The effects of trunk stimulation on bimanual seated workspace

Anatomical Registration of Implanted Sensors Improves Accuracy of Trunk Tilt Estimates with a Networked Neuroprosthesis

For individuals with spinal cord injuries (SCIs) above the midthoracic level, a common complication is the partial or complete loss of trunk stability in the seated position. Functional neuromuscular stimulation (FNS) can restore seated posture and other motor functions after paralysis by applying small electrical currents to the peripheral motor nerves. In particular, the Networked Neuroprosthesis (NNP) is a fully implanted, modular FNS system that is also capable of capturing information from embedded accelerometers for measuring trunk tilt for feedback control of stimulation. The NNP modules containing the accelerometers are located in the body based on surgical constraints. As such, their exact orientations are generally unknown and cannot be easily assessed. In this study, a method for estimating trunk tilt that employed the Gram-Schmidt method to reorient acceleration signals to the anatomical axes of the body was developed and deployed in individuals with SCI using the implanted NNP system. An anatomically realistic model of a human trunk and five accelerometer sensors was developed to verify the accuracy of the reorientation algorithm. Correlation coefficients and root mean square errors (RMSEs) were calculated to compare target trunk tilt estimates and tilt estimates derived from simulated accelerometer signals under a variety of conditions. Simulated trunk tilt estimates with correlation coefficients above 0.92 and RMSEs below 5° were achieved. The algorithm was then applied to accelerometer signals from implanted sensors installed in three NNP recipients. Error analysis was performed by comparing the correlation coefficients and RMSEs derived from trunk tilt estimates calculated from implanted sensor signals to those calculated via motion capture data, which served as the gold standard. NNP-derived trunk tilt estimates exhibited correlation coefficients between 0.80 and 0.95 and RMSEs below 13° for both pitch and roll in most cases. These findings suggest that the algorithm is effective at estimating trunk tilt with the implanted sensors of the NNP system, which implies that the method may be appropriate for extracting feedback signals for control systems for seated stability with NNP technology for individuals who have reduced control of their trunk due to paralysis.

Home-based arm cycling exercise improves trunk control in persons with incomplete spinal cord injury: an observational study

Arm cycling is used for cardiorespiratory rehabilitation but its therapeutic effects on the neural control of the trunk after spinal cord injury (SCI) remain unclear. We investigated the effects of single session of arm cycling on corticospinal excitability, and the feasibility of home-based arm cycling exercise training on volitional control of the erector spinae (ES) in individuals with incomplete SCI. Using transcranial magnetic stimulation, we assessed motor evoked potentials (MEPs) in the ES before and after 30 min of arm cycling in 15 individuals with SCI and 15 able-bodied controls (Experiment 1). Both groups showed increased ES MEP size after the arm cycling. The participants with SCI subsequently underwent a 6-week home-based arm cycling exercise training (Experiment 2). MEP amplitudes and activity of the ES, and movements of the trunk during reaching, self-initiated rapid shoulder flexion, and predicted external perturbation tasks were measured. After the training, individuals with SCI reached further and improved trajectory of the trunk during the rapid shoulder flexion task, accompanied by increased ES activity and MEP amplitudes. Exercise adherence was excellent. We demonstrate preserved corticospinal drive after a single arm cycling session and the effects of home-based arm cycling exercise training on trunk function in individuals with SCI.

Stabilizing leaning postures with feedback controlled functional neuromuscular stimulation after trunk paralysis

Spinal cord injury (SCI) can cause paralysis of trunk and hip musculature that negatively impacts seated balance and ability to lean away from an upright posture and interact fully with the environment. Constant levels of electrical stimulation of peripheral nerves can activate typically paralyzed muscles and aid in maintaining a single upright seated posture. However, in the absence of a feedback controller, such seated postures and leaning motions are inherently unstable and unable to respond to perturbations. Three individuals with motor complete SCI who had previously received a neuroprosthesis capable of activating the hip and trunk musculature volunteered for this study. Subject-specific muscle synergies were identified through system identification of the lumbar moments produced via neural stimulation. Synergy-based calculations determined the real-time stimulation parameters required to assume leaning postures. When combined with a proportional, integral, derivative (PID) feedback controller and an accelerometer to infer trunk orientation, all individuals were able to assume non-erect postures of 30-40° flexion and 15° lateral bending. Leaning postures increased forward reaching capabilities by 10.2, 46.7, and 16 cm respectively for each subject when compared with no stimulation. Additionally, the leaning controllers were able to resist perturbations of up to 90 N, and all subjects perceived the leaning postures as moderately to very stable. Implementation of leaning controllers for neuroprostheses have the potential of expanding workspaces, increasing independence, and facilitating activities of daily living for individuals with paralysis.

Neuromodulation for recovery of trunk and sitting functions following spinal cord injury: a comprehensive review of the literature

Trunk stability is crucial for people with trunk paralysis resulting from spinal cord injuries (SCI), as it plays a significant role in performing daily life activities and preventing from fall-related accidents. Traditional therapy used assistive methods or seating modifications to provide passive assistance while restricting their daily functionality. The recent emergence of neuromodulation techniques has been reported as an alternative therapy that could improve trunk and sitting functions following SCI. The aim of this review was to provide a broad perspective on the existing studies using neuromodulation techniques and identify their potentials in terms of trunk recovery for people with SCI. Five databases were searched (PubMed, Embase, Science Direct, Medline-Ovid, and Web of Science) from inception to December 31, 2022 to identify relevant studies. A total of 21 studies, involving 117 participants with SCI, were included in this review. According to these studies, neuromodulation significantly improved the reaching ability, restored trunk stability and seated posture, increased sitting balance, as well as elevated activity of trunk and back muscles, which were considered early predictors of trunk recovery after SCI. However, there is limited evidence regarding neuromodulation techniques on the improvement of trunk and sitting functions. Therefore, future large-scale randomized controlled trials are warranted to validate these preliminary findings.

