Impaired balance control in paraplegic subjects

The Impact of Sports Training on the Spinal Cord Injury Individual's Balance

Spinal cord injury (SCI) causes major challenges to mobility and daily life activities and maintaining balance becomes a crucial issue. Individuals with SCI often need to adopt new strategies to manage balance with minimal discomfort. Sports and physical activities have become one of the most popular rehabilitation methods for people with SCI. The assessment of balance improvement currently relies on subjective evaluation scales, and this study aims to quantitively assess the efficacy of sports on the balance strategies of people with SCI. Twenty-two SCI people remained seated still for 30 s, with their eyes open and closed, and we recorded trunk kinematics with an optoelectronic system before and after a three-months sports program. We also computed trunk total sway length, mean velocity, and sway density curve. Statistical analyses were performed to compare SCI people before and after the rehabilitation program and to investigate any correlations between the trunk balance parameters and the clinical scales. The results demonstrate improvements in static balance, with significant reductions in sway length and mean velocity. In conclusion, our findings confirm the potential of sports to enhance balance in SCI individuals and suggest that integrating structured sports programs into rehabilitation can improve stability and postural control.

Trunk muscle activity and kinematics during boxing and battle rope exercise in people with motor-complete spinal cord injury

CONTEXT

Recovery of seated balance is a rehabilitation priority for people with motor-complete spinal cord injury (mcSCI). Previous research has demonstrated that people with mcSCI can voluntarily engage their trunk muscles during different exercise programs that have the potential to improve seated balance control. Boxing and battle rope exercises could offer another opportunity to improve seated balance for people with mcSCI, but it is unknown if this type of exercise engages trunk musculature and challenges seated balance.

OBJECTIVE

To describe the movement patterns of people with mcSCI compared to controls by characterizing the muscle activation patterns and kinematics of the trunk and upper-body during boxing and battle rope exercise.

DESIGN

Cross-sectional study.

PARTICIPANTS

4 males with mcSCI between C7-T9, and 4 able-bodied controls.

METHODS

Participants performed different boxing and battle rope exercises while kinematics and electromyography (EMG) from the trunk and arms were recorded.

OUTCOME MEASURES

Trunk EMG amplitude, trunk and arm joint angles, and trunk curvature.

RESULTS

Boxing and battle ropes elicited higher relative EMG activity in people with mcSCI compared to controls (P < 0.001). Participants with mcSCI had similar upper-limb kinematics during the exercises to controls, but demonstrated reduced trunk rotation and increased trunk curvature.

CONCLUSIONS

These findings suggest that boxing and battle rope can elicit trunk activity in people with mcSCI, though they may adopt increased trunk curvatures. Future research should explore if such exercise programs may improve seated balance in people with mcSCI.

Trunk and glenohumeral joint adaptations to manual wheelchair propulsion over a cross-slope: An exploratory study

BACKGROUND

Cross-slopes are often encountered by manual wheelchair users propelling within an urban setting. While propulsion over cross-slopes is more difficult than on level surfaces, little is known about how the users counter the downhill turning tendency of the wheelchair over cross-slopes. This study aimed to identify the adaptations of the manual wheelchair users to the presence of cross-slopes and examine how these might impact shoulder injury.

METHODS

Nine manual wheelchair users propelled themselves across a cross-slope and over a level surface. The trunk and glenohumeral joint kinematics, as well as the handrim contact tangential force were compared between both conditions for the uphill and downhill limbs.

FINDINGS

The uphill arm technique used to counter the downhill turning tendency varied greatly in terms of potential injury risk and efficiency between participants. Trunk flexion increased the turning tendency of the manual wheelchair, yet only one participant decreased his flexion when rolling over the cross-slope. Various potential pathomecanisms related to the trunk lateral flexion and the glenohumeral kinematics over a cross-slope were identified.

INTERPRETATION

Both the uphill arm technique and trunk kinematics are important to propel over a cross-slope both efficiently and safely. Accordingly, tips about posture and kinematics are needed to teach this skill to manual wheelchair users. Additionally, as wheelchair positioning seems to influence the cross-slope skill, more research is needed to explore the impact of positioning devices (e.g., lateral supports) and wheelchair modifications (e.g., power assist wheels, handrim projections) on this skill.

Prognostic validity of trunk control scales for mobility in individuals with motor complete thoracic SCI: a prospective cohort study

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To investigate the sensitivity to change and prognostic validity of Trunk Control Test (TCT) and Thoracic-Lumbar Control Scale (TLC) in terms of mobility in persons with motor complete thoracic spinal cord injury (SCI).

SETTING

Participants were recruited at an Italian SCI rehabilitation facility from October 2015 to January 2020.

METHODS

Inclusion criteria were acute traumatic or non-traumatic event and T1-L1 neurological level. Trunk control and mobility were assessed at baseline, discharge, and at 6 and 18-month follow-ups. Mobility was measured using Spinal Cord Independence Measure III mobility subscale. Linear regression models were used to analyze changes in trunk control and mobility over time, and the relationship between these measures.

RESULTS

The 39 participants were predominantly male, with a mean age of 38 years. Trunk control improved during rehabilitation, at 6-month follow-up, and remained stable thereafter, according to TCT and TLC scales. A higher baseline TCT score was associated with improvements in mobility at discharge and at follow-ups. Baseline TLC score and its change during rehabilitation were unrelated with changes in mobility.

CONCLUSIONS

Results suggest that the TCT and TLC scales are useful to capture changes in trunk control during the acute and subacute phases. Improvements in functional mobility are however associated with TCT score only, suggesting the potential of this test as a useful prognostic indicator. Further research with larger sample sizes is warranted to determine whether these findings are consistent across neurological level strata.

Spinal Cord Epidural Stimulation Improves Lower Spine Sitting Posture Following Severe Cervical Spinal Cord Injury

Cervical spinal cord injury (SCI) leads to impaired trunk motor control, negatively impacting the performance of activities of daily living in the affected individuals. Improved trunk control with better sitting posture has been previously observed due to neuromuscular electrical stimulation and transcutaneous spinal stimulation, while improved postural stability has been observed with spinal cord epidural stimulation (scES). Hence, we studied how trunk-specific scES impacts sitting independence and posture. Fourteen individuals with chronic, severe cervical SCI with an implanted neurostimulator performed a 5-min tall-sit task without and with trunk-specific scES. Spine posture was assessed by placing markers on five spine levels and evaluating vertical spine inclination angles. Duration of trunk manual assistance was used to assess independence along with the number of independence changes and average independence score across those changes. With scES, the sacrum-L1 inclination and number of independence changes tended to decrease by 1.64 ± 3.16° (p = 0.07; Cohen's d = 0.53) and 9.86 ± 16.8 (p = 0.047; Cohen's d = 0.59), respectively. Additionally, for the participants who had poor sitting independence without scES, level of independence tended to increase by 12.91% [0%, 31.52%] (p = 0.38; Cohen's d = 0.96) when scES was present. Hence, trunk-specific scES promoted improvements in lower spine posture and lower levels of trunk assistance.

Inspiratory Muscle Performance Is Related to Seated Balance Function in People With Spinal Cord Injury: An Observational Study

OBJECTIVE

To examine the relationship between inspiratory muscle performance (IMP) and functional sitting balance (FSB) in persons with chronic spinal cord injury (SCI). We hypothesized that a moderate correlation would be found between IMP and FSB and that individuals with better balance would have better IMP.

DESIGN

The SCI-specific modification of the Function in Sitting Test (FIST-SCI) measured FSB. The IMP measures included (1) maximal inspiratory pressure (MIP), (2) sustained MIP (SMIP), and (3) inspiratory duration. Upper extremity motor score (UEMS) and level of injury (LOI) were taken from International Standards for Neurological Classification of Spinal Cord Injury examinations. Spearman correlational analyses assessed relationships among these factors in the sample (N=37). Mann-Whitney U tests explored differences between 2 comparison group pairs (tetraplegia group [TG] vs paraplegia group [PG]; independent transfer group [ITG] vs assisted transfer group [ATG]). Regression analysis examined variables predictive of FSB in the TG.

