Relationship between Timed Up and Go performance and quantitative biomechanical measures of balance.

Traumatic brain injury (TBI) impairs sensory-motor functions, with debilitating consequences on postural control and balance, which persist during the chronic stages of recovery. The Timed Up and Go (TUG) test is a reliable, safe, time-efficient, and one of the most widely used clinical measures to assess gait, balance, and fall risk in TBI patients and is extensively used in inpatient and outpatient settings. Although the TUG test has been used extensively due to its ease of performance and excellent reliability, limited research has been published that investigates the relationship between TUG performance and quantitative biomechanical measures of balance. The objective of this paper was to quantify the relationship between biomechanical variables of balance and the TUG scores in individuals with chronic TBI. Regression models were constructed using six biomechanical variables to predict TUG scores. The model that conservatively removed gait speed (i.e., TUG-1/GS) gave the best results, achieving a root-mean-square error of ∼±2 s and explaining over 69% of the variability.

Enhancing Anticipatory and Compensatory Postural Responses to Improve Balance in Individuals with TBI.

Traumatic Brain Injury (TBI) is one of the leading causes of sensorimotor deficits in adults and often results in balance impairments. Two types of postural mechanisms are employed to achieve balance during perturbations: Anticipatory Postural Adjustments (APA) and Compensatory Postural Adjustments (CPA). People with TBI have reduced APA/CPA responses due to sensory-motor deficits from the injury. The objective of this feasibility study was to evaluate a Perturbation-based Balance Training program with visual cues (PBTvc) to target both APA/CPA responses to improve balance. The evaluation included biomechanical (reactive balance during random perturbation) and functional (Berg Balance Scale, Timed Up and Go and Falls Efficacy Scale) metrics. Preliminary data is presented for two participants with chronic TBI who received 16 sessions of PBTvc. The results show an improved range of trunk oscillation and time to stability during random perturbation tasks with corresponding improvements in Berg Balance Scale, Timed Up & Go, and Falls Efficacy Scale. The results suggest that PBTvc has the potential to improve APA/CPA mechanisms for functional recovery.Clinical Relevance- Preliminary data provides initial evidence for PBTvc as a therapeutic intervention for balance rehabilitation in adults with TBI.

Intensity Modulated Exoskeleton Gait Training Post Stroke.

Stroke is a leading cause of long-term disability. While major advances have been made in early intervention for the treatment of patients post stroke, the majority of survivors have residual mobility challenges. Recovery of motor function is dependent on the interrelationship between dosing, intensity, and task specific practice applied during rehabilitation. Robotic exoskeleton (RE) based gait training utilizes progressive repetitive task-oriented movements to promote functional recovery. The purpose of this investigation was to demonstrate the utilization of intensity modulated exoskeleton gait training on functional outcomes and walking speed post stoke. Preliminary data is presented for individuals diagnosed with stroke who received RE gait training. The intensity modulated RE gait training was delivered by a physical therapist and participants trained at 75-85% of calculated max heart rates at each session, over 10 weeks (30 sessions). After 10 weeks of training participants increased walking speed (10 meter walk test) and functional measures (timed up and go, berg balance assessment, dynamic gait index and functional ambulation category). These preliminary results demonstrate the utilization of intensity modulated gait training for improved functional ambulation and motor recovery using a robotic exoskeleton overground gait training post stroke.Clinical Relevance- Preliminary data provides initial evidence for intensity modulated exoskeleton gait training as a therapeutic intervention post stroke. More research is needed to demonstrate the potential relationships between intensity based gait training, exoskeletons and improved functional ambulation in post stroke rehabilitation.

Motor-Cognitive Virtual Reality Training to Improve Gait and Balance in Young Adults with TBI.

Traumatic Brain Injury (TBI) is one of the leading causes of motor and cognitive deficits in adults, and often results in motor control and balance impairments. Motor deficits include gait dysfunction and decreased postural control & coordination; leading to compromised functional ambulation and reduced quality of life. Research has shown that cognitive (attention and executive) function contributes to motor deficits and recovery. Hence, targeting the motor and the cognitive domains simultaneously by increasing cognitive and motor effort to perform the task may lead to improved ambulation recovery. The objective of this investigation was to evaluate the efficacy of simultaneous motor & cognitive training (MCT) using virtual reality to improve ambulation; assessed using biomechanical, cognitive, and functional outcomes. Preliminary data is presented for three participants with chronic TBI who received MCT. The results show improved cognition, speed, endurance, step length, gait cycle time, static & reactive balance, dual-task performance, and progression towards healthy ambulation. These preliminary results suggest that integrated cognitive motor training has the potential to induce functional recovery in young adults with TBI.Clinical Relevance - Preliminary data provides initial evidence for MCT as a therapeutic intervention for gait and balance rehabilitation in young adults with TBI.

