Characterization of standing balance after incomplete spinal cord injury: Alteration in integration of sensory information in ambulatory individuals

A systematic review of validity and reliability assessment of measuring balance and walking at the level of International Classification of Functioning, Disability and Health (ICF) in people with spinal cord injury

CONTEXT

A spinal cord injury (SCI) is associated with a wide range of impairments in functioning, many limitations in activity, and restrictions for patients.

OBJECTIVES

The present study aimed to systematically review the psychometric properties (reliability and validity) of outcome measures used to assess walking and balance in people with spinal cord injury.

METHODS

Databases such as PubMed, Embase, Scopus, and Web of Sciences were searched for relevant articles using various terms (title and abstract). Articles including the outcome measures of spinal cord injury patients and published in English from 2010 until 2021 were selected, and the quality of the selected studies was determined by applying the COSMIN checklist. Reliability and validity values were extracted, and conclusions were drawn about the psychometric quality of each measure.

RESULTS

A total of 1253 records were retrieved, and among them 22 potentially eligible articles were identified, 15 of which were included in the present study. The COSMIN tool (Consensus-based Standards for the selection of health status Measurement Instruments) was used to evaluate the quality level of imported articles based on the inclusion criteria.

CONCLUSIONS

One consideration for testing people with disabilities is to observe the reliability and validity of the instrument, which was addressed in this study in various fields. In our study, seven tools for assessing SCI were evaluated, and it was found that the 10-meter walk (10MWT) tool performs better and more easily than other tools. The Mini-BESTest tool was suggested as a reliable tool for assessing standing balance in SCI subjects.

The relationship between balance control and thigh muscle strength and muscle activity in persons with incomplete spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

A spinal cord injury (SCI) can compromise the ability to maintain sufficient balance control during activities in an upraised position. The objective of the study was to explore the relationship between balance control and muscle strength and muscle activation in the lower extremities in persons with incomplete SCI (iSCI).

SETTING

Sunnaas Rehabilitation Hospital, Norway.

METHODS

Thirteen men and two women with iSCI and 15 healthy, matched controls were included. Performance of the Berg Balance Scale (BBS) short version (7 items) was used to indicate balance control. Maximal voluntary contraction (MVC) was performed to measure isometric muscle strength in thigh muscles (knee extension/flexion), while surface electromyography (EMG) was measured from M. Vastus Lateralis and M. Biceps Femoris. The relative activation of each muscle during each of the BBS tasks was reported as the percentage of the maximal activation during the MVC (%EMGmax).

RESULTS

The iSCI participants had a significantly lower BBS sum score and up to 40% lower muscle strength in knee- flexion and extension compared to the matched healthy controls. They also exhibited a significantly higher %EMGmax, i.e. a higher muscle activation, during most of the balance tests. Univariate regression analysis revealed a significant association between balance control and mean values of %EMGmax in Biceps Femoris, averaged over the seven BBS tests.

CONCLUSIONS

The participants with iSCI had poorer balance control, reduced thigh muscle strength and a higher relative muscle activation in their thigh muscles, during balance-demanding activities.

Effect of test duration and sensor location on the reliability of standing balance parameters derived using body-mounted accelerometers

BACKGROUND

Balance parameters derived from wearable sensor measurements during postural sway have been shown to be sensitive to experimental variables such as test duration, sensor number, and sensor location that influence the magnitude and frequency-related properties of measured center-of-mass (COM) and center-of-pressure (COP) excursions. In this study, we investigated the effects of test duration, the number of sensors, and sensor location on the reliability of standing balance parameters derived using body-mounted accelerometers.

METHODS

Twelve volunteers without any prior history of balance disorders were enrolled in the study. They were asked to perform two 2-min quiet standing tests with two different testing conditions (eyes open and eyes closed). Five inertial measurement units (IMUs) were employed to capture postural sway data from each participant. IMUs were attached to the participants' right legs, the second sacral vertebra, sternum, and the left mastoid processes. Balance parameters of interest were calculated for the single head, sternum, and sacrum accelerometers, as well as, a three-sensor combination (leg, sacrum, and sternum). Accelerometer data were used to estimate COP-based and COM-based balance parameters during quiet standing. To examine the effect of test duration and sensor location, each 120-s recording from different sensor locations was segmented into 20-, 30-, 40-, 50-, 60-, 70-, 80-, 90-, 100-, and 110-s intervals. For each of these time intervals, time- and frequency-domain balance parameters were calculated for all sensor locations.

