Mandy Miller Koop

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.

Using Accelerometer and Gyroscopic Measures to Quantify Postural Stability

CONTEXT Force platforms and 3-dimensional motion-capture systems provide an accurate method of quantifying postural stability. Substantial cost, space, time to administer, and need for trained personnel limit widespread use of biomechanical techniques in the assessment of postural stability in clinical or field environments. OBJECTIVE To determine whether accelerometer and gyroscope data sampled from a consumer electronics device (iPad2) provide sufficient resolution of center-of-gravity (COG) movements to accurately quantify postural stability in healthy young people. DESIGN Controlled laboratory study. SETTING Research laboratory in an academic medical center. PATIENTS OR OTHER PARTICIPANTS A total of 49 healthy individuals (age = 19.5 ± 3.1 years, height = 167.7 ± 13.2 cm, mass = 68.5 ± 17.5 kg). INTERVENTION(S) Participants completed the NeuroCom Sensory Organization Test (SOT) with an iPad2 affixed at the sacral level. MAIN OUTCOME MEASURE(S) Primary outcomes were equilibrium scores from both systems and the time series of the angular displacement of the anteroposterior COG sway during each trial. A Bland-Altman assessment for agreement was used to compare equilibrium scores produced by the NeuroCom and iPad2 devices. Limits of agreement was defined as the mean bias (NeuroCom - iPad) ± 2 standard deviations. Mean absolute percentage error and median difference between the NeuroCom and iPad2 measurements were used to evaluate how closely the real-time COG sway measured by the 2 systems tracked each other. RESULTS The limits between the 2 devices ranged from -0.5° to 0.5° in SOT condition 1 to -2.9° to 1.3° in SOT condition 5. The largest absolute value of the measurement error within the 95% confidence intervals for all conditions was 2.9°. The mean absolute percentage error analysis indicated that the iPad2 tracked NeuroCom COG with an average error ranging from 5.87% to 10.42% of the NeuroCom measurement across SOT conditions. CONCLUSIONS The iPad2 hardware provided data of sufficient precision and accuracy to quantify postural stability. Accuracy, portability, and affordability make using the iPad2 a reasonable approach for assessing postural stability in clinical and field environments.

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.

Altered kinematics of arm swing in Parkinson's disease patients indicates declines in gait under dual-task conditions

OBJECTIVE Declines in simultaneous performance of a cognitive and motor task are present in Parkinsons disease due to compromised basal ganglia function related to information processing. The aim of this project was to determine if biomechanical measures of arm swing could be used as a marker of gait function under dual-task conditions in Parkinsons disease patients. METHODS Twenty-three patients with Parkinsons disease completed single and dual-task cognitive-motor tests while walking on a treadmill at a self-selected rate. Multiple cognitive domains were evaluated with five cognitive tests. Cognitive tests were completed in isolation (single-task) and simultaneously with gait (dual-task). Upper extremity biomechanical data were gathered using the Motek CAREN system. Primary outcomes characterizing arm swing were: path length, normalized jerk, coefficient of variation of arm swing time, and cognitive performance. RESULTS Performance on the cognitive tasks were similar across single and dual-task conditions. However, biomechanical measures exhibited significant changes between single and dual-task conditions, with the greatest changes occurring in the most challenging conditions. Arm swing path length decreased significantly from single to dual-task, with the greatest decrease of 21.16%. Jerk, characterizing smoothness, increased significantly when moving from single to dual-task conditions. CONCLUSION The simultaneous performance of a cognitive and gait task resulted in decrements in arm swing while cognitive performance was maintained. Arm swing outcomes provide a sensitive measure of declines in gait function in Parkinsons disease under dual-task conditions. The quantification of arm swing is a feasible approach to identifying and evaluating gait related declines under dual-task conditions.

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.

Dual-task Interference Disrupts Parkinson's Gait Across Multiple Cognitive Domains

Gait dysfunction, a hallmark of Parkinsons disease, contributes to a relatively high incidence of falling. Gait function is further diminished during the performance of a motor-cognitive task (i.e., dual-task). It is unclear if Parkinsons disease-related dual-task deficits are related to a specific area of cognitive function or are the result of a more global decline in executive function. The aim of this project was to systematically evaluate gait performance to determine if gait dysfunction is restricted to certain types of executive function or a global phenomenon in individuals with Parkinsons disease. Twenty-three individuals with mild-moderate Parkinsons disease completed a series of dual-task conditions in which gait was paired with cognitive tasks requiring: working memory (0, 1, and 2-back), attention and problem solving (serial-7 subtraction), verbal memory (digit recall), semantic memory (Controlled Oral Word Association) and information processing speed (visual Stroop test). The results demonstrate that individuals with mild-moderate Parkinsons disease have a generalized worsening of spatial-temporal gait parameters regardless of the specific cognitive demand being performed concurrently. Overall, gait velocity decreased (p < 0.01) and stride and stance time both increased (p < 0.01) across all cognitive conditions. The attention and problem solving task resulted in the greatest number of gait parameter decrements. Results indicated that performance on cognitive tasks remained unchanged from single-task to dual-task conditions. Diminished gait performance under dual-task conditions across different cognitive function domains suggests a global Parkinsons disease-related deficit in information processing and regulation of gait.

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.