Attention demands of postural control in non-specific chronic low back pain subjects with low and high pain-related anxiety

Different montages of transcranial direct current stimulation on postural stability in chronic low back pain patients: A randomized sham-controlled study

BACKGROUND

Impairment in both the motor and cognitive aspects of postural control is a critical issue in patients with chronic low back pain (CLBP) who experience high pain anxiety (HPA).

OBJECTIVE

This study aimed to compare the effects of cathodal and anodal transcranial direct current stimulation (c-tDCS and a-tDCS) over the dorsolateral prefrontal cortex (DLPFC) on postural control during cognitive postural tasks in CLBP patients with HPA.

METHODS

This study included 66 patients randomly assigned to three groups: DLPFC a-tDCS, DLPFC c-tDCS, and sham tDCS. All groups received 20 minutes of tDCS, but the stimulation was gradually turned off in the sham group. Postural stability indices were assessed using the Biodex Balance System.

RESULTS

Both the a-tDCS and c-tDCS groups showed a significant reduction in most postural stability indices at static and dynamic levels after the interventions (immediately, 24 hours, and one-week follow-up) during the cognitive postural task (P< 0.01). Additionally, there was a significant improvement in postural balance in the a-tDCS and c-tDCS groups compared to the sham tDCS group (P< 0.01). Furthermore, the a-tDCS group showed significantly greater improvement than the c-tDCS group (P< 0.01).

CONCLUSION

Based on the results, both a-tDCS and c-tDCS over the DLPFC had positive effects on postural control during cognitive postural tasks in CLBP patients with HPA.

The association between pain-related psychological variables and postural control in low back pain: A systematic review and meta-analysis

BACKGROUND

Alterations in postural control have been found in individuals with low back pain (LBP), particularly during challenging postural tasks. Moreover, higher levels of negative pain-related psychological variables are associated with increased trunk muscle activity, reduced spinal movement, and worse maximal physical performance in individuals with LBP.

RESEARCH QUESTION

Are pain-related psychological variables associated with postural control during static bipedal standing tasks in individuals with LBP?

METHODS

A systematic review and meta-analysis were conducted. Pubmed, Web of Science, and PsycINFO were searched until March 2023. Studies were included if they evaluated postural control during static bipedal standing in individuals with LBP by measuring center of pressure (CoP) variables, and reported at least one pain-related psychological variable. Correlation coefficients between pain-related psychological variables and CoP variables were extracted. Study quality was assessed with the "Quality In Prognosis Studies" tool (QUIPS). Random-effect models were used to calculate pooled correlation coefficients for different postural tasks. Sub-analyses were performed for positional or dynamic CoP variables. Certainty of evidence was assessed with an adjusted "Grading of Recommendations, Assessment, Development, and Evaluations" tool (GRADE). The protocol was registered on PROSPERO (CRD42021241739).

RESULTS

Sixteen studies (n = 723 participants) were included. Pain-related fear (16 studies) and pain catastrophizing (three studies) were the only reported pain-related psychological variables. Both pain-related fear (-0.04 < pooled r < 0.14) and pain catastrophizing (0.28 < pooled r < 0.29) were weakly associated with CoP variables during different postural tasks. For all associations, the certainty of evidence was very low.

SIGNIFICANCE

Pain-related fear and pain catastrophizing are only weakly associated with postural control during static bipedal standing in individuals with LBP, regardless of postural task difficulty. Certainty of evidence is very low thus it is conceivable that future studies accounting for current study limitations might reveal different findings.

Transcranial direct current stimulation over dorsolateral prefrontal cortex improves postural stability in non-specific chronic low back pain patients with high fear of pain: A randomized sham-controlled trial

Deficits in postural stability in response to environmental challenges are seen in chronic low back pain (CLBP) patients with high fear of pain (HFP). Hence, it is essential to follow effective approaches to treat postural stability deficits and improve the health status of these patients. The current study aimed to compare the effects of cathodal and anodal transcranial direct current stimulation (c-tDCS and a-tDCS) over the left dorsolateral prefrontal cortex (DLPFC) on postural stability in non-specific CLBP patients with HFP. In this randomized clinical trial study, 75 patients were randomly assigned to left DLPFC a-tDCS, left DLPFC c-tDCS and sham stimulation groups (n = 25 in each group). All groups received a single-session 2 mA tDCS for 20 min, but the stimulation was slowly turned off after 30 s in the sham group. Before, immediately, 24 h and 1 week after the interventions, postural stability indices were assessed using a Biodex Balance System. A significant reduction in most indices was shown in both a-tDCS and c-tDCS groups after interventions (immediately, 24 h and 1 week follow-up) during static and dynamic postural tasks compared with the sham tDCS group (p < .01). In addition, some tests showed a significant difference between a-tDCS and c-tDCS (p < .05). The findings indicated positive effects of both a-tDCS and c-tDCS on the left DLPFC, with more efficacy of a-tDCS on postural stability in LBP patients with HFP.