SETTING

Research facility.

PARTICIPANTS

Volunteers with tetraplegia (n=21, American Spinal Injury Association Impairment Scale (AIS) A=8, B=7, C=6) and paraplegia (n=16, AIS A=9, B=4, C=3) (N=37).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

IMP, LOI, UEMS, FIST-SCI.

RESULTS

UEMS, MIP, SMIP, and LOI had moderate to high correlations with FIST-SCI scores (ρ=0.720 (P<.001), 0.480 (P=.003), 0.467 (P=.004), 0.527 (P=.001), respectively). UEMS, MIP, and FIST-SCI scores were higher in the PG and ITG than the TG and ATG, respectively (PG vs. TG P values=<.001, .008, .002, respectively, and ITG vs. ATG P values=<.001, .032, <.001, respectively). Further, SMIP and UEMS predicted FIST-SCI balance scores in the TG, accounting for 55% of total variance (P<.001) (FIST-SCI=11.88+0.03 [SMIP]+0.425 [UEMS]).

CONCLUSIONS

The relationship between IMP and balance appears preserved after SCI. FSB was predicted, in part, via UEMS and SMIP in the TG. Future research should focus on the effect of SCI-based breathing interventions on FSB.

User-centered design and development of a trunk control device for persons with spinal cord injury: A pilot study

CONTEXT/OBJECTIVE

There are no wheelchair products designed to allow users to dynamically control trunk posture to both significantly improve functional reach and provide pressure relief during forward lean. This pilot study sought to (1) gather stakeholder desires regarding necessary features for a trunk control system and (2) subsequently develop and pilot test a first-generation trunk control prototype.

DESIGN

Multi-staged mixed methods study design.

SETTING

Minneapolis VA Health Care System, Minneapolis, MN.

PARTICIPANTS

Eight people with spinal cord injuries were recruited to participate in a focus group. Five participants returned to discuss, rate, and select a design concepts for prototype development. Two participants returned to test the first-generation trunk control prototype.

INTERVENTIONS

The focus group members selected a trunk control device design that uses backpack straps with a single cable as the most desired option. Our design team then manufactured the first-generation prototype at the Minneapolis VA.

OUTCOME MEASURES

Bimanual workspace capabilities (n = 1) and pressure map relief changes (n = 2) during supported forward lean were measured. Both participants also provided feedback on the trunk control devices usability.

RESULTS

Bimanual workspace (for Participant 1) was increased by 311% in the sagittal plane with use of the trunk control device as compared to without. Pressure relief during a forward lean was increased with an overall dispersion index reduction of 87.6% and 27.7% for Participant 1 and Participant 2 respectfully.

CONCLUSION

This pilot study successfully elicited desired features for a trunk control device from stakeholders and successfully developed and tested a first-generation trunk control prototype.

Effects of trunk muscle activation on trunk stability, arm power, blood pressure and performance in wheelchair rugby players with a spinal cord injury

Objective: In wheelchair rugby (WR) athletes with tetraplegia, wheelchair performance may be impaired due to (partial) loss of innervation of upper extremity and trunk muscles, and low blood pressure (BP). The objective was to assess the effects of electrical stimulation (ES)-induced co-contraction of trunk muscles on trunk stability, arm force/power, BP, and WR performance.Design: Cross-sectional study.Setting: Rehabilitation research laboratory and WR court.Participants: Eleven WR athletes with tetraplegia.Interventions: ES was applied to the rectus abdominis, obliquus externus abdominis and erector spinae muscles. For every test, the ES condition was compared to the non-ES condition.Outcome measures: Stability was assessed with reaching tasks, arm force/power with an isokinetic test on a dynamometer, BP during an ES protocol and WR skill performance with the USA Wheelchair Rugby Skill Assessment.Results: Overall reaching distance (ES 14.6 ± 7.5 cm, non-ES 13.4 ± 8.2 cm), and BP showed a significant increase with ES. Arm force (ES 154 ± 106 N, non-ES 148 ± 102 N) and power (ES 37 ± 26 W, non-ES 36 ± 25 W), and WR skills were not significantly improved.Conclusion: ES-induced trunk muscle activation positively affects trunk stability and BP, but not arm force/power. No effects were found in WR skill performance, probably due to abdominal strapping. More research is needed to assess different ES (training) protocols and longitudinal effects.

Case Report: Galvanic Vestibular Stimulation in the Chronic Spinal Cord Injury Patient

The traumatic spinal cord injury can generate sequels with high clinical severity and dysfunction and limitations of irreversible character. Current studies seek to reverse the sequelae and gain functionality in these individuals. Galvanic vestibular stimulation (GVS) has shown to be beneficial in spinal cord function as an evaluation correlated to functionality and for stimulation with physiological and functional characteristics in disease and healthy people. The present study observed the effects of Noise Galvanic Vestibular Stimulation in a patient with chronic spinal cord injury with tetraplegia on postural and trunk control. The evaluations were the Functional Independence Measure (FIM), the American Spinal Injury Association (ASIA) evaluation, and the Clinical Posturography, using force platform to assess postural balance, in the sitting position, through Sensory Organization and Functional Reach Tests. Ten sessions of Noise Galvanic Vestibular Stimulation associated with customized vestibular and neurofunctional rehabilitation were performed. The effects observed were increments in all assessments and tests that include modifications in functional independence, motor and sensory levels, change in disability grade from A (complete) to C (incomplete), and improvements in postural balance and trunk control. The phenomenon of stochastic resonance has shown benefits in postural control in people without vestibular lesions and we could observe some of these phenomena in our patients. We emphasize the need for evaluation with larger populations to observe the phenomena and effects in this group of patients and potential benefits and limitations.

Noninvasive spinal stimulation safely enables upright posture in children with spinal cord injury

In children with spinal cord injury (SCI), scoliosis due to trunk muscle paralysis frequently requires surgical treatment. Transcutaneous spinal stimulation enables trunk stability in adults with SCI and may pose a non-invasive preventative therapeutic alternative. This non-randomized, non-blinded pilot clinical trial (NCT03975634) determined the safety and efficacy of transcutaneous spinal stimulation to enable upright sitting posture in 8 children with trunk control impairment due to acquired SCI using within-subject repeated measures study design. Primary safety and efficacy outcomes (pain, hemodynamics stability, skin irritation, trunk kinematics) and secondary outcomes (center of pressure displacement, compliance rate) were assessed within the pre-specified endpoints. One participant did not complete the study due to pain with stimulation on the first day. One episode of autonomic dysreflexia during stimulation was recorded. Following hemodynamic normalization, the participant completed the study. Overall, spinal stimulation was well-tolerated and enabled upright sitting posture in 7 out of the 8 participants.

Scoliosis due to trunk muscle paralysis frequently requires surgical treatment in children with spinal cord injury. The authors demonstrate the safety and efficacy of transcutaneous spinal stimulation to enable upright sitting posture in 7/8 children with trunk control impairment in a within-subjects, repeated measures pilot clinical trial.