Effects of trunk neuromuscular electrical stimulation on the motor circuits of able-bodied individuals

Upper- and lower-limb neuromuscular electrical stimulation (NMES) is known to modulate the excitability of the neural motor circuits. However, it remains unclear whether short-duration trunk muscle NMES could achieve similar neuromodulation effects. We assessed motor evoked potentials (MEPs) elicited through transcranial magnetic stimulation of the primary motor cortex representation of the trunk extensor muscles to evaluate corticospinal excitability. Moreover, cervicomedullary motor evoked potentials (CMEPs) were assessed through cervicomedullary junction magnetic stimulation to evaluate subcortical excitability. Twelve able-bodied individuals participated in the MEP study, and another twelve in the CMEP study. During the interventions, NMES was applied bilaterally to activate the erector spinae muscle and produce intermittent contractions (20 s ON/20 s OFF) for a total of 20 min while participants remained seated. Assessments were performed: (i) before; (ii) during (in brief periods when NMES was OFF); and (iii) immediately after the interventions to compare MEP or CMEP excitability. Our results showed that MEP responses were not affected by trunk NMES, while CMEP responses were facilitated for approximately 8 min during the intervention, and returned to baseline before the end of the 20 min stimulating period. Our findings therefore suggest that short-duration NMES of the trunk extensor muscles likely does not affect the corticospinal excitability, but it has a potential to facilitate subcortical neural circuits immediately after starting the intervention. These findings indicate that short-duration application of NEMS may be helpful in rehabilitation to enhance neuromodulation of the trunk subcortical neural motor circuits.

Feedback control of upright seating with functional neuromuscular stimulation during a reaching task after spinal cord injury: a feasibility study

BACKGROUND

Restoring or improving seated stability after spinal cord injury (SCI) can improve the ability to perform activities of daily living by providing a dynamic, yet stable, base for upper extremity motion. Seated stability can be obtained with activation of the otherwise paralyzed trunk and hip musculature with neural stimulation, which has been shown to extend upper limb reach and improve seated posture.

METHODS

We implemented a proportional, integral, derivative (PID) controller to maintain upright seated posture by simultaneously modulating both forward flexion and lateral bending with functional neuromuscular stimulation. The controller was tested with a functional reaching task meant to require trunk movements and impart internal perturbations through rapid changes in inertia due to acquiring, moving, and replacing objects with one upper extremity. Five subjects with SCI at various injury levels who had received implanted stimulators targeting their trunk and hip muscles participated in the study. Each subject was asked to move a weighted jar radially from a center home station to one of three target stations. The task was performed with the controller active, inactive, or with a constant low level of neural stimulation. Trunk pitch (flexion) and roll (lateral bending) angles were measured with motion capture and plotted against each other to generate elliptical movement profiles for each task and condition. Postural sway was quantified by calculating the ellipse area. Additionally, the mean effective reach (distance between the shoulder and wrist) and the time required to return to an upright posture was determined during reaching movements.

RESULTS

Postural sway was reduced by the controller in two of the subjects, and mean effective reach was increased in three subjects and decreased for one. Analysis of the major direction of motion showed return to upright movements were quickened by 0.17 to 0.32 s. A 15 to 25% improvement over low/no stimulation was observed for four subjects.

CONCLUSION

These results suggest that feedback control of neural stimulation is a viable way to maintain upright seated posture by facilitating trunk movements necessary to complete reaching tasks in individuals with SCI. Replication of these findings on a larger number of subjects would be necessary for generalization to the various segments of the SCI population.

Trunk Posture from Randomly Oriented Accelerometers

Feedback control of functional neuromuscular stimulation has the potential to improve daily function for individuals with spinal cord injuries (SCIs) by enhancing seated stability. Our fully implanted networked neuroprosthesis (NNP) can provide real-time feedback signals for controlling the trunk through accelerometers embedded in modules distributed throughout the trunk. Typically, inertial sensors are aligned with the relevant body segment. However, NNP implanted modules are placed according to surgical constraints and their precise locations and orientations are generally unknown. We have developed a method for calibrating multiple randomly oriented accelerometers and fusing their signals into a measure of trunk orientation. Six accelerometers were externally attached in random orientations to the trunks of six individuals with SCI. Calibration with an optical motion capture system resulted in RMSE below 5° and correlation coefficients above 0.97. Calibration with a handheld goniometer resulted in RMSE of 7° and correlation coefficients above 0.93. Our method can obtain trunk orientation from a network of sensors without a priori knowledge of their relationships to the body anatomical axes. The results of this study will be invaluable in the design of feedback control systems for stabilizing the trunk of individuals with SCI in combination with the NNP implanted technology.

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.

Sudden stop detection and automatic seating support with neural stimulation during manual wheelchair propulsion

Objective: Wheelchair safety is of great importance since falls from wheelchairs are prevalent and often have devastating consequences. We developed an automatic system to detect destabilizing events during wheelchair propulsion under real-world conditions and trigger neural stimulation to stiffen the trunk to maintain seated postures of users with paralysis.Design: Cross-over interventionSetting: Laboratory and community settingsParticipants: Three able-bodied subjects and three individuals with SCI with previously implanted neurostimulation systemsInterventions: An algorithm to detect wheelchair sudden stops was developed. This was used to randomly trigger trunk extensor stimulation during sudden stops eventsOutcome Measures: Algorithm success and false positive rates were determined. SCI users rated each condition on a seven-point Usability Rating Scale to indicate safety.Results: The system detected sudden stops with a success rate of over 93% in community settings. When used to trigger trunk neurostimulation to ensure stability, the implant recipients consistently reported feeling safer (P<.05 for 2/3 subjects) with the system while encountering sudden stops as indicated by a 1-3 point change in safety rating.Conclusion: These preliminary results suggest that this system could monitor wheelchair activity and only apply stabilizing neurostimulation when appropriate to maintain posture. Larger scale, unsupervised and longer-term trials at home and in the community are indicated. This system could be generalized and applied to individuals without an implanted stimulation by utilizing surface stimulation, or by actuating a mechanical restraint when necessary, thus allowing unrestricted trunk movements and only restraining the user when necessary to ensure safety.Trial Registration: NCT01474148.