The effect of dual-task conditions on postural control in adults with low back pain: a systematic review and meta-analysis

BACKGROUND

Dual-task conditions, which involve performing two tasks simultaneously, may exacerbate pain and further impair daily functioning in individuals with low back pain (LBP). Understanding the effects of dual-task conditions on postural control in patients with LBP is crucial for the development of effective rehabilitation programs. Our objective was to investigate the impact of dual-task conditions on postural control in individuals with LBP compared to those without LBP.

METHODS

We conducted a comprehensive search of Medline via PubMed, Scopus, the Cochrane Central Register of Controlled Trials, Web of Science, and EMBASE databases, with no language restrictions, from inception to January 1, 2023. The primary outcome measures of the study were velocity, area, amplitude, phase plane portrait, and path/sway length of the center of pressure (CoP). Standardized mean difference (SMD) effect sizes were calculated, and the quality of the studies was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

From 196 studies, five involving 242 adults (≥ 18 years) met the inclusion criteria. Three studies were rated as high quality, while two were deemed moderate. In the included studies, 140 participants had non-specific LBP, while 102 participants did not report any symptoms, with mean ages of 36.68 (± 14.21) and 36.35 (± 15.39) years, respectively. Three studies had both genders, one exclusively included females, and one did not specify gender. Meta-analyses of primary outcomes revealed no significant differences in postural control between patients with LBP and pain-free controls during both easy and difficult postural tasks and cognitive load for velocity (easy: SMD - 0.09, 95% CI - 0.91 to 0.74; difficult: SMD 0.12, 95% CI - 0.67 to 0.91), area (easy: SMD 0.82, 95% CI - 2.99 to 4.62; difficult: SMD 0.14, 95% CI - 2.62 to 2.89), phase plane (easy: SMD - 0.59, 95% CI - 1.19 to 0.02; difficult: SMD - 0.18, 95% CI - 0.77 to 0.42), path/sway length (easy: SMD - 0.18, 95% CI - 0.77 to 0.42; difficult: SMD - 0.14, 95% CI - 0.84 to 0.55), and amplitude (easy: SMD 0.89, 95% CI - 1.62 to 3.39; difficult: SMD 1.31, 95% CI - 1.48 to 4.10).

CONCLUSIONS

The current evidence suggests that there are no significant differences in postural control parameters during dual-task conditions between individuals with non-specific LBP and pain-free subjects. However, due to the limited number of available studies, significant publication bias, and considerable statistical heterogeneity, definitive conclusions cannot be drawn. Therefore, further research comprising high-quality studies with larger sample sizes is necessary to obtain conclusive results. Trial registration PROSPERO CRD42022359263.

Comparison of the Dynamic Postural Control During Lifting and Lowering an External Load in Low Back Pain: A Cross-Sectional Study

OBJECTIVE

This study aimed to compare dynamic postural control between individuals with and without chronic low back pain (LBP) through load lifting and lowering.

METHODS

This cross-sectional study included 52 male patients with chronic LBP (age: 33.37 ± 9.23 years) and 20 healthy male individuals (age: 31.75 ± 7.43 years). The postural control parameters were measured using a force plate system. The participants were instructed to stand barefoot (hip-width apart) on the force plate and lift a box (10% of the weight of the participants) from the waist height to overhead and then lower it from overhead to waist height. The interaction between the groups and tasks was determined using a 2-way repeated-measures analysis of variance.

RESULTS

There was no significant interaction between the groups and tasks. Regardless of the groups, postural control parameters including amplitude (P = .001) and velocity (P < .001) in anterior-posterior (AP) direction, phase plane in medial-lateral (ML) direction (P = .001), phase plane in AP-ML direction (P = .001), and the mean total velocity (P < .001) were lesser during the lowering compared with lifting. The results indicated that, regardless of the tasks, the postural control parameters including velocity (P = .004) and phase plane in AP direction (P = .004), velocity in ML direction (P < .001), phase plane (AP-ML) (P = .028), and mean total velocity (P = .001) in LBP were lesser compared with the normal group.

