Precision Balance Assessment in Parkinson's Disease: Utilizing Vision-Based 3D Pose Tracking for Pull Test Analysis.

Postural instability is a common complication in advanced Parkinson's disease (PD) associated with recurrent falls and fall-related injuries. The test of retropulsion, consisting of a rapid balance perturbation by a pull in the backward direction, is regarded as the gold standard for evaluating postural instability in PD and is a key component of the neurological examination and clinical rating in PD (e.g., MDS-UPDRS). However, significant variability in test execution and interpretation contributes to a low intra- and inter-rater test reliability. Here, we explore the potential for objective, vision-based assessment of the pull test (vPull) using 3D pose tracking applied to single-sensor RGB-Depth recordings of clinical assessments. The initial results in a cohort of healthy individuals (n = 15) demonstrate overall excellent agreement of vPull-derived metrics with the gold standard marker-based motion capture. Subsequently, in a cohort of PD patients and controls (n = 15 each), we assessed the inter-rater reliability of vPull and analyzed PD-related impairments in postural response (including pull-to-step latency, number of steps, retropulsion angle). These quantitative metrics effectively distinguish healthy performance from and within varying degrees of postural impairment in PD. vPull shows promise for straightforward clinical implementation with the potential to enhance the sensitivity and specificity of postural instability assessment and fall risk prediction in PD.

A non-expensive bidimensional kinematic balance assessment can detect early postural instability in people with Parkinson's disease.

Background: Postural instability is a debilitating cardinal symptom of Parkinson's disease (PD). Its onset marks a pivotal milestone in PD when balance impairment results in disability in many activities of daily living. Early detection of postural instability by non-expensive tools that can be widely used in clinical practice is a key factor in the prevention of falls in widespread population and their negative consequences. Objective: This study aimed to investigate the effectiveness of a two-dimensional balance assessment to identify the decline in postural control associated with PD progression. Methods: This study recruited 55 people with PD, of which 37 were men. Eleven participants were in stage I, twenty-three in stage II, and twenty-one in stage III. According to the Hoehn and Yahr (H&Y) rating scale, three clinical balance tests (Timed Up and Go test, Balance Evaluation Systems Test, and Push and Release test) were carried out in addition to a static stance test recorded by a two-dimensional movement analysis software. Based on kinematic variables generated by the software, a Postural Instability Index (PII) was created, allowing a comparison between its results and those obtained by clinical tests. Results: There were differences between sociodemographic variables directly related to PD evolution. Although all tests were correlated with H&Y stages, only the PII was able to differentiate the first three stages of disease evolution (H&Y I and II: p = 0.03; H&Y I and III: p = 0.00001; H&Y II and III: p = 0.02). Other clinical tests were able to differentiate only people in the moderate PD stage (H&Y III). Conclusion: Based on the PII index, it was possible to differentiate the postural control decline among the first three stages of PD evolution. This study offers a promising possibility of a low-cost, early identification of subtle changes in postural control in people with PD in clinical practice.

Wearable sensors-based postural analysis and fall risk assessment among patients with diabetic foot neuropathy.

AIMS: To investigate the cross-sectional association between deep and superficial diabetic neuropathy, postural impairment assessed by wearable inertial sensors, and the risk of fall among patients with diabetic foot. METHODS: Diabetic patients attending a University Podiatric Clinic were evaluated for the presence of deep and superficial peripheral neuropathy in sensory tests. Postural impairment was assessed using a wearable inertial sensor, and the evaluation of balance/gait and risk of fall was determined by the Tinetti Scale and Downton Index, respectively. Glycemic control was measured by glycated haemoglobin concentration and fasting glycaemia. The postural parameters measured were the anteroposterior and medio-lateral sway of the center of mass (CoM) and the sway area (area traveled by the CoM per second). The results were analyzed through a logistic regression model to assess those posture variables mostly significantly associated with neuropathy and risk of fall scales. RESULTS: A total of 85 patients were evaluated. Spearman's rank correlation coefficients showed a strong and significant relationship (p < 0.05) between deep diabetic neuropathy assessed by Semmes-Weinstein monofilament, diapason and biothensiometer and postural alterations, whereas no significant correlations between superficial (painful sensitivity) neuropathy and the postural parameters. The sway path of the displacement along the anterior-posterior axis recorded during tests performed with eyes open and feet close together were significantly (p < 0.05) correlated with a poor glycemic (glycated haemoglobin concentration) control and each other with all diabetic neuropathy tests, fall risk scales, muscular weakness, ankle joint limitation and history of ulcers. CONCLUSIONS: The results support the existence of a strong association between alterations of the deep somato-sensitive pathway (although depending on the tool used to measure peripheral neuropathy), glycemic control and balance impairments assessed using a wearable sensors. Wearable-based postural analysis might be part of the clinical assessment that enables the detection of balance impairments and the risk of fall in diabetic patients with diabetic peripheral neuropathy.

Instrumental Assessment of Stepping in Place Captures Clinically Relevant Motor Symptoms of Parkinson's Disease.