The role of electrical stimulation for rehabilitation and regeneration after spinal cord injury

Electrical stimulation is used to elicit muscle contraction and can be utilized for neurorehabilitation following spinal cord injury when paired with voluntary motor training. This technology is now an important therapeutic intervention that results in improvement in motor function in patients with spinal cord injuries. The purpose of this review is to summarize the various forms of electrical stimulation technology that exist and their applications. Furthermore, this paper addresses the potential future of the technology.

Epidural Electrical Stimulation of the Lumbosacral Spinal Cord Improves Trunk Stability During Seated Reaching in Two Humans With Severe Thoracic Spinal Cord Injury

Background: Quality of life measurements indicate that independent performance of activities of daily living, such as reaching to manipulate objects, is a high priority of individuals living with motor impairments due to spinal cord injury (SCI). In a small number of research participants with SCI, electrical stimulation applied to the dorsal epidural surface of the spinal cord, termed epidural spinal electrical stimulation (ES), has been shown to improve motor functions, such as standing and stepping. However, the impact of ES on seated reaching performance, as well as the approach to identifying stimulation parameters that improve reaching ability, have yet to be described. Objective: Herein, we characterize the effects of ES on seated reaching performance in two participants with chronic, complete loss of motor and sensory functions below thoracic-level SCI. Additionally, we report the effects of delivering stimulation to discrete cathode/anode locations on a 16-contact electrode array spanning the lumbosacral spinal segments on reach distance while participants were seated on a mat and/or in their wheelchair. Methods: Two males with mid-thoracic SCI due to trauma, each of which occurred more than 3 years prior to study participation, were enrolled in a clinical trial at Mayo Clinic, Rochester, MN, USA. Reaching performance was assessed, with and without ES, at several time points throughout the study using the modified functional reach test (mFRT). Altogether, participant 1 performed 1,164 reach tests over 26-time points. Participant 2 performed 480 reach tests over 17-time points. Results: Median reach distances during ES were higher for both participants compared to without ES. Forward reach distances were greater than lateral reach distances in all environments, mat or wheelchair, for both participants. Stimulation delivered in the caudal region of the array resulted in improved forward reach distance compared to stimulation in the rostral region. For both participants, when stimulation was turned off, no significant changes in reach distance were observed throughout the study. Conclusion: ES enhanced seated reaching-performance of individuals with chronic SCI. Additionally, electrode configurations delivering stimulation in caudal regions of the lumbosacral spinal segments may improve reaching ability compared to rostral regions.

Crossed Corticospinal Facilitation Between Arm and Trunk Muscles Correlates With Trunk Control After Spinal Cord Injury

Objective: To investigate whether crossed corticospinal facilitation between arm and trunk muscles is preserved following spinal cord injury (SCI) and to elucidate these neural interactions for postural control during functional arm movements.

Methods: Using transcranial magnetic stimulation (TMS) in 22 subjects with incomplete SCI motor evoked potentials (MEPs) in the erector spinae (ES) muscle were examined when the contralateral arm was at rest or performed 20% of maximal voluntary contraction (MVC) of biceps brachii (BB) or triceps brachii (TB). Trunk function was assessed with rapid shoulder flexion and forward-reaching tasks.

Results: MEP amplitudes in ES were increased during elbow flexion in some subjects and this facilitatory effect was more prominent in subjects with thoracic SCI than in the subjects with cervical SCI. Those who showed the increased MEPs during elbow flexion had faster reaction times and quicker anticipatory postural adjustments of the trunk in the rapid shoulder flexion task. The onset of EMG activity in ES during the rapid shoulder flexion task correlated with the trunk excursion in forward-reaching.

Conclusions: Our findings demonstrate that crossed corticospinal facilitation in the trunk muscles can be preserved after SCI and is reflected in trunk control during functional arm movements.

Why brain-controlled neuroprosthetics matter: mechanisms underlying electrical stimulation of muscles and nerves in rehabilitation

Delivering short trains of electric pulses to the muscles and nerves can elicit action potentials resulting in muscle contractions. When the stimulations are sequenced to generate functional movements, such as grasping or walking, the application is referred to as functional electrical stimulation (FES). Implications of the motor and sensory recruitment of muscles using FES go beyond simple contraction of muscles. Evidence suggests that FES can induce short- and long-term neurophysiological changes in the central nervous system by varying the stimulation parameters and delivery methods. By taking advantage of this, FES has been used to restore voluntary movement in individuals with neurological injuries with a technique called FES therapy (FEST). However, long-lasting cortical re-organization (neuroplasticity) depends on the ability to synchronize the descending (voluntary) commands and the successful execution of the intended task using a FES. Brain-computer interface (BCI) technologies offer a way to synchronize cortical commands and movements generated by FES, which can be advantageous for inducing neuroplasticity. Therefore, the aim of this review paper is to discuss the neurophysiological mechanisms of electrical stimulation of muscles and nerves and how BCI-controlled FES can be used in rehabilitation to improve motor function.