CONCLUSION

Different tasks affected postural control differently in patients with LBP and healthy individuals. Moreover, postural control was more challenged during the load-lowering than the load-lifting task. This may have been a result of a stiffening strategy. It may be that the load-lowering task might be considered as a more influential factor for the postural control strategy. These results may provide a novel understanding of selecting the rehabilitation programs for postural control disorders in patients.

Association between functional disability with postural balance among patients with chronic low back pain

Introduction

Postural balance is impaired in patients with chronic low back pain (CLBP). In addition, the swaying velocity can be affected by low back pain (LBP) dysfunction. However, the extent to which the dysfunction affects postural balance in CLBP patients remains unclear. Therefore, this study aimed to investigate the effect of LBP-related disability on postural balance among CLBP patients and determine factors associated with postural balance impairments.

Methods

Participants with CLBP were recruited and instructed to complete the one-leg stance and Y-balance test. Moreover, they were divided into two subgroups (i.e., low and medium to high LBP-related disability groups) to compare the difference in postural balance based on the degree of LBP-related disability measured by the Roland Morris Disability Questionnaire. The relationships between postural balance and negative emotions as well as LBP characteristics were determined using the Spearman correlations.

Results

A total of 49 participants with low LBP-related disabilities and 33 participants with medium to high LBP-related disabilities participated in the study. Compared to the medium to high LBP-related disability group, patients in the low LBP-related disability group performed better in one-leg stance on the left leg (z = -2.081, p = 0.037). For Y-balance test, patients in the low LBP-related disability group also had greater normalized values of left leg reach in posteromedial (t = 2.108, p = 0.038) direction and composite score (t = 2.261, p = 0.026) and of right leg reach in posteromedial (t = 2.185, p = 0.032), and posterolateral (t = 2.137, p = 0.036) directions as well as composite score (t = 2.258, p = 0.027). Factors associated with postural balance impairments were also revealed, such as anxiety, depression, and fear avoidance belief.

Discussion

The greater the dysfunction degree, the worse the CLBP patient's postural balance impairment. Negative emotions could also be considered contributing factors for postural balance impairments.

Effect of Cognitive Load on Anticipatory Postural Adjustment Latency and its Relationship with Pain-Related Dysfunction in Non-specific Chronic Low Back Pain: A Cross-Sectional Study

INTRODUCTION

This study aimed to investigate the effect of cognitive load on anticipatory postural adjustment (APA) latency in patients with non-specific chronic low back pain (NCLBP) and its relationship with pain-related functional changes.

METHODS

A cross-sectional study was conducted from December 15, 2022 to January 25, 2023. Participants were divided into a healthy control group (n = 29) and an NCLBP group (n = 29). Each group was assigned a single task of rapid arm raising and a dual task of rapid arm raising combined with a cognitive load. The cognitive load task was conducted using visual conflict. The APA latency for bilateral trunk muscles was observed using electromyography. The duration of electromyography recording in each task cycle was 28 s. Pain related-functional changes were evaluated using Roland-Morris Disability Questionnaire (RMDQ) before all tasks.

RESULTS

The APA latency for the right multifidus was significantly delayed in the NCLBP group [25.38, 95% confidence interval (CI) 13.41-37.35] than in the healthy control group (- 5.80, 95% CI - 19.28 to 7.68) during dual task (p = 0.0416). The APA latency for the right multifidus (25.38, 95% CI 13.41-37.35) and transverse abdominis/internal oblique (29.15, 95% CI 18.81-39.50) were significantly delayed compared with on the left side in the NCLBP group during dual task (- 3.03, 95% CI - 15.18-9.13, p = 0.0220; 3.69, 95% CI - 6.81 to 14.18, p = 0.0363). The latency delay of the right and left multifidus APA in the NCLBP group under the dual-task was positively correlated with RMDQ scores (r = 0.5560, p = 0.0017; r = 0.4010, p = 0.0311).

CONCLUSIONS

Cognitive load could induce APA delay in the right trunk muscles and co-activation pattern changes in bilateral trunk muscle APA in patients with NCLBP. The APA onset delay in multifidus is positively related to pain-related daily dysfunction. Trial Registration ChiCTR2300068580 (retrospectively registered in February 23, 2023).