Properties of the surface electromyogram following traumatic spinal cord injury: a scoping review

Traumatic spinal cord injury (SCI) disrupts spinal and supraspinal pathways, and this process is reflected in changes in surface electromyography (sEMG). sEMG is an informative complement to current clinical testing and can capture the residual motor command in great detail-including in muscles below the level of injury with seemingly absent motor activities. In this comprehensive review, we sought to describe how the sEMG properties are changed after SCI. We conducted a systematic literature search followed by a narrative review focusing on sEMG analysis techniques and signal properties post-SCI. We found that early reports were mostly focused on the qualitative analysis of sEMG patterns and evolved to semi-quantitative scores and a more detailed amplitude-based quantification. Nonetheless, recent studies are still constrained to an amplitude-based analysis of the sEMG, and there are opportunities to more broadly characterize the time- and frequency-domain properties of the signal as well as to take fuller advantage of high-density EMG techniques. We recommend the incorporation of a broader range of signal properties into the neurophysiological assessment post-SCI and the development of a greater understanding of the relation between these sEMG properties and underlying physiology. Enhanced sEMG analysis could contribute to a more complete description of the effects of SCI on upper and lower motor neuron function and their interactions, and also assist in understanding the mechanisms of change following neuromodulation or exercise therapy.

The Relationship between Clinical Tests, Ultrasound Findings and Selected Field-Based Wheelchair Skills Tests in a Cohort of Quadriplegic Wheelchair Rugby Athletes: A Pilot Study

Manual wheelchair use may determine shoulder joint overload and rotator cuff injury. Chronic shoulder pathologies can also influence the propulsion ability of wheelchair athletes with spinal cord injury (SCI) during sport activities. However, the relationship between shoulder pathology and wheelchair performances has never been explored. Therefore, the study aimed to investigate the correlation between shoulder pathologic findings with clinical tests and ultrasonography evaluation and the results of wheelchair performance tests. Nineteen quadriplegic wheelchair rugby players were evaluated to investigate the association between clinical and ultrasound shoulder pathologic findings and their correlation with the performance of field-based selected wheelchair skills tests (WSTs). The outcome measures were the International Wheelchair Rugby Classification Score, dominant and non-dominant Physical Examination Shoulder Score, and dominant and non-dominant Ultrasound Shoulder Pathology Rating Scale (USPRS). The WST was measured at the beginning and at one-year follow-up. A statistically significant correlation was found between the time since SCI and dominant USPRS (p < 0.005). The non-dominant USPRS was strongly related to WST at the beginning (p < 0.005) and the end of the study (p < 0.05). Data suggest that the severity of the non-dominant shoulder pathology detected on the ultrasound is related to lower performance on the WST. Chronic manual wheelchair use could be responsible for dominant SCI shoulder joint and rotator cuff muscle damage, while non-dominant USPRS could be related to performance on the WST.

Energy cost and psychological impact of robotic-assisted gait training in people with spinal cord injury: effect of two different types of devices

BACKGROUND

In the last years, there has been an intense technological development of robotic devices for gait rehabilitation in spinal cord injury (SCI) patients. The aim of the present study was to evaluate energy cost and psychological impact during a rehabilitation program with two different types of robotic rehabilitation systems (stationary system on a treadmill, Lokomat, and overground walking system, Ekso GT).

METHODS

Fifteen SCI patients with different injury levels underwent robot-assisted gait training sessions, divided into 2 phases: in the first phase, all subjects completed 3 sessions both Lokomat and Ekso GT. Afterwards, participants were randomly assigned to Lokomat or the Ekso for 17 sessions. A questionnaire, investigating the subjective psychological impact (SPI) during gait training, was administered. The functional outcome measures were oxygen consumption (VO₂), carbon dioxide production (VCO₂), metabolic equivalent of task (MET), walking economy, and heart rate (HR).

RESULTS

The metabolic responses (7.73 ± 1.02 mL/kg/min) and MET values (3.20 ± 1.01) during robotic overground walking resulted to be higher than those during robotic treadmill walking (3.91 ± 0.93 mL/kg/min and 1.58 ± 0.44; p < 0.01). Both devices showed high scores in emotion and satisfaction. Overground walking resulted in higher scores of fatigue, mental effort, and discomfort while walking with Lokomat showed a higher score in muscle relaxation. All patients showed improvements in walking economy due to a decrease in energy cost with increased speed and workload.

CONCLUSIONS

Overground robotic-assisted gait training in rehabilitation program needs higher cognitive and cardiovascular efforts than robot-assisted gait training on a treadmill.

Postural control and the influence of the extent of thigh support on dynamic sitting balance among individuals with thoracic spinal cord injury

BACKGROUND

Unsupported sitting balance with reduced thigh support is necessary during several daily living activities among individuals with spinal cord injury. This study proposed to compare dynamic unsupported sitting postural control under reduced thigh support conditions in individuals with motor-complete thoracic spinal cord injury and able-bodied individuals.

METHODS

Thirteen individuals with spinal cord injury and thirteen able-bodied individuals were asked to put on a t-shirt and reach forward while sitting on a force platform using maximum, medium or minimum thigh support extent. Postural control was measured by the center of pressure parameters.

FINDINGS

Individuals with spinal cord injury presented larger postural sway parameters and mean velocity of the center of pressure displacement in anterior-posterior direction during the t-shirt wearing task. On the other hand, these parameters were lower in the medial-lateral direction. These results are more expressive when the task was performed in reduced thigh support conditions [F(1,76) = 5.05-18.70; p < 0.05]. Lower postural sway parameters and mean velocity of the center of pressure displacement in anterior-posterior, and postural sway in medial-lateral direction in the three thigh support conditions were observed when individuals with spinal cord injury performed the forward reaching task [F(1,76) = 9.81-185.46; p < 0.01].

INTERPRETATION

The results confirm that individuals with motor-complete thoracic spinal cord injury have poor postural stability and show a trunk postural sway constraint to maintain the suboptimal unsupported sitting balance. Reduced thigh support extent can challenge the dynamic sitting balance in individuals with thoracic spinal cord injury and should be indicated to train new and diversified postural control strategies.

The robotic Trunk-Support-Trainer (TruST) to measure and increase postural workspace during sitting in people with spinal cord injury

Study design

Cross-sectional study.

Objectives

To measure and expand the sitting workspace of participants with spinal cord injury (SCI) with the Trunk-Support-Trainer (TruST).

Setting

Columbia University.

Methods

TruST is a motorized-cable belt placed around the torso. Participants performed maximal trunk excursions along eight directions, radiating in a star-shape, to define their seated postural limits and workspace area (cm2). TruST was configured to apply "assist-as-needed" forces when the trunk moved beyond these postural limits. Kinematics were collected to examine trunk control. The clinical features of the sample (n = 5) were documented by neurological injury, dynamometry, the American Spinal Injury Association Impairment Scale, and Spinal Cord Independence Measure-III.

Results

Statistical significance was examined with paired t-tests. TruST successfully recreated the postural limits of participants and expanded their active sitting workspace (Mean: 123.3 ± SE: 42.8 cm2, p < 0.05). Furthermore, participants improved their trunk excursions to posterior (Mean: 5.1 ± SE: 0.8 cm, p < 0.01), right (Mean: 3.1 ± SE: 1.1 cm, p < 0.05), and left (Mean: 5.0 ± SE: 1.7 cm, p = 0.05) directions with TruST-force field.

Conclusions

TruST can accurately define and expand the active seated workspace of people with SCI during volitional trunk movements. The capacity of TruST to deliver continuous force-feedback at the user's postural limits opens new frontiers to implement motor learning-based paradigms to retrain functional sitting in people with SCI.

