Sarah J. Ozinga

Objective assessment of postural stability in Parkinson's disease using mobile technology

A significant gap remains in the ability to effectively characterize postural instability in individuals with Parkinsons disease. Clinical evaluation of postural declines is largely subjective, whereas objective biomechanical approaches are expensive and time consuming, thus limiting clinical adoption. Recent advances in mobile devices present an opportunity to address the gap in the quantification of postural stability. The aim of this project was to determine whether kinematic data measured by hardware within a tablet device, a 3rd generation iPad, was of sufficient quantity and quality to characterize postural stability.

Quantification of the Balance Error Scoring System with Mobile Technology.

PURPOSE The aim of this project was to develop a biomechanically based quantification of the Balance Error Scoring System (BESS) using data derived from the accelerometer and gyroscope of a mobile tablet device. METHODS Thirty-two healthy young adults completed the BESS while an iPad was positioned at the sacrum. Data from the iPad were compared to position data gathered from a three-dimensional motion capture system. Peak-to-peak (P2P), normalized path length (NPL), and root mean squared (RMS) were calculated for each system and compared. Additionally, a 95% ellipsoid volume, iBESS volume, was calculated using center of mass (CoM) movements in the anteroposterior (AP), mediolateral (ML), and trunk rotation planes of movement to provide a comprehensive, 3D metric of postural stability. RESULTS Across all kinematic outcomes, data from the iPad were significantly correlated with the same outcomes derived from the motion capture system (rho range, 0.37-0.94; P < 0.05). The iBESS volume metric was able to detect a difference in postural stability across stance and surface, showing a significant increase in volume in increasingly difficult conditions, whereas traditional error scoring was not as sensitive to these factors. CONCLUSIONS The kinematic data provided by the iPad are of sufficient quality relative to motion capture data to accurately quantify postural stability in healthy young adults. The iBESS volume provides a more sensitive measure of postural stability than error scoring alone, particularly in conditions 1 and 4, which often suffer from floor effects, and condition 5, which can experience ceiling effects. The iBESS metric is ideally suited for clinical and in the field applications in which characterizing postural stability is of interest.

Use of Mobile Device Accelerometry to Enhance Evaluation of Postural Instability in Parkinson Disease

OBJECTIVE To determine the accuracy of inertial measurement unit data from a mobile device using the mobile device relative to posturography to quantify postural stability in individuals with Parkinson disease (PD). DESIGN Criterion standard. SETTING Motor control laboratory at a clinic. PARTICIPANTS A sample (N=28) of individuals with mild to moderate PD (n=14) and age-matched community-dwelling individuals without PD (n=14) completed the study. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Center of mass (COM) acceleration measures were compared between the mobile device and the NeuroCom force platform to determine the accuracy of mobile device measurements during performance of the Sensory Organization Test (SOT). Analyses examined test-retest reliability of both systems and sensitivity of (1) the equilibrium score from the SOT and (2) COM acceleration measures from the force platform and mobile device to quantify postural stability across populations. RESULTS Metrics of COM acceleration from inertial measurement unit data and the NeuroCom force platform were significantly correlated across balance conditions and groups (Pearson r range, .35 to .97). The SOT equilibrium scores failed to discriminate individuals with and without PD. However, the multiplanar measures of COM acceleration from the mobile device exhibited good to excellent reliability across SOT conditions and were able to discriminate individuals with and without PD in conditions with the greatest balance demands. CONCLUSIONS Metrics employing medial-lateral movement produce a more sensitive outcome than the equilibrium score in identifying postural instability associated with PD. Overall, the output from the mobile device provides an accurate and reliable method of rapidly quantifying balance in individuals with PD. The portable and affordable nature of a mobile device with the application makes it ideally suited to use biomechanical data to aid in clinical decision making.

Improved lower extremity pedaling mechanics in individuals with stroke under maximal workloads

ABSTRACT Background Individuals with stroke present with motor control deficits resulting in the abnormal activation and timing of agonist and antagonist muscles and inefficient movement patterns. The analysis of pedaling biomechanics provides a window into understanding motor control deficits, which vary as a function of workload. Understanding the relationship between workload and motor control is critical when considering exercise prescription during stroke rehabilitation. Objectives To characterize pedaling kinematics and motor control processes under conditions in which workload was systematically increased to an eventual patient-specific maximum. Methods A cohort study was conducted in which 18 individuals with chronic stroke underwent a maximal exertion cardiopulmonary exercise test on a stationary cycle ergometer, during which pedaling torque was continuously recorded. Measures of force production, pedaling symmetry, and pedaling smoothness were obtained. Results Mean Torque increased significantly (p < 0.05) for both legs from initial to terminal workloads. Mean torque Symmetry Index, calculated for down and upstroke portions of the pedaling action, improved from 0.37(0.29) to 0.29(0.35) during downstroke (p = 0.007), and worsened during the upstroke: −0.37(0.38) to −0.62(0.46) (p < 0.001) from initial to terminal workloads. Low Torque Duration improved from initial to terminal workloads, decreasing from 121.1(52.9) to 58.1(39.6) degrees (p < 0.001), respectively. Smoothness of pedaling improved significantly from initial to terminal workloads (p < 0.001). Conclusions Improved pedaling kinematics at terminal workloads indicate that individuals with stroke demonstrate improved motor control with respect to the timing, sequencing, and activation of hemiparetic lower extremity musculature compared to lower workloads. Therapeutic prescription involving higher resistance may be necessary to sufficiently engage and activate the paretic lower extremity.

