Incidence of Gait Abnormalities After Traumatic Brain Injury

Mitigating Crouch Gait With an Autonomous Pediatric Knee Exoskeleton in the Neurologically Impaired

Crouch gait is one of the most common compensatory walking patterns found in individuals with neurological disorders, often accompanied by their limited physical capacity. Notable kinematic characteristics of crouch gait are excessive knee flexion during stance and reduced range of motion during swing. Knee exoskeletons have the potential to improve crouch gait by providing precisely controlled torque assistance directly to the knee joint. In this study, we implemented a finite-state machine-based impedance controller for a powered knee exoskeleton to provide assistance during both stance and swing phases for five children and young adults who exhibit chronic crouch gait. The assistance provided a strong orthotic effect, increasing stance phase knee extension by an average of 12 deg. Additionally, the knee range of motion during swing was increased by an average of 15 deg. Changes to spatiotemporal outcomes, such as preferred walking speed and percent stance phase, were inconsistent across subjects and indicative of the underlying intricacies of user response to assistance. This study demonstrates the potential of knee exoskeletons operating in impedance control to mitigate the negative kinematic characteristics of crouch gait during both stance and swing phases of gait.

The Effect of Botulinum Neurotoxin-A (BoNT-A) on Muscle Strength in Adult-Onset Neurological Conditions with Focal Muscle Spasticity: A Systematic Review

Botulinum neurotoxin-A (BoNT-A) injections are effective for focal spasticity. However, the impact on muscle strength is not established. This study aimed to investigate the effect of BoNT-A injections on muscle strength in adult neurological conditions. Studies were included if they were Randomised Controlled Trials (RCTs), non-RCTs, or cohort studies (n ≥ 10) involving participants ≥18 years old receiving BoNT-A injection for spasticity in their upper and/or lower limbs. Eight databases (CINAHL, Cochrane, EMBASE, Google Scholar, Medline, PEDro, Pubmed, Web of Science) were searched in March 2024. The methodology followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered in the Prospective Register of Systematic Reviews (PROSPERO: CRD42022315241). Quality was assessed using the modified Downs and Black checklist and the PEDro scale. Pre-/post-injection agonist, antagonist, and global strength outcomes at short-, medium-, and long-term time points were extracted for analysis. Following duplicate removal, 8536 studies were identified; 54 met the inclusion criteria (3176 participants) and were rated as fair-quality. Twenty studies were analysed as they reported muscle strength specific to the muscle injected. No change in agonist strength after BoNT-A injection was reported in 74% of the results. Most studies' outcomes were within six weeks post-injection, with few long-term results (i.e., >three months). Overall, the impact of BoNT-A on muscle strength remains inconclusive.

Exploring the challenges of avoiding collisions with virtual pedestrians using a dual-task paradigm in individuals with chronic moderate to severe traumatic brain injury

BACKGROUND

Individuals with a moderate-to-severe traumatic brain injury (m/sTBI), despite experiencing good locomotor recovery six months post-injury, face challenges in adapting their locomotion to the environment. They also present with altered cognitive functions, which may impact dual-task walking abilities. Whether they present collision avoidance strategies with moving pedestrians that are altered under dual-task conditions, however, remains unclear. This study aimed to compare between individuals with m/sTBI and age-matched control individuals: (1), the locomotor and cognitive costs associated with the concurrent performance of circumventing approaching virtual pedestrians (VRPs) while attending to an auditory-based cognitive task and; (2) gaze behaviour associated with the VRP circumvention task in single and dual-task conditions.

METHODOLOGY

Twelve individuals with m/sTBI (age = 43.3 ± 9.5 yrs; >6 mo. post injury) and 12 healthy controls (CTLs) (age = 41.8 ± 8.3 yrs) were assessed while walking in a virtual subway station viewed in a head-mounted display. They performed a collision avoidance task with VRPs, as well as auditory-based cognitive tasks (pitch discrimination and auditory Stroop), both under single and dual-task conditions. Dual-task cost (DTC) for onset distance of trajectory deviation, minimum distance from the VRP, maximum lateral deviation, walking speed, gaze fixations and cognitive task accuracy were contrasted between groups using generalized estimating equations.

RESULTS

In contrast to CTLs who showed locomotor DTCs only, individuals with m/sTBI displayed both locomotor and cognitive DTCs. While both groups walked slower under dual-task conditions, only individuals with m/sTBI failed to modify their onset distance of trajectory deviation and maintained smaller minimum distances and smaller maximum lateral deviation compared to single-task walking. Both groups showed shorter gaze fixations on the approaching VRP under dual-task conditions, but this reduction was less pronounced in the individuals with m/sTBI. A reduction in cognitive task accuracy under dual-task conditions was found in the m/sTBI group only.

CONCLUSION

Individuals with m/sTBI present altered locomotor and gaze behaviours, as well as altered cognitive performances, when executing a collision avoidance task involving moving pedestrians in dual-task conditions. Potential mechanisms explaining those alterations are discussed. Present findings highlight the compromised complex walking abilities in individuals with m/sTBI who otherwise present a good locomotor recovery.

An integrated approach to the assessment of balance and functional mobility in individuals with history of severe traumatic brain injury

Individuals who experienced severe Traumatic Brain Injury (sTBI) are often characterized by relevant motor dysfunctions which are likely to negatively affect activities of daily living and quality of life and often persist for years. However, detailed objective information about their magnitude are scarce. The aim of this study was to quantitatively assess the extent of motor deficits in terms of postural control effectiveness under static and dynamic conditions and to investigate the existence of possible correlations between the results of clinical tests and instrumental measures. Postural sway and functional mobility (i.e., instrumented Timed Up and Go test, iTUG) were objectively measured in 18 individuals with sTBI and 18 healthy controls using a pressure plate and a wearable inertial sensor. Additionally, participants with history of sTBI completed the Rivermead Mobility Index (RMI). One-way ANOVA and Spearman's rank correlation analysis were employed to examine differences between the two groups and determine potential correlations between the instrumental tests and clinical scales. The results show that people with sTBI were characterized by larger sway area and longer iTUG walking sub-phase. Significant correlations were also detected between RMI scores and iTUG total duration, as well as the walking phase. Taken together, these findings suggest that, even years after the initial injury, individuals with sTBI appear characterized by impaired postural control and functional mobility, which appears correlated with the RMI score. The integration of instrumental measures with clinical scales in the routine assessment and treatment of individuals with sTBI would result in more comprehensive, objective, and sensitive evaluations, thus improving precision in treatment planning, enabling ongoing progress monitoring, and highlighting the presence of motor deficits even years after the initial injury. Such integration is of importance for enhancing the long-term quality of life for individuals with sTBI.

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.

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.

Mild traumatic brain injury as a pathological process

Traumatic brain injury (TBI) is defined as dysfunction or other evidence of brain pathology caused by external physical force. More than 69 million new cases of TBI are registered worldwide each year, 80% of them - mild TBI. Based on the physical mechanism of induced trauma, we can separate its pathophysiology into primary and secondary injuries. Many literature sources have confirmed that mechanically induced brain injury initiates ionic, metabolic, inflammatory, and neurovascular changes in the CNS, which can lead to acute, subacute, and chronic neurological consequences. Despite the global nature of the disease, its high heterogeneity, lack of a unified classification system, rapid fluctuation of epidemiological trends, and variability of long-term consequences significantly complicate research and the development of new therapeutic strategies. In this review paper, we systematize current knowledge of biomechanical and molecular mechanisms of mild TBI and provide general information on the classification and epidemiology of this complex disorder.