Reliability and validity of the function in sitting test among non-ambulatory individuals with spinal cord injury

Context: Trunk impairment among non-ambulatory individuals with spinal cord injury (SCI) reduces the ability to maintain a functional sitting position and perform activities of daily living. Measuring functional sitting balance is complex and difficult in a clinical setting. The function in sitting test (FIST) is a clinical measure that includes the assessment of all the components of sitting balance. The purpose of this study is to assess the reliability and validity of the 14-item FIST among non-ambulatory individuals with SCI. Participants: Twenty-six individuals with chronic SCI. Outcome measures: Participants were evaluated with the FIST, the modified Functional Reach Test (lateral and forward mFRT) and a posturography assessment (virtual time to contact - VTC). The FIST was re-assessed during a second study visit 12 weeks later. Test-retest reliability was evaluated using intraclass coefficient correlation (ICC), the minimal detectable change (MDC) was calculated and the internal consistency reliability was assessed using Cronbach's coefficient-α. Concurrent validity of the FIST was also tested with the mFRT and the VTC. Results: Test-retest reliability was found to be excellent (ICC = 0.95) with a MDC of 4. The internal consistency was satisfactory (0.81). Moreover, the FIST correlates with the lateral mFRT (r = 0.64, P = 0.001) but not with the forward mFRT and the VTC. Conclusion: These observations provide evidence that the FIST is a reliable clinical measure with partially established validity for non-ambulatory individuals with SCI. Further studies are needed to strengthen the validity of the FIST and explore this measure in a larger sample.

A closed-loop self-righting controller for seated balance in the coronal and diagonal planes following spinal cord injury

Spinal cord injury (SCI) often results in loss of the ability to keep the trunk erect and stable while seated. Functional neuromuscular stimulation (FNS) can cause muscles paralyzed by SCI to contract and assist with trunk stability. We have extended the results of a previously reported threshold-based controller for restoring upright posture using FNS in the sagittal plane to more challenging displacements of the trunk in the coronal plane. The system was applied to five individuals with mid-thoracic or higher SCI, and in all cases the control system successfully restored upright sitting. The potential of the control system to maintain posture in forward-sideways (diagonal) directions was also tested in three of the subjects. In all cases, the controller successfully restored posture to erect. Clinically, these results imply that a simple, threshold based control scheme can restore upright sitting from forward, lateral or diagonal leaning without a chest strap; and that removal of barriers to upper extremity interaction with the surrounding environment could potentially allow objects to be more readily retrieved from around the wheelchair. Technical performance of the system was assessed in terms of three variables: response time, recovery time and percent maximum deviation from erect. Overall response and recovery times varied widely among subjects in the coronal plane (415±213 ms and 1381±883 ms, respectively) and in the diagonal planes (530±230 ms and 1800±820 ms, respectively). Average response time was significantly lower (p < 0.05) than the recovery time in all cases. The percent maximum deviation from erect was of the order of 40% or less for 9 out of 10 cases in the coronal plane and 5 out of 6 cases in diagonal directions.

The Effect of Functional Electrical Stimulation and Therapeutic Exercises on Trunk Muscle Tone and Dynamic Sitting Balance in Persons with Chronic Spinal Cord Injury: A Crossover Trial

Background and objectives: Functional electrical stimulation (FES) has shown good results in improving static and dynamic sitting balance in persons with spinal cord injuries. There is limited information about how regular surface FES combined with therapeutic exercise (TE) affect dynamic sitting balance and muscle tone. The objective of this study was to evaluate the effectiveness of a six-week physical therapy program consisting of FES and TE on muscle tone and sitting balance in persons with spinal cord injury (SCI). It was also important to explore the relationship between muscle tone and dynamic sitting balance. The third objective was to assess the change of characteristics over a six month period, when no intervention was carried out. Material and methods: Five men with SCI were alternately allocated to two study groups: SCI_FES+TE and SCI_TE. Eight healthy control group participants were recruited to collect reference data. SCI participants’ intervention lasted for six weeks in their homes. SCI_FES+TE conducted exercises with FES applied on erector spinae (ES) and rectus abdominis (RA) muscles. SCI_TE conducted exercises only. Muscle oscillation frequency (MOF; characterizing muscle tone) and limits of stability (LOS; characterizing sitting balance) were measured. A crossover study design was used. The time between the initial intervention and the crossover was seven months (ClinicalTrials registration ID NCT03517787). Results: MOF in SCI_FES+TE increased by 6.0% for ES and 6.1% for RA muscles. LOS of flexion increased 30.1% in SCI_FES+TE. Increase in lateral directions was similar for both study groups. Moderate to high negative correlation was found between MOF and LOS. After seven months, MOF of ES decreased 0.8%, MOF or RA decreased 1.4%, LOS of flexion decreased 31.9%, and LOS of lateral flexion to the left decreased 46.4%. Conclusions: The six-week therapy program combining FES and TE increased trunk muscle tone and dynamic sitting balance in flexion more than TE alone. Higher antagonist muscle tone negatively affects dynamic sitting balance and center of pressure (COP) trajectory distance in various directions. After seven months, a slight decline in trunk muscles tone values and an extensive decrease in sitting balance values were noticed.

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.

Postural regulatory strategies during quiet sitting are affected in individuals with thoracic spinal cord injury

Thoracic spinal cord injury (SCI) can have significant negative consequences, which can affect the ability to maintain unsupported sitting. The objectives of this study were to compare postural control of individuals with high- and low-thoracic SCI to able-bodied people and evaluate the effects of upper-limb support on postural control during quiet sitting. Twenty-five individuals were recruited into: (a) high-thoracic SCI; (b) low-thoracic SCI; and (c) able-body subgroups. Participants were seated and asked to maintain a steady balance in the following postures: (1) both hands resting on thighs; (2) both arms crossed over the chest; and (3) both arms extended. Center of pressure (COP) fluctuations were evaluated to compare postural performance between groups and different postures. Results showed that individuals with high- and low-thoracic SCI swayed more compared to the able-bodied group regardless of upper-limb support. No differences between the two SCI groups were observed, but the neurological level of injury was correlated to postural performance implying that those with higher injuries swayed more and faster. Unsupported sitting was more unstable in comparison to supported sitting posture, especially in the anterior-posterior direction. The velocity of postural sway was not different between groups, but the results suggest that postural regulation had unique effect during different postures in different groups. These results imply reduced postural stability after thoracic SCI. Overall, the way individuals with high-thoracic SCI achieved stability was different from that of individuals with low-thoracic SCI, suggesting different postural regulation strategies.

