Is there a relationship between pain intensity and postural sway in patients with non-specific low back pain?
TL;DR: COP mean velocity and sway area are closely related to self-reported pain scores and may be of clinical use as an objective monitoring tool for patients under treatment or rehabilitation.
Abstract: Increased center of pressure excursions are well documented in patients suffering from non-specific low back pain, whereby the altered postural sway includes both higher mean sway velocities and larger sway area. No investigation has been conducted to evaluate a relationship between pain intensity and postural sway in adults (aged 50 or less) with non-specific low back pain. Seventy-seven patients with non-specific low back pain and a matching number of healthy controls were enrolled. Center of pressure parameters were measured by three static bipedal standing tasks of 90 sec duration with eyes closed in narrow stance on a firm surface. The perceived pain intensity was assessed by a numeric rating scale (NRS-11), an equal number of patients (n = 11) was enrolled per pain score. Generally, our results confirmed increased postural instability in pain sufferers compared to healthy controls. In addition, regression analysis revealed a significant and linear increase in postural sway with higher pain ratings for all included COP parameters. Statistically significant changes in mean sway velocity in antero-posterior and medio-lateral direction and sway area were reached with an incremental change in NRS scores of two to three points. COP mean velocity and sway area are closely related to self-reported pain scores. This relationship may be of clinical use as an objective monitoring tool for patients under treatment or rehabilitation.
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TL;DR: The findings suggest that chronic low back pain patients with clinical lumbar instability have increased postural sway when vision is deprived, and may provide an opportunity for therapy directed at improving balance control in this patient group.
Abstract: [Purpose] The current study aimed to investigate the center of pressure, as an indicator of postural sway, to determine any differences between women with clinical lumbar instability and asymptomatic low back pain. [Participants and Methods] Thirty healthy and fifteen clinical lumbar instability participants were measured for their postural sway in the anterior-posterior and medial-lateral directions. The women were tested for postural sway on a force plate in quiet standing and eyes closed. Center of pressure path length and mean velocity in the anterior-posterior and medial-lateral directions and total area of excursion were measured and analyzed for 30 seconds. [Results] Clinical lumbar instability participants showed a significantly increase when compared with healthy participants, in path length and mean velocity in both directions and total area of excursion. [Conclusion] The findings suggest that chronic low back pain patients with clinical lumbar instability have increased postural sway when vision is deprived. The clinical significance of this has not yet been determined but may provide an opportunity for therapy directed at improving balance control in this patient group.
5 citations
31 Dec 2014
TL;DR: There is mixed evidence regarding the possible underlying cause of LPP (in pregnant and non-pregnant populations) where several biological and psychological factors have been suggested as the underlying driver of the condition.
Abstract: Description: When assessing a person suffering from low backand pelvic girdle pain (lumbopelvic pain, LPP) in clinical practice it is considered important to do so within a bio-psychosocial framework. There is however, mixed evidence regarding the possible underlying cause of LPP (in pregnant and non-pregnant populations) where several biological and psychological factors have been suggested as the underlying driver of the condition.
5 citations
Dissertation•
01 Jan 2011
TL;DR: The experimental setup was found to be safe and a sub-sample of predominantly low back pain patients (n=20) reported no difficulties complying with the postural tasks involved, and the symptomatic participants exhibited greater postural sway than healthy controls.
Abstract: Postural stability is an important component in maintaining upright stance and balance during normal daily movements and activities. Postural stability is also an important factor in the elderly where balance disability may increase the risk of falls and subsequent injury. In sport, problems with balance may lead to serious injuries. Thus, postural stability has important implications in rehabilitation and sports.
Many different methods exist today for assessing postural sway. Centre of pressure (COP) evaluation is a frequently used method of measuring this stability and gain insights into potential pathological mechanisms e.g. in association with pain. This is possible as the COP signal is proportional to ankle torque, a combination of descending motor commands as well as mechanical properties of the musculature around.
Over the last decades, postural sway has been most commonly evaluated by using spatial measures such as sway distance, velocity and area traversed based upon sequential locations of the COP in the plane of the force platform. However, despite its common usage, important clinical aspects of the COP measurements such as its potential suitability for clinical monitoring purposes in pain patients remained unaddressed. Several literature reviews were conducted that identified relevant gaps in current knowledge to focus our research.