Lower extremity robotic exoskeleton devices for overground ambulation recovery in acquired brain injury-A review.

Acquired brain injury (ABI) is a leading cause of ambulation deficits in the United States every year. ABI (stroke, traumatic brain injury and cerebral palsy) results in ambulation deficits with residual gait and balance deviations persisting even after 1 year. Current research is focused on evaluating the effect of robotic exoskeleton devices (RD) for overground gait and balance training. In order to understand the device effectiveness on neuroplasticity, it is important to understand RD effectiveness in the context of both downstream (functional, biomechanical and physiological) and upstream (cortical) metrics. The review identifies gaps in research areas and suggests recommendations for future research. We carefully delineate between the preliminary studies and randomized clinical trials in the interpretation of existing evidence. We present a comprehensive review of the clinical and pre-clinical research that evaluated therapeutic effects of RDs using various domains, diagnosis and stage of recovery.

Assessing the Cognitive Demand of Hand Controlled Exoskeleton Walking.

Individuals with spinal cord injury have motor and sensory deficits leading to ambulatory problems. Our current research is focused on developing innovative control mechanisms for wearable robotic exoskeletons to provide such users with complete control of their gait while allowing them to perform other activities (such as conversing, etc.). In this study, we evaluated the cognitive load due to using the user's hand movement to control the gait of a robot using a dual-task paradigm. The results show that there was no difference in symmetry and duty cycle between with and without a competing cognitive task, and the number of cognitive responses was similar to healthy controls walking on the treadmill. There was also no difference in obstacle navigation with and without the cognitive task. Results of this study suggest that using our control mechanisms is intuitive, easy to learn, and requires cognitive attention that is similar to normal human walking. Clinical Relevance-Initial evidence to understand the effects of the novel control mechanism on cognitive load over that of typical walking.

Changes in Center of Pressure after Robotic Exoskeleton Gait Training in Adults with Acquired Brain Injury.

Acquired brain injury (ABI) resulting in hemiplegia, is one of the leading causes of gait and balance deficits in adults. Gait and balance deficits include reduced momentum for forward progression, reduced step length, increased spatial and temporal asymmetry, and decreased speed; resulting in reduced functional ambulation, activities of daily living, and quality of life. Wearable lower extremity robotic exoskeletons (REs) are becoming an effective method for gait neurorehabilitation in individuals with ABI. REs can provide high dose, consistent, goal-directed repetition of movements as well as balance & stability for individuals with ABI. The objective of this study is to understand the effect of RE gait training using center of pressure (COP) displacement, temporal & spatial parameters, and functional outcomes for individuals with ABI. The results from this investigation show improved anterior-posterior COP displacement & rate of progression, spatial symmetry, step length, walking speed, and decreased time during the gait cycle. These preliminary results suggest that high dose, repetitive gait training using robotic exoskeletons has the potential to induce recovery of function in adults diagnosed with ABI.

Utilization of Robotic Exoskeleton for Overground Walking in Acute and Chronic Stroke.

Stroke commonly results in gait deficits which impacts functional ambulation and quality of life. Robotic exoskeletons (RE) for overground walking are devices that are programmable to provide high dose and movement-impairment specific assistance thus offering new rehabilitation possibilities for recovery progression in individuals post stroke. The purpose of this investigation is to present preliminary utilization data in individuals with acute and chronic stroke after walking overground with an RE. Secondary analysis on a subset of individuals is presented to understand the mechanistic changes due to RE overground walking. Thirty-eight participants with hemiplegia secondary to stroke were enrolled in a clinical trial conducted at eight rehabilitation centers. Data is presented for four sessions of overground walking in the RE over the course of 2 weeks. Participants continued their standard of care if they had any ongoing therapy at the time of study enrollment. Gait speed during the 10 Meter Walk Test, Gait deviations and the Functional Ambulation Category (FAC) data were collected before (baseline) and after (follow-up) the RE walking sessions. Walking speed significantly increased between baseline and follow-up for participants in the chronic (p <0.01) and acute (p < 0.05) stage of stroke recovery. FAC level significantly improved (p < 0.05) and there were significantly fewer (p < 0.05) gait deviations observed for participants in the acute stages of stroke recovery between baseline and follow-up. Secondary analysis on a subset of eight participants indicated that after four sessions of overground walking with the RE, the participants significantly improved their spatial symmetry. The walk time, step count and ratio of walk time to up time increased from first session to the last session for participants in the chronic and acute stages of stroke. The RE was effectively utilized for overground walking for individuals with acute and chronic stroke with varying severity levels. The results demonstrated an increase in walking speed, improvement in FAC and a decrease in gait deviations (from baseline to follow-up) after four sessions of overground walking in the RE for participants. In addition, preliminary data indicated that spatial symmetry and step length also improved after utilization of an RE for overground walking.

