Multimodal Mobility Assessment Predicts Fall Frequency and Severity in Cerebellar Ataxia.

This cohort study aims to evaluate the predictive validity of multimodal clinical assessment and quantitative measures of in- and off-laboratory mobility for fall-risk estimation in patients with cerebellar ataxia (CA).Occurrence, severity, and consequences of falling were prospectively assessed for 6 months in 93 patients with hereditary (N = 36) and sporadic or secondary (N = 57) forms of CA and 63 healthy controls. Participants completed a multimodal clinical and functional fall risk assessment, in-laboratory gait examination, and a 2-week inertial sensor-based daily mobility monitoring. Multivariate logistic regression analyses were performed to evaluate the predictive capacity of all clinical and in- and off-laboratory mobility measures with respect to fall (1) status (non-faller vs. faller), (2) frequency (occasional vs. frequent falls), and (3) severity (benign vs. injurious fall) of patients. 64% of patients experienced one or recurrent falls and 65% of these severe fall-related injuries during prospective assessment. Mobility impairments in patients corresponded to a mild-to-moderate ataxic gait disorder. Patients' fall status and frequency could be reliably predicted (78% and 81% accuracy, respectively), primarily based on their retrospective fall status. Clinical scoring of ataxic symptoms and in- and off-laboratory gait and mobility measures improved classification and provided unique information for the prediction of fall severity (84% accuracy).These results encourage a stepwise approach for fall risk assessment in patients with CA: fall history-taking readily and reliably informs the clinician about patients' general fall risk. Clinical scoring and instrument-based mobility measures provide further in-depth information on the risk of recurrent and injurious falling.

Quantification of pathological gait parameter thresholds of idiopathic normal pressure hydrocephalus patients in clinical gait analysis.

The aim of the study was to distinguish the hypokinetic gait disorder in idiopathic normal pressure hydrocephalus (NPH) patients from the gait decline in the elderly population by quantifying pathological gait parameter thresholds utilizing a multiple condition gait assessment. 55 NPH patients and 55 age-matched healthy subjects underwent a standardized gait assessment with eight gait conditions. Spatiotemporal gait parameters were assessed through a pressure-sensitive carpet. Statistical analysis consisted of a binary logistic regression (BLR) model, logistic curve-fit evaluated by a Chi-square goodness-of-fit-test, receiver operating characteristic models with area under the curves (AUC), and inverse BLR. Most discriminative gait parameter thresholds were observed in pace, gait cycle, and support gait domains. The most distinct gait conditions were preferred walking speed and semantic dual task. During preferred walking speed, the most significant gait parameter thresholds were stride length ≤ 1.02 m (sensitivity 0.93/specificity 0.91/AUC 0.96), gait velocity ≤ 0.83 m/s (0.80/0.91/0.93), double support phase ≥ 27.0% (0.96/0.76/0.91), and stride length coefficient of variation ≥ 3.4% (0.93/0.72/0.90). In conclusion, the hypokinetic gait disorder in NPH can be quantitatively differentiated from gait patterns of the elderly population. In future studies, this approach may be useful to differentiate clinical entities with similar gait disorders utilizing instrumented gait analysis procedures.

Style transfer-based domain adaptation for vegetation segmentation with optical imagery.

Style transfer methods are an important task for domain adaptation of optical imagery to improve the performance of deep learning models when using different sensor systems. For the transformation between datasets, cycle-consistent adversarial networks achieve good results. However, during the style transfer process, characteristic spectral information that is essential for the analysis of vegetation could get lost. This issue is especially important since optical airborne- and spaceborne-based sensors are frequently used to investigate vegetation ground coverage and its condition. In this paper, we present a cycle-consistent adversarial domain adaptation method with four input channels for the segmentation of vegetation areas using index-based metrics. We show that our method preserves the specific ratio between the near-IR and RGB bands and improves the segmentation network performance for the target domain.

Fall prediction in neurological gait disorders: differential contributions from clinical assessment, gait analysis, and daily-life mobility monitoring.