This led to the following primary research questions:
a) Can a best evidence experimental setup be identified that is suitable for spinal pain sufferers?
b) Is there a relationship between pain intensity and the COP excursions?
c) Are there alterations in postural sway associated with diminishing pain?
Based on a systematic review of the literature the following experimental protocol was developed: Three measurements of 90sec each were conducted in bipedal narrow stance with closed eyes at a sampling frequency of 100Hz. We selected the COP parameters 90% circle diameter as a descriptor of sway area and mean sway velocity as it has shown its discriminative value for various pain conditions.
The prospective part of this thesis was preceded by pilot studies that confirmed the excellent reliability of the selected experimental setup for mean sway velocity in antero-posterior (AP) and the medio-lateral (ML) direction (ICC2,k 0.85-0.89, 95% CI 0.63-0.97, SEM 0.66-0.78) and 90% circle diameter (ICC2,k 0.80, 95% CI 0.54-0.94, SEM 0.89). Later on, very similar values were observed for sway data obtained from the symptomatic groups.
The experimental setup was found to be safe and a sub-sample of predominantly low back pain patients (n=20) reported no difficulties complying with the postural tasks involved. Furthermore, no effects of learning or fatigue could be demonstrated in 10 healthy individuals either during inter-session (10 consecutive measurements) or intra-session (three times 3 measurements at 2-3 day intervals). No adverse incidents associated with the measurements occurred in approximately 1500 measurements.
By enrolling age matched healthy individuals as a control group (n=77), reference values for the included COP parameters were established to which all subsequent data obtained from symptomatic individuals could be compared.
A total of 210 patients were enrolled subdivided into three groups for non-specific neck, mid back and low back pain. A physical examination was conducted for all pain sufferers, who were asked to rate their pain intensity on a NRS-11 scale. The associated disability was assessed by means of the Disability Rating Index. Depending on the reported severity of their complaint, the symptomatic individuals were subdivided into seven pain intensity groups (NRS 2-8) for each of the painful regions: low back (n=77, n=11/group), mid back (n=63, n=9/group) and neck (n=70, n=10/group).
The symptomatic participants exhibited greater postural sway than healthy controls. As a general trend, a statistically significant increase was reached beginning at about NRS score 4 for all three pain regions. Depending on the COP parameter and painful region, significant differences between individual NRS levels were reached about every 2-3 NRS levels. Significant differences in COP excursions between mid back, low back and neck pain sufferers could be identified. However, in the light of the expected inter-subject variability in pain perception as well as the low number of participants per NRS group this conclusion warrants caution.
A major finding from a univariate regression analysis was a linear relationship between pain intensity and the COP parameters (p<0.001) for all painful regions, while a multivariate regression analysis showed that other variables such as age, gender, height, weight and BMI did not have a statistically significant effect on postural sway.
This close relationship was maintained even with diminishing pain levels after a course of manual therapy treatments conducted in a group of low back (n=38) and neck pain patients (n=36). In this instance three measurements and interventions were performed at 3-4 day intervals. With few exceptions, the follow-up COP measures in connection with specific pain intensities did not show a significant difference in postural sway compared to reference values for identical NRS levels at baseline.
In addition, a similar linear relationship between pain intensity, the COP sway parameters and the patient's disability ratings was identified for all painful regions.
At the same time, a clear trend towards predominant sway in the medio-lateral direction was observed with increasing pain intensities, until 70% of sway occurred in ML direction at NRS score 8. In comparison, healthy controls showed a nearly equal sway distribution between AP (52%) and ML (48%) direction.
In the absence of learning effects, the reduced COP excursions with decreasing NRS scores in subacute and chronic pain sufferers further suggests that pain interference rather than long-term neuro-physiological adaptations (such as central sensitization) are the primary causative factor for increased sway.
Our findings may have clinical implications for COP measures in patients with significant pain. These include routine sway analyses as an objective outcome measure during the rehabilitation and treatment process. It also stresses the importance of an initial focus on pain regulation rather than proprioceptive training.
5 citations
TL;DR: The results show that virtual reality training has positive effects on the radiological and biochemical aspects in university football players with chronic low back pain.