Postural Control of Patients with Low Back Pain Under Dual-Task Conditions

Low back pain is a major global public health problem, but the current intervention effect is not ideal. A large body of previous literature suggests that patients with chronic low back pain may have abnormal postural control, which is more evident in the dual task situation. In recent years, research on postural control in patients with low back pain under dual-task conditions has gradually become a hot topic. However, the results obtained from these studies were not entirely consistent. In this review, we summarized relevant studies on the performance of postural control in patients with low back pain under dual-task conditions, analyze it from the perspective of the theoretical model of dual-task interaction, the specific research paradigm of dual task, the performance of postural control, and the related factors affecting postural control performance, etc. It was reasonable to assume that patients with low back pain might have a certain degree of abnormal postural control, and this abnormality was affected by comprehensive factors such as age, cognitive resource capacity, attention needs, complex sensorimotor integration, external environment, etc. Furthermore, postural control performance in low back pain patients under dual-task conditions was further influenced by the nature and complexity of the different tasks. In general, the more attention resources were needed, the external environmental conditions were worse, and the age-related functions were degenerate, etc., the weaker posture control ability was. In short, a deeper understanding of postural control in patients with low back pain under dual-task conditions may shed light on more references for the rehabilitation and management of low back pain, as well as some new ideas for scientific research on cognition and postural control.

The association of fear of movement and postural sway in people with low back pain

BACKGROUND

Fear of movement is thought to interfere with the recovery from low back pain (LBP). To date, the relationship between fear of movement and postural balance has not been adequately elucidated. Recent findings suggest that more specific fears need to be assessed and put in relation to a specific movement task. We propose that the fear to bend the trunk in a certain direction is distinctly related to the amount of postural sway in different directions. Therefore, our aim was to investigate whether fear of movement in general and fear of bending the trunk in a certain plane is related to postural sway.

METHODS

Data was collected from participants with LBP during two assessments ~3 weeks apart. Postural sway was measured with a force-platform during quiet standing with the eyes closed. Fear of movement was assessed with an abbreviated version of the Tampa Scale of Kinesiophobia (TSK-11) and custom items referring to fear of bending the trunk in the sagittal and the frontal plane.

RESULTS

Based on data from 25 participants, fear of bending the trunk in the frontal plane was positively related to displacement in the sagittal and frontal plane and to velocity in the frontal plane (χ 2 = 4.35, p = 0.04; χ 2 = 8.15, p = 0.004; χ 2 = 9.79, p = 0.002). Fear of bending the trunk in the sagittal plane was not associated with any direction specific measure of sway. A positive relation of the TSK-11 with velocity of the frontal plane (χ 2 = 7.14, p = 0.008) was found, but no association with undirected measures of sway.

DISCUSSION

Fear of bending the trunk in the frontal plane may be especially relevant to postural sway under the investigated stance conditions. It is possible that fear of bending the trunk in the frontal plane could interfere with balance control at the hip, shifting the weight from side to side to control balance.

CONCLUSION

For the first time the directional relationship of fear of movement and postural sway was studied. Fear of bending the trunk in the frontal plane was positively associated with several measures of postural sway.

Ankle reaction times with tray usage following a slip perturbation between subjects with and without chronic low back pain

BACKGROUND

Abnormal stepping strategies have been associated with handheld tasks in subjects with chronic low back pain (LBP). However, the dominant ankle reactions of subjects with LBP remain unclear following a perturbation during handheld tasks.

RESEARCH QUESTION

Are there differences in the reaction times of the ankle muscles during handheld tasks between subjects with and without LBP following a treadmill-induced slip perturbation?

METHODS

Thirty-seven right limb dominant subjects with LBP and 37 subjects without LBP participated in the study. Each subject was introduced to a slip perturbation (1.37 m/sec velocity for 8.22 cm) with and without a handheld tray in random order. Subjects were allowed to recover by stepping forward for a 0.12 s duration while bilateral tibialis anterior (TA) and gastrocnemius (GA) muscle reaction times were measured by electromyography (EMG).

RESULTS

The EMG results indicated that the groups demonstrated significant interactions on the limb sides and muscles (F = 4.86, p = 0.03). The dominant TA reaction time was significantly faster in the LBP group (t = 2.14, p = 0.03) while holding a tray.

SIGNIFICANCE

The LBP group demonstrated faster reaction times on the dominant TA muscles during perturbations. Clinicians need to consider dominance-dependent compensatory ankle dorsiflexion strategies in LBP patients to help enhance dynamic balance and control.

Difference in postural stability between STarT Back Tool subgroups of patients with low back pain under conditions of sensory deprivation and cognitive load

Objective

We explored differences in postural stability between subgroups of patients with low back pain (LBP) and varying risk levels for developing chronicity measured using the Subgroups for Targeted Treatment (STarT) Back Tool.