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.

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.

Chronic motor performance following different traumatic brain injury severity-A systematic review

Introduction

Traumatic brain injury (TBI) is now known to be a chronic disease, causing ongoing neurodegeneration and linked to increased risk of neurodegenerative motor diseases, such as Parkinson's disease and amyotrophic lateral sclerosis. While the presentation of motor deficits acutely following traumatic brain injury is well-documented, however, less is known about how these evolve in the long-term post-injury, or how the initial severity of injury affects these outcomes. The purpose of this review, therefore, was to examine objective assessment of chronic motor impairment across the spectrum of TBI in both preclinical and clinical models.

Methods

PubMed, Embase, Scopus, and PsycINFO databases were searched with a search strategy containing key search terms for TBI and motor function. Original research articles reporting chronic motor outcomes with a clearly defined TBI severity (mild, repeated mild, moderate, moderate-severe, and severe) in an adult population were included.

Results

A total of 97 studies met the inclusion criteria, incorporating 62 preclinical and 35 clinical studies. Motor domains examined included neuroscore, gait, fine-motor, balance, and locomotion for preclinical studies and neuroscore, fine-motor, posture, and gait for clinical studies. There was little consensus among the articles presented, with extensive differences both in assessment methodology of the tests and parameters reported. In general, an effect of severity was seen, with more severe injury leading to persistent motor deficits, although subtle fine motor deficits were also seen clinically following repeated injury. Only six clinical studies investigated motor outcomes beyond 10 years post-injury and two preclinical studies to 18-24 months post-injury, and, as such, the interaction between a previous TBI and aging on motor performance is yet to be comprehensively examined.

Conclusion

Further research is required to establish standardized motor assessment procedures to fully characterize chronic motor impairment across the spectrum of TBI with comprehensive outcomes and consistent protocols. Longitudinal studies investigating the same cohort over time are also a key for understanding the interaction between TBI and aging. This is particularly critical, given the risk of neurodegenerative motor disease development following TBI.

Focal muscle spasticity has little impact on muscle power for walking in people with Traumatic Brain Injury

BACKGROUND

Spasticity is prevalent following Traumatic Brain Injury. 'Focal' muscle spasticity has been defined as spasticity affecting a localised muscle group, but it's impact on gait kinetics remains unclear. The aim of this study was to investigate the relationship between focal muscle spasticity and gait kinetics following Traumatic Brain Injury.

METHODS

Ninety-three participants attending physiotherapy for mobility limitations following Traumatic Brain Injury were invited to participate in the study. Participants underwent clinical gait analysis and were grouped depending on the presence or absence of focal muscle spasticity. Kinetic data was obtained for each sub-group, and participants were compared to healthy controls.

FINDINGS

Hip extensor power generation at initial contact, hip flexor power generation at terminal stance, and knee extensor power absorption at terminal stance were all significantly increased, and ankle power generation was significantly reduced at push-off when comparing Traumatic Brain Injury to healthy control populations. There were only two significant differences between participants with and without focal muscle spasticity, hip extensor power generation at initial contact was increased (1.53 vs 1.03 W/kg, P < .05) for those with focal hamstring spasticity, and knee extensor power absorption in early stance was reduced (-0.28 vs -0.64 W/kg, P < .05) for those with focal rectus femoris spasticity. However, these results should be interpreted with caution as the sub-group of participants with focal hamstring and rectus femoris spasticity was small.

INTERPRETATION

Focal muscle spasticity had little association with abnormal gait kinetics in this cohort of independently ambulant people with Traumatic Brain Injury.

Does Music Therapy Improve Gait after Traumatic Brain Injury and Spinal Cord Injury? A Mini Systematic Review and Meta-Analysis

There is a growing body of research examining the potential benefits of music therapy-based auditory stimulation (MT) for individuals with movement disorders in improving gait performance. However, there is limited knowledge about the effects of MT on gait outcomes in individuals with traumatic brain injury (TBI) or spinal cord injury (SCI). A previous review of MT's impact on gait in TBI had limitations, and there are no studies on its effects on gait in SCI. In this study, we conducted a meta-analysis to more thoroughly evaluate the impact of MT on gait outcomes in individuals with TBI and SCI. We systematically searched through eight databases and found six studies on MT in TBI and four on SCI. Our meta-analysis showed that MT has positive medium effect improvements on spatiotemporal aspects of gait in individuals with TBI (Hedge's g: 0.52) and SCI (0.53). These findings suggest that MT could be a practical intervention for enhancing different aspects of gait in these populations, although the limited number and "fair" quality of the studies included in the meta-analysis may affect the generalizability of the outcomes. Further research is needed to fully understand the mechanisms by which MT may influence gait and determine the optimal parameters for its use.

Clinical gait characteristics in the early post-concussion phase: A systematic review

BACKGROUND

Understanding gait alterations immediately post-concussion can improve identification, management and prognosis of concussion.

OBJECTIVE

To identify and define gait characteristics immediately post-concussion.

METHOD

A review of electronic databases was conducted using terms gait alteration AND mTBI OR concussion. 172 reports were identified. After restricting to English and human studies, 158 remained. Reports were screened to include studies assessing quantifiable gait change post-concussion. 12 studies were included.

DISCUSSION

Multiple gait features are altered post-impact: stability, step length, walking speed and postural control. There is evidence that postural measures in gait initiation and termination may identify more subtle deficits. There is paucity of data evaluating the impact of concussion on gait function acutely and the authors identified no studies examining immediate changes.

CONCLUSION

Acutely post-concussion, various gait alterations are seen and correlate with degree of deficit and prognosis. Slowed gait, instability and postural control are several features. Dynamic gait and postural assessments identify more subtle gait alterations. Given the absence in literature, high quality prospective studies examining immediate gait alterations post-concussion would contribute to improved assessment, management and prognostication. Given difficulty in participant recruitment, technological and standardised gait assessments should be used to assess force of impact and immediate gait alteration.

Gait classification in a population of adults with hereditary spastic paresis

BACKGROUND

Classification of gait in adults with hereditary spastic paresis is limited. Our aim was to use a previously established system to classify gait.

METHODS

Forty-nine participants were retrospectively recruited and grouped into existing classifications based on sagittal plane knee joint kinematic data extracted from a 3D analysis. Waveform analysis was used to compare the grouped data to determine if and where differences in the subjective classifications appeared.

FINDINGS

Classification of gait patterns in adults with hereditary spastic paresis is successful. Differences between groups in line with the classification system were confirmed by statistical analysis. Crouch gait is illustrated by a flexed knee throughout stance phase. Recurvatum gait is dominated by knee hyperextension in mid-late stance. Stiff-knee gait demonstrates limited knee range of motion in stance and jump-knee gait is characterised by less knee flexion in early and mid-stance phase than all groups. Sagittal plane hip and ankle kinematics compliment group differences at the knee joint. The jump-knee group is more flexed at the hip than all groups during loading response phase and mid-stance; and the recurvatum group is more extended at the hip than the crouch, jump-knee, and stiff-knee groups during mid and late-stance phase. There is less ankle dorsiflexion throughout stance phase in the recurvatum group than in all other groups.

