The video head impulse test predicts the ability to reweight vestibular information during stance in patients with vestibular disorders

INTRODUCTION: During stance, vestibular information is used and weighted based on its reliability. Vestibular deficits affect the reliability of vestibular information and therefore affect the ability to reweight vestibular information during stance. Vestibular information during stance mainly consists of frequencies up to 5 Hz. However, vestibular-ocular reflex (VOR) tests designed to detect vestibular deficits mainly operate in restricted frequency ranges such as 0.002 - 0.004 Hz for the caloric test, 0.1 - 1 Hz for the rotational chair test and 1 - 6 Hz for the head impulse test. In this study we investigated how these three VOR tests are related to the ability to reweight vestibular information under different sensory disturbance conditions in patients with vestibular disorders. METHODS: 11 Patients (5 female) with vestibular disorders (mean ± SD age: 59.3 ± 9.9 years) were included. All patients underwent VOR examination using videonystagmography during bilateral cold caloric test, the rotational chair test at horizontal harmonic oscillations of the chair at 0.4 Hz and the head impulse test. In addition, balance control experiments were conducted using continuous support surface rotations (SS) which followed a pseudo-random ternary sequence (PRTS). Patients stood with their eyes closed during two SS conditions: 1) 0.5 degrees peak-to-peak amplitude and 2) 1.0 degrees peak-to-peak amplitude. System identification and parameter estimation were used to estimate balance control model parameters, including the vestibular weight Wv which indicates how much patients relied on vestibular information in each condition. Spearman correlation coefficients were calculated to establish the relation between VOR tests (caloric test, rotational chair test and head impulse test) and the difference in the vestibular weight (Wv_diff) between 0.5 and 1.0 degrees peak-to-peak amplitude. RESULTS: Only the head impulse test was significantly related to Wv_diff (ρ = -0.67, p = 0.033), indicating that patients who showed more asymmetric ocular responses to left and right head impulses showed less sensory reweighting between SS conditions during balance control. DISCUSSION: Our results suggest that out of the three VOR tests included in this study the video head impulse test is most predictive of a reduced ability to reweight vestibular information during stance in patients with vestibular disorders. The video head impulse test mainly operates in the 1-6 Hz frequency range, which is comparable to the frequency range of joint torque and body sway oscillations and could therefore explain this high association

ExpertiSZe, a tool for determining the effects of social security legislation

Social security legislation plays an important role in the Dutch society. In view of this, the effects of social security legislation have to be analysed carefully before new legislation can be made. Due to the growing complexity of legislation on the social security domain, this analysis has become a demanding task. ExpertiSZe is a knowledge-based system developed to support the process of analysing juridical and socio-economic effects of social security legislation. The ExpertiSZe system consists of three modules: a consultation module, a consistency module and a simulation module. These modules, which all work on the basis of the same rule-based model, provide the legislator with more insight into the impact of legislation. This article describes the potential of ExpertiSZe to support the analysis of effects of legislation

Smoothness metrics for reaching performance after stroke:Part 1: which one to choose?

BACKGROUND: Smoothness is commonly used for measuring movement quality of the upper paretic limb during reaching tasks after stroke. Many different smoothness metrics have been used in stroke research, but a ‘valid’ metric has not been identified. A systematic review and subsequent rigorous analysis of smoothness metrics used in stroke research, in terms of their mathematical definitions and response to simulated perturbations, is needed to conclude whether they are valid for measuring smoothness. Our objective was to provide a recommendation for metrics that reflect smoothness after stroke based on: (1) a systematic review of smoothness metrics for reaching used in stroke research, (2) the mathematical description of the metrics, and (3) the response of metrics to simulated changes associated with smoothness deficits in the reaching profile. METHODS: The systematic review was performed by screening electronic databases using combined keyword groups Stroke, Reaching and Smoothness. Subsequently, each metric identified was assessed with mathematical criteria regarding smoothness: (a) being dimensionless, (b) being reproducible, (c) being based on rate of change of position, and (d) not being a linear transform of other smoothness metrics. The resulting metrics were tested for their response to simulated changes in reaching using models of velocity profiles with varying reaching distances and durations, harmonic disturbances, noise, and sub-movements. Two reaching tasks were simulated; reach-to-point and reach-to-grasp. The metrics that responded as expected in all simulation analyses were considered to be valid. RESULTS: The systematic review identified 32 different smoothness metrics, 17 of which were excluded based on mathematical criteria, and 13 more as they did not respond as expected in all simulation analyses. Eventually, we found that, for reach-to-point and reach-to-grasp movements, only Spectral Arc Length (SPARC) was found to be a valid metric. CONCLUSIONS: Based on this systematic review and simulation analyses, we recommend the use of SPARC as a valid smoothness metric in both reach-to-point and reach-to-grasp tasks of the upper limb after stroke. However, further research is needed to understand the time course of smoothness measured with SPARC for the upper limb early post stroke, preferably in longitudinal studies. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12984-021-00949-6

Technology-assisted training of arm-hand skills in stroke: concepts on reacquisition of motor control and therapist guidelines for rehabilitation technology design

<p>Abstract</p> <p>Background</p> <p>It is the purpose of this article to identify and review criteria that rehabilitation technology should meet in order to offer arm-hand training to stroke patients, based on recent principles of motor learning.</p> <p>Methods</p> <p>A literature search was conducted in PubMed, MEDLINE, CINAHL, and EMBASE (1997–2007).</p> <p>Results</p> <p>One hundred and eighty seven scientific papers/book references were identified as being relevant. Rehabilitation approaches for upper limb training after stroke show to have shifted in the last decade from being analytical towards being focussed on environmentally contextual skill training (task-oriented training). Training programmes for enhancing motor skills use patient and goal-tailored exercise schedules and individual feedback on exercise performance. Therapist criteria for upper limb rehabilitation technology are suggested which are used to evaluate the strengths and weaknesses of a number of current technological systems.</p> <p>Conclusion</p> <p>This review shows that technology for supporting upper limb training after stroke needs to align with the evolution in rehabilitation training approaches of the last decade. A major challenge for related technological developments is to provide engaging patient-tailored task oriented arm-hand training in natural environments with patient-tailored feedback to support (re) learning of motor skills.</p

Recovery of the paretic upper limb early after stroke: restitution or substitution of motor control?

promotiedatum: 12-11-2014 � prom-id: 970

Estrogen receptor interaction and pharmacokinetics of contraceptive steroids: in vivo and in vitro studies on lynestrenol and related compounds

Contains fulltext : mmubn000001_025234633.pdf (publisher's version ) (Open Access)Promotores : J. van Rossum en T. Eskesxviii, 231 p