Precious Metal Free Hydrogen Evolution Catalyst Design and Application.

The quest to identify precious metal free hydrogen evolution reaction catalysts has received unprecedented attention in the past decade. In this Review, we focus our attention to recent developments in precious metal free hydrogen evolution reactions in acidic and alkaline electrolyte owing to their relevance to commercial and near-commercial low-temperature electrolyzers. We provide a detailed review and critical analysis of catalyst activity and stability performance measurements and metrics commonly deployed in the literature, as well as review best practices for experimental measurements (both in half-cell three-electrode configurations and in two-electrode device testing). In particular, we discuss the transition from laboratory-scale hydrogen evolution reaction (HER) catalyst measurements to those in single cells, which is a critical aspect crucial for scaling up from laboratory to industrial settings but often overlooked. Furthermore, we review the numerous catalyst design strategies deployed across the precious metal free HER literature. Subsequently, we showcase some of the most commonly investigated families of precious metal free HER catalysts; molybdenum disulfide-based, transition metal phosphides, and transition metal carbides for acidic electrolyte; nickel molybdenum and transition metal phosphides for alkaline. This includes a comprehensive analysis comparing the HER activity between several families of materials highlighting the recent stagnation with regards to enhancing the intrinsic activity of precious metal free hydrogen evolution reaction catalysts. Finally, we summarize future directions and provide recommendations for the field in this area of electrocatalysis.

Balance telerehabilitation and wearable technology for people with Parkinson's disease (TelePD trial).

BACKGROUND: Balance impairments, that lead to falls, are one of the main symptoms of Parkinson's disease (PD). Telerehabilitation is becoming more common for people with PD; however, balance is particularly challenging to assess and treat virtually. The feasibility and efficacy of virtual assessment and virtual treatment of balance in people with PD are unknown. The present study protocol has three aims: I) to determine if a virtual balance and gait assessment (instrumented L-shape mobility test) with wearable sensors can predict a gold-standard, in-person clinical assessment of balance, the Mini Balance Evaluation Systems Test (Mini-BESTest); II) to explore the effects of 12 sessions of balance telerehabilitation and unsupervised home exercises on balance, gait, executive function, and clinical scales; and III) to explore if improvements after balance telerehabilitation transfer to daily-life mobility, as measured by instrumented socks with inertial sensors worn for 7 days. METHODS: The TelePD Trial is a prospective, single-center, parallel-group, single-blind, pilot, randomized, controlled trial. This trial will enroll 80 eligible people with PD. Participants will be randomized at a 1:1 ratio into receiving home-based balance exercises in either: 1) balance telerehabilitation (experimental group, n = 40) or 2) unsupervised exercises (control group, n = 40). Both groups will perform 12 sessions of exercise at home that are 60 min long. The primary outcome will be Mini-BESTest. The secondary outcomes will be upper and lower body gait metrics from a prescribed task (instrumented L-shape mobility test); daily-life mobility measures over 7 days with wearable sensors in socks, instrumented executive function tests, and clinical scales. Baseline testing and 7 days of daily-life mobility measurement will occur before and after the intervention period. CONCLUSION: The TelePD Trial will be the first to explore the usefulness of using wearable sensor-based measures of balance and gait remotely to assess balance, the feasibility and efficacy of balance telerehabilitation in people with PD, and the translation of balance improvements after telerehabilitation to daily-life mobility. These results will help to develop a more effective home-based balance telerehabilitation and virtual assessment that can be used remotely in people with balance impairments. TRIAL REGISTRATION: This trial was prospectively registered on ClinicalTrials.gov (NCT05680597).

A Hybrid Assessment of Clinical Mobility Test Items for Evaluating Individuals With Mild Traumatic Brain Injury.