Abstract: Background Virtual reality training is commonly used for balance problems in neurological conditions with the use of visual and auditory biofeedback. The knowledge about the effective implementation of this training in chronic low back pain is lacking. Objective The objective of this study is to find the radiological and biochemical effects of virtual reality training in football players with chronic low back pain. Methods A randomized, single-blinded controlled study was conducted on 36 participants. The first group received virtual reality training (VRT; n= 12), the second group received combined physical rehabilitation (CPR; n= 12), and the third group (control group; n= 12) received conventional training exercises for four weeks. Radiological (muscle cross-sectional area and muscle thickness) and biochemical (CRP, TNF-α, IL-2, IL-4, IL-6) values were measured at baseline and after four weeks. Results Four weeks following training, the VRT group showed more significant changes in the muscle cross-sectional area than the CPR and control groups (p⩽ 0.001). Biochemical measures such as CRP, TNF-α, IL-2, IL-4, and IL-6 also showed significant improvement in the VRT group compared to the other two groups (p⩽ 0.001). Conclusion The results show that virtual reality training has positive effects on the radiological and biochemical aspects in university football players with chronic low back pain.
4 citations
TL;DR: In this paper, the effects of virtual reality games with those of core stabilization training on physical efficiency in soccer players with chronic low back pain were compared to conventional training exercises for four weeks, and after 4 weeks, 8 weeks and 6 months.
Abstract: Introduction: Virtual reality training (VRT) is an advanced technology that creates virtual games by a computer through specific software. It is a type of rehabilitation training commonly used in balance problems to treat musculoskeletal conditions. Objective: To determine and compare the effects of virtual reality games with those of core stabilization training on physical efficiency in soccer players with chronic low back pain. Methods: A randomized, double-blinded, controlled study was conducted on 60 LBP participants at a university hospital. The first group (n=20) received virtual reality (VR) training; the second group (n=20) received core stabilization (CS) training; and the third group (n=20) received conventional training exercises for four weeks. Scores of clinical and sports performance were measured at baseline, and after 4 weeks, 8 weeks and 6 months. Results: The baseline demographic and clinical characters did not show any significant differences (p>0.05) in the statistical analysis, which shows a homogenous population. Four weeks following the training, the VR training group showed more significant changes in clinical scores than the CS training and control groups (p≤0.001). The scores for sports performance also showed more significant improvement in the VR training group than in the other two groups (p≤0.001). The same improved clinical and sports performance changes were seen at 8 weeks and 6 months of follow-up in the VR training group, when compared to the other two groups (p≤0.001). Conclusion: This study suggests that training through virtual reality games results in long-term improvement in clinical and sports performance compared to other forms of training in soccer players with chronic low back pain.Level of evidence I b; Therapeutic studies – Investigation of treatment results.
4 citations
References
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TL;DR: In this article, the authors present guidelines for choosing among six different forms of the intraclass correlation for reliability studies in which n target are rated by k judges, and the confidence intervals for each of the forms are reviewed.
Abstract: Reliability coefficients often take the form of intraclass correlation coefficients. In this article, guidelines are given for choosing among six different forms of the intraclass correlation for reliability studies in which n target are rated by k judges. Relevant to the choice of the coefficient are the appropriate statistical model for the reliability and the application to be made of the reliability results. Confidence intervals for each of the forms are reviewed.
21,185 citations
"Is there a relationship between pai..." refers methods in this paper
...To test the reliability of the COP measures for this experimental setup for both controls and pain sufferers, the two-way random-effect intra-class correlation coefficient (ICC2,k) as described by Shrout and Fleiss [18] was computed using absolute agreement....
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...Shrout PE, Fleiss JL: Intraclass correlations: uses in assessing rater reliability....
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TL;DR: In this review, the basics of classic reliability theory are addressed in the context of choosing and interpreting an ICC and how the SEM and its variants can be used to construct confidence intervals for individual scores and to determine the minimal difference needed to be exhibited for one to be confident that a true change in performance of an individual has occurred.