Specificity and variability of trunk kinematics on a mechanical horse

As perturbation training is gaining popularity, it is important to better understand postural control during complex three-dimensional stimuli. One clinically relevant and commonly used three-dimensional stimulus is found in hippotherapy and simulated hippotherapy on a mechanical horse. We tested nine healthy participants on a horse simulator, measured head and trunk kinematics, and characterized data in time (root-mean-square and variability) and frequency (amplitude spectra, gains, and phases) domains. We addressed three fundamental questions: 1) What is the specificity of postural responses to the simulator? 2) Which plane of motion is associated with the most and least variability (repeatable movements across repeated stimuli and across participants)? 3) To what extent are postural responses influenced by different degrees of stability (addition of pelvis straps and trunk support)? We found head and trunk responses were highly specific to the three-dimensional simulator perturbation direction and frequency. Frontal plane responses had the least variability across repetitions and participants whereas transverse motion was most variable. Head motion was more variable than the trunk at low frequencies and exhibited a marked decrease in tilt in the sagittal plane. Finally, the inclusion of pelvis straps had minimal effect on kinematics at low frequencies but altered higher frequencies; whereas added trunk support reduced head and trunk responses to perturbations and altered timing characteristics in all three planes. In conclusion, the present study suggests that frontal plane motion was under a high level of control, and results support the idea that specific head and trunk postural responses can be elicited from a complex three-dimensional stimuli, such as those found in hippotherapy. Researchers and clinicians can use results from this study to help interpret variability, implement mechanical adjustments to stability, and assess responses in pathological populations.

Overground walking with a robotic exoskeleton elicits trunk muscle activity in people with high-thoracic motor-complete spinal cord injury

Background

The trunk muscles are critical for postural control. Recent neurophysiological studies have revealed sparing of trunk muscle function in individuals with spinal cord injury (SCI) classified with thoracic or cervical motor-complete injuries. These findings raise the possibility for recruiting and retraining this spared trunk function through rehabilitation. Robotic gait training devices may provide a means to promote trunk muscle activation. Thus, the objective of this study was to characterize and compare the activation of the trunk muscles during walking with two robotic gait training devices (Ekso and Lokomat) in people with high thoracic motor-complete SCI.

Methods

Participants with chronic motor-complete paraplegia performed 3 speed-matched walking conditions: Lokomat-assisted walking, Ekso-assisted walking overground, and Ekso-assisted walking on a treadmill. Surface electromyography (EMG) signals were recorded bilaterally from the rectus abdominis (RA), external oblique (EO), and erector spinae (ES) muscles.

Results

Greater recruitment of trunk muscle EMG was elicited with Ekso-assisted walking compared to the Lokomat. Similar levels of trunk EMG activation were observed between Ekso overground and Ekso on the treadmill, indicating that differences between Ekso and Lokomat could not be attributed to the use of a hand-held gait aid. The level of trunk EMG activation during Lokomat walking was not different than that recorded during quiescent supine lying.

Conclusions

Ekso-assisted walking elicits greater activation of trunk muscles compared to Lokomat-assisted walking, even after controlling for the use of hand-held assistive devices. The requirement of the Ekso for lateral weight-shifting in order to activate each step could lead to better postural muscle activation.

Electronic supplementary material

The online version of this article (10.1186/s12984-018-0453-0) contains supplementary material, which is available to authorized users.

Movement variability in adults with low back pain during sit-to-stand-to-sit

BACKGROUND

Differences in movement variability may be related to a guarded response to pain or a less robust movement pattern, indicating a potential dysfunction in motor control. The study objective was to compare patterns of lumbo-pelvic coordinative variability, during repeated sit-to-stand-to-sit, in individuals with low back pain and healthy adults.

METHODS

Participants were adults with low back pain (n = 16) and healthy controls (n = 21). Kinematics for the T12-L3, L3-S1, and hip segments were measured using electromagnetic motion capture during 10 sit-to-stand-to-sit trials. Continuous relative phase analysis using the Hilbert transform method determined coordination and variability of the Hip-L3S1, and L3S1-T12L3 segments, deconstructed into 4 periods (start/up/down/end). T-tests compared coordination and variability of the full task between groups, and a mixed ANOVA compared the effects of group and period for the two segments.

FINDINGS

Across the full task, the low back pain group demonstrated more variable (mean difference = -6.95, 95% CI = -12.3 to -1.59) and greater out-of-phase behavior (mean difference = -22.6, 95% CI = -39.1 to -6.03) in the LHip-L3S1 segment. Group-period interaction effects revealed greater variability in the start period (mean difference = -0.325, 95% CI = -0.493 to -0.156) and more out-of-phase behavior in the start (mean difference = -0.350, 95% CI = -0.549 to -0.150) and end (mean difference = -0.354, 95% CI = -0.602 to -0.105) periods for the LHip-L3S1 segment.

INTERPRETATION

Excessive variability may relate to reports of poor spinal proprioception in low back pain; however, based on our sample characteristics (low pain and disability) and lack of symptoms during the task, classifying our findings as dysfunctional may not be fully warranted.

Trunk Stability Enabled by Noninvasive Spinal Electrical Stimulation after Spinal Cord Injury

Electrical neuromodulation of spinal networks improves the control of movement of the paralyzed limbs after spinal cord injury (SCI). However, the potential of noninvasive spinal stimulation to facilitate postural trunk control during sitting in humans with SCI has not been investigated. We hypothesized that transcutaneous electrical stimulation of the lumbosacral enlargement can improve trunk posture. Eight participants with non-progressive SCI at C3-T9, American Spinal Injury Association Impairment Scale (AIS) A or C, performed different motor tasks during sitting. Electromyography of the trunk muscles, three-dimensional kinematics, and force plate data were acquired. Spinal stimulation improved trunk control during sitting in all tested individuals. Stimulation resulted in elevated activity of the erector spinae, rectus abdominis, and external obliques, contributing to improved trunk control, more natural anterior pelvic tilt and lordotic curve, and greater multi-directional seated stability. During spinal stimulation, the center of pressure (COP) displacements decreased to 1.36 ± 0.98 mm compared with 4.74 ± 5.41 mm without stimulation (p = 0.0156) in quiet sitting, and the limits of stable displacement increased by 46.92 ± 35.66% (p = 0.0156), 36.92 ± 30.48% (p = 0.0156), 54.67 ± 77.99% (p = 0.0234), and 22.70 ± 26.09% (p = 0.0391) in the forward, backward, right, and left directions, respectively. During self-initiated perturbations, the correlation between anteroposterior arm velocity and the COP displacement decreased from r = 0.5821 (p = 0.0007) without to r = 0.5115 (p = 0.0039) with stimulation, indicating improved trunk stability. These data demonstrate that the spinal networks can be modulated transcutaneously with tonic electrical spinal stimulation to physiological states sufficient to generate a more stable, erect sitting posture after chronic paralysis.

Sensorimotor control of the trunk in sitting sway referencing

We developed a sway-referenced system for sitting to highlight the role of vestibular and visual contributions to trunk control. Motor control was investigated by measuring trunk kinematics in the frontal plane while manipulating visual availability and introducing a concurrent cognitive task. We examined motor learning on three timescales (within the same trial, minutes), within the same test session (1 h), and between sessions (1 wk). Posture sway was analyzed through time-based measures [root mean square (RMS) sway and RMS velocity], frequency-based measures (amplitude spectra), and parameterized feedback modeling. We found that posture differed in both magnitude and frequency distribution during sway referencing compared with quiet sitting. Modeling indicated that sway referencing caused greater uncertainty/noise in sensory feedback and motor outputs. Sway referencing was also associated with lower active stiffness and damping model parameters. The influence of vision and a cognitive task was more apparent during sway referencing compared with quiet sitting. Short-term learning was reflected by reduced RMS velocity in quiet sitting immediately following sway referencing. Longer term learning was evident from one week to the next, with a 23% decrease in RMS sway and 9% decrease in RMS velocity. These changes occurred predominantly during cognitive tests at lower frequencies and were associated with lower sensory noise and higher stiffness and integral gains in the model. With the findings taken together, the sitting sway-referenced test elicited neural changes consistent with optimal integration and sensory reweighting, similar to standing, and should be a valuable tool to closely examine sensorimotor control of the trunk. NEW & NOTEWORTHY We developed the first sway-referenced system for sitting to highlight the role of vestibular and visual contributions to trunk control. A parametric feedback model explained sensorimotor control and motor learning in the task with and between two test sessions. The sitting sway-referenced test elicited neural changes consistent with optimal integration and sensory reweighting, similar to standing, and should be a valuable tool to closely examine sensorimotor control of the trunk.