BACKGROUND AND PURPOSE: The Functional Gait Assessment (FGA) and High Level Mobility Assessment Tool (HiMAT) are clinical batteries used to assess people with mild traumatic brain injury (mTBI). However, neither assessment was specifically developed for people with mTBI; the FGA was developed to evaluate vestibular deficits, and the HiMAT was developed for individuals with more severe TBI. To maximize the sensitivity and reduce the time burden of these assessments, the purpose of this study was to determine the combination of FGA and HiMAT items that best discriminates persons with persistent symptoms from mTBI from healthy controls. METHODS: Fifty-three symptomatic civilians with persistent symptoms from mTBI (21% male, aged 31 (9.5) years, 328 [267] days since concussion) and 57 healthy adults (28% male, aged 32 (9.6) years) participated across 3 sites. The FGA and HiMAT were evaluated sequentially as part of a larger study. To determine the best combination of items, a lasso-based generalized linear model (glm) was fit to all data. RESULTS: The area under the curve (AUC) for FGA and HiMAT total scores was 0.68 and 0.66, respectively. Lasso regression selected 4 items, including FGA Gait with Horizontal Head Turns and with Pivot Turn, and HiMAT Fast Forward and Backward Walk, and yielded an AUC (95% confidence interval) of 0.71 (0.61-0.79) using standard scoring. DISCUSSION AND CONCLUSIONS: The results provide initial evidence supporting a reduced, 4-Item Hybrid Assessment of Mobility for mTBI (HAM-4-mTBI) for monitoring individuals with mTBI. Future work should validate the HAM-4-mTBI and investigate its utility for tracking progression throughout rehabilitation.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A409 ).

Relation Between Cognitive Assessment and Clinical Physical Performance Measures After Mild Traumatic Brain Injury.

OBJECTIVES: To investigate the relation between cognitive and motor performance in individuals with mild traumatic brain injury (mTBI) and examine differences in both cognitive and motor performance between adults after mTBI and healthy controls. DESIGN: Multi-center, cross-sectional study. SETTING: Three institutional sites (Courage Kenny Research Center, Minneapolis, MN, Oregon Health & Science University, Portland, OR, and University of Utah, Salt Lake City, UT). PARTICIPANTS: Data were collected from 110 participants (N=110), including those with mTBI and healthy controls, who completed cognitive and physical performance assessments. INTERVENTIONS: Not applicable. OUTCOME MEASURES: Cognitive assessments involved the Automated Neuropsychological Assessment Metrics to evaluate domains of attention, memory, reaction time, processing speed, and executive function. Physical performance was evaluated through clinical performance assessments, such as the 1-min walk test, the modified Illinois Agility Test, the Functional Gait Assessment Tool, the High-Level Mobility Assessment Tool, a complex turning course, and a 4-Item Hybrid Assessment of Mobility for mTBI. Participants also completed additional trials of the 1-min walk test, modified Illinois Agility Test, and complex turning course with a simultaneous cognitive task. RESULTS: Individuals with mTBI performed worse on cognitive assessments, as well as several of the physical performance assessments compared with healthy controls. Complex tasks were more strongly related to cognitive assessments compared with simple walking tasks. CONCLUSIONS: Combining complex motor tasks with cognitive demands may better demonstrate functional performance in individuals recovering from mTBI. By understanding the relation between cognitive and physical performance in individuals recovering from mTBI, clinicians may be able to improve clinical care and assist in return to activity decision-making.

Volitional Head Movement Deficits and Alterations in Gait Speed Following Mild Traumatic Brain Injury.

