Head and pelvis stride-to-stride oscillations in gait: validation and interpretation of measurements from wearable accelerometers.

Unstable gait is a risk factor for falls. Wearable accelerometers enable remote monitoring of daily walking. Here, new methods for measuring stride-to-stride oscillations are validated against optical motion capture, normative data determined, and dependency on walking speed investigated. Walks by 13 young people (mean age 32 years) at fast, usual, and slow speeds were completed. Accelerometers were attached to the head and pelvis and stride-to-stride oscillation velocity and displacement were measured. Continuous tilt corrections were applied, filter cut-offs scaled by step frequency, and thresholds optimized using optical motion capture as a reference. Oscillations depended on walking speed, accelerometer placement, and measurement axis. Vertical oscillations increased with walking speed (Pearson's r = 0.78-0.89) and were the most accurate (1.4-2.3% error). Mediolateral or anterioposterior oscillations were less accurate (5.9-19.5% error) and had more complex relationships with walking speed (increasing, decreasing, uncorrelated, and/or 'U-shaped' minimum at usual speed). In healthy gait, the head and pelvis undergo regular oscillations, measurable with accelerometers. The results suggest head oscillations in the transverse plane are attenuated by the trunk, and there may be advantages in minimizing stride-to-stride oscillations that coincide with self-selected usual pace. These methods may prove useful for remote assessment of changing health, mental status, and/or fall risk.

Uncontrolled head oscillations in people with Parkinson's disease may reflect an inability to respond to perturbations while walking.

Fall injuries in people with Parkinson's disease (PD) are a major health problem. Increased sway while walking is a risk factor and further understanding of this destabilizing gait change may assist with rehabilitation and help prevent falls.Here, stride-to-stride head oscillations are used to help characterise different aspects of gait impairment in 10 people with PD on medication (67 years, SD 4), 10 healthy age-matched (HAM) participants (66 years, SD 7), and 10 young (30 years, SD 7). A wearable accelerometer was used to analyse head oscillations during five repeat 17 m walks by each participant.People with PD had significantly faster transverse plane head oscillations than the HAM or young groups; both along mediolateral (PD 47.2 cm s(-1), HAM 32.5 cm s(-1), and young 32.7 cm s(-1)) and anterioposterior axes (PD 33.3 cm s(-1), HAM 24.5 cm s(-1), and young 20.6 cm s(-1)). These differences were uncorrelated with reduced vertical oscillation velocity (PD 15.5 cm s(-1), HAM 18.8 cm s(-1), and young 20.1 cm s(-1)) and reduced walking speed (PD 1.2 m s(-1), HAM 1.4 m s(-1), and young 1.4 m s(-1)).Increased transverse plane head oscillations in people with PD may reflect motor impairment and the inability to respond sufficiently to perturbations while walking, which appears to be distinct from gait hyperkinesia, reduced vertical oscillations, step length, and walking speed.

Symmetry matched auditory cues improve gait steadiness in most people with Parkinson's disease but not in healthy older people.

BACKGROUND: Unsteady gait and falls are major problems for people with Parkinson's disease (PD). Symmetric auditory cues at altered cadences have been used to improve walking speed or step length. However, few people are exactly symmetric in terms of morphology or movement patterns and effects of symmetric cueing on gait steadiness are inconclusive. OBJECTIVES: To investigate if matching auditory cue a/symmetry to an individual's intrinsic symmetry or asymmetry affects gait steadiness, gait symmetry, and comfort to cues, in people with PD, healthy age-matched controls (HAM) and young. METHODS: Thirty participants; 10 with PD, 11 HAM (66 years), and 9 young (30 years), completed five baseline walks (no cues) and twenty-five cued walks at habitual cadence but different a/symmetries. Outcomes included; gait steadiness (step time variability and smoothness by harmonic ratios), walking speed, symmetry, comfort, and cue lag times. RESULTS: Without cues, PD participants had slower and less steady gait than HAM or young. Gait symmetry was distinct from gait steadiness, and unaffected by cue symmetry or a diagnosis of PD, but associated with aging. All participants maintained preferred gait symmetry and lag times independent of cue symmetry. When cues were matched to the individual's habitual gait symmetry and cadence: Gait steadiness improved in the PD group, but deteriorated in the HAM controls, and was unchanged in the young. Gait outcomes worsened for the two PD participants who reported discomfort to cued walking and had high New Freezing of Gait scores. CONCLUSIONS: It cannot be assumed all individuals benefit equally from auditory cues. Symmetry matched auditory cues compensated for unsteady gait in most people with PD, but interfered with gait steadiness in older people without basal ganglia deficits.

Comparison of handheld video camera and GAITRite® measurement of gait impairment in people with early stage Parkinson's disease: a pilot study.

In this pilot study, we investigated the validity and reliability of low-cost handheld video camera recordings for measuring gait in people with early stage Parkinson's disease (PD). Five participants with PD, Hoehn & Yahr stage I-II, mean age 66.2 years and five healthy age-matched controls were recruited. Participants walked across a GAITRite® electronic walkway at self-selected pace while video was simultaneously recorded. Data from both systems were analyzed and compared. Step time variability, measured from handheld video recordings, revealed significant (p ≤ 0.05) differences between the gait of early stage PD and controls. Concurrent validity between video analyses and GAITRite were good (ICC(2,1) ≥ 0.86) for mean step time and mean dual support duration. However, the inter-assessor reliability for the video analysis was poor for step time variability (ICC(2,1) = 0.18). More reliable measurement of step time variability may require a system to measure extended periods of walking. Further research involving longer walks and more participants with higher stages of PD is required to investigate if step time variability can be measured with acceptable reliability using video recordings. If this could be demonstrated, this simple technology could be adapted to run on a tablet or smart phone, providing low cost gait assessments without the need for specialized equipment and expensive infrastructure.

4D-CT angiography differentiating arteriovenous fistula subtypes.

OBJECTIVE AND METHODS: In the diagnostic work-up of patients suspected of a dural arteriovenous fistula (dAVF), imaging has a key role in order to diagnose the dAVF, assess its bleeding risk and choose optimal treatment strategy. Digital subtraction angiography (DSA) is the gold standard for the most detailed image of a dAVF. Nowadays four-dimensional CT angiography (4D-CTA) could possibly be an additional first-line tool in the work-up of a patient suspected of a dAVF. We describe three cases clinically suspected of a dAVF which had a diagnostic work-up with 4D-CTA as well as DSA. We evaluated the angioarchitecture of the dAVF both on 4D-CTA and DSA, with emphasis on the patterns of venous drainage as this is important in assessing the bleeding risk of a dAVF. RESULTS AND CONCLUSION: 4D-CTA identified the dAVF, revealed its angioarchitecture and correctly differentiated different patterns of venous drainage (Borden type I, II and III) as confirmed on DSA. Although DSA has the advantage of higher spatial and temporal resolution, 4D-CTA seems to be a new useful non-invasive tool in the diagnostic work-up of a patient suspected of a dAVF.