RESULTS

Most COM-based and COP-based balance parameters could be derived reliably for clinical applications (Intraclass-Correlation Coefficient, ICC ≥ 0.90) with a minimum test duration of 70 and 110 s, respectively. The exceptions were COP-based parameters obtained using a sacrum-mounted sensor, especially in the eyes-closed condition, which could not be reliably used for clinical applications even with a 120-s test duration.

CONCLUSIONS

Most standing balance parameters can be reliably measured using a single head- or sternum-mounted sensor within a 120-s test duration. For other sensor locations, the minimum test duration may be longer and may depend on the specific test conditions.

Clinical Static Balance Assessment: A Narrative Review of Traditional and IMU-Based Posturography in Older Adults and Individuals with Incomplete Spinal Cord Injury

Maintaining a stable upright posture is essential for performing activities of daily living, and impaired standing balance may impact an individual's quality of life. Therefore, accurate and sensitive methods for assessing static balance are crucial for identifying balance impairments, understanding the underlying mechanisms of the balance deficiencies, and developing targeted interventions to improve standing balance and prevent falls. This review paper first explores the methods to quantify standing balance. Then, it reviews traditional posturography and recent advancements in using wearable inertial measurement units (IMUs) to assess static balance in two populations: older adults and those with incomplete spinal cord injury (iSCI). The inclusion of these two groups is supported by their large representation among individuals with balance impairments. Also, each group exhibits distinct aspects in balance assessment due to diverse underlying causes associated with aging and neurological impairment. Given the high vulnerability of both demographics to balance impairments and falls, the significance of targeted interventions to improve standing balance and mitigate fall risk becomes apparent. Overall, this review highlights the importance of static balance assessment and the potential of emerging methods and technologies to improve our understanding of postural control in different populations.

Accelerometry applications and methods to assess standing balance in older adults and mobility-limited patient populations: a narrative review

Accelerometers provide an opportunity to expand standing balance assessments outside of the laboratory. The purpose of this narrative review is to show that accelerometers are accurate, objective, and accessible tools for balance assessment. Accelerometry has been validated against current gold standard technology, such as optical motion capture systems and force plates. Many studies have been conducted to show how accelerometers can be useful for clinical examinations. Recent studies have begun to apply classification algorithms to accelerometry balance measures to discriminate populations at risk for falls. In addition to healthy older adults, accelerometry can monitor balance in patient populations such as Parkinson's disease, multiple sclerosis, and traumatic brain injury. The lack of software packages or easy-to-use applications have hindered the shift into the clinical space. Lack of consensus on outcome metrics has also slowed the clinical adoption of accelerometer-based balance assessments. Future studies should focus on metrics that are most helpful to evaluate balance in specific populations and protocols that are clinically efficacious.

Interventions to Improve Standing Balance in Individuals With Incomplete Spinal Cord Injury: A Systematic Review and Meta-Analysis

Background

Incomplete spinal cord injury (iSCI) often results in impaired balance leading to functional impairments. Recovery of standing balance ability is an important aim of rehabilitative programs. However, limited information is available on effective balance training protocols for individuals with iSCI.

Objectives

To assess the methodological quality and effectiveness of various rehabilitation interventions for improving standing balance in individuals with iSCI.

Methods

A systematic search was performed in SCOPUS, PEDro, PubMed, and Web of Science from inception until March 2021. Two independent reviewers screened articles for inclusion, extracted data, and evaluated methodological quality of the trials. PEDro Scale was used to assess the quality of randomized controlled trials (RCT) and crossover studies while pre-post trials were assessed using the modified Downs and Black tool. A meta-analysis was performed to quantitatively describe the results. The random effects model was applied to present the pooled effect.

Results

Ten RCTs with a total of 222 participants and 15 pre-post trials with 967 participants were analyzed. The mean PEDro score and modified Downs and Black score was 7/10 and 6/9, respectively. The pooled standardized mean difference (SMD) for controlled and uncontrolled trials of body weight-supported training (BWST) interventions was -0.26 (95% CI, -0.70 to 0.18; p = .25) and 0.46 (95% CI, 0.33 to 0.59; p < .001), respectively. The pooled effect size of -0.98 (95% CI, -1.93 to -0.03; p = .04) indicated significant improvements in balance after a combination of BWST and stimulation. Pre-post studies analyzing the effect of virtual reality (VR) training interventions on Berg Balance Scale (BBS) scores in individuals with iSCI reported a mean difference (MD) of 4.22 (95% CI, 1.78 to 6.66; p = .0007). Small effect sizes were seen in pre-post studies of VR+stimulation and aerobic exercise training interventions indicating no significant improvements after training on standing balance measures.

