Gillian Barry

Accuracy of the Microsoft Kinect sensor for measuring movement in people with Parkinson's disease

BACKGROUND The Microsoft Kinect sensor (Kinect) is potentially a low-cost solution for clinical and home-based assessment of movement symptoms in people with Parkinsons disease (PD). The purpose of this study was to establish the accuracy of the Kinect in measuring clinically relevant movements in people with PD. METHODS Nine people with PD and 10 controls performed a series of movements which were measured concurrently with a Vicon three-dimensional motion analysis system (gold-standard) and the Kinect. The movements included quiet standing, multidirectional reaching and stepping and walking on the spot, and the following items from the Unified Parkinsons Disease Rating Scale: hand clasping, finger tapping, foot, leg agility, chair rising and hand pronation. Outcomes included mean timing and range of motion across movement repetitions. RESULTS The Kinect measured timing of movement repetitions very accurately (low bias, 95% limits of agreement <10% of the group mean, ICCs >0.9 and Pearsons r>0.9). However, the Kinect had varied success measuring spatial characteristics, ranging from excellent for gross movements such as sit-to-stand (ICC=.989) to very poor for fine movement such as hand clasping (ICC=.012). Despite this, results from the Kinect related strongly to those obtained with the Vicon system (Pearsons r>0.8) for most movements. CONCLUSIONS The Kinect can accurately measure timing and gross spatial characteristics of clinically relevant movements but not with the same spatial accuracy for smaller movements, such as hand clasping.

Retraining function in people with Parkinson’s disease using the Microsoft kinect: game design and pilot testing

BackgroundComputer based gaming systems, such as the Microsoft Kinect (Kinect), can facilitate complex task practice, enhance sensory feedback and action observation in novel, relevant and motivating modes of exercise which can be difficult to achieve with standard physiotherapy for people with Parkinson’s disease (PD). However, there is a current need for safe, feasible and effective exercise games that are appropriate for PD rehabilitation. The aims of this study were to i) develop a computer game to rehabilitate dynamic postural control for people with PD using the Kinect; and ii) pilot test the game’s safety and feasibility in a group of people with PD.MethodsA rehabilitation game aimed at training dynamic postural control was developed through an iterative process with input from a design workshop of people with PD. The game trains dynamic postural control through multi-directional reaching and stepping tasks, with increasing complexity across 12 levels of difficulty. Nine people with PD pilot tested the game for one session. Participant feedback to identify issues relating to safety and feasibility were collected using semi-structured interviews.ResultsParticipants reported that they felt safe whilst playing the game. In addition, there were no adverse events whilst playing. In general, the participants stated that they enjoyed the game and seven of the nine participants said they could imagine themselves using the game at home, especially if they felt it would improve their balance. The Flow State Scale indicated participants were immersed in the gameplay and enjoyed the experience. However, some participants reported that they found it difficult to discriminate between different types and orientations of visual objects in the game and some also had difficulty with the stepping tasks, especially when performed at the same time as the reaching tasks.ConclusionComputer-based rehabilitation games using the Kinect are safe and feasible for people with PD although intervention trials are needed to test their safety, feasibility and efficacy in the home.

Instrumenting gait with an accelerometer: A system and algorithm examination

Highlights • Detailed investigation to explain poor variability/asymmetry agreement between accelerometers and instrumented walkway.• Caution is urged in the choice of reference system for validation studies.• Accelerometers have potential to gather continuous and robust spatio-temporal gait data, representative of normal living.• Further refinement of the gait algorithms are required.

A comparison of methods to detect postural transitions using a single tri-axial accelerometer

Two algorithms for evaluating postural transitions (PTs) in cohorts of 40 healthy younger and 40 older adults are described and evaluated. The time of sit-to-stand (SiSt) and stand-to-sit (StSi) transitions and their duration were measured with two tri-axial accelerometers, one on the chest and one on the lower back. Each algorithm was optimized for these sensor placements. The first algorithm for sensor placement on the chest used a scalar product and vertical velocity estimates. The second algorithm for sensor placement on the lower back used a vector magnitude and a discrete wavelet transform. Both algorithms performed excellently in PT classification for younger and older adults (>86%). However, the chest based sensor and algorithm were better for estimating transition duration (TD) with ICCs to video analysis ranging from 0.678 to 0.969.

