Patrick Esser

IMU: Inertial sensing of vertical CoM movement

The purpose of this study was to use a quaternion rotation matrix in combination with an integration approach to transform translatory accelerations of the centre of mass (CoM) from an inertial measurement unit (IMU) during walking, from the object system onto the global frame. Second, this paper utilises double integration to determine the relative change in position of the CoM from the vertical acceleration data. Five participants were tested in which an IMU, consisting of accelerometers, gyroscopes and magnetometers was attached on the lower spine estimated centre of mass. Participants were asked to walk three times through a calibrated volume at their self-selected walking speed. Synchronized data were collected by an IMU and an optical motion capture system (OMCS); both measured at 100 Hz. Accelerations of the IMU were transposed onto the global frame using a quaternion rotation matrix. Translatory acceleration, speed and relative change in position from the IMU were compared with the derived data from the OMCS. Peak acceleration in vertical axis showed no significant difference (p> or =0.05). Difference between peak and trough speed showed significant difference (p<0.05) but relative peak-trough position between the IMU and OMCS did not show any significant difference (p> or =0.05). These results indicate that quaternions, in combination with Simpsons rule integration, can be used in transforming translatory acceleration from the object frame to the global frame and therefore obtain relative change in position, thus offering a solution for using accelerometers in accurate global frame kinematic gait analyses.

Assessment of spatio-temporal gait parameters using inertial measurement units in neurological populations

Laboratory based gait analysis techniques are expensive, time consuming and require technical expertise. Inertial measurement units can directly measure temporal parameters and in combination with gait models may provide a solution to obtain spatial gait measurements within daily clinical assessments. However it is not known if a model and standard correction factor determined by Zijlstra and Hof [8] to estimate step and stride length parameters in typically developed adults (TDA) can be accurately used in neurologically impaired gaits. This research estimated the stride length over two 10 m walks at self selected walking speed in people with neurological conditions, using a previously established model and correction factor for TDA. The relation of the correction factor to walking speed was explored. We recruited TDA (n=10) and participants with Parkinsons disease (PD; n=24), muscular dystrophy (MD; n=13), motor neuron disease (MND; n=7) and stroke survivors (n=18) for the study who twice walked 10 m at a self-selected pace. Stride length correction factors, for TDA (1.25±0.01), PD (1.25±0.03), and MD (1.21±0.08) (p=0.833 and p=0.242) were the same as previously reported in TDA (Zijlstra and Hof [8]). Correction factors for stroke (1.17±0.42) and MND (1.10±0.08) were different (p<0.01 and p=0.028 respectively). However there was a high level of variability for correction factors within groups, which did not relate to walking speed. Our findings support that correction factors should be determined for each individual to estimate average step/stride length in patients suffering from a neurological condition.

Relationships between functional and structural corticospinal tract integrity and walking post stroke

Highlights ► We investigated the relationship between walking impairment after stroke and integrity of the corticospinal tract (CST). ► We used transcranial magnetic stimulation and diffusion tensor imaging to assess CST integrity. ► We demonstrate that patients with more ipsilateral connectivity between the unlesioned M1 and the affected leg had more structural damage to their CST.

Wearable accelerometry-based technology capable of assessing functional activities in neurological populations in community settings: a systematic review

BackgroundIntegrating rehabilitation services through wearable systems has the potential to accurately assess the type, intensity, duration, and quality of movement necessary for procuring key outcome measures.ObjectivesThis review aims to explore wearable accelerometry-based technology (ABT) capable of assessing mobility-related functional activities intended for rehabilitation purposes in community settings for neurological populations. In this review, we focus on the accuracy of ABT-based methods, types of outcome measures, and the implementation of ABT in non-clinical settings for rehabilitation purposes.Data sourcesCochrane, PubMed, Web of Knowledge, EMBASE, and IEEE Xplore. The search strategy covered three main areas, namely wearable technology, rehabilitation, and setting.Study selectionPotentially relevant studies were categorized as systems either evaluating methods or outcome parameters.MethodsMethodological qualities of studies were assessed by two customized checklists, depending on their categorization and rated independently by three blinded reviewers.ResultsTwelve studies involving ABT met the eligibility criteria, of which three studies were identified as having implemented ABT for rehabilitation purposes in non-clinical settings. From the twelve studies, seven studies achieved high methodological quality scores. These studies were not only capable of assessing the type, quantity, and quality measures of functional activities, but could also distinguish healthy from non-healthy subjects and/or address disease severity levels.ConclusionWhile many studies support ABT’s potential for telerehabilitation, few actually utilized it to assess mobility-related functional activities outside laboratory settings. To generate more appropriate outcome measures, there is a clear need to translate research findings and novel methods into practice.