Clinical Instruments for Measuring Unsupported Sitting Balance in Subjects with Spinal Cord Injury: A Systematic Review

Background: Evidence of intervention effectiveness depends on, among other things, the use of a common set of valid and reliable measures that are responsive to change and reflect clinically important outcomes. Objective: To identify clinical assessment instruments with properties for measuring unsupported sitting balance in subjects with spinal cord injury (SCI). Methods: Bibliographic databases (PubMed, Science Direct, CINAHL, and Central) were searched for articles with the key words "spinal cord injury," "unsupported sitting," and "outcome assessment" in combination with a specific methodological search filter for each database. Studies describing the application of any assessment instrument for measuring unsupported sitting balance in subjects with SCI, which had the evaluation of any measurement property, were included in the review. Publication details, measure's name, setting, summary statistics, measurement properties (reliability, validity, responsiveness), and statistical significance (p values) were extracted. Results: Eight hundred forty publications were identified; 8 articles were included in the systematic review. Twelve instruments were identified and analyzed, showing limited and incomplete measurement properties. Among them, 10 addressed activity, 1 addressed structures/body functions, and 1 addressed both activity and structures/body functions domains of the International Classification of Functioning, Disability and Health (ICF). Conclusion: Based mainly on the measurement properties and the development of the instruments analyzed in this review, the Sitting Balance Measure, the Trunk Control Test, and the Set of Assessment Tools for Measuring Unsupported Sitting seem to be the most appropriate and recommended measures to assess unsupported sitting in subjects with SCI.

Paraplegic patients: how to measure balance and what is normal or functional?

PURPOSE

To review the current understanding and data of sagittal balance and alignment considerations in paraplegic patients.

METHODS

A PubMed literature search was conducted to identify all relevant articles relating to sagittal alignment and sagittal balance considerations in paraplegic and spinal cord injury patients.

RESULTS

While there are numerous studies and publications on sagittal balance in the ambulatory patient with spinal deformity or complex spine disorders, there is paucity of the literature on "normal" sagittal balance in the paraplegic patients. Studies have reported significantly alterations of the sagittal alignment parameters in the non-ambulatory paraplegic patients compared to ambulatory patients. The variability of the alignment changes is related to the differences in the level of the spinal cord injury and their differences in the activations of truncal muscles to allow functional movements in those patients, particularly in optimizing sitting and transferring. Surgical goal in treating paraplegic patients with complex pathologies should not be solely directed to achieve the "normal" radiographic parameters of sagittal alignment in the ambulatory patients. The goal should be to maintain good coronal balance to allow ideal sitting position and to preserve motion segment to optimize functions of paraplegia patients.

CONCLUSION

Current available literature data have not defined normal sagittal parameters for paraplegic patients. There are significant differences in postural sagittal parameters and muscle activations in paraplegic and non-spinal cord injury patients that can lead to differences in sagittal alignment and balance. Treatment goal in spine surgery for paraplegic patients should address their global function, sitting balance, and ability to perform self-care rather than the accepted radiographic parameters for adult spinal deformity in ambulatory patients.

Trunk Function and Ischial Pressure Offloading in Individuals with Spinal Cord Injury

OBJECTIVE

To determine if there is a relationship between trunk function and offloading of the ischial tuberosities in individuals with Spinal Cord Injury (SCI).

DESIGN

Prospective cross-sectional evaluation.

SETTING

Sub-acute rehabilitation hospital.

PARTICIPANTS

Fifteen non-ambulatory participants with complete or incomplete traumatic and non-traumatic SCI, American Spinal Injury Association Impairment Scale (AIS), Classification A-D.

OUTCOME MEASURES

Isometric trunk strength using a hand held dynamometer, the ability to reach using the multidirectional reach test and offloading times of the ischial tuberosities using a customized pressure mat.

RESULTS

Participants who were able to engage in the multidirectional reach test were defined as "Reachers", whereas individuals who were unable to engage in the multidirectional reach test were defined as "Non-Reachers". Trunk strength was significantly higher in Reachers compared with Non-Reachers (P < 0.05). Offloading times over the left and right ischial tuberosities were lower in Non-Reachers when compared with Reachers, however the results were statistically significant only for offloading over the right ischial tuberosity (P < 0.05). There was no correlation between trunk strength and pressure offloading times for both groups.

CONCLUSIONS

Regardless of an individual's ability to engage in a reaching task, participants with spinal cord injury spent more time offloading the left ischial tuberosity compared with the right ischial tuberosity. The study highlights the need to identify factors that may contribute to offloading behavior in individuals with spinal cord injury who lack sufficient trunk strength.

Spinal Cord Injury and Seated Postural Control: A Test of the Rambling and Trembling Hypothesis

Rambling-trembling analysis separates the center of pressure into two components: the rambling component (RM: supraspinal) and trembling component (TM: muscle stiffness/reflex). We hypothesized that persons with spinal cord injury (SCI) would demonstrate decreased RM resulting from altered supraspinal processing and increased TM resulting from increased muscle stiffness. We also anticipated that the TM component would be greater in SCI patients with Harrington rods than in those without them. The seated postural control was assessed in 18 persons with SCI, comprising 12 with and six without Harrington rods, and 18 age-matched controls. The SCI group had greater center of pressure sway, RM, and TM components than the controls, with no difference in the postural sway between the SCI subgroups, suggesting that the impairment of seated postural control in individuals with SCI results from disturbed supraspinal and peripheral mechanisms, but that the control itself is unaffected by internal fixation with Harrington rods. These were not entirely consistent with our hypothesis.

Modeling Wheelchair-Users Undergoing Vibrations

A procedure for modeling wheelchair-users undergoing vibrations was developed. Experimental data acquired with a wheelchair simulator were used to develop a model of a seated wheelchair user. Maximum likelihood estimation procedure was used to determine the model complexity required to characterize wheelchair-user's response. It was determined that a two segment rotational link model is adequate for characterization of vibratory response. The parameters of the proposed model were identified using the experimental data and verified using additional experimental results. The proposed approach can be used to develop subject-specific design criteria for wheelchair seating and suspension.

POSTURAL CONTROL ASSESSMENT IN PHYSICALLY ACTIVE AND SEDENTARY INDIVIDUALS WITH PARAPLEGIA

Objective:

The aim of this study was to evaluate functional independence and trunk control during maximum-range tasks in individuals with spinal cord injuries, who were divided into sedentary (SSI, n=10) and physically active (PASI, n=10) groups .

Methods:

Anamnesis was conducted and level and type of injury were identified (according to the American Spinal Injury Association protocol, ASIA) and the Functional Independence Measure (FIM) questionnaire was applied. For the forward and lateral reach task, the subjects were instructed to reach as far as possible. Mean data were compared using the unpaired t test and Mann-Whitney test and differences were considered significant when p<0.05 .

Results:

The PASI group performed better in self-care activities (PASI: 40.8±0.42 points, SSI: 38.0±3.58 points, p=0.01), sphincter control (PASI: 10.5±1.84 points, SSI: 8.2±3.04 points, p=0.02), transfers (PASI: 20.7±0.48 points, SSI: 16.9±4.27 points, p=0.04), and total FIM score (PASI: 104.0±2.30 points, SSI 105.1±8.56 points, p=0.01). On the maximum reach task, the PASI group had a greater average range in all directions evaluated (p<0.05) .

Conclusion:

The continuous practice of exercise increased motor function independence and trunk control in individuals with complete spinal cord injury. Level of Evidence II, Prospective Comparative Study.