INTERPRETATION

Sagittal plane knee joint kinematic data can be subjectively used to classify gait features in adults with hereditary spastic paresis. Novel analysis show hip and ankle sagittal plane kinematics can be used to further assist classification.

Using Inertial Measurement Unit Sensor Single Axis Rotation Angles for Knee and Hip Flexion Angle Calculations During Gait

BACKGROUND

Hip and knee flexion joint motions are frequently examined in clinical practice using camera based motion capture (CBMC) systems; however, these systems require elaborate setups and dedicated space. Inertial measurement unit (IMU) based systems avoid these disadvantages but require validation before widespread adoption. Moreover, it is important for clinical practice to determine the stability of these systems for prolonged evaluation periods. The purpose of this study was to assess the validity of a three-sensor inertial measurement unit system for calculating hip and knee flexion angles during gait by comparing with a gold standard CBMC system. Validity was also examined before and after a treadmill walking session.

METHODS

Twenty healthy participants were tested. Twenty seconds of gait at preferred walking speed were analyzed before and after thirty-two minutes of treadmill walking using previously validated CBMC methods and with a custom IMU model. Measurement validity for the IMU system was evaluated using Bland & Altman 95 percent limits of agreement, linear regression, mean absolute error and root mean square error. The effects of a measurement zeroing calibration strategy were also investigated.

RESULTS

Strong measurement agreement was observed for both hip and knee flexion angles, although overall agreement for the hip exceeded that for the knee. Linear regressions between the datasets for each participant illustrated strong (> 0.94) relationships between IMU and CBMC measurements. More significant changes between timepoints were observed for the knee than for the hip. Error values were generally reduced when zeroing calibration was implemented.

CONCLUSION

The IMU system presented in this study is a convenient and accessible technique to measure joint angles. The protocol described in the current study can be easily applied in the clinical setting for evaluation of clinical populations. Additional development work on sensor placement and calibration methods may further increase the accuracy of such methods. Clinical translation statement: The IMU system presented in this study is a convenient and accessible technique to measure joint angles. Additional developmentwork on sensor placement and calibration methods may further increase the accuracy of such methods.

Lateral Centre of Mass Displacement can predict running in adults with traumatic brain injury

BACKGROUND

Running is an important skill that improves a person's ability to participate in community-based social, leisure and work activities, and therefore improve quality of life. Following traumatic brain injury, many ambulant people are unable to run. Whilst established for walking, the physical impairments that limit running following traumatic brain injury remain unknown. Therefore, the primary aim of this study was to identify which physical impairments contribute to a person's ability to run post traumatic brain injury.

METHODS

In this study, 88 adults with traumatic brain injury were included. Runners and non-runners were compared regarding their clinical assessment of physical impairments, including postural control, focal muscle spasticity, muscle strength, self-selected walking speed and ability to run. Participants also completed a three-dimensional quantitative gait analysis to assess motor skill using the Gait Profile Score. Logistic regression was applied to identify the most important predictors for the ability to run.

FINDINGS

Significant differences between runners and non-runners were found for postural control, motor control and strength. Dynamic postural control, measured by lateral center of mass displacement, was the best predictor of running, with every centimeter increase in lateral center of mass movement during walking associated with a 30% reduction in the chance of being able to run.

INTERPRETATION

Lateral center of mass displacement should be considered when selecting interventions for ambulant patients with the goal to run. Although postural control, motor control and muscle strength were all different between runners and non-runners, they did not contribute to a person's ability to run.

Activity of a Novel Anti-Inflammatory Agent F-3,6'-dithiopomalidomide as a Treatment for Traumatic Brain Injury

Traumatic brain injury (TBI) is a major risk factor for several neurodegenerative disorders, including Parkinson's disease (PD) and Alzheimer's disease (AD). Neuroinflammation is a cause of later secondary cell death following TBI, has the potential to aggravate the initial impact, and provides a therapeutic target, albeit that has failed to translate into clinical trial success. Thalidomide-like compounds have neuroinflammation reduction properties across cellular and animal models of TBI and neurodegenerative disorders. They lower the generation of proinflammatory cytokines, particularly TNF-α which is pivotal in microglial cell activation. Unfortunately, thalidomide-like drugs possess adverse effects in humans before achieving anti-inflammatory drug levels. We developed F-3,6'-dithiopomalidomide (F-3,6'-DP) as a novel thalidomide-like compound to ameliorate inflammation. F-3,6'-DP binds to cereblon but does not efficiently trigger the degradation of the transcription factors (SALL4, Ikaros, and Aiolos) associated with the teratogenic and anti-proliferative responses of thalidomide-like drugs. We utilized a phenotypic drug discovery approach that employed cellular and animal models in the selection and development of F-3,6'-DP. F-3,6'-DP significantly mitigated LPS-induced inflammatory markers in RAW 264.7 cells, and lowered proinflammatory cytokine/chemokine levels in the plasma and brain of rats challenged with systemic LPS. We subsequently examined immunohistochemical, biochemical, and behavioral measures following controlled cortical impact (CCI) in mice, a model of moderate TBI known to induce inflammation. F-3,6'-DP decreased CCI-induced neuroinflammation, neuronal loss, and behavioral deficits when administered after TBI. F-3,6'-DP represents a novel class of thalidomide-like drugs that do not lower classical cereblon-associated transcription factors but retain anti-inflammatory actions and possess efficacy in the treatment of TBI and potentially longer-term neurodegenerative disorders.

Feasibility of virtual reality and treadmill training in traumatic brain injury: a randomized controlled pilot trial

OBJECTIVE

To evaluate the safety and efficacy of treadmill training with virtual reality compared to treadmill training alone and standard of care balance and mobility treatment in chronic traumatic brain injury (TBI).

PARTICIPANTS AND DESIGN

Thirty-one individuals with chronic TBI with self-reported and objective balance deficits participated in a 4-week 12 session intervention of treadmill training with virtual reality, treadmill training alone, or standard of care overground therapy.

OUTCOME MEASURES

Primary measures included recruitment and enrollment rates, retention, tolerance to intervention, completeness of outcome measures, and adverse events. Secondary measures included the Community Balance and Mobility Scale, 10 Meter Walk Test, 6 Minute Walk Test, and Timed Up and Go.

RESULTS

No serious adverse events were reported. All participants completed all training sessions and assessments at all time points. Recruitment, enrollment, and retention rates were high. All groups showed a trend toward improvement in all balance and mobility measures following treatment.

CONCLUSION

Virtual reality and treadmill training are safe and feasibile for individuals with TBI. Participants show improvements on balance and mobility measures following a 4-week intervention. Future research is needed to evaluate the efficacy of this intervention compared to other modes of balance and mobility training.