Effect of robotic exoskeleton gait training during acute stroke on functional ambulation.

BACKGROUND: Stroke is a leading cause of disability resulting in long-term functional ambulation deficits. Conventional therapy can improve ambulation, but may not be able to provide consistent, high dose repetition of movement, resulting in variable recovery with residual gait deviations. OBJECTIVE: The objective of this preliminary prospective investigation is to evaluate the ability of a robotic exoskeleton (RE) to provide high dose gait training, and measure the resulting therapeutic effect on functional ambulation in adults with acute stroke. METHODS: Participants (n = 14) received standard of care (SOC) and RE overground gait training during their scheduled physical therapy (PT) sessions at the same inpatient rehabilitation facility. The outcome measures included distance walked during their PT training sessions (RE and SOC), and functional ambulation measures (10-meter walk test (10MWT), 6-minute walk test (6 MWT), and timed up and go (TUG)). RESULTS: The average total distance walked during RE and the average distance per RE session was significantly higher than SOC sessions. Total walking distance during PT (RE+SOC) showed a strong positive correlation to the total number of steps during RE sessions and number of RE sessions. All functional ambulation measures showed significant improvement at follow-up compared to baseline. The improvement in functional ambulation measures showed a positive correlation with the increase in number of RE gait training sessions. CONCLUSION: The RE can be utilized for inpatient rehabilitation in conjunction with SOC gait training sessions and may result in improved functional ambulation in adults with acute stroke. This preliminary research provides information on the ability of the robotic exoskeleton to provide high dose therapy and its therapeutic effect on functional ambulation in adults with acute stroke during inpatient rehabilitation.

Robotic Exoskeleton Gait Training During Acute Stroke Inpatient Rehabilitation.

Stroke is the leading cause of severe disability in adults resulting in mobility, balance, and coordination deficits. Robotic exoskeletons (REs) for stroke rehabilitation can provide the user with consistent, high dose repetition of movement, as well as balance and stability. The goal of this intervention study is to evaluate the ability of a RE to provide high dose gait therapy and the resulting effect on functional recovery for individuals with acute stroke. The investigation included a total of 44 participants. Twenty-two participants received RE gait training during inpatient rehabilitation (RE+SOC Group), and a matched sample of 22 individuals admitted to the same inpatient rehabilitation facility-receiving conventional standard of care treatment (SOC group). The effect of RE training was quantified using total distance walked during inpatient rehabilitation and functional independence measure (FIM). The total distance walked during inpatient rehabilitation showed a significant difference between the SOC and RE+SOC groups. RE+SOC walked twice the distance as SOC during the same duration (time spent in inpatient rehabilitation) of training. In addition, the average change in motor FIM showed a significant difference between the SOC and RE+SOC groups, where the average difference in motor FIM was higher in RE+SOC compared to the SOC group. The results suggest that RE provided increased dosing of gait training without increasing the duration of training during acute stroke rehabilitation. The RE+SOC group increased their motor FIM score (change from admission to discharge) compared to SOC group, both groups were matched for admission motor FIM scores suggesting that increased dosing may have improved motor function.

Kinetic Gait Changes after Robotic Exoskeleton Training in Adolescents and Young Adults with Acquired Brain Injury.

BACKGROUND: Acquired brain injury (ABI) is one of the leading causes of motor deficits in children and adults and often results in motor control and balance impairments. Motor deficits include abnormal loading and unloading, increased double support time, decreased walking speed, control, and coordination. These deficits lead to diminished functional ambulation and reduced quality of life. Robotic exoskeletons (RE) for motor rehabilitation can provide the user with consistent, symmetrical, goal-directed repetition of movement, as well as balance and stability. PURPOSE: The goal of this preliminary prospective before and after study is to evaluate the therapeutic effect of RE training on the loading/unloading and spatial-temporal characteristics in adolescents and young adults with chronic ABI. METHOD: Seven participants diagnosed with ABI between the ages of 14 and 27 years participated in the study. All participants received twelve 45 minute sessions of RE gait training. The bilateral loading (linearity of loading and rate of loading), speed, step length, swing time, stance time, and total time were collected using Zeno™ walkway (ProtoKinetics, Havertown, PA, USA) before and after RE training. RESULTS: Results from the study showed improved step length, speed, and an overall progression towards healthy bilateral loading, with linearity of loading showing a significant therapeutic effect (p < 0.05). CONCLUSION: These preliminary results suggest that high dose, repetitive, consistent gait training using RE has the potential to induce recovery of function in adolescents and young adults diagnosed with ABI.

