Listing 1 - 10 of 62 | << page >> |
Sort by
|
Choose an application
Haemophilia is a rare coagulation disorder mostly affecting men. It is characterized by the absence or deficiency of circulating factor VIII (haemophilia A) or factor IX (haemophilia B). In severe cases (factor level < 1%), it could result in abnormal, sometimes spontaneous bleedings and impaired blood coagulation. Up to 90% of these bleedings occur in the musculoskeletal system, with the ankle joint being most prone to recurrent bleeding episodes. Secondary arthropathy due to recurrent ankle joint bleeds, called haemophilic ankle arthropathy, is the most disabling complication in adults with haemophilia. Yet, the functional impact of haemophilic ankle arthropathy during gait in these patients is not welldefined and the potential role of joint loading on the pathophysiological cascade remains unclear.Recent research emphasized the importance of musculoskeletal biomechanics in developing pathological/disruptive compensation mechanisms in the ankle and foot joints due to the pathophysiological cascade of haemophilic ankle arthropathy. Based on previous evidence, improvement of clinical decision-making processes in patients with haemophilic ankle arthropathy beyond current state-of-the-art can only be achieved when including dynamic biomechanical gait features assessed with 3D gait analysis. Of particular interest for these patients is the investigation of mechanical loading in the ankle and foot complex. The main objective of this project was therefore to unravel the biomechanical joint loading in adults with haemophilia using a skin marker-based multi-segment foot model.In the first, methodological part of this doctoral thesis, we substantiated the use of such a multi-segment foot model in clinical motion analysis. A current methodological challenge in multi-segment kinetic models is the partitioning of shear forces across each foot joint. As no technical devices yet exist which allow the measurement of these shear forces with an appropriate spatial resolution, the shear force partitioning currently is based on an existing proportionality scheme. The scientific community therefore claimed that these estimations might lead to measurement errors. In chapter 2, we could reject this claim as we did not find any differences between kinetic measurements obtained with the proportionality scheme and those directly obtained using an adjacent force plate method. We could therefore reliably measure ankle and foot joint biomechanics in pathological gait.We also quantified the clinical misinterpretations of earlier one-segment or rigid kinetic foot models (chapter 3). In this study it was found that one-segment kinetic foot models overestimate the ankle joint peak power generation on average 14% in pathological gait - due to an overestimation of the joint angular velocity - and future research should therefore use a multi-segment foot model to overcome this clinical misinterpretation. It is generally known that walking speed is often lowered in adult patients with haemophilia. In chapter 4 of this thesis, we confirmed that walking speed affects the multisegment foot kinetics and caution is warranted when interpreting the kinetic output of the ankle and foot joints in patients with haemophilic ankle arthropathy.In the second clinical part of this doctoral thesis, we implemented the skin markerbased multi-segment foot model to investigate the impact of haemophilic ankle arthropathy on the ankle and foot joint biomechanics during walking. In chapter 5, we established a relationship between the structural ankle joint damage (based on MRI) and the ankle joint power output in patients with haemophilia. It could therefore be concluded in this study that patients with severe blood-induced ankle joint damage have a lowered tolerance towards ankle joint mechanical loading during walking. It was also found that the biomechanical load on the ankle joint is significantly altered in PwH compared to healthy subjects, potentially triggered by the arthropathy-induced ankle joint stiffness (chapter 6). Future longitudinal studies are required to confirm this hypothesis and to determine the treatment efficacy of conservative strategies to overcome these biomechanical alterations, such as therapeutic footwear or orthopedic devices. We explored the effect of conventional footwear on the biomechanical alterations in these patients and found that these increased the ankle joint mobility and simultaneously lowered the excessive mechanical loading during mid-stance of walking (chapter 7).In conclusion, most of the biomechanical alterations during walking in patients with haemophilia were present whenever the ankle joint had existing blood-induced ankle joint damage. The clinical relevance of this project therefore dictates that haemophilia care should focus on protecting adults with haemophilia against recurrent ankle joint bleeds in order to maintain proper gait functionality. Conservative treatment strategies could be initiated with the aim to preserve or improve the ankle joint mobility, which would positively impact the ankle and foot joint biomechanics in these patients.