Association of Lower Limb Focal Spasticity With Kinematic Variables During Walking in Traumatic Brain Injury

BACKGROUND AND PURPOSE

Focal muscle spasticity is defined as spasticity that affects a localized group of muscles. It is prevalent in many adult-onset neurological conditions, yet the relationship of focal muscle spasticity with walking remains unclear. Therefore, the aim of this study was to determine the relationship of focal muscle spasticity with the kinematics of walking in traumatic brain injury (TBI).

METHODS

Ninety-one participants with TBI underwent clinical gait analysis and assessment of focal lower limb muscle spasticity in a prospective cross-sectional study. A matched group of 25 healthy controls (HCs) were recruited to establish a reference dataset. Kinematic data for each person with and without focal muscle spasticity following TBI were compared with the HC cohort at a matched walking speed.

RESULTS

The TBI and HC cohorts were well matched. Only those with focal hamstring muscle spasticity walked significantly different to those without. They had significantly greater knee flexion (23.4° compared with 10.5°, P < 0.01) at initial contact. There were no other significant differences in kinematic variables between those with and without focal muscle spasticity. There was no significant association between focal muscle spasticity and walking speed.

DISCUSSION AND CONCLUSIONS

Focal muscle spasticity and abnormal kinematics whilst walking were common in this cohort of people with TBI. However, focal muscle spasticity had little relationship with kinematic variables, and no significant relationship with walking speed. This finding has implications for the treatment of focal muscle spasticity to improve walking following TBI. Focal muscle spasticity had little relationship with kinematic variables and walking speed in this cohort of people with TBI who could walk without assistance.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A381).

Altered Muscle Contributions are Required to Support the Stance Limb During Voluntary Toe-Walking

Toe-walking characterizes several neuromuscular conditions and is associated with a reduction in gait stability and efficiency, as well as in life quality. The optimal choice of treatment depends on a correct understanding of the underlying pathology and on the individual biomechanics of walking. The objective of this study was to describe gait deviations occurring in a cohort of healthy adult subjects when mimicking a unilateral toe-walking pattern compared to their normal heel-to-toe gait pattern. The focus was to characterize the functional adaptations of the major lower-limb muscles which are required in order to toe walk. Musculoskeletal modeling was used to estimate the required muscle contributions to the joint sagittal moments. The support moment, defined as the sum of the sagittal extensive moments at the ankle, knee, and hip joints, was used to evaluate the overall muscular effort necessary to maintain stance limb stability and prevent the collapse of the knee. Compared to a normal heel-to-toe gait pattern, toe-walking was characterized by significantly different lower-limb kinematics and kinetics. The altered kinetic demands at each joint translated into different necessary moment contributions from most muscles. In particular, an earlier and prolonged ankle plantarflexion contribution was required from the soleus and gastrocnemius during most of the stance phase. The hip extensors had to provide a higher extensive moment during loading response, while a significantly higher knee extension contribution from the vasti was necessary during mid-stance. Compensatory muscular activations are therefore functionally required at every joint level in order to toe walk. A higher support moment during toe-walking indicates an overall higher muscular effort necessary to maintain stance limb stability and prevent the collapse of the knee. Higher muscular demands during gait may lead to fatigue, pain, and reduced quality of life. Toe-walking is indeed associated with significantly larger muscle forces exerted by the quadriceps to the patella and prolonged force transmission through the Achilles tendon during stance phase. Optimal treatment options should therefore account for muscular demands and potential overloads associated with specific compensatory mechanisms.

Mild Traumatic Brain Injury Is Associated With Increased Dual-Task Cost During Ambulation: A Preliminary Study

OBJECTIVE

The aim of the study was to determine the impact of dual-task conditions on mobility after mild traumatic brain injury.

DESIGN

Eleven adults with mild traumatic brain injury within 1 wk of injury and 10 age- and sex-matched healthy controls completed gait trials with a single-task condition and three separate dual-task conditions: counting by 1 (low), serial subtraction by 3 (medium), and alternating letters and numbers (high). Dual-task cost was calculated as dual-task cost = ([dual-task performance] - [single-task performance]) / [single-task performance] × 100%.

RESULTS

Participants with mild traumatic brain injury ambulated slower than control subjects (P < 0.001). Significant differences in dual-task cost were noted for both group (P < 0.001) and dual-task condition (P = 0.005). Dual-task cost was greater for those with mild traumatic brain injury compared with controls with significant group differences for the low and high cognitive loads (P < 0.05). Only 1 of the 11 individuals with mild traumatic brain injury and 1 of the 10 controls demonstrated gait speed less than 80 cm/sec, which is predictive of community mobility, during any dual-task condition. Dual-task cost exceeded 11.9%, previously determined to be the minimal detectable change in healthy adults, for 9 of the 11 individuals with mild traumatic brain injury compared with 3 of the 10 controls.

CONCLUSIONS

Dual-task cost may be a more sensitive measure for impairment during dual-task conditions than gait speed after mild traumatic brain injury.

Gait Impairment in Traumatic Brain Injury: A Systematic Review

Introduction: Gait impairment occurs across the spectrum of traumatic brain injury (TBI); from mild (mTBI) to moderate (modTBI), to severe (sevTBI). Recent evidence suggests that objective gait assessment may be a surrogate marker for neurological impairment such as TBI. However, the most optimal method of objective gait assessment is still not well understood due to previous reliance on subjective assessment approaches. The purpose of this review was to examine objective assessment of gait impairments across the spectrum of TBI. Methods: PubMed, AMED, OVID and CINAHL databases were searched with a search strategy containing key search terms for TBI and gait. Original research articles reporting gait outcomes in adults with TBI (mTBI, modTBI, sevTBI) were included. Results: 156 citations were identified from the search, of these, 13 studies met the initial criteria and were included into the review. The findings from the reviewed studies suggest that gait is impaired in mTBI, modTBI and sevTBI (in acute and chronic stages), but methodological limitations were evident within all studies. Inertial measurement units were most used to assess gait, with single-task, dual-task and obstacle crossing conditions used. No studies examined gait across the full spectrum of TBI and all studies differed in their gait assessment protocols. Recommendations for future studies are provided. Conclusion: Gait was found to be impaired in TBI within the reviewed studies regardless of severity level (mTBI, modTBI, sevTBI), but methodological limitations of studies (transparency and reproducibility) limit clinical application. Further research is required to establish a standardised gait assessment procedure to fully determine gait impairment across the spectrum of TBI with comprehensive outcomes and consistent protocols.