Phase-dependent deficits during reach-to-grasp after human spinal cord injury

Most cervical spinal cord injuries result in asymmetrical functional impairments in hand and arm function. However, the extent to which reach-to-grasp movements are affected in humans with incomplete cervical spinal cord injury (SCI) remains poorly understood. Using kinematics and electromyographic (EMG) recordings in hand and arm muscles we studied the different phases of unilateral self-paced reach-to-grasp movements (arm acceleration, hand opening and closing) to a small cylinder in the more and less affected arms of individuals with cervical SCI and in age-matched controls. We found that SCI subjects showed prolonged movement duration in both arms during arm acceleration, and hand opening and closing compared with controls. Notably, the more affected arm showed an additional increase in movement duration at the time to close the hand compared with the less affected arm. Also, the time at which the index finger and thumb contacted the object and the variability of finger movement trajectory were increased in the more compared with the less affected arm of SCI participants. Participants with prolonged movement duration during hand closing were those with more pronounced deficits in sensory function. The muscle activation ratio between the first dorsal interosseous and abductor pollicis brevis muscles decreased during hand closing in the more compared with the less affected arm of SCI participants. Our results suggest that deficits in movement kinematics during reach-to-grasp movements are more pronounced at the time to close the hand in the more affected arm of SCI participants, likely related to deficits in EMG muscle activation and sensory function. NEW & NOTEWORTHY Humans with cervical spinal cord injury usually present asymmetrical functional impairments in hand and arm function. Here, we demonstrate for the first time that deficits in movement kinematics during reaching and grasping movements are more pronounced at the time to close the hand in the more affected arm of spinal cord injury. We suggest that this is in part related to deficits in muscle activation ratios between hand muscles and a decrease in sensory function.

Trunk muscle co-activation using functional electrical stimulation modifies center of pressure fluctuations during quiet sitting by increasing trunk stiffness

BACKGROUND

The purpose of this study was to examine the impact of functional electrical stimulation (FES) induced co-activation of trunk muscles during quiet sitting. We hypothesized that FES applied to the trunk muscles will increase trunk stiffness. The objectives of this study were to: 1) compare the center of pressure (COP) fluctuations during unsupported and FES-assisted quiet sitting - an experimental study and; 2) investigate how FES influences sitting balance - an analytical (simulation) study.

METHODS

The experimental study involved 15 able-bodied individuals who were seated on an instrumented chair. During the experiment, COP of the body projected on the seating surface was calculated to compare sitting stability of participants during unsupported and FES-assisted quiet sitting. The analytical (simulation) study examined dynamics of quiet sitting using an inverted pendulum model, representing the body, and a proportional-derivative (PD) controller, representing the central nervous system control. This model was used to analyze the relationship between increased trunk stiffness and COP fluctuations.

RESULTS

In the experimental study, the COP fluctuations showed that: i) the mean velocity, mean frequency and the power frequency were higher during FES-assisted sitting; ii) the frequency dispersion for anterior-posterior fluctuations was smaller during FES-assisted sitting; and iii) the mean distance, range and centroidal frequency did not change during FES-assisted sitting. The analytical (simulation) study showed that increased mechanical stiffness of the trunk had the same effect on COP fluctuations as the FES.

CONCLUSIONS

The results of this study suggest that FES applied to the key trunk muscles increases the speed of the COP fluctuations by increasing the trunk stiffness during quiet sitting.

Bilateral reach-to-grasp movement asymmetries after human spinal cord injury

Cervical spinal cord injury (SCI) in humans typically damages both sides of the spinal cord, resulting in asymmetric functional impairments in the arms. Despite this well-accepted notion and the growing emphasis on the use of bimanual training strategies, how movement of one arm affects the motion of the contralateral arm after SCI remains unknown. Using kinematics and multichannel electromyographic (EMG) recordings we studied unilateral and bilateral reach-to-grasp movements to a small and a large cylinder in individuals with asymmetric arm impairments due to cervical SCI and age-matched control subjects. We found that the stronger arm of SCI subjects showed movement durations longer than control subjects during bilateral compared with unilateral trials. Specifically, movement duration was prolonged when opening and closing the hand when reaching for a large and a small object, respectively, accompanied by deficient activation of finger flexor and extensor muscles. In subjects with SCI interlimb coordination was reduced compared with control subjects, and individuals with lesser coordination between hands were those who showed prolonged times to open the hand. Although the weaker arm showed movement durations during bilateral compared with unilateral trials that were proportional to controls, the stronger arm was excessively delayed during bilateral reaching. Altogether, our findings demonstrate that during bilateral reach-to-grasp movements the more impaired arm has detrimental effects on hand opening and closing of the less impaired arm and that they are related, at least in part, to deficient control of EMG activity of hand muscles. We suggest that hand opening might provide a time to drive bimanual coordination adjustments after human SCI.

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.

Functional electrical stimulation and spinal cord injury

Spinal cord injuries (SCI) can disrupt communications between the brain and the body, resulting in loss of control over otherwise intact neuromuscular systems. Functional electrical stimulation (FES) of the central and peripheral nervous system can use these intact neuromuscular systems to provide therapeutic exercise options to allow functional restoration and to manage medical complications following SCI. The use of FES for the restoration of muscular and organ functions may significantly decrease the morbidity and mortality following SCI. Many FES devices are commercially available and should be considered as part of the lifelong rehabilitation care plan for all eligible persons with SCI.