OBJECTIVE: To evaluate the predictive validity of multimodal clinical assessment outcomes and quantitative measures of in- and off-laboratory mobility for fall-risk estimation in patients with different forms of neurological gait disorders. METHODS: The occurrence, severity, and consequences of falls were prospectively assessed for 6 months in 333 patients with early stage gait disorders due to vestibular, cerebellar, hypokinetic, vascular, functional, or other neurological diseases and 63 healthy controls. At inclusion, participants completed a comprehensive multimodal clinical and functional fall-risk assessment, an in-laboratory gait examination, and an inertial-sensor-based daily mobility monitoring for 14 days. Multivariate logistic regression analyses were performed to identify explanatory characteristics for predicting the (1) the fall status (non-faller vs. faller), (2) the fall frequency (occasional vs. frequent falls), and (3) the fall severity (benign vs. injurious fall) of patients. RESULTS: 40% of patients experienced one or frequent falls and 21% severe fall-related injuries during prospective fall assessment. Fall status and frequency could be reliably predicted (accuracy of 78 and 91%, respectively) primarily based on patients' retrospective fall status. Instrumented-based gait and mobility measures further improved prediction and provided independent, unique information for predicting the severity of fall-related consequences. INTERPRETATION: Falls- and fall-related injuries are a relevant health problem already in early stage neurological gait disorders. Multivariate regression analysis encourages a stepwise approach for fall assessment in these patients: fall history taking readily informs the clinician about patients' general fall risk. In patients at risk of falling, instrument-based measures of gait and mobility provide critical information on the likelihood of severe fall-related injuries.

The gait disorder in primary orthostatic tremor.

OBJECTIVE: To uncover possible impairments of walking and dynamic postural stability in patients with primary orthostatic tremor (OT). METHODS: Spatiotemporal gait characteristics were quantified in 18 patients with primary OT (mean age 70.5 ± 5.9 years, 10 females) and 18 age-matched healthy controls. One-third of patients reported disease-related fall events. Walking performance was assessed on a pressure-sensitive carpet under seven conditions: walking at preferred, slow, and maximal speed, with head reclination or eyes closed, and while performing a cognitive or motor dual-task paradigm. RESULTS: Patients exhibited a significant gait impairment characterized by a broadened base of support (p = 0.018) with increased spatiotemporal gait variability (p = 0.010). Walking speed was moderately reduced (p = 0.026) with shortened stride length (p = 0.001) and increased periods of double support (p = 0.001). Gait dysfunction became more pronounced during slow walking (p < 0.001); this was not present during fast walking. Walking with eyes closed aggravated gait disability as did walking during cognitive dual task (p < 0.001). CONCLUSION: OT is associated with a specific gait disorder with a staggering wide-based walking pattern indicative of a sensory and/or a cerebellar ataxic gait. The aggravation of gait instability during visual withdrawal and the normalization of walking with faster speeds further suggest a proprioceptive or vestibulo-cerebellar deficit as the primary source of gait disturbance in OT. In addition, the gait decline during cognitive dual task may imply cognitive processing deficits. In the end, OT is presumably a complex network disorder resulting in a specific spino-cerebello-frontocortical gait disorder that goes beyond mere tremor networks.

Clinical and neurophysiological risk factors for falls in patients with bilateral vestibulopathy.

Patients with bilateral vestibular failure (BVF) exhibit imbalance when standing and walking that is linked to a higher fall risk. The purpose of this study was to identify risk factors for falls in BVF. We therefore systematically investigated the interrelationship of clinical and demographic characteristics, gait impairments, and the fall frequency of these patients. Clinical and demographic characteristics as well as quantitative measures of gait performance on a pressure-sensitive gait carpet were collected from 55 patients with different etiologies of BVF. Clinical and demographic data as well as spatiotemporal gait characteristics were used for ANOVA testing and a logistic regression model with categorized fall events as dependent variables. The impairment of peripheral vestibular function, duration of disease, and the overall gait status were not associated with the history of falls in patients with BVF. In contrast, the most predictive factors for falls in BVF were an increase in temporal gait variability, especially at slow walking speeds (p < 0.001; OR = 1.3), and the presence of a concomitant peripheral neuropathy (p < 0.045; OR = 3.6). BVF patients with a high risk of falling exhibit specific gait alterations in a speed-dependent manner. In particular, increased gait fluctuations during slow walking are most predictive for an increased fall risk. The presence of a concomitant peripheral neuropathy further critically impairs postural stability in these patients. Clinical assessment of both these aspects is therefore important to identify those patients at a particularly high fall risk and to initiate preventive procedures early.