Fluctuations of motor symptoms make clinical assessment in Parkinson's disease a complex task. New technologies aim to quantify motor symptoms, and their remote application holds potential for a closer monitoring of treatment effects. The focus of this study was to explore the potential of a stepping in place task using RGB-Depth (RGBD) camera technology to assess motor symptoms of people with Parkinson's disease. In total, 25 persons performed a 40 s stepping in place task in front of a single RGBD camera (Kinect for Xbox One) in up to two different therapeutic states. Eight kinematic parameters were derived from knee movements to describe features of hypokinesia, asymmetry, and arrhythmicity of stepping. To explore their potential clinical utility, these parameters were analyzed for their Spearman's Rho rank correlation to clinical ratings, and for intraindividual changes between treatment conditions using standard response mean and paired t-test. Test performance not only differed between ON and OFF treatment conditions, but showed moderate correlations to clinical ratings, specifically ratings of postural instability (pull test). Furthermore, the test elicited freezing in some subjects. Results suggest that this single standardized motor task is a promising candidate to assess an array of relevant motor symptoms of Parkinson's disease. The simple technical test setup would allow future use by patients themselves.

An automated, electronic assessment tool can accurately classify older adult postural stability.

Current methods of balance assessment in the clinical environment are often subjective, time-consuming and lack clinical relevance for non-ambulatory older adults. The objective of this study was to develop a novel method of balance assessment that utilizes data collected using the Microsoft Kinect 2 to create a Berg Balance Scale score, which is completely determined by statistical methods rather than by human evaluators. 74 older adults, both healthy and balance impaired, were recruited for this trial. All participants completed the Berg Balance Scale (BBS) which was scored independently by trained physical therapists. Participants then completed the items of the "Modified Berg Balance Scale" in front of the Microsoft Kinect camera. Kinematic data collected during this measurement was used to train a feed-forward neural network that was used to assign a Berg Balance Scale score. The neural network model estimated the clinician-assigned BBS score to within a median of 0.93 points for the participants in our sample population (range: 0.02-5.69). Using low-cost depth sensing camera technology and a clinical protocol that takes less than 5 min to complete in both ambulatory and non-ambulatory older adults, the method outlined in this manuscript can accurately predict a participant's BBS score and thereby identify whether they are deemed a high fall risk or not. If implemented correctly, this could enable fall prevention services to be deployed in a timely fashion using low-cost, accessible technology, resulting in improved safety of older adults.

Comparative Study of Two Systems for the Assessment of Static Balance in Veterans with Mild Traumatic Brain Injury.

BACKGROUND: Traditionally, the diagnosis of postural instability relies on the clinical examination of static balance. In recent years, computerized technologies have provided a new approach for the accurate detection of positional changes during functional balance. AIM: The aim of this study was to investigate the similarities and differences between two electronic systems, NeuroCom and BioSensics, and their application in the clinical assessment of impaired balance in American veterans. MATERIALS AND METHODS: We examined the sway around the center of mass during static balance conditions in 25 veterans with mild traumatic brain injury, using the two electronic systems. These patients met the inclusion criteria and were assessed for their impaired balance at the District of Columbia Veterans Affair Medical Center, Washington, DC, USA. RESULTS: There were six static balance tests conducted on either NeuroCom or BioSensics system in triplicate. Of the data for 36 sets of statistical data analyses, there were significant correlations among those for eight data sets (22.2%) between the two systems. The strongest positive correlation between the data from the two systems was found during the baseline test, when inputs from visual, vestibular and sensorymotor sources were uninterrupted. The data from the remaining experimental conditions did not correlate significantly with one another. CONCLUSIONS: Both NeuroCom and BioSensics provided comparable data in eight out of 36 experimental conditions in the assessment of static balance in patients with mild traumatic brain injury. The findings clarified the ambiguities in the application of NeuroCom versus BioSensics, provided new knowledge for the field of physical medicine and rehabilitation, and improved the clinical assessment of static balance in patients with mTBI.

Usefulness Differs Between the Visual Assessment and Specific Binding Ratio of 123I-Ioflupane SPECT in Assessing Clinical Symptoms of Drug-Naïve Parkinson's Disease Patients.