OBJECTIVE: Unconstrained head motion is necessary to scan for visual cues during navigation, for minimizing threats, and to allow regulation of balance. Following mild traumatic brain injury (mTBI) people may experience alterations in head movement kinematics, which may be pronounced during gait tasks. Gait speed may also be impacted by the need to turn the head while walking in these individuals. The aim of this study was to examine head kinematics during dynamic gait tasks and the interaction between kinematics and gait speed in people with persistent symptoms after mTBI. SETTING: A clinical assessment laboratory. DESIGN: A cross-sectional, matched-cohort study. PARTICIPANTS: Forty-five individuals with a history of mTBI and 46 age-matched control individuals. MAIN MEASURES: All participants were tested at a single time point and completed the Functional Gait Assessment (FGA) while wearing a suite of body-mounted inertial measurement units (IMUs). Data collected from the IMUs were gait speed, and peak head rotation speed and amplitude in the yaw and pitch planes during the FGA-1, -3, and -4 tasks. RESULTS: Participants with mTBI demonstrated significantly slower head rotations in the yaw ( P = .0008) and pitch ( P = .002) planes. They also demonstrated significantly reduced amplitude of yaw plane head rotations ( P < .0001), but not pitch plane head rotations ( P = .84). Participants with mTBI had significantly slower gait speed during normal gait (FGA-1) ( P < .001) and experienced a significantly greater percent decrease in gait speed than healthy controls when walking with yaw plane head rotations (FGA-3) ( P = .02), but not pitch plane head rotations (FGA-4) ( P = .11). CONCLUSIONS: Participants with mTBI demonstrated smaller amplitudes and slower speeds of yaw plane head rotations and slower speeds of pitch plane head rotations during gait. Additionally, people with mTBI walked slower during normal gait and demonstrated a greater reduction in gait speed while walking with yaw plane head rotations compared with healthy controls.

Assessing the Effects of Mild Traumatic Brain Injury on Vestibular Home Exercise Performance with Wearable Sensors.

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.

Implementation and Adoption of Telerehabilitation for Treating Mild Traumatic Brain Injury.

BACKGROUND AND PURPOSE: Multimodal physical therapy for mild traumatic brain injury (mTBI) has been shown to improve recovery. Due to the coronavirus disease-2019 (COVID-19) pandemic, a clinical trial assessing the timing of multimodal intervention was adapted for telerehabilitation. This pilot study explored feasibility and adoption of an in-person rehabilitation program for subacute mTBI delivered through telerehabilitation. METHODS: Fifty-six in-person participants-9 males; mean (SD) age 34.3 (12.2); 67 (31) days post-injury-and 17 telerehabilitation participants-8 males; age 38.3 (12.7); 61 (37) days post-injury-with subacute mTBI (between 2 and 12 weeks from injury) were enrolled. Intervention included 8, 60-minute visits over 6 weeks and included subcategories that targeted cervical spine, cardiovascular, static balance, and dynamic balance impairments. Telerehabilitation was modified to be safely performed at home with minimal equipment. Outcome measures included feasibility (the number that withdrew from the study, session attendance, home exercise program adherence, adverse events, telerehabilitation satisfaction, and progression of exercises performed), and changes in mTBI symptoms pre- and post-rehabilitation were estimated with Hedges' g effect sizes. RESULTS: In-person and telerehabilitation had a similar study withdrawal rate (13% vs 12%), high session attendance (92% vs 97%), and no adverse events. The telerehabilitation group found the program easy to use (4.2/5), were satisfied with care (4.7/5), and thought it helped recovery (4.7/5). The telerehabilitation intervention was adapted by removing manual therapy and cardiovascular portions and decreasing dynamic balance exercises compared with the in-person group. The in-person group had a large effect size (-0.94) in decreases in symptoms following rehabilitation, while the telerehabilitation group had a moderate effect size (-0.73). DISCUSSION AND CONCLUSIONS: Telerehabilitation may be feasible for subacute mTBI. Limited ability to address cervical spine, cardiovascular, and dynamic balance domains along with underdosage of exercise progression may explain group differences in symptom resolution.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A392 ).

Exploring Vestibular Ocular Motor Screening in Adults With Persistent Complaints After Mild Traumatic Brain Injury.