Development of a control system for artificially rehabilitated limbs: a review

Development of an advanced control system for prostheses (artificial limbs) is necessary to provide functionality, effectiveness, and preferably the feeling of a sound living limb. The development of the control system has introduced varieties of control strategies depending on the application. This paper reviews some control systems used for prosthetics, orthotics, and exoskeletons. The advantages and limitations of different control systems for particular applications have been discussed and presented in a comparative manner to help in deciding the appropriate method for pertinent application.

Effects of intramuscular trunk stimulation on manual wheelchair propulsion mechanics in 6 subjects with spinal cord injury

OBJECTIVE

To quantify the effects of stabilizing the paralyzed trunk and pelvis with electrical stimulation on manual wheelchair propulsion.

DESIGN

Single-subject design case series with subjects acting as their own concurrent controls.

SETTING

Hospital-based clinical biomechanics laboratory.

PARTICIPANTS

Individuals (N=6; 4 men, 2 women; mean age ± SD, 46 ± 10.8y) who were long-time users (6.1 ± 3.9y) of implanted neuroprostheses for lower extremity function and had chronic (8.6 ± 2.8y) midcervical- or thoracic-level injuries (C6-T10).

INTERVENTIONS

Continuous low-level stimulation to the hip (gluteus maximus, posterior adductor, or hamstrings) and trunk extensor (lumbar erector spinae and/or quadratus lumborum) muscles with implanted intramuscular electrodes.

MAIN OUTCOME MEASURES

Pushrim kinetics (peak resultant force, fraction effective force), kinematics (cadence, stroke length, maximum forward lean), and peak shoulder moment at preferred speed over 10-m level surface; speed, pushrim kinetics, and subjective ratings of effort for level 100-m sprints and up a 30.5-m ramp of approximately 5% grade.

RESULTS

Three of 5 subjects demonstrated reduced peak resultant pushrim forces (P≤.014) and improved efficiency (P≤.048) with stimulation during self-paced level propulsion. Peak sagittal shoulder moment remained unchanged in 3 subjects and increased in 2 others (P<.001). Maximal forward trunk lean also increased by 19% to 26% (P<.001) with stimulation in these 3 subjects. Stroke lengths were unchanged by stimulation in all subjects, and 2 showed extremely small (5%) but statistically significant increases in cadence (P≤.021). Performance measures for sprints and inclines were generally unchanged with stimulation; however, subjects consistently rated propulsion with stimulation to be easier for both surfaces.

CONCLUSIONS

Stabilizing the pelvis and trunk with low levels of continuous electrical stimulation to the lumbar trunk and hip extensors can positively impact the mechanics of manual wheelchair propulsion and reduce both perceived and physical measures of effort.

The effects of combined trunk and gluteal neuromuscular electrical stimulation on posture and tissue health in spinal cord injury

OBJECTIVE

To investigate whether combined trunk and gluteal neuromuscular electrical stimulation (NMES) alters seated posture and improves pelvic tissue health in persons with a spinal cord injury.

DESIGN

Intervention study; case series.

SETTING

Research laboratory, medical center.

PARTICIPANTS

Seven persons with spinal cord injury recruited from a group of experienced implanted lower extremity NMES system users.

INTERVENTION

Combined trunk and gluteal NMES in the sitting position. Five minutes of preintervention sitting was assessed, followed by 5 minutes of NMES application, and then 5 minutes of postintervention.

MAIN OUTCOME MEASURES

Pelvic tissue health was evaluated by concurrently measuring transcutaneous oxygen tension (TcPO2) bilaterally over the ischia and the seating interface pressure (IP). TcPO2 data were binned into low (<10 mm Hg), medium (10-30 mm Hg), and high (>30 mm Hg) ranges, and the percentage time that TcPO2 was in each range was calculated. Ischial and sacral regions of interest were defined and the maximum region of interest and mean IP were determined, together with the maximum IP gradient for the entire contact area. Initial seating postures varied; 4 persons were initially sacral sitters. Tissue health responses to NMES were reviewed for sacral and nonsacral sitters.

RESULTS

For sacral sitters, the sacral region IP and the maximum IP gradient tended to decrease during NMES and increased again after the intervention. Mean ischial TcPO2 increased during NMES and remained elevated after the intervention, increasing high TcPO2 percentage time for 50% of the sacral sitters both during and after the intervention. Nonsacral sitters showed few changes in tissue health as the result of the application of NMES.

CONCLUSIONS

Trunk and gluteal stimulation acutely corrects anterior/posterior IP distribution, improving regional tissue health for sacral sitters. This correction requires constant application of NMES. The potential for positive changes in tissue health would be maximized by regular NMES use incorporating weight shifting.

Effects of stimulating hip and trunk muscles on seated stability, posture, and reach after spinal cord injury

OBJECTIVE

To determine the stimulated strength of the paralyzed gluteal and paraspinal muscles and their effects on the seated function of individuals with paralysis.

DESIGN

Case series with subjects acting as their own concurrent controls.

SETTING

Hospital-based clinical biomechanics laboratory.

PARTICIPANTS

Users (N=8) of implanted neuroprostheses for lower extremity function with low-cervical or thoracic level injuries.

INTERVENTIONS

Dynamometry and digital motion capture both with and without stimulation to the hip and trunk muscles.

MAIN OUTCOME MEASURES

Isometric trunk extension moment at 0°, 15°, and 30° of flexion; seated stability in terms of simulated isokinetic rowing; pelvic tilt, shoulder height, loaded and unloaded bimanual reaching to different heights, and subjective ratings of difficulty during unsupported sitting.