Abstract: Reliability, the consistency of a test or measurement, is frequently quantified in the movement sciences literature. A common metric is the intraclass correlation coefficient (ICC). In addition, the SEM, which can be calculated from the ICC, is also frequently reported in reliability studies. However, there are several versions of the ICC, and confusion exists in the movement sciences regarding which ICC to use. Further, the utility of the SEM is not fully appreciated. In this review, the basics of classic reliability theory are addressed in the context of choosing and interpreting an ICC. The primary distinction between ICC equations is argued to be one concerning the inclusion (equations 2,1 and 2,k) or exclusion (equations 3,1 and 3,k) of systematic error in the denominator of the ICC equation. Inferential tests of mean differences, which are performed in the process of deriving the necessary variance components for the calculation of ICC values, are useful to determine if systematic error is present. If so, the measurement schedule should be modified (removing trials where learning and/or fatigue effects are present) to remove systematic error, and ICC equations that only consider random error may be safely used. The use of ICC values is discussed in the context of estimating the effects of measurement error on sample size, statistical power, and correlation attenuation. Finally, calculation and application of the SEM are discussed. It is shown how the SEM and its variants can be used to construct confidence intervals for individual scores and to determine the minimal difference needed to be exhibited for one to be confident that a true change in performance of an individual has occurred.
3,992 citations
"Is there a relationship between pai..." refers background or methods in this paper
...Weir JP: Quantifying test-retest reliability using the intraclass correlation coefficient and the SEM....
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...Secondly, given the linear relationship between pain intensity and, for example, mVel, a clinically significant decrease of two points on a pain NRS [20] is equivalent to a reduction in mean sway velocity of 3....
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...In addition, the 95% confidence intervals (CI) and the standard error of measurement (SEM) [20] were calculated....
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TL;DR: The results indicate that, for the present sample, the scales yield similar results in terms of the number of subjects who respond correctly to them and their predictive validity, however, when considering the remaining 3 criteria, the 101‐point numerical rating scale appears to be the most practical index.
Abstract: The measurement of subjective pain intensity continues to be important to both researchers and clinicians. Although several scales are currently used to assess the intensity construct, it remains unclear which of these provides the most precise, replicable, and predictively valid measure. Five criteria for judging intensity scales have been considered in previous research: ease of administration of scoring; relative rates of incorrect responding; sensitivity as defined by the number of available response categories; sensitivity as defined by statistical power; and the magnitude of the relationship between each scale and a linear combination of pain intensity indices. In order to judge commonly used pain intensity measures, 75 chronic pain patients were asked to rate 4 kinds of pain (present, least, most, and average) using 6 scales. The utility and validity of the scales was judged using the criteria listed above. The results indicate that, for the present sample, the scales yield similar results in terms of the number of subjects who respond correctly to them and their predictive validity. However, when considering the remaining 3 criteria, the 101-point numerical rating scale appears to be the most practical index.
2,921 citations
"Is there a relationship between pai..." refers methods in this paper
...The NSLBP participants were further asked to describe their pain intensity at the time of recording by means of an NRS-11, a rating scale ranging from 0 (no pain) to 10 (worst possible pain) [15]....
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Journal Article•
TL;DR: A set of criteria based upon biostatistical considerations for determining the interrater reliability of specific adaptive behavior items in a given setting was presented and guidelines for differentiating type of adaptive behavior that are statistically reliable from those that are reliable in a clinical or practical sense were delineated.
Abstract: A set of criteria based upon biostatistical considerations for determining the interrater reliability of specific adaptive behavior items in a given setting was presented. The advantages and limitations of extant statistical assessment procedures were discussed. Also, a set of guidelines for differentiating type of adaptive behavior that are statistically reliable from those that are reliable in a clinical or practical sense was delineated. Data sets were presented throughout in order to illustrate the advantages of recommended statistical procedures over other available ones.
2,017 citations
TL;DR: The studies reviewed show that bipedal static COP measures may be used as a reliable tool for investigating general postural stability and balance performance under specific conditions and recommendations for maximizing the reliability of COP data are provided.
500 citations
"Is there a relationship between pai..." refers methods in this paper
...Our results were derived using a protocol based on best evidence [16], nevertheless future studies are needed to confirm these findings using the same protocol....
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...Mean velocity (mVel) was chosen as the main COP parameter as this has consistently shown to be both reliable [16] and discriminative for NSLBP [1]....
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...The experimental setup was based on an earlier literature review where a best practice setup for obtaining reliable COP data was published [16]....
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