Background: In clinical practice, assessment of the striatal accumulation in 123I-ioflupane single photon emission computed tomography (SPECT) is commonly performed calculating the specific binding ratio (SBR) for the whole striatum. On the other hand, visual assessment of striatal accumulation in the SPECT was recently established. However, correlations of visual assessment with motor and cognitive functions in Parkinson's disease (PD) have rarely been examined. Differences in the usefulness of these assessments at clinics are uncertain. Objective: We performed this study to compare correlations of cognitive and motor functions in drug-naive PD between the SBR and visual assessment using 123I-ioflupane SPECT. Methods: Cognitive and motor assessments and 123I-ioflupane SPECT were performed in 47 drug-naïve PD patients with Mini-mental State Examination scores of ≥25. Cognitive function was assessed using the total score and 6 subscores of the Montreal Cognitive Assessment (MoCA) and 10 separate subtests of the Neurobehavioral Cognitive Status Examination (COGNISTAT). Motor function was assessed using the Hoehn and Yahr scale and Unified Parkinson's Disease Rating Scale. Accumulation of 123I-ioflupane was determined by visual assessment based on five grades: 1, burst striatum; 2, egg-shaped; 3, mixed type; 4, eagle wing; 5, normal striatum; and by calculating SBR averaged for the bilateral striatum using the DaTView computer software commonly used in clinical practice. Each SPECT assessment was compared with each subscore for cognitive and motor assessments. Results: Spearman correlation analysis showed SBR was significantly correlated with the MoCA subscores of visuospatial function and attention, and with COGNISTAT subtests of attention. Visual assessment showed significant negative correlation with the Hoehn and Yahr scale. Mean score of postural instability in patients with visual grade of 1 was significantly higher than those in patients with visual grades of 2 and 3. Conclusion: Clinical symptoms reflected by 123I-ioflupane SPECT differ between the SBR and visual assessment. SBR reflects some cognitive functions, whereas a visual assessment grade of 1, which signifies decreased uptake of 123I-Ioflupane in the caudate nucleus, reflects postural instability. Thus, the caudate nucleus may play an important role in posture maintenance. Our results suggest that performing both assessments is of value.

Comprehensive, blinded assessment of balance in orthostatic tremor.

INTRODUCTION: Orthostatic Tremor (OT) is a movement disorder characterized by a sensation of unsteadiness and tremors in the 13-18 Hz range present upon standing. The pathophysiology of OT is not well understood but there is a relationship between the sensation of instability and leg tremors. Despite the sensation of unsteadiness, OT patients do not fall often and balance in OT has not been formally assessed. We present a prospective blinded study comparing balance assessment in patients with OT versus healthy controls. METHODS: We prospectively enrolled 34 surface Electromyography (EMG)-confirmed primary OT subjects and 21 healthy controls. Participants underwent evaluations of balance by blinded physical therapists (PT) with standardized, validated, commonly used balance scales and tasks. RESULTS: OT subjects were mostly female (30/34, 88%) and controls were majority males (13/20, 65%). The average age of OT subjects was 68.5 years (range 54-87) and for controls was 69.4 (range 32-86). The average duration of OT symptoms was 18 years. OT subjects did significantly worse on all the balance scales and on most balance tasks including Berg Balance Scale, Functional Gait Assessment, Dynamic Gait Index, Unipedal Stance Test, Functional Reach Test and pull test. Gait speed and five times sit to stand were normal in OT. CONCLUSIONS: Common validated balance scales are significantly abnormal in primary OT. Despite the objective finding of impaired balance, OT patients do not commonly have falls. The reported sensation of unsteadiness in this patient population seems to be out of proportion to the number of actual falls. Further studies are needed to determine which components of commonly used balance scales are affected by a sensation of unsteadiness and fear of falling.

A Prospective Evaluation of an Outpatient Assessment of Postural Instability to Predict Risk of Falls in Patients with Parkinson's Disease Presenting for Deep Brain Stimulation.

BACKGROUND: Postural instability (PI) and falls, major causes of morbidity in patients with PD, are often overlooked. DBS is a mainstay therapy for Parkinson's disease (PD) and has been purported to both worsen and improve PI. An effective PI evaluation that can predict fall risk in patients with PD presenting for DBS is needed. METHODS: Forty-nine consecutive patients with PD were enrolled. Self-reported falls were the gold standard. Tests evaluated were the Berg Balance Scale (BBS), Timed-Up-and-Go (TUG), Pull Test, and Biodex Balance System Sway Index on firm (SI-FIRM) and soft (SI-SOFT) surfaces. RESULTS: The best single tests for fall risk were the BBS and SI-FIRM, each with sensitivities of 79% and specificities of 60% and 65%, respectively. When the evaluation was combined into a composite measure requiring four positive tests out of five, the sensitivity was 72% and specificity was 80%. CONCLUSIONS: A simple, efficient outpatient physical therapy assessment is effective in diagnosing fall risk in patients with PD.

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

BACKGROUND: A significant gap remains in the ability to effectively characterize postural instability in individuals with Parkinson's 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. METHODS: Seventeen patients and 17 age-matched controls completed six balance conditions under altered surface, stance, and vision. Simultaneous kinematic measurements were gathered from a three-dimensional motion capture system and tablet. RESULTS: The motion capture system and tablet provided similar measures of stability across groups. In particular, within the patient population, correlation between the two systems for peak-to-peak, normalized path length, root mean square, 95% volume, and total power values ranged from 0.66 to 1.00. Kinematic data from five balance conditions--double-leg stance with eyes open on a foam surface, double-leg stance with eyes closed on firm and foam surfaces, and tandem stance on firm and foam surfaces--were capable of discriminating patients from controls. CONCLUSIONS: The hardware within the tablet provides data of sufficient accuracy for the quantification of postural stability in patients with Parkinson's disease. The objectivity, portability, and ease of use of this device make it ideal for use in clinical environments lacking sophisticated biomechanical systems.