OBJECTIVE: The purpose of this study was to (1) explore differences in vestibular ocular motor screening (VOMS) symptoms between healthy adults and adults with persistent symptoms after mild traumatic brain injury (mTBI), and (2) explore the relationships between VOMS symptoms and other measures (self-reported vestibular symptoms, clinical measures of balance and gait, and higher-level motor ability tasks). SETTING: Research laboratory setting. PARTICIPANTS: Fifty-three persons with persistent symptoms (>3 weeks) following mTBI and 57 healthy controls were recruited. Eligibility for participation included being 18 to 50 years of age and free of medical conditions that may affect balance, with the exception of recent mTBI for the mTBI group. DESIGN: Cross-sectional. MAIN MEASURES: The primary outcomes were the VOMS symptom scores and near point of convergence (NPC) distance. Secondary outcomes included the Dizziness Handicap Inventory (DHI) total and subdomain scores, sway area, Functional Gait Analysis total score, gait speed, and modified Illinois Agility Task completion time, and Revised High-Level Mobility Assessment Tool total score. RESULTS: The mTBI group reported more VOMS symptoms ( z range, -7.28 to -7.89) and a further NPC ( t = -4.16) than healthy controls (all P s < .001). DHI self-reported symptoms (total and all subdomain scores) were strongly associated with the VOMS symptom scores (rho range, 0.53-0.68; all P s < .001). No significant relationships existed between VOMS symptoms and other measures. CONCLUSION: Significant group differences support the relevance of the VOMS for mTBI in an age-diverse sample with persistent symptoms. Furthermore, strong association with DHI symptoms supports the ability of the VOMS to capture vestibular complaints in this population.

Free-living gait does not differentiate chronic mTBI patients compared to healthy controls.

BACKGROUND: Physical function remains a crucial component of mild traumatic brain injury (mTBI) assessment and recovery. Traditional approaches to assess mTBI lack sensitivity to detect subtle deficits post-injury, which can impact a patient's quality of life, daily function and can lead to chronic issues. Inertial measurement units (IMU) provide an opportunity for objective assessment of physical function and can be used in any environment. A single waist worn IMU has the potential to provide broad/macro quantity characteristics to estimate gait mobility, as well as more high-resolution micro spatial or temporal gait characteristics (herein, we refer to these as measures of quality). Our recent work showed that quantity measures of mobility were less sensitive than measures of turning quality when comparing the free-living physical function of chronic mTBI patients and healthy controls. However, no studies have examined whether measures of gait quality in free-living conditions can differentiate chronic mTBI patients and healthy controls. This study aimed to determine whether measures of free-living gait quality can differentiate chronic mTBI patients from controls. METHODS: Thirty-two patients with chronic self-reported balance symptoms after mTBI (age: 40.88 ± 11.78 years, median days post-injury: 440.68 days) and 23 healthy controls (age: 48.56 ± 22.56 years) were assessed for ~ 7 days using a single IMU at the waist on a belt. Free-living gait quality metrics were evaluated for chronic mTBI patients and controls using multi-variate analysis. Receiver operating characteristics (ROC) and Area Under the Curve (AUC) analysis were used to determine outcome sensitivity to chronic mTBI. RESULTS: Free-living gait quality metrics were not different between chronic mTBI patients and controls (all p > 0.05) whilst controlling for age and sex. ROC and AUC analysis showed stride length (0.63) was the most sensitive measure for differentiating chronic mTBI patients from controls. CONCLUSIONS: Our results show that gait quality metrics determined through a free-living assessment were not significantly different between chronic mTBI patients and controls. These results suggest that measures of free-living gait quality were not impaired in our chronic mTBI patients, and/or, that the metrics chosen were not sensitive enough to detect subtle impairments in our sample.

Inertial Sensors Reveal Subtle Motor Deficits When Walking With Horizontal Head Turns After Concussion.