Choose an application
Wereldwijd is een beroerte de meest frequente oorzaak van blijvende ernstige beperkingen, waarbij niet goed kunnen gebruiken van de hand en de arm één van de meest voorkomende gevolgen is. Omdat voor de meeste dagelijkse activiteiten beide handen nodig zijn, leidt een beroerte vaak tot afhankelijkheid voor deze activiteiten. Levensbalans staat voor het hebben van een evenwichtig patroon van activiteiten en kan ook worden verstoord door een beroerte. Het algemene doel van dit doctoraat het bimanuele handelen en levensbalans te onderzoeken bij personen tijdens het eerste jaar na het optreden van een beroerte, aangezien hierover nog weinig gekend is. Meer specifiek focust dit doctoraat zich op het verder nagaan van de kwaliteiten van een test die het bimanuele handelen in kaart brengt, het nagaan van de kwaliteiten van een vragenlijst die levensbalans meet, het onderzoeken van welke factoren het bimanuele handelen en levensbalans kunnen voorspellen op zes maanden en een jaar na de beroerte en tot slot wordt ook de invloed van het bimanuele handelen op levensbalans nagegaan.Worldwide, stroke is the most frequent cause of long-term disability, with loss of hand and arm use being one of the most common consequences. Because most daily activities require the use both hands working together, a stroke often results in dependency for daily activities. Life balance stands for having a balanced pattern of activities and may be compromised after a stroke. As little is known about bimanual performance and life balance in persons after stroke, the general aim of this PhD is to investigate bimanual performance and life balance within the first year after stroke. More specific, this PhD project focuses on further examining the features of a test that assesses bimanual performance, examining the qualities of a questionnaire that measures life balance, investigating which factors can predict bimanual performance and life balance at six months and a year after the stroke and finally, to investigate the influence of bimanual performance on life balance.
Choose an application
In children with unilateral cerebral palsy (CP), sensory and motor impairments are often more pronounced in the upper limb (UL) than in the lower limb, though the variability in outcome is large. This is not surprising since these children present with various brain lesions. So far, it is still unclear which neurological factors determine UL function in these children. Further research is necessary to unravel the complex neuropathophysiology underlying UL dysfunction.Magnetic resonance imaging (MRI) is the standard clinical technique to investigate brain lesions in children with CP. However, more recently developed medical imaging techniques can provide a more complete picture of the brain lesion. Diffusion tensor imaging (DTI) is found to be superior to structural MRI to identify white matter tract injury in children with CP. Limited studies using DTI have focused on the associations with UL function in children with unilateral CP presenting contradicting results on the importance of the corticospinal versus thalamocortical tracts. Recently, diffusion kurtosis imaging (DKI) was suggested as a minimal extensionof DTI as it provides a more accurate quantification of water diffusion in the brain. Until know, DKI still has not been used in the research are of CP.Furthermore, there is increasing evidence that constrained-induced movement therapy and intensive bimanual training are efficient for improving UL function in children with unilateral CP. However, until now no one treatment modality has shown to be superior. Moreover, studies reported large variability which cannot befully explained based on age or initial severity.15 Therefore, it has become an intriguing question whether the efficacy of therapy models depends on brain lesion characteristics and this requires further investigation.The overall aim of this project is to investigate which neurological factors determine UL sensorimotor outcome as well as treatment response via a clinical and biomechanical approach in children with unilateral CP. In a first study, we will try to get a betterinsight in the relation between clinical and biomechanical measures of UL function. Secondly, we will explore in how far sensorimotor function depends on white matter tract integrity (DKI) combined with brain lesioncharacteristics (MRI). Finally, we will conduct an intervention study to identify neurological predictors for treatment response.Most neuroimaging studies investigated the association between imaging findings and motor function, while we will emphasize more on identifying neurological predictors of UL function as well as treatment response. This project is, to our knowledge, the first to use DKI in children with CP also combined with the neuroanatomical characterization of the lesion and relate this to UL function. Secondly, studies using UL kinematics in combination with neuroimaging findings do not exist yet. Sothis project will provide new knowledge in this field which will help us to better understand the neuropathophysiology underlying UL dysfunction.