Defining ambulatory bouts in free-living activity: Impact of brief stationary periods on bout metrics

The aim of this study was to assess the effect of varying the maximum resting period between consecutive ambulatory bouts in community-based outcomes. Ambulation was assessed in 97 community-dwelling older adults (mean (SD) age 69.2 (7.7) years) using an accelerometer (activPAL™) worn on the upper thigh for 7 consecutive days. The volume, pattern and variability of ambulation were calculated over a range of maximum resting periods (1-30s). Outcomes with a maximum resting period from 1 to 6s did not vary due to device functionality. Non-linear regression (power law, r(2) > 0.99) showed that increasing the maximum resting period from 6 to 30s resulted in changes in volume (increased duration spent walking, and decreased number of bouts), variability (S2 increased) and pattern (α decreased), and a linear relationship with an increase in average bout length. With a MRP of 6s, 6% of the cohort achieved the public health guidelines of 150 min of ambulation/week accumulated in bouts ≥ 10 min, which increased to 40% using a maximum resting period of 30s. Modifying the maximum resting period impacts on volume, pattern and variability measures of community based ambulation, and attainment of public health guidelines. This highlights the need for standardised algorithms to aid interpretation and explicit reporting of the maximum resting period to aid comparison between studies.

Within trial validation and reliability of a single tri-axial accelerometer for gait assessment

Gait is a sensitive biomarker of decline in both cognitive and physical function. Therefore, the collection of gait data is an important feature of clinical assessments. Accelerometer-based body worn sensors are quickly becoming the preferred tool for assessing gait because they are small, useable in a wide variety of settings, offer more continuous spatio-temporal analysis and are inexpensive when compared with traditional gait assessment methodologies. The purpose of this study was to determine the validity and within test reliability of a low cost body worn movement sensor with associated algorithms to assess gait in a large group of older and younger healthy adults. We collected gait data over intermittent walks on an instrumented walkway for a within trial validation and also used the same accelerometer derived gait data for a within test reliability analysis. ICCs for validation and reliability were >0.756 and >0.965, respectively.

A systematic review and meta-analysis of outcome measures to assess postural control in older adults who undertake exergaming

Exergaming has been shown to be an effective tool to improve postural control (PC) in older community-dwelling individuals. The outcome measures (OMs) used to assess PC are varied and this could limit the estimation of the effectiveness of the intervention. This systematic review and meta-analysis aims to explore the OMs currently used to assess PC in exergaming interventions, for healthy elderly individuals aged over 60 years. The literature search was conducted across five databases (CINAHL, EMBASE, PubMed, ISI, SPORTdiscus and Science Direct) using a range of search terms and combinations relating to exergaming, balance, exercise, falls and elderly. Quality assessment was conducted using the PEDro Scale and a custom-made quality assessment tool. Eleven trials were included in the meta-analysis, with a mean (SD) PEDro score of 5.36 (1.57). Primary and secondary OMs showed small effects in favour of alternative training modes, although these effects were statistically insignificant for all primary OMs. Tertiary OMs could not be included in the meta-analysis due to varying output parameters from different instruments. Heterogeneity remained high across trials and no studies performed long-term follow-up. Exergaming is a potential alternative to PC training, although still in its infancy. Strong and well-designed RCTs are needed, targeting specific populations aged over 60 years. Variability in instrumented OMs prevents generalisation of results. Technological improvements may provide data not currently available from clinical and laboratory-based methods, and may allow PC to be assessed more realistically and specifically in relation to a populations activities of daily living, though this remains a new area of research.