A systematic review and meta-analysis of cross-sectional studies examining the relationship between mobility and cognition in healthy older adults

Highlights • Twenty-six studies were identified as eligible for this systematic review.• Mobility was positively associated with cognitive measures in healthy older adults.• The cognition-mobility relationship spans across cognitive domains.• Meta-analyses on extracted data revealed significant, albeit small, effect sizes.

Validity and inter-rater reliability of inertial gait measurements in Parkinson's disease: A pilot study

Walking models driven by centre of mass (CoM) data obtained from inertial measurement units (IMU) or optical motion capture systems (OMCS) can be used to objectively measure gait. However current models have only been validated within typical developed adults (TDA). The purpose of this study was to compare the projected CoM movement within Parkinsons disease (PD) measured by an IMU with data collected from an OMCS after which spatio-temporal gait measures were derived using an inverted pendulum model. The inter-rater reliability of spatio-temporal parameters was explored between expert researchers and clinicians using the IMU processed data. Participants walked 10 m with an IMU attached over their centre of mass which was simultaneously recorded by an OMCS. Data was collected on two occasions, each by an expert researcher and clinician. Ten people with PD showed no difference (p=0.13) for vertical, translatory acceleration, velocity and relative position of the projected centre of mass between IMU and OMCS data. Furthermore no difference (p=0.18) was found for the derived step time, stride length and walking speed for people with PD. Measurements of step time (p=0.299), stride length (p=0.883) and walking speed (p=0.751) did not differ between experts and clinicians. There was good inter-rater reliability for these parameters (ICC3.1=0.979, ICC3.1=0.958 and ICC3.1=0.978, respectively). The findings are encouraging and support the use of IMUs by clinicians to measure CoM movement in people with PD.

Supported community exercise in people with long-term neurological conditions: a phase II randomized controlled trial

Objective: Adults with long-term neurological conditions have low levels of participation in physical activities and report many barriers to participation in exercise. This study examines the feasibility and safety of supporting community exercise for people with long-term neurological conditions using a physical activity support system. Design: A phase II randomized controlled trial using computer-generated block randomization, allocation concealment and single blind outcome assessment. Setting: Oxfordshire and Birmingham community Inclusive Fitness Initiative gyms. Subjects: Patients with a long-term neurological condition. Interventions: The intervention group (n = 51) received a 12-week, supported exercise programme. The control group (n = 48) participants received standard care for 12 weeks and were then offered the intervention. Main measures: Physical activity, adherence to exercise, measures of mobility, health and well-being. Results: Forty-eight patients (n = 51) completed the intervention, achieving 14 gym attendances (range 0–39) over the 12 weeks. Overall activity did not increase as measured by the Physical Activity Scale for the Elderly (change score mean 14.31; 95% confidence interval (CI) −8.27 to 36.89) and there were no statistically significant changes in body function and health and well-being measures. Conclusions: People with long-term neurological conditions can safely exercise in community gyms when supported and achieve similar attendance to standard exercise referral schemes, but may reduce other life activities in order to participate at a gym.