Alterations in Cortical Activity due to Robotic Gait Training in Traumatic Brain Injury.

Traumatic brain injury (TBI), is one of the leading causes of motor deficits in children and adults, affecting motor control, coordination, and acuity. This results in reduced functional ambulation and quality of life. Robotic exoskeletons (REs) are quickly becoming an effective method for gait neurorehabilitation in individuals with TBI. Neurorehabilitation is based on the principle that the human brain is capable of reorganization due to high dose motor training. Understanding the underlying mechanisms of cortical reorganization will help improve current rehabilitation. The objective of the study is to understand the cortical activity differences due to RE training and recovery of functional ambulation for individuals with chronic TBI, using functional near-infrared spectroscopy. There was an increase in cortical activation in the prefrontal cortex (PFC), bilateral premotor cortex (PMC) and motor cortex (M1) while walking with RE versus without RE at follow-up. Furthermore, decreased activation was observed in PFC, bilateral PMC and M1 from baseline to follow-up while walking without RE with a corresponding improvement in functional ambulation. These preliminary results for one participant provide initial evidence to understand the cortical mechanisms during RE gait training and the recovery induced due to the training.

Evaluating Sensory Acuity as a Marker of Balance Dysfunction After a Traumatic Brain Injury: A Psychophysical Approach.

There is limited research on sensory acuity i.e., ability to perceive external perturbations via body-sway during standing in individuals with a traumatic brain injury (TBI). It is unclear whether sensory acuity diminishes after a TBI and if it is a contributing factor to balance dysfunction. The objective of this investigation is to first objectively quantify the sensory acuity in terms of perturbation perception threshold (PPT) and determine if it is related to functional outcomes of static and dynamic balance. Ten individuals with chronic TBI and 11 age-matched healthy controls (HC) performed PPT assessments at 0.33, 0.5, and 1 Hz horizontal perturbations to the base of support in the anterior-posterior direction, and a battery of functional assessments of static and dynamic balance and mobility [Berg balance scale (BBS), timed-up and go (TUG) and 5-m (5MWT) and 10-m walk test (10MWT)]. A psychophysical approach based on Single Interval Adjustment Matrix Protocol (SIAM), i.e., a yes-no task, was used to quantify the multi-sensory thresholds of perceived external perturbations to calculate PPT. A mixed-design analysis of variance (ANOVA) and post-hoc analyses were performed using independent and paired t-tests to evaluate within and between-group differences. Pearson correlation was computed to determine the relationship between the PPT and functional measures. The PPT values were significantly higher for the TBI group (0.33 Hz: 2.97 ± 1.0, 0.5 Hz: 2.39 ± 0.7, 1 Hz: 1.22 ± 0.4) compared to the HC group (0.33 Hz: 1.03 ± 0.6, 0.5 Hz: 0.89 ± 0.4, 1 Hz: 0.42 ± 0.2) for all three perturbation frequencies (p < 0.006 post Bonferroni correction). For the TBI group, the PPT for 1 Hz perturbations showed significant correlation with the functional measures of balance (BBS: r = -0.66, p = 0.037; TUG: r = 0.78, p = 0.008; 5MWT: r = 0.67, p = 0.034, 10MWT: r = 0.76, p = 0.012). These findings demonstrate that individuals with TBI have diminished sensory acuity during standing which may be linked to impaired balance function after TBI.

A Novel User Control for Lower Extremity Rehabilitation Exoskeletons.

Lower extremity exoskeletons offer the potential to restore ambulation to individuals with paraplegia due to spinal cord injury. However, they often rely on preprogrammed gait, initiated by switches, sensors, and/or EEG triggers. Users can exercise only limited independent control over the trajectory of the feet, the speed of walking, and the placement of feet to avoid obstacles. In this paper, we introduce and evaluate a novel approach that naturally decodes a neuromuscular surrogate for a user's neutrally planned foot control, uses the exoskeleton's motors to move the user's legs in real-time, and provides sensory feedback to the user allowing real-time sensation and path correction resulting in gait similar to biological ambulation. Users express their desired gait by applying Cartesian forces via their hands to rigid trekking poles that are connected to the exoskeleton feet through multi-axis force sensors. Using admittance control, the forces applied by the hands are converted into desired foot positions, every 10 milliseconds (ms), to which the exoskeleton is moved by its motors. As the trekking poles reflect the resulting foot movement, users receive sensory feedback of foot kinematics and ground contact that allows on-the-fly force corrections to maintain the desired foot behavior. We present preliminary results showing that our novel control can allow users to produce biologically similar exoskeleton gait.

