains and stratified allocation to biopsychosocial treatments accordingly.

Conclusion

The screening tools, developed in compliance with the PROGRESS and TRIPOD statements, revealed good validation and prognostic strength. These tools improve on existing screening tools because of their utility for secondary preventions, incorporation of exercise effect modifiers, exact pain estimations, and personalized allocation to multimodal treatments.

Temporal summation and motor function modulation during repeated jaw movements in patients with temporomandibular disorder pain and healthy controls

Temporal summation of nociceptive inputs may be an important pathophysiological mechanism in temporomandibular disorders (TMD) pain; however, it remains unknown how natural jaw function relates to underlying pain mechanisms. This study evaluated changes in pain and movement patterns during repeated jaw movements in patients with painful temporomandibular joints (TMJ) compared with healthy controls. Twenty patients with TMD with TMJ pain, and an anterior disk displacement without reduction and 20 age- and gender-matched healthy volunteers were included. Participants performed 20 trials (4 × 5 sessions) of standardized and repeated mandibular movements, and scored the movement-associated pain intensity on 0 to 10 numeric rating scale in addition to measurements of jaw movements. Patients with TMJ pain reported higher baseline pain compared to the control group for all types of jaw movements (P = 0.001) and significant increases in numeric rating scale pain scores by repetition of jaw movements (P < 0.001), which was not observed in the control group (P > 0.05). Jaw total opening distance (P = 0.030), maximum opening velocity (P = 0.043) and average closing velocity (P = 0.044) in the TMJ pain group were significantly reduced during the repeated movements. In the control group, however, total opening distance (P = 0.499), maximum opening velocity (P = 0.064), and average closing velocity (P = 0.261) remained unchanged, whereas average opening velocity (P = 0.040) and maximum closing velocity (P = 0.039) increased. The study demonstrates that repeated jaw movements constitute a sufficient and adequate stimulation for triggering temporal summation effects associated with significant inhibition of motor function in painful TMJs. These findings have practical implications for diagnosis of TMD pain and for more mechanism-driven management protocols in the future.