Choose an application
Physics-based simulations of human movement have the potential to predict the functional outcome of treatments, thereby allowing clinicians to personalize and optimize clinical decision-making. These predictive simulations would be particularly valuable for treatments with modest and unpredictable outcomes, such as orthopedic surgeries aiming to improve walking abilities of children with cerebral palsy (CP). Yet computational and modeling challenges still limit the applicability of such simulations in clinical practice. This dissertation aimed to address some of these limitations by improving model-based predictions of walking in children with CP, paving the way for treatment outcome predictions.The central hypothesis of this dissertation was that predictive simulations can be exploited to explore the differential effects of motor control and mechanical deficits on the walking abilities of children with CP. We carried out five studies addressing three objectives to investigate this hypothesis.The first objective was to develop methods and models to characterize the mechanical and motor control deficits of children with CP. Mechanical deficits include altered muscle-tendon properties represented through Hill-type muscle-tendon parameters, whereas motor control deficits include muscle spasticity described as exaggerated muscle reflex activity.In study 1, we proposed a computationally efficient approach based on optimal control and musculoskeletal modeling to estimate subject-specific Hill-type muscle-tendon parameters. The approach identifies parameters that minimize the difference between experimental and model-based joint torques during functional movements. We applied this optimization procedure to estimate optimal fiber lengths and tendon slack lengths of several knee actuators of healthy adults. In addition, we evaluated which functional movements contained sufficient information to provide valid (i.e., representative of the subjects) parameter estimates. We showed that our estimation procedure identified subject-specific parameters that improved the accuracy of joint torque simulations as compared to generic parameters. Further, we found that only specific functional movements contained enough information for a valid estimation, underlining the importance of the experimental data selection.In study 2, we developed and compared three models of spasticity based on delayed sensory feedback from muscle states. The models relied on feedback from muscle length and velocity, feedback from muscle length, velocity, and acceleration, and feedback from muscle force and force rate, respectively. It is thought that the muscle spindle proprioceptive receptors encode information about muscle length and velocity changes. Yet recent experimental findings suggest that spindle firing might be more directly related to muscle force and force rate. Hence, we hypothesized that the force-based model would better explain spastic activity than the length-based models. We developed an optimal control formulation to identify feedback gains that minimized the difference between feedback and measured muscle activity during passive muscle stretches eliciting spastic responses. We found that the force-based model better explained spastic activity than the length-based models, confirming our hypothesis. In addition, we showed that only the force-based model was able to predict muscle activity in agreement with pathological activity measured during gait, opening perspectives for studying the controversial influence of spasticity during gait.The second objective was to develop methods to generate computationally efficient predictive simulations of human movement. We formulated predictive simulations as optimal control problems. Solving such problems is, however, challenging. On the one hand, the equations describing the dynamics of the musculoskeletal system are stiff and nonlinear. On the other hand, using complex musculoskeletal models results in large and computationally expensive problems.In study 3, we developed a framework to generate computationally efficient predictive simulations with complex three-dimensional musculoskeletal models. Key to this efficiency is the combination of direct collocation methods, implicit differential equations, and algorithmic differentiation. We evaluated the computational benefits of using algorithmic differentiation against finite differences to compute derivatives when generating predictive simulations of walking. As expected, algorithmic differentiation drastically reduced the computational time as compared to finite differences. The proposed simulation framework allows overcoming computational roadblocks that have long limited the use of optimal control simulations for biomechanical applications.The third objective was to exploit predictive simulations to i) evaluate candidate walking control strategies in healthy and impaired individuals and ii) explore the differential effects of motor control and mechanical deficits on the walking pattern of a child with CP. In predictive simulations formulated as optimal control problems, the performance criterion determines the control strategy of the motor task. Yet it remains unclear what such criterion would be for human gait. Further, it is unknown whether the same performance criterion can explain the range of gaits adopted by humans in different contexts.In study 4, we identified a multi-objective performance criterion combining energy and effort considerations that produces physiologically realistic predictive simulations of walking based on a three-dimensional musculoskeletal model. We then showed that the same criterion predicts the walk-to-run transition and clinical gait deficiencies caused by muscle weakness and prosthesis use, suggesting that diverse gaits can emerge from the same control strategy. This finding is in line with prior experimental and simulation studies based on two-dimensional models. The ability to predict the mechanics and energetics of diverse gaits suggests that our neuro-musculoskeletal model and simulation framework are generalizable enough for studying healthy and pathological gaits.In study 5, we tested the ability of our simulations to identify the main treatment targets for a child with CP. We generated predictive simulations of walking with a medical imaging based three-dimensional neuro-musculoskeletal model of a child with CP and explored the influence of altered muscle-tendon properties, reduced neuromuscular control complexity, and spasticity on walking performance. We modeled altered muscle-tendon properties through personalized Hill-type muscle-tendon parameters, reduced neuromuscular control complexity through muscle synergies, and spasticity through delayed muscle force and force rate feedback. We found that, in the presence of aberrant musculoskeletal geometries, altered muscle-tendon properties were the primary driver of the crouch gait pattern observed for this child, which is in line with the clinical examination. This suggests that muscle-tendon properties should be the primary target of treatments aiming to restore a more upright gait pattern for this child, which is in accordance with the orthopedic intervention that was performed.The ability of our framework for personalized modeling and predictive simulation to distinguish the contribution of different impairments on walking performance opens the door for modeling the effect of treatments, with the aim of designing optimal and personalized interventions for neuro-musculoskeletal disorders.