Long-term increase in sensitivity to ketamine's behavioral effects in mice exposed to mild blast induced traumatic brain injury

Neurobehavioral deficits emerge in nearly 50% of patients following a mild traumatic brain injury (TBI) and may persist for months. Ketamine is used frequently as an anesthetic, analgesic and for management of persistent psychiatric complications. Although ketamine may produce beneficial effects in patients with a history of TBI, differential sensitivity to its impairing effects could make the therapeutic use of ketamine in TBI patients unsafe. This series of studies examined male C57BL/6 J mice exposed to a mild single blast overpressure (mbTBI) for indications of altered sensitivity to ketamine at varying times after injury. Dystaxia (altered gait), diminished sensorimotor gating (reduced prepulse inhibition) impaired working memory (step-down inhibitory avoidance) were examined in mbTBI and sham animals 15 min following intraperitoneal injections of saline or R,S-ketamine hydrochloride, from day 7-16 post injury and again from day 35-43 post injury. Behavioral performance in the forced swim test and sucrose preference test were evaluated on day 28 and day 74 post injury respectively, 24 h following drug administration. Dynamic gait stability was compromised in mbTBI mice on day 7 and 35 post injury and further exacerbated following ketamine administration. On day 14 and 42 post injury, prepulse inhibition was robustly decreased by mbTBI, which ketamine further reduced. Ketamine-associated memory impairment was apparent selectively in mbTBI animals 1 h, 24 h and day 28 post shock (tested on day 15/16/43 post injury). Ketamine selectively reduced immobility scores in the FST in mbTBI animals (day 28) and reversed mbTBI induced decreases in sucrose consumption (Day 74). These results demonstrate increased sensitivity to ketamine in mice when tested for extended periods after TBI. The results suggest that ketamine may be effective for treating neuropsychiatric complications that emerge after TBI but urge caution when used in clinical practice for enhanced sensitivity to its side effects in this patient population.

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.

Wearable devices for tracking physical activity in the community after an acquired brain injury: A systematic review

OBJECTIVE

The application of wearable devices in individuals with acquired brain injury (ABI) resulting from stroke or traumatic brain injury (TBI) for monitoring physical activity (PA) has been relatively recent. The current systematic review aims to provide insights into the adaption of these devices, outcome metrics, and their transition from the laboratory to the community for PA monitoring of individuals with ABI.

LITERATURE SURVEY

The PubMed and Google Scholar databases were systematically reviewed using appropriate search terms. A total of 20 articles were reviewed from the past 15 years.

METHODOLOGY

Articles were classified into three categories - PA measurement studies, PA classification studies, and validation studies. The quality of studies was assessed using a quality appraisal checklist.

SYNTHESIS

It was found that the transition of wearable devices from in-lab to community-based studies in individuals with stroke has started but is not widespread. The transition of wearable devices in the community has not yet started for individuals with TBI. Accelerometer-based devices were more frequently chosen than pedometers and inertial measurement units. No consensus on a preferred wearable device (make or model) or wear location could be identified, though step count was the most common outcome metric. The accuracy and validity of most outcome metrics used in the community were not reported for many studies.

CONCLUSIONS

To facilitate future studies use wearable devices for PA measurement in the community, we recommend that researchers provide details on the accuracy and validity of the outcome metrics specific to the study environment. Once the accuracy and validity are established for a specific population, wearable devices and their derived outcomes can provide objective information on mobility impairment as well as the effect of rehabilitation in the community. This article is protected by copyright. All rights reserved.

The timeframe for safe resumption of high-level mobility following traumatic brain injury is currently unknown: a systematic review

PURPOSE

To examine the safety of high-level mobility (HLM) prescription in the early sub-acute phase of recovery following moderate-to-extremely severe traumatic brain injury (TBI) with specific focus on provocation of concussion-like symptoms.

DESIGN

Systematic review. PROSPERO ID: CRD42017069369.

MAIN MEASURES

Extracted data included study design, brain injury severity, time to commence HLM, type of HLM, physiological and symptom monitoring, and rate of adverse events.

RESULTS

Nineteen studies were included in the review. Fifteen studies included participants who commenced HLM within 6 weeks of injury, with the earliest time to commencement being 3 days. Overall, adverse events and symptom monitoring were poorly reported. A total of six adverse events were reported across three studies. One of the six adverse events was a concussion-like symptom. No falls were reported. No studies monitored concussion-like symptom provocation in direct relation to HLM.

CONCLUSION

A safe timeframe for return to HLM after moderate-to-extremely severe TBI could not be determined due to insufficient reporting of symptom monitoring and adverse events. Further research into the safety of HLM in the early sub-acute rehabilitative stage after moderate-to-extremely severe TBI is required in order to better understand potential sequelae in this population.IMPLICATIONS FOR REHABILITATIONHigh-level mobility assessment and training is commonly reported in the early sub-acute phase of recovery following moderate-to-extremely severe traumatic brain injury.There is no consensus on a safe timeframe to commence high-level mobility assessment or training after moderate-to-extremely severe traumatic brain injury.High-level mobility assessment and training appears to be safe in the early sub-acute phase following moderate-to-extremely severe traumatic brain injury, however, adverse events and symptoms are poorly reported.Clinicians should continue to proceed with caution when assessing and prescribing high-level mobility for patients with moderate-to-extremely severe traumatic brain injury in the early sub-acute phase of recovery and monitor for risks such as falls and exacerbation of concussion-like symptoms.

Feasibility of a rhythmic auditory stimulation gait training program in community-dwelling adults after TBI: A case report

BACKGROUND

Traumatic brain injury has multiple impacts on gait including decreased speed and increased gait variability. Rhythmic auditory stimulation (RAS) gait training uses the rhythm and timing structure of music to train and ultimately improve slow and variable walking patterns.

OBJECTIVE

To describe the feasibility of RAS gait training in community-dwelling adults with traumatic brain injury (TBI). A secondary objective is to report changes in spatiotemporal gait parameters and clinical measures of balance and walking endurance.

METHODS

Two individuals with a TBI participated in nine sessions of gait training with RAS over a 3-week period. At baseline, post-training and 3-week follow-up, spatiotemporal parameters of walking were analyzed at preferred pace, maximum pace and dual-task walking conditions. Secondary outcomes included the Community Balance and Mobility Scale and the 6-Minute Walk Test. Feasibility was assessed using reports of physical fatigue, adverse event reporting, and perceived satisfaction.

RESULTS

Both participants completed all 9 planned intervention sessions. The sessions were well tolerated with no adverse events. Participant 1 and 2 exhibited different responses to the intervention in line with the therapeutic goals set with the therapist. Participant 1 exhibited improved speed and decreased gait variability. Participant 2 exhibited reduced gait speed but less fatigue during the 6MWT.

CONCLUSIONS

RAS was found to be a safe and feasible gait intervention with the potential to improve some aspects of gait impairments related to gait speed, gait variability, dynamic balance and walking endurance. Further investigation including a pilot randomized controlled trial is warranted.

Ankle Power Generation Has a Greater Influence on Walking Speed Reserve Than Balance Following Traumatic Brain Injury

OBJECTIVE

Reduced walking speed is common following traumatic brain injury (TBI). Walking speed reserve (WSR) refers to the ability to increase walking speed on demand and is calculated as the difference between self-selected and fast walking speeds. Walking speed reserve is important for adaptive functional mobility in the community. Predictors of WSR following TBI are yet to be determined. The aim of the study was to identify whether static balance or ankle power generation (APG) was a stronger predictor of WSR following TBI.

SETTING

A major metropolitan rehabilitation hospital.

PARTICIPANTS

A total of 92 individuals receiving inpatient physiotherapy for mobility limitations following TBI were recruited.

DESIGN

A cross-sectional study.

METHODS

Walking speed (self-selected and fast), APG, and a summed single-leg stance scores were measured. The ability to increase walking speed on demand by 0.20 m/s or more defined WSR. Correlations, logistic regression, and receiver operating characteristic (ROC) curve analyses were performed to investigate independent relationships between WSR, APG, and static balance.