OBJECTIVE: To examine whether horizontal head turns while seated or while walking, when instrumented with inertial sensors, were sensitive to the acute effects of concussion and whether horizontal head turns had utility for concussion management. SETTING: Applied field setting, athletic training room. PARTICIPANTS: Twenty-four collegiate athletes with sports-related concussion and 25 healthy control athletes. DESIGN: Case-control; longitudinal. MAIN MEASURES: Peak head angular velocity and peak head angle (range of motion) when performing head turns toward an auditory cue while seated or walking. Gait speed when walking with and without head turns. RESULTS: Athletes with acute sports-related concussion turned their head slower than healthy control subjects initially (group ß = -49.47; SE = 16.33; P = .003) and gradually recovered to healthy control levels within 10 days postconcussion (group × time ß = 4.80; SE = 1.41; P < .001). Peak head velocity had fair diagnostic accuracy in differentiating subjects with acute concussion compared with controls (areas under the receiver operating characteristic curve [AUC] = 0.71-0.73). Peak head angle (P = .17) and gait speed (P = .64) were not different between groups and showed poor diagnostic utility (AUC = 0.57-0.62). CONCLUSION: Inertial sensors can improve traditional clinical assessments by quantifying subtle, nonobservable deficits in people following sports-related concussion.

Validation of an Inertial Sensor Algorithm to Quantify Head and Trunk Movement in Healthy Young Adults and Individuals with Mild Traumatic Brain Injury.

Wearable inertial measurement units (IMUs) may provide useful, objective information to clinicians interested in quantifying head movements as patients' progress through vestibular rehabilitation. The purpose of this study was to validate an IMU-based algorithm against criterion data (motion capture) to estimate average head and trunk range of motion (ROM) and average peak velocity. Ten participants completed two trials of standing and walking tasks while moving the head with and without moving the trunk. Validity was assessed using a combination of Intra-class Correlation Coefficients (ICC), root mean square error (RMSE), and percent error. Bland-Altman plots were used to assess bias. Excellent agreement was found between the IMU and criterion data for head ROM and peak rotational velocity (average ICC > 0.9). The trunk showed good agreement for most conditions (average ICC > 0.8). Average RMSE for both ROM (head = 2.64°; trunk = 2.48°) and peak rotational velocity (head = 11.76 °/s; trunk = 7.37 °/s) was low. The average percent error was below 5% for head and trunk ROM and peak rotational velocity. No clear pattern of bias was found for any measure across conditions. Findings suggest IMUs may provide a promising solution for estimating head and trunk movement, and a practical solution for tracking progression throughout rehabilitation or home exercise monitoring.

Probing the Relative Photoinjection Yields of Monomer and Aggregated Dyes into ZnO Crystals.

Cyanine dyes, often used in dye-sensitized solar cells (DSSCs), form a range of molecular species from monomers to large H and J aggregates in both solution and when adsorbed at a photoelectrode surface. To determine the relative capability of the different dye species to inject photoexcited electrons into a wideband gap oxide semiconductor, sensitization at a single-crystal zinc oxide surface was studied by simultaneous attenuated reflection (ATR) ultraviolet-visible (UV-vis) absorption and photocurrent spectroscopy measurements. ATR measurements enable identification of the dye species populating the surface with simultaneous photocurrent spectroscopy to identify the contribution of the various dye forms to photocurrent signal. We study the dye 2,2'-carboxymethylthiodicarbocyanine bromide that is particularly prone to aggregation both in solution and at the surface of sensitized oxide semiconductors.

Assessment and rehabilitation of central sensory impairments for balance in mTBI using auditory biofeedback: a randomized clinical trial.

