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Background: Concussions result in transient symptoms stemming from a cortical metabolic energy crisis. Though this metabolic energy crisis typically resolves in a month, symptoms can persist for years. The symptomatic period is associated with gait dysfunction, the cortical underpinnings of which are poorly understood. Quantifying prefrontal cortex (PFC) activity during gait may provide insight into post-concussion gait dysfunction. The purpose of this study was to explore the effects of persisting concussion symptoms on PFC activity during gait. We hypothesized that adults with persisting concussion symptoms would have greater PFC activity during gait than controls. Within the concussed group, we hypothesized that worse symptoms would relate to increased PFC activity during gait, and that increased PFC activity would relate to worse gait characteristics., Methods: The Neurobehavior Symptom Inventory (NSI) characterized concussion symptoms. Functional near-infrared spectroscopy quantified PFC activity (relative concentration changes of oxygenated hemoglobin [HbO 2 ]) in 14 people with a concussion and 25 controls. Gait was assessed using six inertial sensors in the concussion group., Results: Average NSI total score was 26.4 (13.2). HbO 2 was significantly higher ( P = .007) for the concussed group (0.058 [0.108]) compared to the control group (-0.016 [0.057]). Within the concussion group, HbO 2 correlated with NSI total symptom score (ρ = .62; P = .02), sagittal range of motion ( r = .79; P = .001), and stride time variability ( r = -.54; P = .046)., Conclusion: These data suggest PFC activity relates to symptom severity and some gait characteristics in people with persistent concussion symptoms. Identifying the neurophysiological underpinnings to gait deficits post-concussion expands our knowledge of motor behavior deficits in people with persistent concussion symptoms., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

After a mild traumatic brain injury (mTBI), dizziness and balance problems are frequently reported, affecting individuals' daily lives and functioning. Vestibular rehabilitation is a standard treatment approach for addressing these issues, but its efficacy in this population remains inconclusive. A potential reason for suboptimal outcomes is the lack of objective monitoring of exercise performance, which is crucial for therapeutic success. This study utilized wearable inertial measurement units (IMUs) to quantify exercise performance in individuals with mTBI during home-based vestibular rehabilitation exercises. Seventy-three people with mTBI and fifty healthy controls were enrolled. Vestibular exercises were performed, and IMUs measured forehead and sternum velocities and range of motions. The mTBI group demonstrated a slower forehead peak angular velocity in all exercises, which may be a compensatory strategy to manage balance issues or symptom exacerbation. Additionally, the mTBI group exhibited a larger forehead range of motion during specific exercises, potentially linked to proprioceptive deficits. These findings emphasize the usefulness of utilizing IMUs to monitor the quality of home-based vestibular exercises for individuals with mTBI and the potential for IMUs improving rehabilitation outcomes.

Introduction: Balance deficits in people with chronic mild traumatic brain injury (mTBI; ≥3 months post-mTBI), thought to relate to central sensory integration deficits, are subtle and often difficult to detect. The purpose of this study was to determine the sensitivity of the instrumented modified clinical test of sensory integration for balance (mCTSIB) in identifying such balance deficits in people with symptomatic, chronic mTBI and to establish the associations between balance and mTBI symptom scores in the chronic mTBI group., Methods: The Institutional Review Board approved these study methods. Forty-one people with chronic mTBI and balance complaints and 53 healthy controls performed the mCTSIB (eyes open/closed on firm/foam surfaces; EoFi, EcFi, EoFo, and EcFo) with a wearable sensor on their waist to quantify sway area (m2/s4). Sensory reweighting variables were calculated for the firm and foam stance conditions. A stopwatch provided the clinical outcome for the mCTSIB (time). Each participant completed the Neurobehavioral Symptom Inventory (NSI), which quantifies mTBI-related symptoms and provides a total score, as well as sub-scores on affective, cognitive, somatic, and vestibular domains., Results: The mTBI group reported significantly higher symptom scores across each NSI sub-score (all Ps < .001). The mTBI group had a significantly larger sway area than the control group across all mCTSIB conditions and the mTBI group had significantly higher sensory reweighting scores compared to the control group on both the firm (P = .01) and foam (P = .04) surfaces. Within the mTBI group, the NSI vestibular score significantly related to the mCTSIB sway area EcFi (r = 0.38; P = .02), sway area EcFo (r = 0.43; P = .006), sensory reweighting firm (r = 0.33; P = .04), and sensory reweighting foam (r = 0.38; P = .02). The average sway area across the 4 mCTSIB conditions was significantly (area under the curve: 0.77; P < .001) better at differentiating groups than the mCTSIB clinical total score. The average sway area across the 4 mCTSIB conditions had a sensitivity of 73% and a specificity of 71%. The clinical mCTSIB outcome scores were not different between groups., Conclusion: People with chronic mTBI appear to have central sensory integration deficits detectable by instrumented measures of postural assessment. These findings suggest that central sensory integration should be targeted in rehabilitation for people with chronic mTBI., (© The Association of Military Surgeons of the United States 2022. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

