Subjective perception of activity level: A prognostic factor for developing chronic dizziness after vestibular schwannoma resection?

IntroductionA vestibular schwannoma (VS) resection causes an acute unilateral vestibular deafferentation resulting in acute postoperative symptoms. Despite the expected resolution of most of the symptoms, due to central vestibular compensation, more than one out of four patients develop chronic dizziness. Several predictive factors, such as age and tumor size, have been suggested. Despite its potential effect on the process of central vestibular compensation, the level of physical activity after VS resection was not yet considered. Therefore, the association between the level of physical activity and chronic dizziness after VS resection will be investigated.MethodsThis retrospective cohort study included 66 patients who underwent a retro-sigmoid VS resection between October 2001 and February 2007. Patients were assessed before surgery and at 9 weeks and 6 months postoperatively. At 9 weeks, patients were asked to report their level of physical activity (PA) during the past week by using a visual analogue scale and their balance performance was assessed by four standing balance conditions with eyes closed and the Timed Up and Go test (TUG). Based on the Dizziness Handicap Inventory (DHI) score at 6 months, patients were divided in a chronic dizziness group (DHI > 30) and non-chronic dizziness group (DHI-score ≤ 30). Age, sex, Koos classification, preoperative vestibular function, treatment group, balance performance, and level of PA were compared between both groups and used as independent variables in linear regression analyses with the DHI score at 6 months as dependent variable.ResultsThe chronic dizzy patients revealed to have significantly lower levels of PA (p < 0.001) and worse static and dynamic balance performance (p = 0.023 and p = 0.041, respectively) 9 weeks after surgery. After elimination, the multiple regression analysis resulted in a model with two variables (PA level, TUG) which significantly predicted the DHI score (F2,42 = 6.581; R2 = 0.239; p = 0.003).ConclusionThis study revealed associations between (1) the level of PA and balance performance in the subacute phase and (2) chronic dizziness after VS resection. Assessment of the level of PA and balance performance during the subacute phase, which can be performed in a non-invasive and non-time-consuming way, might therefore provide prognostic information after VS resection

An exploratory investigation on spatiotemporal parameters, margins of stability, and their interaction in bilateral vestibulopathy

Integration of accurate vestibular, visual, and proprioceptive information is crucial in managing the centre of mass in relation to the base of support during gait. Therefore, bilateral loss of peripheral vestibular function can be highly debilitating when performing activities of daily life. To further investigate the influence of an impaired peripheral vestibular system on gait stability, spatiotemporal parameters, step-to-step variability, and mechanical stability parameters were examined in 20 patients with bilateral vestibulopathy and 20 matched healthy controls during preferred overground walking. Additionally, using a partial least squares analysis the relationship between spatiotemporal parameters of gait and the margins of stability was explored in both groups. Patients with bilateral vestibulopathy showed an increased cadence compared to healthy controls (121 ± 9 vs 115 ± 8 steps/min; p = 0.02; d = 0.77). In addition, although not significant (p = 0.07), a moderate effect size (d = 0.60) was found for step width variability (Coefficient of Variation (%); Bilateral vestibulopathy: 19 ± 11%; Healthy controls: 13 ± 5%). Results of the partial least squares analysis suggest that patients with peripheral vestibular failure implement a different balance control strategy. Instead of altering the step parameters, as is the case in healthy controls, they use the single and double support phases to control the state of the centre of mass to improve the mechanical stability

Physics-based simulations to predict the differential effects of motor control and musculoskeletal deficits on gait dysfunction in cerebral palsy : a retrospective case study

Physics-based simulations of walking have the theoretical potential to support clinical decision-making by predicting the functional outcome of treatments in terms of walking performance. Yet before using such simulations in clinical practice, their ability to identify the main treatment targets in specific patients needs to be demonstrated. In this study, we generated predictive simulations of walking with a medical imaging based neuro-musculoskeletal model of a child with cerebral palsy presenting crouch gait. We explored the influence of altered muscle-tendon properties, reduced neuromuscular control complexity, and spasticity on gait dysfunction in terms of joint kinematics, kinetics, muscle activity, and metabolic cost of transport. We modeled altered muscle-tendon properties by personalizing Hill-type muscle-tendon parameters based on data collected during functional movements, simpler neuromuscular control by reducing the number of independent muscle synergies, and spasticity through delayed muscle activity feedback from muscle force and force rate. Our simulations revealed that, in the presence of aberrant musculoskeletal geometries, altered muscle-tendon properties rather than reduced neuromuscular control complexity and spasticity were the primary cause of the crouch gait pattern observed for this child, which is in agreement with the clinical examination. These results suggest that muscle-tendon properties should be the primary target of interventions aiming to restore an upright gait pattern for this child. This suggestion is in line with the gait analysis following muscle-tendon property and bone deformity corrections. Future work should extend this single case analysis to more patients in order to validate the ability of our physics-based simulations to capture the gait patterns of individual patients pre- and post-treatment. Such validation would open the door for identifying targeted treatment strategies with the aim of designing optimized interventions for neuro-musculoskeletal disorders

Bilateral vestibulopathy and age:experimental considerations for testing dynamic visual acuity on a treadmill