BACKGROUND: Complaints of imbalance are common non-resolving signs in individuals with post-concussive syndrome. Yet, there is no consensus rehabilitation for non-resolving balance complaints following mild traumatic brain injury (mTBI). The heterogeneity of balance deficits and varied rates of recovery suggest varied etiologies and a need for interventions that address the underlying causes of poor balance function. Our central hypothesis is that most chronic balance deficits after mTBI result from impairments in central sensorimotor integration that may be helped by rehabilitation. Two studies are described to 1) characterize balance deficits in people with mTBI who have chronic, non-resolving balance deficits compared to healthy control subjects, and 2) determine the efficacy of an augmented vestibular rehabilitation program using auditory biofeedback to improve central sensorimotor integration, static and dynamic balance, and functional activity in patients with chronic mTBI. METHODS: Two studies are described. Study 1 is a cross-sectional study to take place jointly at Oregon Health and Science University and the VA Portland Health Care System. The study participants will be individuals with non-resolving complaints of balance following mTBI and age- and gender-matched controls who meet all inclusion criteria. The primary outcome will be measures of central sensorimotor integration derived from a novel central sensorimotor integration test. Study 2 is a randomized controlled intervention to take place at Oregon Health & Science University. In this study, participants from Study 1 with mTBI and abnormal central sensorimotor integration will be randomized into two rehabilitation interventions. The interventions will be 6 weeks of vestibular rehabilitation 1) with or 2) without the use of an auditory biofeedback device. The primary outcome measure is the daily activity of the participants measured using an inertial sensor. DISCUSSION: The results of these two studies will improve our understanding of the nature of balance deficits in people with mTBI by providing quantitative metrics of central sensorimotor integration, balance, and vestibular and ocular motor function. Study 2 will examine the potential for augmented rehabilitation interventions to improve central sensorimotor integration. TRIAL REGISTRATION: This trial is registered at clinicaltrials.gov ( NCT02748109 ).

The quality of turning in Parkinson's disease: a compensatory strategy to prevent postural instability?

BACKGROUND: The ability to turn while walking is essential for daily living activities. Turning is slower and more steps are required to complete a turn in people with Parkinson's disease (PD) compared to control subjects but it is unclear whether this altered strategy is pathological or compensatory. The aim of our study is to characterize the dynamics of postural stability during continuous series of turns while walking at various speeds in subjects with PD compared to control subjects. We hypothesize that people with PD slow their turns to compensate for impaired postural stability. METHOD: Motion analysis was used to compare gait kinematics between 12 subjects with PD in their ON state and 19 control subjects while walking continuously on a route composed of short, straight paths interspersed with eleven right and left turns between 30 and 180°. We asked subjects to perform the route at three different speeds: preferred, faster, and slower. Features describing gait spatio-temporal parameters and turning characteristics were extracted from marker trajectories. In addition, to quantify dynamic stability during turns we calculated the distance between the lateral edge of the base of support and the body center of mass, as well as the extrapolated body center of mass. RESULTS: Subjects with PD had slower turns and did not widen the distance between their feet for turning, compared to control subjects. Subjects with PD tended to cut short their turns compared to control subjects, resulting in a shorter walking path. Dynamic stability was smaller in the PD, compared to the healthy group, particularly for fast turning angles of 90°. CONCLUSIONS: The slower turning speeds and larger turning angles in people with PD might reflect a compensatory strategy to prevent dynamic postural instability given their narrow base of support.

Effects of Group, Individual, and Home Exercise in Persons With Parkinson Disease: A Randomized Clinical Trial.

BACKGROUND AND PURPOSE: Comparative studies of exercise interventions for people with Parkinson disease (PD) rarely considered how one should deliver the intervention. The objective of this study was to compare the success of exercise when administered by (1) home exercise program, (2) individualized physical therapy, or (3) a group class. We examined if common comorbidities associated with PD impacted success of each intervention. METHODS: Fifty-eight people (age = 63.9 ± 8 years) with PD participated. People were randomized into (1) home exercise program, (2) individual physical therapy, or (3) group class intervention. All arms were standardized and based on the Agility Boot Camp exercise program for PD, 3 times per week for 4 weeks. The primary outcome measure was the 7-item Physical Performance Test. Other measures of balance, gait, mobility, quality of life, balance confidence, depressions, apathy, self-efficacy and UPDRS-Motor, and activity of daily living scores were included. RESULTS: Only the individual group significantly improved in the Physical Performance Test. The individual exercise showed the most improvements in functional and balance measures, whereas the group class showed the most improvements in gait. The home exercise program improved the least across all outcomes. Several factors effected success, particularly for the home group. DISCUSSION AND CONCLUSIONS: An unsupervised, home exercise program is the least effective way to deliver exercise to people with PD, and individual and group exercises have differing benefits. Furthermore, people with PD who also have other comorbidities did better in a program directly supervised by a physical therapist.Video Abstract available for additional insights from the authors (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A112).