Conclusion

This study demonstrated weak evidence to support the use of BWST interventions for overground training for balance rehabilitation in individuals with iSCI. A combination of BWST with stimulation however showed promising results. There is a need for further RCTs in this field to generalize findings. Virtual reality-based balance training has shown significant improvement in standing balance post iSCI. However, these results are based on single group pre-post trials and lack appropriately powered RCTs involving a larger sample size to support this intervention. Given the importance of balance control underpinning all aspects of daily activities, there is a need for further well-designed and appropriately powered RCTs to evaluate specific features of training interventions to improve standing balance function in iSCI.

Effect of virtual reality training on standing balance in individuals with incomplete spinal cord injury

Recovery of balance ability during standing is one of the primary and essential aims of rehabilitative programs in individuals with incomplete spinal cord injury (iSCI). A sample of ten participants (mean age: 35.7 years, range: 25-63 years) with traumatic or non-traumatic iSCI (AIS grade C or D) and were able to stand with or without the support of an assistive device for a minimum of 2 min were recruited from the rehabilitation department of the Indian Spinal Injuries Centre, New Delhi, India. The participants received Virtual Reality (VR) based balance training for one hour, three times a week for four weeks on the Nintendo Wii gaming console. Participants were assessed three times: pre-intervention, post-intervention and follow-up assessment for the total ellipse area (TEA), total sway perimeter (TSP), sway range (anterior-posterior/medio-lateral (AP/ML)) and limits of stability (LOS). At post-intervention assessment, significant increases in comparison with pre-intervention scores was found in LOS (P=0.00), TEA with eyes open (EO) (P=0.00) and eyes closed (EC) (P=0.00), TSP with EO (P=0.00) and EC (P=0.00), sway range in AP direction (SD-AP) with EO (P=0.01) and EC (P=0.02) and sway range in ML direction (SD-ML) with EO (P=0.02) and EC (P=0.01). At follow-up assessment, a significant improvement in comparison to post intervention scores was found in TEA measured both in EO (P=0.01) and EC conditions (P=0.02), TSP measured with EO (P=0.01) and SD-ML both with EO (P=0.04) and EC (P=0.01). No significant changes were found in LOS (P=0.89), TSP measured with EC (P=0.38) and SD-AP both with EO (P=0.50) and EC (P=1). However, significant improvement was seen on comparing follow-up assessment scores with pre-intervention scores for all variables, such as LOS (P=0.00), TEA in EO (P=0.00) and EC (P=0.00), TSP with EO (P=0.00) and EC (P=0.00), SD-AP with EO (P=0.01) and EC (P=0.02) and SD-ML with EO (P=0.01) and EC (P=0.00). VR-based balance training intervention was able to elicit improvements in balance ability and maintain it during follow-up despite a small training dosage suggesting that it is a promising intervention for standing balance rehabilitation among individuals with iSCI. The VR-based balance training challenges elements of balance, which physical therapists may want to consider when designing a comprehensive rehabilitation program.

Clinical Trials Registry-India: CTRI/2018/12/016814.

Technology-assisted balance assessment and rehabilitation in individuals with spinal cord injury: A systematic review

BACKGROUND: Balance is a crucial function of basic Activities of Daily Living (ADL) and is often considered the priority in Spinal Cord Injury (SCI) patients’ rehabilitation. Technological devices have been developed to support balance assessment and training, ensuring an earlier, intensive, and goal-oriented motor therapy. OBJECTIVE: The aim of this systematic review is to explore the technology-assisted strategies to assess and rehabilitate balance function in persons with SCI. METHODS: A systematic review was conducted in the databases PubMed, Scopus, IEEE Xplore, Cochrane Library, and Embase. Full reports on Randomized Clinical Trials (RCTs) of parallel-group or cross-over design and non-RCTs were included according to the following criteria: i) publication year from 1990 to 2021; ii) balance considered as a primary or secondary outcome; iii) population of individuals with SCI with age over 18 years old, regardless of traumatic or non-traumatic lesions, Time Since Injury, lesion level, Asia Impairment Scale score and gender. The methodological quality was determined for each included study according to the recognized Downs and Black (D&B) tool. RESULTS: Nineteen articles met the inclusion criteria and were included in the analysis. Four articles focused on balance assessment while 15 targeted rehabilitation interventions to improve balance by using Treadmill-Based Devices (TBD), OverGround Devices (OGD) and Tilt Table Devices (TTD). Statistically significant effects on balance can be found in TBD subcategory, in the hip-knee guidance subcategory of OGD and in the study of TTD category. CONCLUSION: Although different studies reported positive effects, improvements due to technology-assisted rehabilitation were not greater than those obtained by means of other rehabilitation therapies. The heterogeneity, low methodological quality, and the small number of the studies included do not allow general conclusions about the usefulness of technology-assisted balance assessment and training in individuals with SCI, even if significant improvements have been reported in some studies.