RESULTS

Stimulation produced significant increases in mean trunk extension moment (9.2±9.5Nm, P<.001) and rowing force (27.4±23.1N, P<.012) over baseline volitional values. Similarly, stimulation induced positive changes in average pelvic tilt (16.7±15.7°) and shoulder height (2.2±2.5cm) during quiet sitting and bimanual reaching, and increased mean reach distance (5.5±6.6cm) over all subjects, target heights, and loading conditions. Subjects consistently rated tasks with stimulation easier than voluntary effort alone.

CONCLUSIONS

In spite of considerable intersubject variability, stabilizing the paralyzed trunk with electrical stimulation can positively impact seated posture, extend forward reach, and allow exertion of larger forces on objects in the environment.

Developing functional workspace for the movement of trunk circumduction in healthy young subjects: a reliability study

Background

The lumbar range of motion has traditionally been used to assess disability in patients with low back disorders. Controversy exists about how movement ranges in static positions or in a single straight plane is related to the functional status of the patients. The trunk circumduction, as the result of neuromuscular coordination, is the integrated movements from three dimensions. The functional workspace stands for the volume of movement configuration from the trunk circumduction and represents all possible positions in three dimensions. By using single quantitative value, the functional workspace substitutes the complicated joint linear or angular motions. The aim of this study is to develop the functional workspace of the trunk circumduction (FWTC) considering possible functional positions in three dimensional planes. The reliability of the trunk circumduction is examined.

Methods

Test-retest reliability was performed with 18 healthy young subjects. A three-dimensional (3-D) Motion Analysis System was used to record the trunk circumduction. The FWTC was defined and calculated based on the volume of the cone that was formed as the resultant scanned area of markers, multiplied by the length of the body segment. The statistical analysis of correlation was performed to describe the relation of maximal displacements of trunk circumduction and straight planes: sagittal and coronal.

Results

The results of this study indicate that the movement of trunk circumduction measured by motion analysis instruments is a reliable tool. The ICC value is 0.90-0.96, and the means and standard deviations of the normalized workspace are: C7 0.425 (0.1162); L1 0.843 (0.2965); and knee 0.014 (0.0106). Little correlations between the maximal displacement of trunk circumduction and that of straight planes are shown and therefore suggest different movement patterns exist.

Conclusions

This study demonstrates high statistical reliability for the FWTC, which is important for the potential development as the functional assessment technique. The FWTC provides a single integrated value to represent angular and linear measurements of different joints and planes. Future study is expected to carry out the FWTC to evaluate the amount of workspace for the functional status of patients with low back injuries or patients with spinal surgery.

Postural bipedance in paraplegics under neuromuscular electrical stimulation: is it possible to improve it based on sagittal spinal alignment?

Study design

Experimental trial based on the analytical study of the radiographic standards of the sagittal spinal alignment in paraplegics in upright position under surface Neuromuscular Electrical Stimulation (NMES).

Objectives

To evaluate changes in radiographic standards of the sagittal spinal alignment of paraplegics under three different models of NMES used to optimize the global bipedal posture.

Setting

The University Hospital Ambulatory (UNICAMP), Campinas, SP, Brazil

Methods

Ten paraplegic patients were selected. Each patient underwent three different models of NMES. The influence that each NMES models exerted over the sagittal balance of the spine was evaluated by lateral panoramic x-rays. Wilcoxon’s Test was used to compare the modifications observed in each NMES model in the group studied.

Results

Using the femoral quadriceps muscles’ NMES as the starting point, the inclusion of the gluteus maximus’ NMES generated an increase of the lumbar lordosis and an decrease of the spinal tilt angle. These alterations resulted in partial improvement of the anterior sagittal imbalance. NMES of the paralyzed paravertebral lumbar muscles resulted in a more expressive increase on the lumbar lordosis with no important change on the spinal tilt. On the latter model, however, an improvement of 20% was observed in the global sagittal imbalance due to a posterior translation of the spine as pointed out by the decrease in the C7-HA horizontal distance.

Conclusions

The proposed NMES models were able to partially amend the anterior sagittal imbalance of the paraplegic patients in bipedal posture.

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.

Responses of the Trunk to Multidirectional Perturbations during Unsupported Sitting in Normal Adults

Understanding how the human body responds to unexpected force perturbations during quiet sitting is important to the science of motor behavior and the design of neuroprostheses for sitting posture. In this study, the performance characteristics of the neck and trunk in healthy individuals were assessed by measuring the kinematic responses to sudden, unexpected force perturbations applied to the thorax. Perturbations were applied in eight horizontal directions. It was hypothesized that displacement of the trunk, settling time and steady-state error would increase when the perturbation direction was diagonal (i.e., anterior-lateral or posterior-lateral) due to the increased complexity of asymmetrical muscle responses. Perturbation forces were applied manually. The neck and trunk responded in a synchronized manner in which all joints achieved peak displacement simultaneously then returned directly to equilibrium. Displacement in the direction of perturbation and perpendicular to the direction of perturbation were both significantly greater in response to diagonal perturbations (p < .001). The center of mass returned to equilibrium in 3.64 ± 1.42 s after the onset of perturbation. Our results suggest that the trunk sometimes behaves like an underdamped oscillator and is not controlled by simple stiffness when subjected to loads of approximately 200 N. The results of this study are intended to be used to develop a neuroprosthesis for artificial control of trunk stability in individuals with spinal cord injury.