Methods

This was a cross-sectional, single-session, double-blind experimental study among 65 participants who had LBP for more than 14 days. Postural stability was assessed by measuring the center of pressure (COP) range, displacement area, and velocity in anterior–posterior and mediolateral directions under four sensory and cognitive conditions: (i) eyes open and counting forward, (ii) eyes closed and counting forward, (iii) eyes closed and counting forward in multiples of seven, and (iv) eyes closed and counting backward in multiples of seven. The participants were stratified into low-/medium- (n = 53) and high-risk (n = 9) subgroups.

Results

There were no significant between-group differences among patients with LBP stratified as having a low/medium or high risk of chronicity in postural stability and sensory and cognitive conditions.

Conclusions

Impaired postural stability is important to consider when treating patients with LBP. However, we found that these impairments were not strongly aggravated in groups with a higher risk of chronicity, as measured using the STarT Back Tool.

Association of pain-related threat beliefs and disability with postural control and trunk motion in individuals with low back pain: a systematic review and meta-analysis

PURPOSE

Low back pain (LBP) individuals with high levels of fear of pain might display changes in motor behavior, which leads to disability. This study aimed to systematically review the influence of pain-related threat beliefs or disability on trunk kinematic or postural control in LBP.

METHOD

Eight electronic databases were searched from January 1990 to July 1, 2020. Meta-analysis using random-effect model was performed for 18 studies on the association between pain-related threat beliefs or disability and lumbar range of motion. Pearson r correlations were used as the effect size.

RESULT

Negative correlations were observed between lumbar range of motion (ROM) and pain-related threat beliefs (r = - 0.31, p < 0.01, 95% CI: - 0.39, - 0.24) and disability (r =  - 0.24, p < 0.01, 95% CI: - 0.40, - 0.21). Nonsignificant correlations were reported between pain-related threat beliefs and center of pressure parameters during static standing in 75% of the studies. In 33% of the studies, moderate negative correlations between disability and postural control were observed.

CONCLUSION

Motor behaviors are influenced by several factors, and therefore, the relatively weak associations observed between reduced lumbar ROM with higher pain-related threat beliefs and perceived disability, and postural control with disability are to be expected. This could aid clinicians in the assessment and planning rehabilitation interventions.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Small Random Angular Variations in Pelvic Tilt and Lower Extremity Can Cause Error in Static Image-based Preoperative Hip Arthroplasty Planning: A Computer Modeling Study

BACKGROUND

Many THA simulation models rely on a limited set of preoperative static radiographs to replicate sagittal pelvic tilt during functional positions and to recommend an implant orientation that minimizes the risk of prosthetic impingement. However, possible random changes in pelvic or lower extremity angular motions and the effect of coronal and axial pelvic tilt are not included in these preoperative models.

QUESTIONS/PURPOSES

(1) Can prosthetic impingement occur if the pelvic tilt or lower extremity alignment randomly varies up to ± 5° from what is measured on a single preoperative static radiographic image? (2) Do changes in coronal and axial pelvic tilt or lower extremity alignment angles have a similar effect on the risk of prosthetic impingement?

METHODS

A de-identified pelvis and lower-body CT image of a male patient without previous THA or lower extremity surgery was used to import the pelvis, femur, and tibia into a verified MATLAB computer model. The motions of standing, pivoting, sitting, sit-to-stand, squatting, and bending forward were simulated. THA implant components included a full hemispherical acetabular cup without an elevated rim, polyethylene liner without an elevated rim, femoral head (diameter: 28 mm, 32 mm, 36 mm, or 40 mm), and a triple-taper cementless stem with three different neck shaft angles (127°, 132°, or 135°) with a trapezoidal neck were used in this model. A static model (cup anatomical abduction 40°, cup anatomical anteversion 20°, stem anatomical anteversion 10°) with a predefined range of sagittal pelvic tilt and hip alignment (0° coronal or axial tilt, without random ± 5° change) was used to simulate each motion. We then randomly varied pelvic tilt in three different pelvic planes and hip alignments (flexion, extension, abduction, adduction, rotation) up to ± 5° and assessed the same motions without changing the implant's anatomical orientation. Prosthetic impingement as the endpoint was defined as mechanical abutment between the prosthetic neck and polyethylene liner. Multiple logistic regression was used to investigate the effect of variation in pelvic tilt and hip alignment (predictors) on prosthetic impingement (primary outcome).