Characterizing inter-limb synchronization after incomplete spinal cord injury: A cross-sectional study

BACKGROUND

Individuals with incomplete spinal cord injury (iSCI) demonstrate greater postural sway and increased dependency on vision to maintain balance compared to able-bodied individuals. Research on standing balance after iSCI has focused on the joint contribution of the lower limbs; however, inter-limb synchrony in quiet standing is a sensitive measure of individual limb contributions to standing balance control in other neurological populations. It is unknown if and how reduced inter-limb synchrony contributes to the poor standing balance of individuals with iSCI.

RESEARCH QUESTION

How does an iSCI affect inter-limb synchrony and weight-bearing symmetry in standing?

METHODS

Eighteen individuals with non-progressive motor iSCI and 15 age- and sex-matched able-bodied individuals (M-AB) were included in the study. Participants stood in a standardized position on two adjacent force plates in eyes open and closed conditions for 70 s per condition. Net centre-of-pressure (COP) root mean square (RMS), net COP velocity, COP inter-limb synchrony (i.e. cross-correlation between left and right COP), and weight-bearing asymmetry (i.e. vertical force from each limb over total vertical force) were calculated. Muscle strength of the lower limbs was assessed with manual muscle testing.

RESULTS

Individuals with iSCI demonstrated reduced inter-limb synchrony when standing with eyes open and eyes closed, but did not differ to M-AB with respect to weight-bearing asymmetry. They also produced greater net COP RMS and velocity when compared to M-AB. Muscle strength of the two lower limbs demonstrated an overall asymmetry in individuals with iSCI.

SIGNIFICANCE

Individuals with iSCI demonstrated impaired balance control as evidenced by reduced inter-limb synchrony and greater COP RMS and velocity compared to M-AB individuals. This increased understanding of how balance control is impaired following iSCI may inform balance assessment and intervention for this population. Future work examining the association between inter-limb synchrony and the occurrence of falls in iSCI is warranted.

Postural control strategy after incomplete spinal cord injury: effect of sensory inputs on trunk-leg movement coordination

BACKGROUND

Postural control is affected after incomplete spinal cord injury (iSCI) due to sensory and motor impairments. Any alteration in the availability of sensory information can challenge postural stability in this population and may lead to a variety of adaptive movement coordination patterns. Hence, identifying the underlying impairments and changes to movement coordination patterns is necessary for effective rehabilitation post-iSCI. This study aims to compare the postural control strategy between iSCI and able-bodied populations by quantifying the trunk-leg movement coordination under conditions that affects sensory information.

METHODS

13 individuals with iSCI and 14 aged-matched able-bodied individuals performed quiet standing on hard and foam surfaces with eyes open and closed. We used mean Magnitude-Squared Coherence between trunk-leg accelerations measured by accelerometers placed over the sacrum and tibia.

RESULTS

We observed a similar ankle strategy at lower frequencies (f ≤ 1.0 Hz) between populations. However, we observed a decreased ability post-iSCI in adapting inter-segment coordination changing from ankle strategy to ankle-hip strategy at higher frequencies (f > 1.0 Hz). Moreover, utilizing the ankle-hip strategy at higher frequencies was challenged when somatosensory input was distorted, whereas depriving visual information did not affect balance strategy.

CONCLUSION

Trunk-leg movement coordination assessment showed sensitivity, discriminatory ability, and excellent test-retest reliability to identify changes in balance control strategy post-iSCI and due to altered sensory inputs. Trunk-leg movement coordination assessment using wearable sensors can be used for objective outcome evaluation of rehabilitative interventions on postural control post-iSCI.