Kinematic and Functional Gait Changes After the Utilization of a Foot Drop Stimulator in Pediatrics.

Foot drop is one of the most common secondary conditions associated with hemiplegia post stroke and cerebral palsy (CP) in children, and is characterized by the inability to lift the foot (dorsiflexion) about the ankle. This investigation focuses on children and adolescents diagnosed with brain injury and aims to evaluate the orthotic and therapeutic effects due to continuous use of a foot drop stimulator (FDS). Seven children (10 ± 3.89 years) with foot drop and hemiplegia secondary to brain injury (stroke or CP) were evaluated at baseline and after 3 months of FDS usage during community ambulation. Primary outcome measures included using mechanistic (joint kinematics, toe displacement, temporal-spatial asymmetry), and functional gait parameters (speed, step length, time) to evaluate the orthotic and therapeutic effects. There was a significant correlation between spatial asymmetry and speed without FDS at 3 months (r = 0.76, p < 0.05, df = 5) and no correlation between temporal asymmetry and speed for all conditions. The results show orthotic effects including significant increase in toe displacement (p < 0.025 N = 7) during the swing phase of gait while using the FDS. A positive correlation exists between toe displacement and speed (with FDS at 3 months: r = 0.62, p > 0.05, without FDS at 3 months: r = 0.44, p > 0.05). The results indicate an orthotic effect of increased dorsiflexion and toe displacement during swing with the use of the FDS in children with hemiplegia. Further, the study suggests that there could be a potential long-term effect of increased dorsiflexion during swing with continuous use of FDS.

Effects of Robotic Exoskeleton Gait Training on an Adolescent with Brain Injury.

Brain injury is one of the leading causes of motor deficits in children and adults, and it often results in motor control and balance impairments. Motor deficits include decreased walking speed, increased double support time, increased temporal and spatial asymmetry, and decreased control and coordination; leading to compromised functional ambulation and reduced quality of life. Robotic exoskeletons for motor rehabilitation can provide the user with consistent, symmetrical, goal-directed repetition of movement as well as balance and stability. The goal of this case study was to evaluate the efficacy of high dose robotic training on dynamic gait using functional and neuromechanical outcome measures in an adolescent with chronic brain injury. The results from this study demonstrated improved spatial symmetry, swing time, stance time, step length and an overall progression towards healthy bilateral loading. These preliminary results suggest that high dose, repetitive, consistent gait training using robotic exoskeletons has the potential to induce recovery of function in adolescents diagnosed with brain injury.

Robotic Exoskeleton Gait Training for Inpatient Rehabilitation in a Young Adult with Traumatic Brain Injury.

Severe and moderate traumatic brain injury (TBI) causes motor deficits leading to impairments in functional ambulation. Motor recovery involves intensive rehabilitation through physical therapy. Current practices in rehabilitation results in variable recovery of motor function and may result in residual gait deviations. Wearable robotic exoskeletons can provide the user with intensive, goal-directed repetition of movement as well as provide the user with stability and balance during gait, compared to conventional physical therapy. During the acute stage of recovery, the brain is healing and relearning and increased intensive motor rehabilitation throughout this stage could result in improved functional ambulation, especially in individuals with severe impairments who are not independent ambulators. This pilot study evaluates the effect of early intervention robotic exoskeleton gait training on lower extremity biomechanics on a 21 year old young adult with TBI.

The Importance of Haptics in Generating Exoskeleton Gait Trajectory Using Alternate Motor Inputs.

Human gait requires both haptic and visual feedback to generate and control rhythmic movements, and navigate environmental obstacles. Current lower extremity wearable exoskeletons that restore gait to individuals with paraplegia due to spinal cord injury rely completely on visual feedback to generate limited pre-programmed gait variations, and generally provide little control by the user over the gait cycle. As an alternative to this limitation, we propose user control of gait in real time using healthy upper extremities. This paper evaluates the feedback conditions required for the hands to generate complex rhythmic trajectories that resemble gait trajectories. This paper involved 18 subjects who performed a virtual locomotor task, where contralateral hand movements were mapped to control virtual feet in three feedback conditions: haptic only, visual only, and haptic and visual. The results indicate that haptic feedback in addition to visual feedback is required to produce rhythmic hand trajectories similar to gait trajectories.