RESULTS

The static-based model without the random variation did not result in any prosthetic impingement under any conditions. However, with up to ± 5° of random variation in the pelvic tilt and hip alignment angles, prosthetic impingement occurred in pivoting (18 possible combinations), sit-to-stand (106 possible combinations), and squatting (one possible combination) when a 28-mm or a 32-mm head was used. Variation in sagittal tilt (odds ratio 4.09 [95% CI 3.11 to 5.37]; p < 0.001), axial tilt (OR 3.87 [95% CI 2.96 to 5.07]; p < 0.001), and coronal tilt (OR 2.39 [95% CI 2.03 to 2.83]; p < 0.001) affected the risk of prosthetic impingement. Variation in hip flexion had a strong impact on the risk of prosthetic impingement (OR 4.11 [95% CI 3.38 to 4.99]; p < 0.001).

CONCLUSION

The combined effect of 2° to 3° of change in multiple pelvic tilt or hip alignment angles relative to what is measured on a single static radiographic image can result in prosthetic impingement. Relying on a few preoperative static radiographic images to minimize the risk of prosthetic impingement, without including femoral implant orientation, axial and coronal pelvic tilt, and random angular variation in pelvis and lower extremity alignment, may not be adequate and may fail to predict prosthetic impingement-free ROM.

CLINICAL RELEVANCE

Determining a safe zone for THA implant positioning with respect to impingement may require a dynamic computer simulation model to fully capture the range of possible impingement conditions. Future work should concentrate on devising simple and easily available methods for dynamic motion analysis instead of using a few static radiographs for preoperative planning.

Postural Control under Cognitive Load: Evidence of Increased Automaticity Revealed by Center-of-Pressure and Head Kinematics

How postural responses change with sensory perturbations while also performing a cognitive task is still debatable. This study investigated this question via comprehensive assessment of postural sway, head kinematics and their coupling. Twenty-three healthy young adults stood in tandem with eyes open or wearing the HTC Vive Head-Mounted Display (HMD) with a static or dynamic (i.e., movement in the anterior-posterior direction at 5 mm or 32 mm at 0.2 Hz) 3-wall stars display. On half of the trials, participants performed a cognitive serial subtraction task. Medio-lateral center-of-pressure (COP) path significantly increased with the cognitive task, particularly with dynamic visuals whereas medio-lateral variance decreased with the cognitive task. Head path and velocity significantly increased with the cognitive task in both directions while variance decreased. Head-COP cross-correlations ranged between 0.78 and 0.66. These findings, accompanied by frequency analysis, suggest that postural control switched to primarily relying on somatosensory input under challenging cognitive load conditions. Several differences between head and COP suggest that head kinematics contribute an important additional facet of postural control and the relationship between head and COP may depend on task and stance position. The potential of HMDs for clinical assessments of balance needs to be further explored.

Dexmedetomidine upregulates microRNA-185 to suppress ovarian cancer growth via inhibiting the SOX9/Wnt/β-catenin signaling pathway

Dexmedetomidine (DEX) could serve as an adjuvant analgesic during cancer therapies. Abnormal expression of microRNAs (miRNAs) could lead to cancer development. This study was aimed to explore the roles of DEX in ovarian cancer (OC) development. OC cell lines SKOV3 and HO-8910 were treated with DEX, after which OC development and the miR-185, SOX9, and Wnt/β-catenin pathway were measured. DEX-treated HO-8910 cells were transfected with miR-185 mimic, miR-185 antisense or miR-185 antisense + silenced SOX9 to further measure the OC cell growth. The target relation between miR-185 and SOX9 was identified, and SOX9 and Wnt/β-catenin pathway were protein levels detected after miR-185 transfection. The role of miR-185 in OC in vivo was also measured. Our study found DEX had a dose-dependent inhibition on OC growth, and DEX promoted miR-185 but suppressed SOX9 expression in OC cells. miR-185 targeted SOX9. After interfering with miR-185 expression, HO-8910 cell proliferation, invasion, migration, and apoptosis were affected. SOX9 knockdown repressed OC development and Wnt/β-catenin pathway. The volume, weight, positive rate of Ki67, CyclinD1, p53 and the degree of tumor necrosis were affected by miR-185 expression. This study demonstrated that DEX could inhibit OC development via upregulating miR-185 expression and inactivating the SOX9/Wnt/β-catenin signaling pathway.

People with persistent postural-perceptual dizziness demonstrate altered postural strategies in complex visual and cognitive environments

BACKGROUND

People with PPPD report imbalance, increase in symptoms and impaired function within complex visual environments, but understanding of the mechanism for these behaviors is still lacking.

OBJECTIVE

To investigate postural control in PPPD we compared changes in center of pressure (COP) and head kinematics of people with PPPD (N = 22) and healthy controls (N = 20) in response to different combinations of visual and cognitive perturbations during a challenging balance task.