RESULTS

Fifty participants (54.3%) had a WSR of 0.20 m/s or more. The strongest predictor of WSR was APG (odds ratio [OR] = 3.34; 95% CI, 1.50-7.43) when compared with static balance (OR = 1.03; 95% CI, 1.01-1.06). The ROC curve demonstrated that APG could accurately discriminate between individuals with a WSR from those without (AUC [area under the ROC curve] = 0.79; 95% CI, 0.70-0.88). The APG cutoff score identified on the curve that maximized combined sensitivity (92.0%) and specificity (54.8%) was 0.75 W/kg.

CONCLUSION

Following TBI, APG was a stronger predictor of WSR than static balance. Clinicians should consider interventions that preferentially target APG in order to increase WSR for community mobility.

Effects of Self-Assisted Shoulder Elevation of the Affected Side Combined with Balance Training on Associated Reactions of Upper Limb and Walking Function in Chronic Stroke Patients: A Randomized Controlled Trial

Background

Associated reactions of the upper limb are frequently seen in stroke patients, especially during dynamic activities, such as walking. The aim of this study was to assess the effect of a method to inhibit the affected upper limb flexors combined with balance training on associated reactions of the affected upper limb and walking function in chronic stroke patients.

Material/Methods

60 patients were randomly allocated into 3 groups (n=20 per group): control group (no upper limb intervention), back group (the unaffected hand assists the affected upper limb in the low back and keep it in an extended position) and shoulder elevation group using the inhibition method (the unaffected hand assists the affected shoulder to elevate above 90°). Before and after the four-week balance training, the surface electromyography was used to evaluate the rate of contraction of affected elbow flexors. Fugl-Meyer Assessment of Upper Extremity (FMA-UE), 10 Meter Walking Test (10MWT) and Barthel Index (BI) were used to measure functional status.

Results

The shoulder elevation group had significant improvement in the percentage changes in the rate of contraction of the affected elbow flexors, 10WMT and FMA-UE (p<0.05) compared with back group and control group. We found no significant difference of 10WMT and FMA-UE between back group and control group.

Conclusions

The combination of the new inhibition method and the standing balance training could reduce the abnormal activity of affected elbow flexors during walking, increase walking speed, and improve the affected upper limb motor function.

Gait analysis in a rat model of traumatic brain injury

Gait disruptions following traumatic brain injury (TBI) are noted in the clinical population. To date, thorough analysis of gait changes in animal models of TBI to allow for correlation of pathological alterations and utilization of this as a therapeutic outcome have been limited. We therefore assessed gait using the DigiGait analysis system as well as overall locomotion using the Beam Walk test in adult male Sprague-Dawley rats following a commonly used model of TBI, parietal lobe controlled cortical impact (CCI). Rats underwent DigiGait baseline analysis 24 h prior to injury, followed by a moderate CCI in the left parietal lobe. Performance on the DigiGait was then assessed at 1, 3, 7, and 14 days post-injury, followed by histological analysis of brain tissue. Beam walk analysis showed a transient but significant impairment acutely after injury. Despite observance of gait disturbance in the clinical population, TBI in the parietal lobe of rats resulted in limited alterations in hind or forelimb function. General hindlimb locomotion showed significant but transient impairment. Significant changes in gait were observed to last through the sub-acute period, including right hindpaw angle of rotation and left forelimb and right hindlimb swing phase duration. Slight changes that did not reach statistical significant but may reflect subtle impacts of TBI on gait were reflected in several other measures, such as stride duration, stance duration and stance width. These results demonstrate that moderate-severe injury to the parietal cortex and underlying structures including corpus callosum, hippocampus, thalamus and basal ganglia result in slight changes to gait that can be detected using the Digigait analysis system.

Health Outcomes Used to Determine Facets of Health-related Quality of Life for Post-9/11 Veterans Using Assistive Technology for A Combat-related Mobility Impairment: A Literature Review

INTRODUCTION

Novel rehabilitation methods, including distribution and adoption of assistive technology for lower extremity impairments, are becoming crucial to ensure positive quality of life in all individuals. The quality of life of post-9/11 combat veterans is not well understood, in comparison to research on other populations. The following essay describes a review on health outcomes used to determine health-related quality of life (HR-QoL) among combat-injured service members who require mobility-related assistive technology.

MATERIALS AND METHODS

Reviews pooled data from research on PubMed, EMBASE, CINAHL, and PsycINFO published after September 11, 2001, and included service members who sustained a mobility impairment because of involvement in a post-9/11 combat operation. Basic descriptors were extracted in addition to health outcomes used, which were then categorized and summarized by six domains for HR-QoL as defined by the World Health Organization.

RESULTS

This review found health outcomes that fit in the pain and discomfort, negative emotions, mobility, social relations, access to and quality of healthcare services, and religious/spiritual/personal beliefs subdomains. The categorized results detailed their application to track and model HR-QoL health states in those with mobility impairments using mobility-based assistive technology.

CONCLUSIONS

The research on combat-induced mobility impairments indicates assistive technology improves otherwise poor health states. The results model these domains and subdomains to determine overall HR-QoL and the quality of a healthcare intervention, though additional research is needed as only one study was identified to be experimental in design.

Identification of predictive MRI and functional biomarkers in a pediatric piglet traumatic brain injury model

Traumatic brain injury (TBI) at a young age can lead to the development of long-term functional impairments. Severity of injury is well demonstrated to have a strong influence on the extent of functional impairments; however, identification of specific magnetic resonance imaging (MRI) biomarkers that are most reflective of injury severity and functional prognosis remain elusive. Therefore, the objective of this study was to utilize advanced statistical approaches to identify clinically relevant MRI biomarkers and predict functional outcomes using MRI metrics in a translational large animal piglet TBI model. TBI was induced via controlled cortical impact and multiparametric MRI was performed at 24 hours and 12 weeks post-TBI using T1-weighted, T2-weighted, T2-weighted fluid attenuated inversion recovery, diffusion-weighted imaging, and diffusion tensor imaging. Changes in spatiotemporal gait parameters were also assessed using an automated gait mat at 24 hours and 12 weeks post-TBI. Principal component analysis was performed to determine the MRI metrics and spatiotemporal gait parameters that explain the largest sources of variation within the datasets. We found that linear combinations of lesion size and midline shift acquired using T2-weighted imaging explained most of the variability of the data at both 24 hours and 12 weeks post-TBI. In addition, linear combinations of velocity, cadence, and stride length were found to explain most of the gait data variability at 24 hours and 12 weeks post-TBI. Linear regression analysis was performed to determine if MRI metrics are predictive of changes in gait. We found that both lesion size and midline shift are significantly correlated with decreases in stride and step length. These results from this study provide an important first step at identifying relevant MRI and functional biomarkers that are predictive of functional outcomes in a clinically relevant piglet TBI model. This study was approved by the University of Georgia Institutional Animal Care and Use Committee (AUP: A2015 11-001) on December 22, 2015.

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.