Effects of Seated Postural Stability and Trunk and Upper Extremity Strength on Performance during Manual Wheelchair Propulsion Tests in Individuals with Spinal Cord Injury: An Exploratory Study

Objectives. To quantify the association between performance-based manual wheelchair propulsion tests (20 m propulsion test, slalom test, and 6 min propulsion test), trunk and upper extremity (U/E) strength, and seated reaching capability and to establish which ones of these variables best predict performance at these tests. Methods. 15 individuals with a spinal cord injury (SCI) performed the three wheelchair propulsion tests prior to discharge from inpatient SCI rehabilitation. Trunk and U/E strength and seated reaching capability with unilateral hand support were also measured. Bivariate correlation and multiple linear regression analyses allowed determining the best determinants and predictors, respectively. Results. The performance at the three tests was moderately or strongly correlated with anterior and lateral flexion trunk strength, anterior seated reaching distance, and the shoulder, elbow, and handgrip strength measures. Shoulder adductor strength-weakest side explained 53% of the variance on the 20-meter propulsion test-maximum velocity. Shoulder adductor strength-strongest side and forward seated reaching distance explained 71% of the variance on the slalom test. Handgrip strength explained 52% of the variance on the 6-minute propulsion test. Conclusion. Performance at the manual wheelchair propulsion tests is explained by a combination of factors that should be considered in rehabilitation.

Adapted sport effect on postural control after spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

The aim of this study was to compare trunk muscle activation during anterior and lateral reach in athletic and sedentary individuals with spinal cord injury (SCI) and able-bodied people.

SETTINGS

University Hospital-UNICAMP, Campinas, Brazil.

METHODS

Individuals with complete traumatic SCI and thoracic neurological level were separated into two groups: sedentary (SSCI: n=10) and physically active (PASCI: n=10). The control group (C: n=10) without SCI was assessed. Trunk muscle activation was recorded during reach and grasp tasks. The significant level was set at P<0.05.

RESULTS

The control group showed a highest mean activation for left longissimus muscle during all activities (P<0.05). The PASCI group presented significant highest activation for left iliocostalis muscles during all activities, except in the anterior reach task of 90% maximum reach (anterior reach (AR) 75: P=0.02; right lateral reach (RLR) 75: P=0.03; RLR90: P=0.01). The SSCI group presented highest activation for the left iliocostalis during the right lateral reach task of 75 and 90% maximum reach and right iliocostalis during the anterior reach task of 75% maximum reach (AR75: P=0.007; RLR75: P=0.02; RLR90: P=0.03). A different pattern of muscle activation between the control group and the groups with SCI was observed.

CONCLUSION

Our results indicated that sports practice did not affect the trunk muscle activation in people with paraplegia. However, the pattern muscle activation in individuals with SCI is different compared with people without SCI during anterior reach tasks.

Surface electromyography as a measure of trunk muscle activity in patients with spinal cord injury: a meta-analytic review

CONTEXT

Surface electromyography (SEMG) may be a sensitive marker for distinguishing the activity of trunk muscles, which are critical to functional mobility recovery in patients with spinal cord injury (SCI).

OBJECTIVES

This manuscript presents a systematic review and meta-analysis of the published literature on the effect of SEMG as a measure of trunk muscle activity in patients with SCI.

METHODS

A comprehensive search of the research literature included Pubmed, Medline, CNKI, WANFANG DATA, Web of Science, Elsevier, Wiley-Blackwell, Karger, OVID, and a review of reference lists within found articles. Case-control, cohort, and cross-sectional studies were included in the review.

RESULTS

Eleven studies were included in this meta-analysis. Trunk muscle activities for the sitting condition were greater in patients with SCI than normal subjects. SEMG activity of trunk muscles for the sitting condition and posterior transfer was greater in patients with high level (HL)-SCI compared to those with low level (LL)-SCI. In addition, across studies, the level of trunk muscle activity for various difficulty settings was different for a given SCI group.

CONCLUSION

This systematic review evaluated the value of trunk muscles for patients with SCI. We recommend use of SEMG as an assessment tool for improving the comparability and interpretability of trunk muscle activity of SCI therapeutic strategies.

Charcot spinal arthropathy: an increasing long-term sequel after spinal cord injury with no straightforward management

Charcot spinal arthropathy (CSA) is most likely increasing in patients suffering from consequences of spinal cord injury. We want to highlight initial symptoms, certain risk factors and perioperative complications of this condition. A single center retrospective case series in a specialized Center for Spinal Cord Injuries, BG Trauma Center Murnau, Germany highlighting the potential obstacles in the management of Charcot spine. We describe four female paraplegic patients (mean age: 50.75 years; range: 42-67), who developed Charcot spinal arthropathies. The mean age at the time of the accident was 21.5 years (3-35), the time lag after the accident before CSA was developed and finally diagnosed was on average 29.5 years (17-39) and the mean follow-up period was 39.5 months (6-73). Patient histories, initial symptoms, risk factors as well as the management and postoperative complications are provided. Charcot spine is an important potential sequel of spinal cord injury, which can lead to significant disability and spinal emergencies in affected individuals. More studies are needed to provide better recommendations for spine surgeons. Conservative treatment is an option. Posterior fixation alone does not seem to be sufficient.

Feasibility of closed-loop controller for righting seated posture after spinal cord injury

Spinal cord injury (SCI) can compromise the ability to maintain an erect seated posture. This study examined the feasibility of a sensor-based threshold controller to automatically modulate stimulation to paralyzed hip and trunk extensor muscles to restore upright sitting from forward leaning postures. Forward trunk tilt was estimated from the anterior-posterior component of gravitational acceleration sensed by a sternum-mounted wireless accelerometer. Stimulation increased if trunk tilt exceeded a specified flexion threshold and ceased once upright sitting was resumed. The controller was verified experimentally in five volunteers with SCI and successfully returned all subjects to upright postures from forward leaning positions. Upper-limb effort exerted while returning to erect posture was significantly reduced (to 7.4% +/- 3.7% of body mass) pooled across all volunteers while using the controller compared with using continuous and no stimulation (p < 0.03). Controller response times were consistent among subjects when applied while sitting with (0.30 +/- 0.05 s) or without a backrest (0.34 +/- 0.11 s). The controller enabled volunteers to lean farther forward (59.7° +/- 16.4°) in wheelchairs without upper-limb effort than with no stimulation. Clinical utility of the system for facilitating reach or preventing falls remains to be determined in future studies.

The impact of trunk impairment on performance of wheelchair activities with a focus on wheelchair court sports: a systematic review

BACKGROUND

Trunk impairment seems to impact significantly on performance in wheelchair court sports, but evidence to support this impression has never been systematically assessed. The objective of this study is to systematically review, describe and synthesise the literature investigating the impact of trunk impairment on wheelchair activities in court sports.

METHODS

This systematic review was performed according to the consensus statement for the meta-analysis of observational studies in epidemiology (MOOSE). The search strategy for original articles comprised Medline (1950- November 2014), Cinahl (1981-November 2014), and Embase (1980- November 2014), using the search terms: trunk, trunk muscles, postural balance, posture and wheelchair. Eligibility criteria for further review were 1) participants included experienced wheelchair users, 2) comparisons were made between a) participants with different levels of trunk impairment or b) between able bodied participants and participants with trunk impairment, or c) between participants with trunk impairment with and without compensatory equipment, and 3) outcome measures were quantitative data on wheelchair activities. For methodological quality assessment, the STROBE (Strengthening the reporting of observational studies in epidemiology) checklist was used.

RESULTS

After assessment of 358 potentially relevant studies for the eligibility criteria, 25 studies were appropriate for methodological assessment. Twelve articles fulfilled the predetermined minimum of 15 reported items on the 22-item STROBE checklist. These studies were limited to observational studies with small populations. All but one study were restricted to patients with spinal cord injury (SCI).