METHODS

Participants stood in a tandem position. Static or moving stars (0.2 Hz, 5 mm or 32 mm amplitude, anterior-posterior direction) were displayed through a head-mounted display (HTC Vive). On half the trials, participants performed a serial-3 subtraction task. We measured medio-lateral and anterior-posterior path and acceleration of COP and head.

RESULTS

Controls significantly increased all COP and head parameters with the cognitive task whereas PPPD increased only COP ML path and acceleration. Only controls significantly increased head anterior-posterior & medio-lateral acceleration with moving visual load. Cognitive task performance was similar between groups.

CONCLUSIONS

We observed altered postural strategies in people with PPPD, in the form of reduced movement with challenge, particularly around the head segment. The potential of this simple and portable head-mounted display setup for differential diagnosis of vestibular disorders should be further explored.

The reaction times and symmetry indices in the bilateral trunk and limb muscles in control subjects and subjects with low back pain that persisted two months or longer

PURPOSE

This study was conducted to investigate the reaction times and symmetry index (SI) of the bilateral trunk and limb muscles between control subjects and subjects with low back pain (LBP) that persisted for two months or longer.

METHODS

Fifty-seven right limb dominant subjects (31 healthy control subjects and 26 subjects with LBP) participated in this study. The subjects were exposed to a slip perturbation (0.24 m/sec velocity for 1.20 cm), which caused them to move forward for 0.10 s in standing while holding a tray. The electromyography (EMG) electrodes were placed on the bilateral erector spinae (ES), rectus abdominis (RA), rectus femoris, hamstring, tibialis anterior, gastrocnemius, biceps brachii (BB), and triceps brachii muscles. The reaction times were analyzed, and the SI was used to compare the bilateral trunk and limb muscles for the degree of asymmetry between groups.

RESULTS

The ES reaction time was significantly delayed in the control group (0.33 ± 0.22 vs. 0.22 ± 0.17; t = 2.25, p = 0.03). The SI of reaction times was significantly different on the RA (t = -2.28, p = 0.03), ES (t = -2.36, p = 0.04), and BB (t = -2.15, p = 0.04) muscles between groups.

CONCLUSION

The delayed non-dominant ES reaction time might indicate a freedom of pain recurrence in the control group. Although the asymmetry increased on the RA and BB muscles in the LBP group, it decreased on the ES muscle. The asymmetries on the trunk and BB muscles were evident in the LBP group. The asymmetrical reactions in the arm-trunk muscles need to be considered for rehabilitation strategies.

Test-Retest Reliability of an iPhone® Inclinometer Application to Assess the Lumbar Joint Repositioning Error in Non-Specific Chronic Low Back Pain

Background: The joint position sense (JPS) has been used as an indirect marker of proprioception in subjects with non-specific chronic low back pain (NSCLBP), showing impairment in previous studies. It seems necessary to devise reliable tests to measure proprioceptive deficits in subjects with NSLBP. The objective of this study was to analyse the test-retest reliability and smallest real difference (SRD) of lumbar proprioception through the JPS indicator in a sample of patients with NSCLBP. Methods: Fifty participants with NSCLBP performed three repetitions of 30° lumbar flexion while standing and sitting using the iPhone^® inclinometer application to measure the lumbar joint repositioning error. For the reliability analysis, we performed an intra-session test-retest. Results: The total sample ICC values were excellent for standing (0.96) and sitting (0.93) 30° lumbar flexion. In addition, our results showed that, for the total sample, an SRD < 12% can be considered as a true change in proprioception concerning this procedure. On the other hand, men have better reliability than women in both standing and sitting positions. Additionally, the sitting position has better reliability than the standing position. The standard error of measurement (SEM) percentage was 4.2 for standing and 3.8 for sitting. The SRD percentage was 11.6 for standing and 10.4 for sitting. Conclusions: The iPhone^® inclinometer seems reliable for assessing proprioceptive ability through the lumbar joint repositioning error in subjects with NSCLBP in both standing (ICC = 0.96) and sitting (ICC = 0.93) positions. This technological device showed a lower measurement error for sitting position (SRD < 12%).

Reliability of postural control during double-leg standing in subjects with nonspecific chronic low back pain: Dual-task paradigm and manipulated visual and somatosensory inputs

BACKGROUND

The aim of this study is to evaluate the test-retest reliability of the Center of Pressure (COP) parameters in quiet double-leg standing in subjects with Non-Specific Chronic Low Back Pain (NSCLBP) during dual taking associated with manipulated visual and somatosensory inputs.