Gait analysis in neurological populations: Progression in the use of wearables

Gait assessment is an essential tool for clinical applications not only to diagnose different neurological conditions but also to monitor disease progression as it contributes to the understanding of underlying deficits. There are established methods and models for data collection and interpretation of gait assessment within different pathologies. This narrative review aims to depict the evolution of gait assessment from observation and rating scales to wearable sensors and laboratory technologies and provide limitations and possible future directions in the field of gait assessment. In this context, we first present an extensive review of current clinical outcomes and gait models. Then, we demonstrate commercially available wearable technologies with their technical capabilities along with their use in gait assessment studies for various neurological conditions. In the next sections, a descriptive knowledge for existing inertial and EMG based algorithms and a sign based guide that shows the outcomes of previous neurological gait assessment studies are presented. Finally, we state a discussion for the use of wearables in gait assessment and speculate the possible research directions by revealing the limitations and knowledge gaps in the literature.

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.

Dynamic neural and glial responses of a head-specific model for traumatic brain injury in Drosophila

Traumatic brain injury (TBI) is the strongest environmental risk factor for the accelerated development of neurodegenerative diseases. There are currently no therapeutics to address this due to lack of insight into mechanisms of injury progression, which are challenging to study in mammalian models. Here, we have developed and extensively characterized a head-specific approach to TBI in Drosophila, a powerful genetic system that shares many conserved genes and pathways with humans. The Drosophila TBI (dTBI) device inflicts mild, moderate, or severe brain trauma by precise compression of the head using a piezoelectric actuator. Head-injured animals display features characteristic of mammalian TBI, including severity-dependent ataxia, life span reduction, and brain degeneration. Severe dTBI is associated with cognitive decline and transient glial dysfunction, and stimulates antioxidant, proteasome, and chaperone activity. Moreover, genetic or environmental augmentation of the stress response protects from severe dTBI-induced brain degeneration and life span deficits. Together, these findings present a tunable, head-specific approach for TBI in Drosophila that recapitulates mammalian injury phenotypes and underscores the ability of the stress response to mitigate TBI-induced brain degeneration.

Indirect measurement of anterior-posterior ground reaction forces using a minimal set of wearable inertial sensors: from healthy to hemiparetic walking

Background

The anterior-posterior ground reaction force (AP-GRF) and propulsion and braking point metrics derived from the AP-GRF time series are indicators of locomotor function across healthy and neurological diagnostic groups. In this paper, we describe the use of a minimal set of wearable inertial measurement units (IMUs) to indirectly measure the AP-GRFs generated during healthy and hemiparetic walking.

Methods

Ten healthy individuals and five individuals with chronic post-stroke hemiparesis completed a 6-minute walk test over a walking track instrumented with six forceplates while wearing three IMUs securely attached to the pelvis, thigh, and shank. Subject-specific models driven by IMU-measured thigh and shank angles and an estimate of body acceleration provided by the pelvis IMU were used to generate indirect estimates of the AP-GRF time series. Propulsion and braking point metrics (i.e., peaks, peak timings, and impulses) were extracted from the IMU-generated time series. Peaks and impulses were expressed as % bodyweight (%bw) and peak timing was expressed as % stance phase (%sp). A 75%-25% split of 6-minute walk test data was used to train and validate the models. Indirect estimates of the AP-GRF time series and point metrics were compared to direct measurements made by the forceplates.

Results

Indirect measurements of the AP-GRF time series approximated the direct measurements made by forceplates, with low error and high consistency in both the healthy (RMSE= 4.5%bw; R²= 0.93) and post-stroke (RMSE= 2.64%bw; R²= 0.90) cohorts. In the healthy cohort, the average errors between indirect and direct measurements of the peak propulsion magnitude, peak propulsion timing, and propulsion impulse point estimates were 2.37%bw, 0.67%sp, and 0.43%bw. In the post-stroke cohort, the average errors for these point estimates were 1.07%bw, 1.27%sp, and 0.31%bw. Average errors for the braking estimates were higher, but comparable.

Conclusions

Accurate estimates of AP-GRF metrics can be generated using three strategically mounted IMUs and subject-specific calibrations. This study advances the development of point-of-care diagnostic systems that can catalyze the routine assessment and management of propulsion and braking locomotor deficits during rehabilitation.

An Update on the Complexity and Importance of Accurately Diagnosing Post-Traumatic Stress Disorder and Comorbid Traumatic Brain Injury

As awareness for diagnosing and screening patients for trauma has grown, more effective evidence-based treatments are available to treat post-traumatic stress disorder (PTSD). Despite these gains, several patients are non-responsive to care and research has shifted to determining barriers for cure or improvement. With the advent of modern warfare, the combination of intermittent explosive devices and more robust armor has resulted in service members surviving blasts that historically would have been lethal, resulting in a rise in traumatic brain injuries (TBIs). Post-traumatic stress disorder and TBI are often comorbid and can serve as the aforementioned barriers for cure or improvement for each other if one goes unrecognized. This mini-review will discuss the importance of diagnosing both entities, especially when they are comorbid, by examining how misdiagnosis may interfere with treatment outcomes. Several recent advances in methods to successfully distinguish between the two disorders will be reviewed.

The association between dual-task walking and counting responses and cognitive function and disability after severe head injury: A preliminary study

Adverse outcomes after severe head injury (SHI) can be difficult to detect in primary care and other settings where there is not specialist expertise for interpretation. Walking and counting dual-task (DT) measures are strongly associated with cognitive impairment and dementia and this preliminary study investigates whether performance on DT walking and counting tasks are associated with cognitive function and disability in 125 participants who sustained a SHI on average 26 years before. Single Task (ST) walking (speed over 6 metres) and ST counting (Serial 3s) and DT performance of concurrent walking and Serial 3s were compared with neuropsychological, wellbeing and disability tests for strength of association. The strongest correlations were between ST Correct Cognitive Responses (CCRs) and MMSE (rho = 0.435), DT CCRs and Short-term Memory Binding Tests (STMBT) binding accuracy (rho = 0,409) and DT CCRs and STROOP (rho = 0.420), but associations were less strong with disability. Developing this test, as a cost-efficient screening tool for triage to onward referral for neuropsychological assessment, holds promise, but requires further research.

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.

The nature and extent of upper limb associated reactions during walking in people with acquired brain injury

BACKGROUND

Upper limb associated reactions (ARs) are common in people with acquired brain injury (ABI). Despite this, there is no gold-standard outcome measure and no kinematic description of this movement disorder. The aim of this study was to determine the upper limb kinematic variables most frequently affected by ARs in people with ABI compared with a healthy cohort at matched walking speed intention.

METHODS

A convenience sample of 36 healthy control adults (HCs) and 42 people with ABI who had upper limb ARs during walking were recruited and underwent assessment of their self-selected walking speed using the criterion-reference three dimensional motion analysis (3DMA) at Epworth Hospital, Melbourne. Shoulder flexion, abduction and rotation, elbow flexion, forearm rotation and wrist flexion were assessed. The mean angle, standard deviation (SD), peak joint angles and total joint angle range of motion (ROM) were calculated for each axis across the gait cycle. On a group level, ANCOVA was used to assess the between-group differences for each upper limb kinematic outcome variable. To quantify abnormality prevalence on an individual participant level, the percentage of ABI participants that were outside of the 95% confidence interval of the HC sample for each variable were calculated.