There is a dearth of knowledge about how symptom severity affects gait in the chronic (>3 months) mild traumatic brain injury (mTBI) population despite up to 53% of people reporting persisting symptoms after mTBI. The aim of this investigation was to determine whether gait is affected in a symptomatic, chronic mTBI group and to assess the relationship between gait performance and symptom severity on the Neurobehavioral Symptom Inventory (NSI). Gait was assessed under single- and dual-task conditions using five inertial sensors in 57 control subjects and 65 persons with chronic mTBI (1.0 year from mTBI). The single- and dual-task gait domains of Pace, Rhythm, Variability, and Turning were calculated from individual gait characteristics. Dual-task cost (DTC) was calculated for each domain. The mTBI group walked (domain z-score mean difference, single-task = 0.70; dual-task = 0.71) and turned (z-score mean difference, single-task = 0.69; dual-task = 0.70) slower ( p  < 0.001) under both gait conditions, with less rhythm under dual-task gait (z-score difference = 0.21; p  = 0.001). DTC was not different between groups. Higher NSI somatic subscore was related to higher single- and dual-task gait variability as well as slower dual-task pace and turning ( p  < 0.01). Persons with chronic mTBI and persistent symptoms exhibited altered gait, particularly under dual-task, and worse gait performance related to greater symptom severity. Future gait research in chronic mTBI should assess the possible underlying physiological mechanisms for persistent symptoms and gait deficits.

Background: Little is known on the peripheral and central sensory contributions to persistent dizziness and imbalance following mild traumatic brain injury (mTBI)., Objective: To identify peripheral vestibular, central integrative, and oculomotor causes for chronic symptoms following mTBI., Methods: Individuals with chronic mTBI symptoms and healthy controls (HC) completed a battery of oculomotor, peripheral vestibular and instrumented posturography evaluations and rated subjective symptoms on validated questionnaires. We defined abnormal oculomotor, peripheral vestibular, and central sensory integration for balance measures among mTBI participants as falling outside a 10-percentile cutoff determined from HC data. A X-squared test associated the proportion of normal and abnormal responses in each group. Partial Spearman's rank correlations evaluated the relationships between chronic symptoms and measures of oculomotor, peripheral vestibular, and central function for balance control., Results: The mTBI group (n = 58) had more abnormal measures of central sensory integration for balance than the HC (n = 61) group (mTBI: 41% -61%; HC: 10%, p's < 0.001), but no differences on oculomotor and peripheral vestibular function (p > 0.113). Symptom severities were negatively correlated with central sensory integration for balance scores (p's < 0.048)., Conclusions: Ongoing balance complaints in people with chronic mTBI are explained more by central sensory integration dysfunction rather than peripheral vestibular or oculomotor dysfunction.

Introduction: Mild traumatic brain injury (mTBI) can impact gait, with deficits linked to underlying neural disturbances in cognitive, motor and sensory systems. Gait is complex as it is comprised of multiple characteristics that are sensitive to underlying neural deficits. However, there is currently no clear framework to guide selection of gait characteristics in mTBI. This study developed a model of gait in chronic mTBI and replicated this in a separate group of controls, to provide a comprehensive and structured methodology on which to base gait assessment and analysis., Methods: Fifty-two people with chronic mTBI and 59 controls completed a controlled laboratory gait assessment; walking for two minutes back and forth over a 13 m distance while wearing five wirelessly synchronized inertial sensors. Thirteen gait characteristics derived from the inertial sensors were selected for entry into the principle component analysis based on previous literature, robustness and novelty. Principle component analysis was then used to derive domains (components) of gait., Results: Four gait domains were derived for our chronic mTBI group (variability, rhythm, pace and turning) and this was replicated in a separate control cohort. Domains totaled 80.8% and 77.4% of variance in gait for chronic mTBI and controls, respectively. Gait characteristic loading was unambiguous for all features, with the exception of gait speed in controls that loaded on pace and rhythm domains., Conclusion: This study contributes a four component model of gait in chronic mTBI and controls that can be used to comprehensively assess and analyze gait and underlying mechanisms involved in impairment, or examine the influence of interventions., Competing Interests: Declaration of Competing Interest None to declare., (Copyright © 2019. Published by Elsevier B.V.)