MATERIALS AND METHODS

In this observational cross-sectional study, the static balance of thirty NSCLBP patients were assessed during a double-leg stance by using the force platform. Subjects were accosted by manipulated somatosensory and visual inputs during dual taking in eight different conditions (with and without vibration, eyes-open and eyes-closed, and with and without auditory Stroop test). The COP parameters were recorded as follows: range sideways and range fore-aft as well as mean velocity and area variables. The cognitive task parameters included the reaction time and error ratio. The intra-class correlation coefficient (ICC) was computed to assess the intersession reliability of COP parameters.

RESULTS

in intersession, range sideways, range fore-aft, and mean velocity measures possessed moderate to high ICC, but area owned high ICC only in one condition (double-leg stance, eyes-close, with vibration, and with auditory Stroop test). Notably, other conditions had low ICC, and moderate to high and low to very high ICC were reported for reaction time and error ratio.

CONCLUSION

Among the parameters studied in the present study, the mean velocity measure seems to be the most reliable variable of postural control in the subjects with NSLBP especially in more challenging conditions, i.e., quiet double-leg standing with eyes closed and adding vibratory inputs during dual-tasking.

Attentional Demands of Postural Control in Chronic Ankle Instability, Copers and Healthy Controls: A Controlled Cross-sectional Study

BACKGROUND

It has been shown that cognitive loading affects postural control in different populations. However, there is limited and conflicting information about dual task challenges on postural control in chronic ankle instability (CAI).

RESEARCH QUESTION

Does cognitive task performance change standing postural control in individuals with CAI, copers and healthy subjects?

METHODS

A descriptive, analytic, and controlled cross-sectional study was conducted on 75 individuals. They were assigned into three matched groups, including CAI, copers, and healthy controls. Postural control variables were collected during single leg standing on a force plate with and without vision and cognition. Parameters of center of pressure (COP), including mean COP area, range, sway index and velocity, were measured. Additionally, cognitive task performance by auditory stroop was assessed by calculating the reaction time and error ratio. Mixed model ANOVAs were used to determine the effects of group and testing conditions.

RESULTS

The CAI group demonstrated greater COP sway parameters compared to other groups under all testing conditions. The main significant effect of vision was observed for all COP parameters with greater COP sway during eyes closed compared to eyes open (P < 0.05). The main effect of a cognitive task was significant with reduced COP sway while performing the secondary cognitive compared to a single task in all three groups (P < 0.05). The cognitive task results revealed significantly longer reaction times in the CAI group compared to copers and healthy individuals (p < 0.05).

SIGNIFICANCE

Considering postural control deficits in CAI, especially in eye-closed condition and effects of cognitive loading, may guide us to improve postural control in those with CAI with neurocognitive training. Furthermore, no difference between coper and healthy groups may imply a successful compensatory postural control mechanism in copers.

The Effects of Cognitive Loading on Motor Behavior in Injured Individuals: A Systematic Review

BACKGROUND

Research suggests that individuals with musculoskeletal injury may have difficulty negotiating physical tasks when they are combined with cognitive loads.

OBJECTIVE

Our objective was to conduct a systematic review to understand the effects of increased cognitive demand on movement patterns among individuals with musculoskeletal injuries.

METHODS

A comprehensive search of PubMed, MEDLINE, the Cumulative Index for Nursing and Allied Health Literature (CINAHL), and SPORTDiscus was conducted to find research reports that included a population that had previously experienced an ankle, knee, or low back injury, included an uninjured control group, and assessed a dual-task paradigm.

RESULTS

Forty-five full-text research reports were assessed, of which 28 studies (six ankle injury, nine knee injury, and 13 low back pain studies) were included in the review. Included studies were assessed for methodological quality and the study design extracted for analysis including the participants, cognitive and physical tasks performed, as well as outcome measures (e.g., three-dimensional kinematics, center of pressure, etc.). All studies included were cross-sectional or case-control with methodological quality scores of 17.8 ± 2.2 out of a possible 22. Twenty-five of the 28 studies found changes in motor performance with dual-task conditions compared with single tasks. Furthermore, 54% of studies reported a significant group by task interaction effect, reporting at least one alteration in injured groups' motor performance under dual-task conditions when compared with an uninjured group.

CONCLUSION

The results of this systematic review indicate that motor performance is further impaired by placing a cognitive load on individuals in populations with musculoskeletal injury. More demanding tasks such as gait appear to be more affected in injured individuals than simple balance tasks. Future investigators may want to consider the difficulty of the tasks included as well as the impact of dual-task paradigms on rehabilitation programs.