Musculoskeletal model of trunk and hips for development of seated-posture-control neuroprosthesis

The paralysis resulting from spinal cord injury severely limits voluntary seated-posture control and increases predisposition to a number of health risks. We developed and verified a musculoskeletal model of the hips and lumbar spine using published data. We then used the model to select the optimal muscles for-and evaluate the likely functional recovery benefit of-an 8-channel seated-posture-control neuroprosthesis based on functional electrical stimulation (FES). We found that the model-predicted optimal muscle set included the erector spinae, oblique abdominals, gluteus maximus, and iliopsoas. We mapped muscle excitations to seated trunk posture so that the required excitations at any posture could be approximated using a static map. Using the optimal muscle set, the model predicted a maximum stimulated range of motion of 49 degrees flexion, 9 degrees extension, and 16 degrees lateral bend. In the nominal upright posture, the modeled user could hold almost 15 kg with arms at sides and elbows bent. We discuss in this article the practicality of using FES with the oblique abdominals. A seated-posture-control neuroprosthesis would increase the user's bimanual work space and include several secondary benefits.

Biomechanical analysis of functional electrical stimulation on trunk musculature during wheelchair propulsion

BACKGROUND

The objective of this study was to examine how surface electrical stimulation of trunk musculature influences the kinematic, kinetic, and metabolic characteristics, as well as shoulder muscle activity, during wheelchair propulsion.

METHODS

Eleven participants with spinal cord injury propelled their own wheelchairs on a dynamometer at a speed of 1.3 m/s for three 5-minute trials. During a propulsion trial, 1 of 3 stimulation levels (HIGH, LOW, and OFF) was randomly applied to the participant's abdominal and back muscle groups with a surface functional electrical stimulation device. Propulsion kinetics, trunk kinematics, metabolic responses, and surface electromyographic (EMG) activity of 6 shoulder muscles were collected synchronously. Kinetic, kinematic, and EMG variables were recorded during 3 time intervals (30 seconds each) within a 5-minute trial. Metabolic variables were recorded through the entire 5-minute trial.

RESULTS

Participants with HIGH stimulation increased their gross mechanical efficiency (P=.05) during wheelchair propulsion. No differences were found in shoulder EMG activity, energy expenditure, and trunk motion between stimulation levels.

CONCLUSION

Functional electrical stimulation on the trunk musculature has potential advantages in helping manual wheelchair users with spinal cord injury improve propulsion efficiency without placing additional demands on shoulder musculature.

Implanted electrical stimulation of the trunk for seated postural stability and function after cervical spinal cord injury: a single case study

OBJECTIVES

To explore and quantify the physical and functional effects of stabilizing the torso with electrical stimulation of the paralyzed hip and trunk musculature after motor complete tetraplegia.

DESIGN

Single-subject case study with repeated measures and concurrent controls.

SETTING

Academic outpatient rehabilitation center.

PARTICIPANTS

Forty-four-year-old man with C4 American Spinal Injury Association grade A tetraplegia 20 years postspinal cord injury.

INTERVENTION

A surgically implanted multichannel pulse generator and intramuscular stimulating electrodes to activate lumbar erector spinae, quadratus lumborum, and gluteus maximus muscles bilaterally.

MAIN OUTCOME MEASURES

Outcomes assessed with and without stimulation included (1) spinal alignment and pelvic orientation, (2) pulmonary function and ventilatory volumes, (3) forward bimanual reaching distance, (4) seated stability and resistance to externally applied disturbances, (5) maximal force and speed of rowing-like movements, and the ability to (6) independently return to an erect seated position from full forward or lateral flexion and (7) roll in bed without assistance.

RESULTS

Stimulation improved spinal convexity and kyphosis by 26 degrees and 21 degrees , reduced posterior pelvic tilt by 11 degrees , increased forced expiratory volume and vital capacity by 10% and 22%, and improved forward reach by more than 7cm. Average resistance to sagittal disturbances increased by more than 40% (P<.002), and mean force exerted during underhanded pulling more than doubled (P=.014) with stimulation. Restoration of upright sitting in both sagittal and coronal planes and bed turning was made possible through appropriately timed activation of the hip and trunk muscles.

CONCLUSIONS

A neuroprosthesis for controlling the paralyzed torso can positively impact spinal alignment, seated posture, pulmonary function, trunk stability, and reach. Stimulation of hip and trunk muscles can improve performance of activities of daily living as well as enable independent wheelchair and bed mobility.

Effect of thoracolumbosacral orthoses on reachable workspace volumes in children with spinal cord injury

BACKGROUND/OBJECTIVE

Wheelchair users often use trunk motion to facilitate or augment their upper extremity reach. Children with spinal cord injury (SCI) are often prescribed thoracic lumbar sacral orthoses (TLSO) to delay or prevent spinal curve progression. The impact of wearing a TLSO while reaching has not been studied. Therefore, the purpose of this study was to see the quantitative effect of the TLSO on reachable workspace volumes and reach of children with SCI.

METHODS

Twenty children with SCI aged 5 to 18 years participated in the present study. Three-dimensional upper extremity motion analysis was used to assess the reachable workspace patterns of children reaching for targets at varying heights. Volumes in and out of TLSO and kinematic ranges of reach were statistically analyzed using paired Student's t tests with a P value set at 0.05.

RESULTS

Reachable workspace volumes were significantly greater for the non-TLSO condition compared with the TLSO condition (112,836 vs. 80,711 cm3; P = 0.0002; a decrement of 28%). Anterior posterior and medial lateral ranges of reach were statistically greater in the non-TLSO condition (P = 0.002, P = 0.01). Nondominant hand medial lateral reaches were statistically greater in the non-TLSO condition (P = 0.003). Dominant hand anterior posterior reaches were greater in the non-TLSO condition (P = 0.009).

CONCLUSIONS

Results suggest the reachable workspace of children with SCI is lessened with the use of a TLSO. This may be an important negative factor for brace compliance in children with SCI. The TLSO interferes with their ability to reach; therefore, children may prefer not to wear the orthosis.