Comorbidity and functional mobility in persons with Parkinson disease.

OBJECTIVES: To report the frequency, severity, and types of comorbidities in people with Parkinson disease (PD) using a validated self-report comorbidity screening tool, and to determine the relationship between comorbidity and functional mobility. DESIGN: A secondary analysis and cross-sectional observational study design. SETTING: University hospital; outpatient balance disorders laboratory. PARTICIPANTS: Persons with mild to moderate idiopathic PD (N=76). INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: The Cumulative Illness Rating Scale-Geriatric (CIRS-G) and a comprehensive mobility assessment including gait (distance walked in 3 min), balance (mini-Balance Evaluation Systems Test), and physical function (Physical Performance Test). RESULTS: All participants reported comorbidities in addition to their diagnosed PD. The average ± SD number of comorbidities was 6.96 ± 2.0 (range, 2-11), and the total CIRS-G score ± SD was 12.7 ± 4.8. The most commonly reported organ systems with comorbidity were eyes and ears (89%), psychiatric (68%), musculoskeletal (64%), lower gastrointestinal (62%), respiratory (60.5%), upper gastrointestinal (59.2%), and genitourinary (53.9%). The total CIRS-G score was significantly related to functional mobility: gait (r=-.53, P=.0001), balance (r=-.43, P=.0003), and physical performance (r=-.36, P=.0041). Of the original 14 organ systems measured, there were 7 systems that, when combined, best predicted gait performance, 6 systems combined that best predicted balance performance, and 4 systems combined that predicted functional performance. CONCLUSIONS: This study reports a high frequency of multiple medical system comorbidity in people with mild to moderate PD. Furthermore, comorbidity scores were associated with mobility disability: gait, balance, and physical function. Early intervention is important to delay mobility disability in PD, and we recommend that people with PD found to have comorbidities should be screened for balance and gait deficits.

Instrumenting the balance error scoring system for use with patients reporting persistent balance problems after mild traumatic brain injury.

OBJECTIVE: To determine whether alterations to the Balance Error Scoring System (BESS), such as modified conditions and/or instrumentation, would improve the ability to correctly classify traumatic brain injury (TBI) status in patients with mild TBI with persistent self-reported balance complaints. DESIGN: Cross-sectional study. SETTING: Outpatient clinic. PARTICIPANTS: Subjects (n=13; age, 16.3±2y) with a recent history of concussion (mild TBI group) and demographically matched control subjects (n=13; age, 16.7±2y; control group). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Outcome measures included the BESS, modified BESS, instrumented BESS, and instrumented modified BESS. All subjects were tested on the noninstrumented BESS and modified BESS and were scored by visual observation of instability in 6 and 3 stance conditions, respectively. Instrumentation of these 2 tests used 1 inertial sensor with an accelerometer and gyroscope to quantify bidirectional body sway. RESULTS: Scores from the BESS and the modified BESS tests were similar between groups. However, results from the instrumented measures using the inertial sensor were significantly different between groups. The instrumented modified BESS had superior diagnostic classification and the largest area under the curve when compared with the other balance measures. CONCLUSIONS: A concussion may disrupt the sensory processing required for optimal postural control, which was measured by sway during quiet stance. These results suggest that the use of portable inertial sensors may be useful in the move toward more objective and sensitive measures of balance control postconcussion, but more work is needed to increase sensitivity.