Balance and mobility issues are common non-resolving symptoms following mild traumatic brain injury (mTBI). Current approaches for evaluating balance and mobility following an mTBI can be subjective and suboptimal as they may not be sensitive to subtle deficits, particularly in those with chronic mTBI. Wearable inertial measurement units (IMU) allow objective quantification of continuous mobility outcomes in natural free-living environments. This study aimed to explore free-living mobility (physical activity and turning) of healthy and chronic mild traumatic brain injury (mTBI) participants using a single IMU. Free-living mobility was examined in 23 healthy control (48.56 ± 23.07 years) and 29 symptomatic mTBI (40.2 ± 12.1 years) participants (average 419 days post-injury, persistent balance complaints) over 1 week, using a single IMU placed at the waist. Free-living mobility was characterized in terms of macro (physical activity volume, pattern and variability) and micro-level (discrete measures of turning) features. Macro-level outcomes showed those with chronic mTBI had similar quantities of mobility compared with controls. Micro-level outcomes within walking bouts showed that chronic mTBI participants had impaired quality of mobility. Specifically, people with chronic mTBI made larger turns, had longer turning durations, slower average and peak velocities (all p  < 0.001), and greater turn variability compared with controls. Results highlighted that the quality rather than quantity of mobility differentiated chronic mTBI from controls. Our findings support the use of free-living IMU continuous monitoring to enhance understanding of specific chronic mTBI-related mobility deficits. Future work is required to develop an optimal battery of free-living measures across the mTBI spectrum to aid application within clinical practice.