CONCLUSIONS

Limited evidence was found about the impact of trunk impairment on wheelchair activities. Reach to the front and multidirectional reach was further in able bodied persons than in persons with SCI. In a perturbation that equals deceleration in wheelchair court sports, able bodied persons maintain balance, whereas persons with SCI lose balance. No evidence was found to support a difference in acceleration between persons with partial trunk muscle strength and persons with full trunk muscle strength. For future research, there is a need for a test that includes all types of trunk impairment and identification of activities that determine performance in wheelchair court sports. Furthermore, populations of athletes with all trunk impairment types should be included.

Acute changes in soleus H-reflex facilitation and central motor conduction after targeted physical exercises

We tested the acute effect of exercises targeted simultaneously at cortical and brainstem circuits on neural transmission through corticobulbar connections. Corticobulbar pathways represent a potential target for rehabilitation after spinal cord injury (SCI), which tends to spare brainstem circuits to a greater degree than cortical circuits. To explore this concept, able-bodied volunteers (n=20) underwent one session each of three exercises targeted at different nervous system components: treadmill walking (spinal locomotor circuits), isolated balance exercise (brainstem and other pathways), and multimodal balance plus skilled hand exercise (hand motor cortex and corticospinal tract). We found that short-interval soleus H-reflex facilitation increased after one session of balance and multimodal exercise by 13.2±4.0% and 8.3±4.7%, and slightly decreased by 1.9±4.4% after treadmill exercise (p=0.042 on ANOVA across exercise type). Increases in long-interval H-reflex facilitation were not significantly different between exercises. Both balance and multimodal exercise increased central motor conduction velocity by 4.3±2.6% and 4.5±2.8%, whereas velocity decreased by 4.3±2.7% after treadmill exercise (p=0.045 on ANOVA across exercise type). In conclusion, electrophysiological transmission between the motor cortex and spinal motor neurons in able-bodied subjects increased more following one session of balance exercise than treadmill exercise.

Sitting tai chi improves the balance control and muscle strength of community-dwelling persons with spinal cord injuries: a pilot study

Objective. To investigate the effects of sitting Tai Chi on muscle strength, balance control, and quality of life (QOL) among survivors with spinal cord injuries (SCI). Methods. Eleven SCI survivors participated in the sitting Tai Chi training (90 minutes/session, 2 times/week for 12 weeks) and eight SCI survivors acted as controls. Dynamic sitting balance was evaluated using limits of stability test and a sequential weight shifting test in sitting. Handgrip strength was also tested using a hand-held dynamometer. QOL was measured using the World Health Organization's Quality of Life Scale. Results. Tai Chi practitioners achieved significant improvements in their reaction time (P = 0.042); maximum excursion (P = 0.016); and directional control (P = 0.025) in the limits of stability test after training. In the sequential weight shifting test, they significantly improved their total time to sequentially hit the 12 targets (P = 0.035). Significant improvement in handgrip strength was also found among the Tai Chi practitioners (P = 0.049). However, no significant within and between-group differences were found in the QOL outcomes (P > 0.05). Conclusions. Twelve weeks of sitting Tai Chi training could improve the dynamic sitting balance and handgrip strength, but not QOL, of the SCI survivors.

Effects of vision and lumbar posture on trunk neuromuscular control

The goal of this study was to determine the effects of vision and lumbar posture on trunk neuromuscular control. Torso perturbations were applied with a pushing device while the subjects were restrained at the pelvis in a kneeling-seated position. Torso kinematics and the muscle activity of the lumbar part of the M. Longissimus were recorded for 14 healthy subjects. Four conditions were included: a flexion, extension and neutral lumbar posture with eyes closed and the neutral posture with eyes open. Frequency response functions of the admittance and reflexes showed that there was no significant difference between the eyes open and eyes closed conditions, thereby confirming that vision does not play a role in the stabilization of the trunk during small-amplitude trunk perturbations. In contrast, manipulating posture did lead to significant differences. In particular, the flexed condition led to a lower admittance and lower reflex contribution compared to the neutral condition. Furthermore, the muscle pre-activation (prior to the onset of the perturbation) was significantly lower in the flexed posture compared to neutral. This confirms that flexing the lumbar spine increases the passive tissue stiffness and decreases the contribution of reflex activity to trunk control.

Sitting imbalance cause and consequence of post-traumatic Charcot spine in paraplegic patients

PURPOSE

To analyze the role of spine alignment in post-traumatic paraplegic patient as a potential cause of late Charcot spine disease (CSD).

METHOD

A retrospective review of three cases in which the disease appeared more than 15 years after a spinal cord injury treated by posterior fusion. A review of the literature concerning spine balance in sitting position, especially referred to paraplegic patients, is done to validate this hypothesis.

RESULTS

Lumbar kyphosis in paraplegic patients during the sitting position may increase the mechanical load on disks and ligament below the previously fused area. This phenomenon, in combination with lack of protective mechanism because of poor muscular support and lack of sensitivity can speed up and amplify the normal degenerative changes in the disk and ligaments.

CONCLUSIONS

More investigations are required to fully understand all the mechanisms underlying CSD pathogenesis to prevent it. Until then, a systematic long-term clinical and radiological follow-up in all post-trauma paraplegic patients is suggested. Combined anterior and posterior fusion, when feasible, can restore the sagittal balance providing a better quality of life in these patients.

Trajectories of musculoskeletal shoulder pain after spinal cord injury: Identification and predictors

OBJECTIVE/BACKGROUND

Although shoulder pain is a problem in up to 86% of persons with a spinal cord injury (SCI), so far, no studies have empirically identified longitudinal patterns (trajectories) of musculoskeletal shoulder pain after SCI. The objective of this study was: (1) to identify distinct trajectories of musculoskeletal shoulder pain in persons with SCI, and (2) to determine possible predictors of these trajectories.

DESIGN/METHODS

Multicenter, prospective cohort study in 225 newly injured persons with SCI.

OUTCOME MEASURE

Shoulder pain was assessed on five occasions up to 5 years after discharge. Latent class growth mixture modeling was used to identify the distinct shoulder pain trajectories.

RESULTS

Three distinct shoulder pain trajectories were identified: (1) a "No or Low pain" trajectory (64%), (2) a "High pain" (30%) trajectory, and (3) a trajectory with a "Decrease of pain" (6%). Compared with the "No or Low pain" pain trajectory, the "High pain" trajectory consisted of more persons with tetraplegia, shoulder pain before injury, limited shoulder range of motion (ROM), lower manual muscle test scores, or more spasticity at t1. Multiple logistic regression analysis showed two significant predictors for the "High pain" trajectory (as compared with the "No or Low pain" trajectory): having a tetraplegia (odds ratio (OR) = 3.2; P = 0.002) and having limited shoulder ROM (OR = 2.8; P = 0.007).

CONCLUSION

Shoulder pain in people with SCI follows distinct trajectories. At risk for belonging to the "High pain" trajectory are persons with tetraplegia and those with a limited shoulder ROM at start of active rehabilitation.

Interactions of touch feedback with muscle vibration and galvanic vestibular stimulation in the control of trunk posture

This study investigated the effect of touch on trunk sway in a seated position. Two touch conditions were included: touching an object with the index finger of the right hand (hand-touch) and maintaining contact with an object at the level of the spine of T10 on the mid back (back-touch). In both touch conditions, the exerted force stayed below 2N. Furthermore, the interaction of touch with paraspinal muscle vibration and galvanic vestibular stimulation (GVS) was studied. Thirteen healthy subjects with no history of low-back pain participated in this study. Subjects sat on a stool and trunk sway was measured with a motion capture system tracking a cluster marker on the trunk. Subjects performed a total of 12 trials of 60-s duration in a randomized order, combining the experimental conditions of no-touch, hand-touch or back-touch with no sensory perturbation, paraspinal muscle vibration or GVS. The results showed that touch through hand or back decreased trunk sway and decreased the effects of muscle vibration and GVS. GVS led to a large increase in sway whereas the effect of muscle vibration was only observed as an increase of drift and not of sway. In the current experimental set-up, the stabilizing effect of touch was strong enough to mask any effects of perturbations of vestibular and paraspinal muscle spindle afference. In conclusion, tactile information, whenever available, seems to play a dominant role in seated postural sway and therefore has important implications for studying trunk control.