Exercise Intolerance After Mild Traumatic Brain Injury Occurs in All Subtypes in the Adult Population.

Thematically grouped symptom clusters are present during the acute timeline of post-mild traumatic brain injuries (mTBI), representing clinical profiles called subtypes. Exercise intolerance has not been evaluated within the subtype classifications and, because guidelines support early submaximal aerobic exercise, further knowledge is required in regard to the exercise capabilities among the concussion subtypes. This cross-sectional study (n = 78) aimed to characterize the presence of exercise intolerance within the clinical subtypes and to explore performance on the Buffalo Concussion Treadmill Test (BCTT) in the adult subacute (2-12 weeks post-injury) mTBI population. All participants were evaluated using the BCTT to determine exercise tolerance. We first used the Neurobehavioral Symptom Inventory (NSI) questionnaire to assign each participant a primary subtype(s). To further explore all five subtypes (headache, cognitive, vestibular, ocular motor, and mood), participants were assessed using a multitude of thematically grouped assessments including self-reported questionnaires, clinical tests of vestibular and ocular motor function, balance function, and computerized cognitive testing. Thirty-seven (47%) subjects were exercise tolerant and 41 (53%) were exercise intolerant. There was no difference in the distribution of primary subtypes between the exercise tolerant and exercise intolerant groups. In addition, no significant differences were found between the exercise tolerant and exercise intolerant groups on other thematically grouped subtype assessments. The exercise intolerant group had a significantly higher resting heart rate (HR), lower percentage of age-predicted maximum HR achieved, lower Borg Rate of Perceived Exertion (RPE), and could walk on the treadmill for less time (lower duration) compared with the exercise tolerant group. The current findings suggest that exercise intolerance is common and pervasive across all five mTBI subtypes. A comprehensive mTBI assessment should include evaluation for exercise intolerance regardless of the primary clustering of symptoms and across patient populations. Therefore, early referral to physical therapists, athletic trainers, or medical clinics that can perform the BCTT may be helpful to initiate appropriate exercise prescriptions for patients with mTBI.

Prefrontal Cortex Activity During Gait in People With Persistent Symptoms After Concussion.

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 [HbO2]) 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). HbO2 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, HbO2 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.

Quantifying Turning Tasks With Wearable Sensors: A Reliability Assessment.

OBJECTIVE: The aim of this study was to establish the test-retest reliability of metrics obtained from wearable inertial sensors that reflect turning performance during tasks designed to imitate various turns in daily activity. METHODS: Seventy-one adults who were healthy completed 3 turning tasks: a 1-minute walk along a 6-m walkway, a modified Illinois Agility Test (mIAT), and a complex turning course (CTC). Peak axial turning and rotational velocity (yaw angular velocity) were extracted from wearable inertial sensors on the head, trunk, and lumbar spine. Intraclass correlation coefficients (ICCs) were established to assess the test-retest reliability of average peak turning speed for each task. Lap time was collected for reliability analysis as well. RESULTS: Turning speed across all tasks demonstrated good to excellent reliability, with the highest reliability noted for the CTC (45-degree turns: ICC = 0.73-0.81; 90-degree turns: ICC = 0.71-0.83; and 135-degree turns: ICC = 0.72-0.80). The reliability of turning speed during 180-degree turns from the 1-minute walk was consistent across all body segments (ICC = 0.74-0.76). mIAT reliability ranged from fair to excellent (end turns: ICC = 0.52-0.72; mid turns: ICC = 0.50-0.56; and slalom turns: ICC = 0.66-0.84). The CTC average lap time demonstrated good test-retest reliability (ICC = 0.69), and the mIAT average lap time test-retest reliability was excellent (ICC = 0.91). CONCLUSION: Turning speed measured by inertial sensors is a reliable outcome across a variety of ecologically valid turning tasks that can be easily tested in a clinical environment. IMPACT: Turning performance is a reliable and important measure that should be included in clinical assessments and clinical trials.