Quantifying the Complexity of Time Series With Applications to Postural Balance Studies of Parkinson's Patients

ABSTRACT The article provides a quantitative assessment of the complexity of random time series via the tool of ε-complexity. The methods is then applied to quantify differences in balance dynamics between Parkinsonian and non-Parkinsonian subjects via the time-dependent data obtained by acceleration measurements for the subjects asked to maintain standing postural balance on hard and soft surfaces. Finally, a comparison of the above novel method with the more classical correlational, and spectral methodologies is carried out. Although all three techniques provide clear separation between the Parkinsonian subjects and controls, it is the complexity analysis of the acceleration signals that separates the two categories most efficiently.

Normative Performance on the Balance Error Scoring System by Youth, High School, and Collegiate Athletes

CONTEXT   Annually, more than 1 million youth athletes in the United States receive or are suspected of receiving a concussion. The Balance Error Scoring System (BESS) is the most commonly used clinical balance evaluation designed to provide a better understanding of the motor-control processes of individuals with concussion. Despite the widespread use of the BESS, a fundamental gap exists in applying this tool to young athletes, as normative values are lacking for this population. OBJECTIVE   To determine age- and sex-specific normative values for the BESS in youth, high school, and collegiate athletes. DESIGN   Cross-sectional study. SETTING   Local youth sport organizations, high schools, and colleges. PATIENTS OR OTHER PARTICIPANTS   Student-athletes (N = 6762) completed preseason baseline concussion testing as part of a comprehensive concussion-management program. Groups were youth males aged 5 to 13 years (n = 360), high school males aged 14 to 18 years (n = 3743), collegiate males aged 19 to 23 years (n = 497), youth females aged 5 to 13 years (n = 246), high school females aged 14 to 18 years (n = 1673), and collegiate females aged 19 to 23 years (n = 243). MAIN OUTCOME MEASURE(S)   Errors according to the BESS specifications. RESULTS   Performance on the BESS was worse ( P < .01) in youth athletes than in high school and collegiate athletes. In the youth and high school cohorts, females exhibited better scores than males ( P < .05). Sex was not a factor for collegiate athletes. Data from the youth cohort were further subdivided into 4-year bins to evaluate potential motor-development differences. The error count was highest for 5- to 9-year-old males and decreased with age. CONCLUSIONS   Performance on the BESS depended on sex and age, particularly in youth athletes. These sex- and age-specific normative values provide a reference to facilitate and unify clinical decision making across multiple providers caring for youth athletes with concussions.

Quantifying turning behavior and gait in Parkinson’s disease using mobile technology

Highlights • Improvements in mobility were detected from meds using a mobile device IMU in PD.• Algorithms using mobile device IMU data can segment the TUG into subtasks.• The Cleveland Clinic Mobility App can provide an objective assessment of mobility.

Three-dimensional evaluation of postural stability in Parkinson’s disease with mobile technology

BACKGROUND Postural instability is a hallmark of Parkinsons disease. Objective metrics to characterize postural stability are necessary for the development of treatment algorithms to aid in the clinical setting. OBJECTIVE The aim of this project was to validate a mobile device platform and resultant three-dimensional balance metric that characterizes postural stability. METHODS A mobile Application was developed, in which biomechanical data from inertial sensors within a mobile device were processed to characterize movement of center of mass in the medial-lateral, anterior-posterior and trunk rotation directions. Twenty-seven individuals with Parkinsons disease and 27 age-matched controls completed various balance tasks. A postural stability metric quantifying the amplitude (peak-to-peak) of sway acceleration in each movement direction was compared between groups. The peak-to-peak value in each direction for each individual with Parkinsons disease across all trials was expressed as a normalized value of the control data to identify individuals with severe postural instability, termed Cleveland Clinic-Postural Stability Index. RESULTS In all conditions, the balance metric for peak-to-peak was significantly greater in Parkinsons disease compared to controls (p < 0.01 for all tests). CONCLUSIONS The balance metric, in conjunction with mobile device sensors, provides a rapid and systematic metric for quantifying postural stability in Parkinsons disease.

Normative performance on cleveland clinic concussion application for youth, high school and college athletes

Objective The utilisation of a multi-factorial approach to evaluating relevant neuro-cognitive and motor function is a critical element in effective and comprehensive concussion management. In this project, normative data were gathered utilising the Cleveland Clinic Concussion (C3) iPad Application in youth, high school and college athletes. Design Prospective normative study. Setting Field-based. Participants Pre-season C3 data were collected in more the 6,500 youth (N=607), high school (N=5415) and college (N=744) athletes; approximately 32% females. Data were collected between Fall 2014 and Spring 2015. Interventions NA. Outcome measures Neurocognitive assessment modules of C3 include information processing (simple and choice reaction time), attention and working memory (Trail Making Test) and postural stability. Balance is quantified through biomechanical processing of accelerometer and gyroscope data gathered from the iPad during performance of the BESS. Main results No gender effects were present for performance on the neurocognitive modules; however, postural stability was significantly worse for youth males compared to female peers (P<0.01). Youth were significantly slower in performance of neurocognitive modules (simple and choice reaction time and Trails; (P<0.0001)). Neurocognitive and postural stability measures were similar across high school and college athletes. Conclusions Slower neurocognitive performance in youth relative to older athletes underscores the need to utilise age appropriate normative data in the management of concussion, particularly if no baseline is acquired. The control of postural stability develops at different rates as a function of age and gender, therefore balance assessment across the injury spectrum must utilise specific age-gender normative values. Competing interests JLA, SML and SBO have authored intellectual property associated with the mobile application presented in this study.