Introduction: Bilateral vestibulopathy (BVP) can affect visual acuity in dynamic conditions, like walking. This can be assessed by testing Dynamic Visual Acuity (DVA) on a treadmill at different walking speeds. Apart from BVP, age itself might influence DVA and the ability to complete the test. The objective of this study was to investigate whether DVA tested while walking, and the drop-out rate (the inability to complete all walking speeds of the test) are significantly influenced by age in BVP-patients and healthy subjects. Methods: Forty-four BVP-patients (20 male, mean age 59 years) and 63 healthy subjects (27 male, mean age 46 years) performed the DVA test on a treadmill at 0 (static condition), 2, 4 and 6 km/h (dynamic conditions). The dynamic visual acuity loss was calculated as the difference between visual acuity in the static condition and visual acuity in each walking condition. The dependency of the drop-out rate and dynamic visual acuity loss on BVP and age was investigated at all walking speeds, as well as the dependency of dynamic visual acuity loss on speed. Results: Age and BVP significantly increased the drop-out rate (p ≤ 0.038). A significantly higher dynamic visual acuity loss was found at all speeds in BVP-patients compared to healthy subjects (p < 0.001). Age showed no effect on dynamic visual acuity loss in both groups. In BVP-patients, increasing walking speeds resulted in higher dynamic visual acuity loss (p ≤ 0.036). Conclusion DVA tested while walking on a treadmill, is one of the few “close to reality” functional outcome measures of vestibular function in the vertical plane. It is able to demonstrate significant loss of DVA in bilateral vestibulopathy patients. However, since bilateral vestibulopathy and age significantly increase the drop-out rate at faster walking speeds, it is recommended to use age-matched controls. Furthermore, it could be considered to use an individual “preferred” walking speed and to limit maximum walking speed in older subjects when testing DVA on a treadmill

Current practices in clinical gait analysis in Europe:A comprehensive survey-based study from the European society for movement analysis in adults and children (ESMAC) standard initiative

BACKGROUND: Clinical gait analysis (CGA) is a systematic approach to comprehensively evaluate gait patterns, quantify impairments, plan targeted interventions, and evaluate the impact of interventions. However, international standards for CGA are currently lacking, resulting in various national initiatives. Standards are important to ensure safe and effective healthcare practices and to enable evidence-based clinical decision-making, facilitating interoperability, and reimbursement under national healthcare policies. Collaborative clinical and research work between European countries would benefit from common standards.RESEARCH OBJECTIVE: This study aimed to review the current laboratory practices for CGA in Europe.METHODS: A comprehensive survey was conducted by the European Society for Movement Analysis in Adults and Children (ESMAC), in close collaboration with the European national societies. The survey involved 97 gait laboratories across 16 countries. The survey assessed several aspects related to CGA, including equipment used, data collection, processing, and reporting methods.RESULTS: There was a consensus between laboratories concerning the data collected during CGA. The Conventional Gait Model (CGM) was the most used biomechanical model for calculating kinematics and kinetics. Respondents also reported the use of video recording, 3D motion capture systems, force plates, and surface electromyography. While there was a consensus on the reporting of CGA data, variations were reported in training, documentation, data preprocessing and equipment maintenance practices.SIGNIFICANCE: The findings of this study will serve as a foundation for the development of standardized guidelines for CGA in Europe.</p

Effects of visual deprivation on intra-limb coordination during walking in children and adults

Following the laws of planar covariation, intersegmental coordination is defined with respect to the vertical and heading direction. This vertical reference can be estimated using multisensory information, amongst others visual cues play a role. In the past it was already shown that visual deprivation and/or perturbation of visual information largely affect gait kinematics. The goal of this study is to investigate the impact of visual deprivation on intra-limb movement coordination. Children aged between 3 and 11 years and young adults are included in this study to investigate age-related differences in the visual control of locomotion. Intersegmental coordination was tested under two different conditions: full vision (FV) and no vision (NV). Heading direction and walking speed were taken into account. A significant interaction effect was observed between visual condition and age for walking speed. Between age groups, no differences are observed in the FV condition but in the NV condition children walk significantly slower than adults. This shows that the relative importance of visual information is age dependent. Between age groups significant differences were found in heading direction. Coordination was characterized using the planar covariation technique, by constructing thigh versus shank and shank versus foot angle-angle plots and by cross-correlation function analysis. Regardless of the presence or absence of visual information, the planarity index remains high, indicating that the laws of planar covariation hold in the absence of visual afferent information. On the other hand, the shape of the gait loop does show significant differences between FV and NV conditions. Changes in the shape of the gait loop are primarily determined by changes in the coupling between the thigh and shank elevation angles. The coupling between the shank and foot elevation angles is dependent upon walking speed and does not differ between FV and NV conditions. Between age groups significant differences are observed in covariation plane orientation

Effects of visual deprivation on intra-limb coordination during walking in children and adults

The encoding strategies to remember as many witnessed events as possible afterwards was discussed. Four types of encoding strategies, which were 1) to verbalize the events as fully as possible, 2) to fix their eyes intentionally on many points, 3) to elaborate the events, and 4) to memorize the scene as it is, were compared with each other, and were also compared with 5) the control group that subjects were told to memorize as much as possible. Subjects were presented with three portraits (Exp.1) or ten slides (Exp.2) as materials, and were to memorize them by one of the strategies mentioned above. As a result of memory tests for details of to-be-remembered materials. 1) the verbalization strategy group and 5) the control group performed significantly better than other three groups. There were no significant interactions between retention intervals and memorization stratedies. The results implies that intentional encoding strategies other than verbalization strategy impair the memory for remembering. The practical use on the actual criminal investigation was discussed on the basis of the results