Non-motor symptoms are associated with change in physical activity over 18 months in incident Parkinson's disease (PD)

Objective: To explore the association between striatal dopaminergic deficits and cognitive impairment within a large cohort of early, drug-naive Parkinson’s disease patients and to test the hypothesis that executive dysfunction in Parkinson’s disease is caused by striatal dopaminergic depletion. Background: Cognitive impairment in Parkinson’s disease is common and influences patients’ everyday functioning, but the mechanisms of early cognitive decline are not known. Understanding of these mechanisms is important for the development of methods preventing cognitive decline in Parkinson’s disease. Previous studies suggest that the dopaminergic system influences cognition in PD. Methods: Neuropsychological and cerebral dopamine transporter SPECT imaging data of 339 Parkinson’s disease patients and 158 Healthy controls of the Parkinson’s Progression Markers Initiative study were analysed. Neuropsychological evaluation consisted of standardized tests of memory, visuospatial and executive function. SPECT imaging was performed with [123I]FP-CIT and specific binding ratios in left and right putamen and caudate nucleus were calculated. The association between specific binding ratios and cognition was performed using a cognitive composite z-score, domain z-scores and individual test scores. Multivariate general linear model regression analyses were performed including age, gender, education, and laterality as predictors and specific binding ratios as dependent variables. Results: Uncorrected analysis showed no associations between dopamine transporter imaging and memory and visuospatial domains. A small but significant positive association between specific binding ratios and the attention/executive domain was found, which was not significant after adjusting for age. However, in a moderated mediation model, we found that cognitive executive differences between controls and patients with Parkinson’s disease were mediated by an age-moderated dopaminergic deficit in the left caudate nucleus. Conclusions: Our findings support the hypothesis that nigrostriatal dopaminergic deficit contributes to executive impairment, but not to memory or visuospatial impairment in early Parkinson’s disease.Objective: To investigate whether spirography-based objective measures of motor dysfunctions are able to discriminate between Parkinson’s disease (PD) patients with different motor states (Off and ...Objective: This study aims to determine PPN’s electrophysiological activities in rats to help future studies and to investigate the effect of subthalamic nucleus stimulation on PPN. Background: Long-duration medical treatment of Parkinson patients causes complications and morbidity. Risks in destructive surgery are releatively high, new treatment methods such as stereotactic functional surgery has been proposed recently. While sensory and behavioral processes of pedunculopontine nucleus (PPN) are well known as a locomotor center, its role on initiating and sustaining motion function in primates or rats has been also demonstrated. All functions of PPN are not fully known yet, and its DBS has been proposed as an alternative therapeutic target in treating gait problems of Parkinson’s disease recently. Methods: In this study, 14 male wistar type healthy rats with average 292 (284-317) gram weight and with the same age group were used. In the sham group, two probes were inserted, one to the STN bilaterally and the other to the right PPN to record PPN’s electrophysiological activities. In the experiment group, in addition to the same procedures used in the sham group, STN was stimulated bilaterally at 0.5 Hz, 10 Hz, 60 Hz ve 130 Hz and PPN’s electrophysiological activities were recorded before and after bilateral STN stimulations. Results: Analyzing the neural activity after the 60 Hz stimulation, it revealed that STN has a stimulus effect on PPN neurons increasing the firing rate. The PPN neurons demonstrated three different patterns of firing, burst random and regular. The majority of the neurons (68%) exhibited a regular pattern of firing in the sham group. After bilateral STN stimulation with very low (0,5 Hz and 10 Hz) and high (130 Hz) frequencies the PPN neurons maintained their firing patterns. However, after 60 Hz stimulation of STN a significant percentage of neurons (82,1 %) fired with a more regular pattern. Conclusions: The results of this study provides additional information to our understanding on PPN’s electrophysiological activities. 60 Hz STN stimulation can increase the firing rates and changes the behaviour of the PPN neurons.Objective: To analyze the relationship between the electric field and the volume of tissue activated (VTA) during model-based investigations of deep brain stimulation (DBS).Background: An important ...This journal suppl. entitled: Supplement: Abstracts of the Eighteenth International Congress of Parkinsons Disease and Movement Disorders / Poster Presentation