Insights into gait disorders: Walking variability using phase plot analysis, Huntington's disease

Huntingtons disease (HD) is a progressive inherited neurodegenerative disorder. Identifying sensitive methodologies to quantitatively measure early motor changes have been difficult to develop. This exploratory observational study investigated gait variability and symmetry in HD using phase plot analysis. We measured the walking of 22 controls and 35 HD gene carriers (7 premanifest (PreHD)), 16 early/mid (HD1) and 12 late stage (HD2) in Oxford and Cardiff, UK. The unified Huntingtons disease rating scale-total motor scores (UHDRS-TMS) and disease burden scores (DBS) were used to quantify disease severity. Data was collected during a clinical walk test (8.8 or 10 m) using an inertial measurement unit attached to the trunk. The 6 middle strides were used to calculate gait variability determined by spatiotemporal parameters (co-efficient of variation (CoV)) and phase plot analysis. Phase plots considered the variability in consecutive wave forms from vertical movement and were quantified by SDA (spatiotemporal variability), SDB (temporal variability), ratio ∀ (ratio SDA:SDB) and Δangleβ (symmetry). Step time CoV was greater in manifest HD (p<0.01, both manifest groups) than controls, as was stride length CoV for HD2 (p<0.01). No differences were found in spatiotemporal variability between PreHD and controls (p>0.05). Phase plot analysis identified differences between manifest HD and controls for SDB, Ratio ∀ and Δangle (all p<0.01, both manifest groups). Furthermore Ratio ∀ was smaller in PreHD compared with controls (p<0.01). Ratio ∀ also produced the strongest correlation with UHDRS-TMS (r=-0.61, p<0.01) and was correlated with DBS (r=-0.42, p=0.02). Phase plot analysis may be a sensitive method of detecting gait changes in HD and can be performed quickly during clinical walking tests.

A smart device inertial-sensing method for gait analysis

The purpose of this study was to establish and cross-validate a method for analyzing gait patterns determined by the center of mass (COM) through inertial sensors embedded in smart devices. The method employed an extended Kalman filter in conjunction with a quaternion rotation matrix approach to transform accelerations from the object onto the global frame. Derived by double integration, peak-to-trough changes in vertical COM position captured by a motion capture system, inertial measurement unit, and smart device were compared in terms of averaged and individual steps. The inter-rater reliability and levels of agreement for systems were discerned through intraclass correlation coefficients (ICC) and Bland-Altman plots. ICCs corresponding to inter-rater reliability were good-to-excellent for position data (ICCs,.80-.95) and acceleration data (ICCs,.54-.81). Levels of agreements were moderate for position data (LOA, 3.1-19.3%) and poor for acceleration data (LOA, 6.8%-17.8%). The Bland-Altman plots, however, revealed a small systematic error, in which peak-to-trough changes in vertical COM position were underestimated by 2.2mm; the Kalman filter׳s accuracy requires further investigation to minimize this oversight. More importantly, however, the study׳s preliminary results indicate that the smart device allows for reliable COM measurements, opening up a cost-effective, user-friendly, and popular solution for remotely monitoring movement. The long-term impact of the smart device method on patient rehabilitation and therapy cannot be underestimated: not only could healthcare expenditures be curbed (smart devices being more affordable than todays motion sensors), but a more refined grasp of individual functioning, activity, and participation within everyday life could be attained.

Utility of the MOCA as a cognitive predictor for fitness to drive

Determining fitness to drive is a major concern affecting aging and disabled populations, particularly concerning reduced cognitive functioning, functional limitations and reduced vision.1 ,2 The Royal Society for Prevention of Accidents encourages aging drivers to maintain their license (for independence, mobility and quality of life), emphasising that prematurely removing someones driving license negatively affects their quality of life—the consequences of which outweigh the chance of being involved in a collision, for both the driver and the remainder of society.3 The gold standard test in the UK to determine the ability to drive is an on-road driving assessment, and clinicians have the opportunity to refer patients to an independent Mobility Centre (accredited by Driving Mobility) where an assessment will be performed based on on-road driving experience as judged by a professional driving instructor and occupational therapist.4 The assessment is resource expensive and only a limited number of individuals are referred. To date no screening test is clinically implemented in the UK which accurately determines fitness to drive.4 This study sets out to evaluate the potential of the Montreal Cognitive Assessment (MOCA) as a screening tool, for people with concerns regarding cognitive capacity; to determine pass/fail cuts-offs …