RESULTS

There were significant between-group differences for all elbow and shoulder abduction outcome variables (p < 0.01), most shoulder flexion variables (except for shoulder extension peak), forearm rotation SD and ROM and for wrist flexion ROM. Elbow flexion and shoulder abduction were the axes most frequently affected by ARs. Despite the elbow being the most prevalently affected (38/42, 90%), a large proportion of participants had abnormality, defined as ±1.96 SD of the HC mean, present at the shoulder (32/42, 76%), forearm (20/42, 48%) and wrist joints (10/42, 24%).

CONCLUSION

This study provides valuable information on ARs, and highlights the need for clinical assessment of ARs to include all of the major joints of the upper limb. This may inform the development of a criterion-reference outcome measure or classification system specific to ARs.

Motor Effects of Minimal Traumatic Brain Injury in Mice

Traumatic brain injury (TBI) is considered to be the leading cause of disability and death among young people. Up to 30% of mTBI patients report motor impairments, such as altered coordination and impaired balance and gait. The objective of the present study was to characterize motor performance and motor learning changes, in order to achieve a more thorough understanding of the possible motor consequences of mTBI in humans. Mice were exposed to traumatic brain injury using the weight-drop model and subsequently subjected to a battery of behavioral motor tests. Immunohistochemistry was conducted in order to evaluate neuronal survival and synaptic connectivity. TBI mice showed a different walking pattern on the Erasmus ladder task, without any significant impairment in motor performance and motor learning. In the running wheels, mTBI mice showed reduced activity during the second dark phase and increased activity during the second light phase compared to the control mice. There was no difference in the sum of wheel revolutions throughout the experiment. On the Cat-Walk paradigm, the mice showed a wider frontal base of support post mTBI. The same mice spent a significantly greater percent of time standing on three paws post mTBI compared with controls. mTBI mice also showed a decrease in the number of neurons in the temporal cortex compared with the control group. In summary, mTBI mice suffered from mild motor impairments, minor changes in the circadian clock, and neuronal damage. A more in-depth examination of the mechanisms by which mTBI compensate for motor deficits is necessary.

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.

Utilizing three dimensional clinical gait analysis to optimize mobility outcomes in incomplete spinal cord damage

BACKGROUND

Three-dimensional gait analysis (3DGA) has not previously been considered by consensus panels of spinal cord experts for use in studies of patients with spinal cord damage (SCD), yet it is frequently used in other neurological populations, such as stroke and cerebral palsy.

RESEARCH QUESTION

How does 3DGA impairment based reporting guide individualised clinical decision-making in people with incomplete SCD?

METHODS

Retrospective open cohort case series recruited 48 adults with incomplete SCD (traumatic or non-traumatic spinal cord dysfunction) referred to the Clinical Gait Analysis Service (CGAS), Melbourne, Australia. Three-dimensional gait data were used to identify gait impairments by the multidisciplinary clinical team. Gait patterns were classified using the plantarflexor-knee extension couple index and the Gait Profile Score (GPS). The reason for referral and the recommendations made post-3DGA were collated in decision trees to extrapolate the potential value of 3DGA in decision making for targeted intervention in this population.

RESULTS

Participants with SCD generally walked at a reduced gait speed. When grouped by neurological level, the tetraplegia group had a significantly lower GPS, but no specific gait patterns emerged. Participants were primarily referred to the CGAS to direct clinical intervention decisions. The most frequent recommendation following 3DGA was the prescription of an ankle foot orthosis and in some cases, the recommendation was incongruent with the referrer's proposed intervention.

SIGNIFICANCE

3DGA can provide specific guidance in management plans for gait of patients with incomplete SCD and may help to avoid inappropriate or unnecessary interventions. This sample of patients referred to the CGAS demonstrates its clinical utility in guiding clinicians in their decision making to target individualised intervention.

Traumatic Brain Injury Results in Dynamic Brain Structure Changes Leading to Acute and Chronic Motor Function Deficits in a Pediatric Piglet Model

Traumatic brain injury (TBI) is a leading cause of death and disability in children. Pediatric TBI patients often suffer from crippling cognitive, emotional, and motor function deficits that have negative lifelong effects. The objective of this study was to longitudinally assess TBI pathophysiology using multi-parametric magnetic resonance imaging (MRI), gait analysis, and histological approaches in a pediatric piglet model. TBI was produced by controlled cortical impact in Landrace piglets. MRI data, including from proton magnetic resonance spectroscopy (MRS), were collected 24 hours and 12 weeks post-TBI, and gait analysis was performed at multiple time-points over 12 weeks post-TBI. A subset of animals was sacrificed 24 hours, 1 week, 4 weeks, and 12 weeks post-TBI for histological analysis. MRI results demonstrated that TBI led to a significant brain lesion and midline shift as well as microscopic tissue damage with altered brain diffusivity, decreased white matter integrity, and reduced cerebral blood flow. MRS showed a range of neurochemical changes after TBI. Histological analysis revealed neuronal loss, astrogliosis/astrocytosis, and microglia activation. Further, gait analysis showed transient impairments in cadence, cycle time, % stance, step length, and stride length, as well as long-term impairments in weight distribution after TBI. Taken together, this study illustrates the distinct time course of TBI pathoanatomic and functional responses up to 12 weeks post-TBI in a piglet TBI model. The study of TBI injury and recovery mechanisms, as well as the testing of therapeutics in this translational model, are likely to be more predictive of human responses and clinical outcomes compared to traditional small animal models.

Behavioral and Structural Effects of Single and Repeat Closed-Head Injury

BACKGROUND AND PURPOSE

The effects of multiple head impacts, even without detectable primary injury, on subsequent behavioral impairment and structural abnormality is yet well explored. Our aim was to uncover the dynamic changes and long-term effects of single and repetitive head injury without focal contusion on tissue microstructure and macrostructure.

MATERIALS AND METHODS

We introduced a repetitive closed-head injury rodent model (n = 70) without parenchymal lesions. We performed a longitudinal MR imaging study during a 50-day study period (T₂-weighted imaging, susceptibility-weighted imaging, and diffusion tensor imaging) as well as sequential behavioral assessment. Immunohistochemical staining for astrogliosis was examined in a subgroup of animals. Paired and independent t tests were used to evaluate the outcome change after injury and the cumulative effects of impact load, respectively.

RESULTS

There was no gross morphologic evidence for head injury such as skull fracture, contusion, or hemorrhage on micro-CT and MR imaging. A significant decrease of white matter fractional anisotropy from day 21 on and an increase of gray matter fractional anisotropy from day 35 on were observed. Smaller mean cortical volume in the double-injury group was shown at day 50 compared with sham and single injury (P < .05). Behavioral deficits (P < .05) in neurologic outcome, balance, and locomotor activity were also aggravated after double injury. Histologic analysis showed astrogliosis 24 hours after injury, which persisted throughout the study period.

CONCLUSIONS

There are measurable and dynamic changes in microstructure, cortical volume, behavior, and histopathology after both single and double injury, with more severe effects seen after double injury. This work bridges cross-sectional evidence from human subject and pathologic studies using animal models with a multi-time point, longitudinal research paradigm.