Motor and cognitive dysfunction is intractable sequela in the acute stage of concussion. While typical concussion recovery occurs in two weeks, empirical evidence suggests that some sequela persist beyond this period, though there is inconsistency surrounding the duration the sequela persist. In part, confusion around the issue is limited by the volume of literature evaluating those with a concussion history, permitting vast interpretations of significance. The purpose of this paper is to review the concussion history literature, summarizing the long-term effects of concussion history on motor and cognitive performance. Additionally, this review intends to provide direction and options of future investigations addressing the long-term effects of concussion on motor and cognitive performance., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Recent evidence suggests that athletes are at a higher risk of lower-body injuries in the months and years following a concussion. However, little is known about how people modify their movements post-concussion. This study examined kinematics during a jump cut motion in young adults with a concussion history (n=9; 4 males, 5 females; 3.1years' post-injury) and 10 controls (6 males, 4 females). Peak center of mass and peak knee angles during the landing phase of a jump-cut maneuver were evaluated. Participants with a concussion history demonstrated decreased knee varus (left: M conc =-0.5±1.0°, M ctrl =3.6±1.0°; right: M conc =5.1±1.2°, M ctrl =7.8±1.12°) and external rotation (left: M conc =2.5±1.6°, M ctrl =13.0±1.5°; right: M conc =7.7±1.6°, M ctrl =12.8±1.5°) regardless of whether the cut was oriented towards to the left or right. The kinematic patterns demonstrated in individuals with a concussion history may be suggestive of increased knee injury risk. This study adds to the growing body of literature linking orthopedic injury in those no longer displaying the acute signs and symptoms of concussion., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: While a growing number of studies have investigated the effects of concussion or mild traumatic brain injury (mTBI) on gait, many studies use different experimental paradigms and outcome measures. The path for translating experimental studies for objective clinical assessments of gait is unclear., Research Question: This review asked 2 questions: 1) is gait abnormal after concussion/mTBI, and 2) what gait paradigms (single-task, dual-task, complex gait) detect abnormalities after concussion., Methods: Data sources included MEDLINE/PubMed, Scopus, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) accessed on March 14, 2017. Original research articles reporting gait outcomes in people with concussion or mTBI were included. Studies of moderate, severe, or unspecified TBI, and studies without a comparator were excluded., Results: After screening 233 articles, 38 studies were included and assigned to one or more sections based on the protocol and reported outcomes. Twenty-six articles reported single-task simple gait outcomes, 24 reported dual-task simple gait outcomes, 21 reported single-task complex gait outcomes, and 10 reported dual-task complex gait outcomes., Significance: Overall, this review provides evidence for two conclusions: 1) gait is abnormal acutely after concussion/mTBI but generally resolves over time; and 2) the inconsistency of findings, small sample sizes, and small number of studies examining homogenous measures at the same time-period post-concussion highlight the need for replication across independent populations and investigators. Future research should concentrate on dual-task and complex gait tasks, as they showed promise for detecting abnormal locomotor function outside of the acute timeframe. Additionally, studies should provide detailed demographic and clinical characteristics to enable more refined comparisons across studies., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Research in sport concussion has increased greatly over the previous decade due to increased scientific interest as well as the media and political spotlight that has been cast on this injury. However, a dearth of literature is available regarding the long-term (>1 year after concussion) effects of adolescent concussion on cognitive and motor performance of high school athletes., Purpose: To evaluate the potential for long-term effects of concussion sustained during high school on cognitive and motor performance across the lifespan., Study Design: Cross-sectional study; Level of evidence, 3., Methods: Adults with (n = 30) and without (n = 53) a concussion history were recruited in 3 age groups: younger (18-30 years; n = 43), middle-aged (40-50 years; n = 18), and older (≥60 years; n = 22). Each participant completed a computerized neurocognitive assessment and continuous tracking and discrete temporal auditory tasks with the hand and foot. Root mean squared error and timing variability were derived from the tracking and temporal auditory tasks, respectively. Data were analyzed by regression analyses for each recorded variable., Results: The analysis revealed significant age effects on neurocognitive task, continuous tracking task, and discrete auditory timing task performance ( P values < .05). No concussion history or interaction (concussion history by age) effects were found for performance on any task ( P values > .05)., Conclusion: While longitudinal investigations are still needed, this cross-sectional study failed to identify any observable effect of adolescent concussion history on cognition or motor performance with age.

The aim of this study was to examine the possible long-term effects of high school concussion history on gait performance across the lifespan. Individuals with and without a concussion history were grouped into 20-year-old (yo) (n=40), 40yo (n=19), and 60yo (n=18) age groups. Participants completed five trials of four walking conditions: a normal walk, a dual task walk, an obstructed walk, and an obstructed, dual task walk. Spatiotemporal gait parameters for gait analyses during single and dual task conditions. Gait velocity, step width, stride length, percent of time in double support, and obstacle toe clearance were the gait variables assessed along with number correct from dual task. Gait was analyzed via optical motion capture. Data were analyzed by two-factor, multivariate ANOVAs and significant interactions were explored using post hoc contrasts. A significant (F=2.62, p=0.03) interaction was observed for the obstructed walk condition. Further analyses yielded no significant concussion history and control group differences, within age. The data indicate that an adolescent concussion history has a non-observable effect on gait across the lifespan., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Objective: To examine the effects of concussion on gait patterns of young adults with and without a history of concussion during single- and dual-task paradigms., Design: Cross-sectional evaluation., Setting: A research laboratory., Participants: Persons with (n=28; mean, 6.32y postinjury) and without (n=40) a concussion history., Intervention: Not applicable., Main Outcome Measures: A battery of gait analyses during single- and dual-task conditions. Normalized velocity, step length, stride width, number correct from cognitive task, time in single-leg stance, and time in double-leg stance were the variables of interest. Gait was analyzed using an electronic walkway system, and the Brooks visuospatial cognitive task was used to index cognition., Results: Data analyses using multiple 2-way repeated-measures analyses of variance and correlations indicated that participants with a history of concussion spent significantly more time in a double-leg stance and significantly decreased time in a single-leg stance and had slower gait velocity. There also was a significant negative correlation between number of concussions and time in single-leg stance and positive correlations between number of concussions and time in double-leg stance and double-stance percent., Conclusion: These findings suggest that persons with a history of concussion adopt a more conservative gait strategy., (Copyright © 2011 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)