Spinal cord injury and time to instability in seated posture

OBJECTIVE

To investigate seated postural control in persons with spinal cord injury (SCI) compared with age-matched controls.

DESIGN

Cohort.

SETTING

University research laboratory.

PARTICIPANTS

Adults (N=36; mean age ± SD, 22.5 ± 3.2y): 7 persons with high SCI (HI group; injury level greater than T10), 11 persons with low SCI (LI group; injury level between T10 and L4), and 18 persons with non-SCI.

INTERVENTION

Not applicable.

MAIN OUTCOMES MEASURES

Participants sat on a force platform on a custom-built wooden box with their arms by their side. Postural control was quantified in several ways. Participants completed a functional reach test. The amount of postural sway was quantified by characterizing the center of pressure (COP) trajectory by determining median velocity and root mean square of the signal. In addition, the virtual time to contact to the functional boundary was quantified. Last, the instability index was determined as the ratio of the COP area to the functional boundary.

RESULTS

There were no group differences in COP-based metrics (P>.05). There was no difference between SCI groups in functional reach (P>.05). The HI group had a smaller virtual time to contact (VTC) than the control group (.50 ± .20s vs .98 ± .24s, P<.05). Both SCI groups had a greater instability index than the control group, with the HI group having the largest amount of instability (P<.05).

CONCLUSIONS

The observations suggest that VTC analysis is appropriate to investigate seated postural control. It is proposed that including VTC of seated postural control as an outcome measure will provide novel information concerning the effectiveness of various rehabilitation approaches and/or technologies aimed at improving seated postural control in persons with SCI.

Sitting balance and limits of stability in persons with paraplegia

STUDY DESIGN

Cross-sectional, observational study of paraplegic and able-bodied persons.

OBJECTIVES

The aim of the study was to analyse the temporal and frequency domains of seated balance to better understand nervous system control in equilibrium in persons with spinal cord injury (SCI) and to explore their centre of pressure (CoP) limits before experiencing a fall.

SETTING

University of Valencia, Spain.

METHODS

Static and dynamic seated balance were assessed in 24 paraplegic persons divided into two groups: low paraplegia group (LP) and high paraplegia group (HP), and 24 healthy volunteers with an extensiometric force plate. Two types of tests were performed: a static test (ST), where data signal was analysed by temporal and frequency domains, and a stability limit test (SLT), where different stability limits were calculated.

RESULTS

The paraplegic group revealed lower static postural control in both domains in most of the parameters analysed compared with the control group (CG). Similar results were obtained with regard to the SLT, showing differences in the three parameters analysed between the CG and SCI groups.

CONCLUSION

Posturographic assessment in ST was useful to explore nervous system control in equilibrium in this population, presenting a decreased balance in paraplegic groups and an altered pattern in the sensorial and cerebellum bands compared with able-bodied individuals. Furthermore, SLT indicated less movement control of the CoP in paraplegic groups, which may influence the performance of their daily activities.

Which trunk inclination directions best predict multidirectional-seated limits of stability among individuals with spinal cord injury?

OBJECTIVE

To determine which trunk inclination directions most accurately predict multidirectional-seated limits of stability among individuals with spinal cord injury (SCI).

DESIGN

Predictive study using cross-sectional data.

SETTING

Pathokinesiology Laboratory.

PARTICIPANTS

Twenty-one individuals with complete or incomplete sensorimotor SCI affecting various vertebral levels participated in this study.

INTERVENTIONS

Participants were instructed to lean their trunk as far as possible in eight directions, separated by 45° intervals, while seated on an instrumented chair with their feet positioned on force plates.

OUTCOMES MEASURES

Eight direction-specific stability indices (DSIs) were used to define an overall stability index (OSI) (limits of stability).

RESULTS

All DSIs significantly correlated with the OSI (r = 0.816-0.925). A protocol that only tests the anterior, left postero-lateral, and right lateral trunk inclinations accurately predicts multidirectional-seated postural stability (r(2) = 0.98; P < 0.001).

CONCLUSION

Multidirectional-seated postural stability can be predicted almost perfectly by evaluating trunk inclinations performed toward the anterior, left postero-lateral, and right lateral directions.

Effects of upper limb positions and weight support roles on quasi-static seated postural stability in individuals with spinal cord injury

Seated postural stability has not been studied extensively in individuals with spinal cord injury (SCI). The main purpose of this study was to compare the effects of upper limb (U/L) positions and U/L weight support roles on quasi-static postural stability between individuals with SCI and healthy controls. Fourteen individuals with SCI and 14 healthy controls sat on an instrumented seat with their feet resting on force plates and randomly maintained five short-sitting positions for 60s with or without hand support. Center-of-pressure (COP) measures based on displacement and frequency series were computed. Individuals with SCI exhibited greater mean COP displacement and velocity measures compared to healthy controls, as well as lower COP frequency measures, irrespective of the U/L positions and weight support roles, confirming reduced stability and a difference in preferential postural regulation strategies. The use of U/L support is a compensatory strategy that influences seated stability in individuals with SCI.

Validation of the Brazilian version in Portuguese of the Thoracic-Lumbar Control Scale for spinal cord injury

STUDY DESIGN

Prospective clinical study.

OBJECTIVES

This study aimed to translate, adapting to Brazilian version in Portuguese, validate and measure inter and intra-examinator reliability and internal consistency of the Thoracic-Lumbar Control Scale instrument.

SETTING

State University of Campinas, São Paulo, Brazil.

METHODS

This instrument was translated to Brazilian Portuguese by a bilingual translator, and it was retranslated to English for conflict correction and cultural adaptation. Two physiotherapists were previously trained to standardize the scale administration. In all, 22 patients were selected and initially assessed through FIM and American Spinal Injury Association (ASIA) instruments. Furthermore, they were evaluated through the Thoracic-Lumbar Control Scale by two examiners and revaluated 1 week after by only one examinator.

RESULTS

The Brazilian Portuguese version of Thoracic-Lumbar Control Scale showed excellent intra and inter-examinator reliability (0.961 and 0.986), high value of internal consistence (0.934) and significant correlation with ASIA sensory score (r=0.83, P=0.001).

CONCLUSIONS

The Brazilian Portuguese version of Thoracic-Lumbar Control Scale is a valid and efficient instrument to assess trunk control of after-spinal cord injury patients, which certifies its replicability by other neurology professionals.

Quantitative analysis of the limits of stability in sitting

This study defines the limits of stability in sitting, and quantitatively assesses two measures of postural control relative to these limits. Young, healthy subjects sat, feet unsupported, on an elevated force plate. The limits of stability were determined by a least square fit of an ellipse to the center of pressure (CoP) excursion during maximal leaning in 8 directions. These were highly symmetrical and centered within the base of support. The ellipses had a mean eccentricity of 0.66 (major axis in the sagittal plane) and covered an area approximately 1/3 of the base of support. The CoP was then monitored over 4 min of quiet sitting, during which the postural sway covered an area<0.05% of the limits of stability and was closely centered within the latter. Finally, target-directed trunk movements were performed, in 5 directions, at 4 movement speeds and 3 target distances. Increased target distance and movement speed both decreased the margin of stability (distance between the CoP and the limits of stability), as did movement in the frontal plane, reflecting the eccentricity of the limits of stability. These combined findings support the validity of this quantitative method of defining the limits of stability in sitting, for healthy individuals.