Choose an application
In patients with neuromuscular disorders (NMD) and thoracic wall deformities (TWD) alveolar hypoventilation can occur once the respiratory muscles become insufficient. Non-invasive ventilation can be started to reduce hypercapnia and to improve symptoms.Previous studies in patients with NMD and TWD showed an increased survival and quality of life after initiation of NIV. Although NIV is mostly applied to reduce alveolar hypoventilation during the night, only very few studies have searched for the effect of NIV on the quantity and quality of sleep.One of the most typical symptoms of alveolar hypoventilation is increased daytime sleepiness, which has a possible negative effect on physical activity. Few small studies (n<10) have found positive effects of NIV on muscle strength and the 6 minute walking distance, but no research has been done on the effect of NIV on physical activity.In a first part we will search for the effects of NIV on the quantity and quality of sleep in patients with amyotrophic lateral sclerosis (ALS). A large group of ALS patients is in follow-up at the Neuromuscular Reference Centre of the University Hospitals Leuven. If alveolar hypoventilation occurs, most of these patients are sent on to our sleep lab to initiate NIV. By using polysomnography (objective measurement) and patient reported outcomes (subjective measurement) the effect on quantity and quality of sleep is measured. Further on, research will be performed to investigate the influence of NIV on the sympathicovagal balance and an attempt will be made to create an “ideal” protocol for titration of NIV.A second part will focus on theeffects of NIV on physical activity in patients with NMD and TWD. Physical activity will be objectively measured before and after initiation ofNIV by physical activity devices together with the measurements of physical capacity and the endurance and strength of peripheral and respiratory muscles.
Choose an application
Due to dopamine loss in the basal ganglia, patients with Parkinson's disease (PD) have problems performing automatic tasks like walking. The capacity to perform tasks automatically can be evaluated by assessing dual-task (DT) performance, which is defined as "the simultaneous performance of two tasks with distinct goals". Under DT situations, people with PD show a larger deterioration of performance than age-matched healthy control subjects, since conscious attention needs to be given to the tasks performed. Up to now, it remains unclear whether DT performance in people with PD can be improved by training and whether training can be offered in a safe way without increasing fall risk. The purpose of this doctoral thesis was therefore to gain more insight into the scope and effectiveness of DT training in people with PD. The basis of this research project was the DUALITY trial, in which two centers (KU Leuven, Belgium and Radboud University Medical Center, Nijmegen) were involved.In a first study, we examined whether DT motor and DT cognitive outcome measures could be used reliably in longitudinal studies in patients with PD. We included data from 62 patients who underwent two DT tests repeated after a 6 week interval. We found that DT gait outcomes, particularly DT gait velocity, showed an excellent reliability, while proportional DT interference measures were less stable. We also showed that a functional dual task, such as using a mobile phone while walking, was a reliable and ecologically valid task with the potential to be used in the clinic.In a second study, we determined which factors contributed to DT motor and DT cognitive performance in different types of dual tasks. In this analysis all patients participating in the DUALITY trial took part (N = 121). As expected, both motor and cognitive factors played a significant role in the determination of DT performance. We found that single-task gait performance together with a test of verbal fluency and task switching contributed most to DT gait performance. Determining factors remained constant in different types of dual tasks, while additional factors emerged in the Mobile Phone and Stroop task. Single-task cognitive performance was the most important determinant of DT cognitive performance.The third study provided a summary of the recent literature on the effects of DT interventions in PD and an overview on current concepts of DT interference. Different strategies for improving DT performance were proposed, based on studies in older adults. Current evidence was inconclusive on whether DT training was useful in PD. However, two types of training strategies theoretically provided the best option: integrated task training (IDT) would increase the efficiency of brain areas thought to play an executive role in combining two tasks, whereas consecutive task training (CTT) would increase task automaticity, resulting in a higher level of residual brain capacity. Therefore, in the fourth study, we compared the effectiveness and safety of these two different training strategies, following the experimental set-up of the DUALITY trial. In this trial, 121 patients with PD were recruited and randomized into one of the two training groups. The first training group practiced gait and cognitive tasks separately (consecutive), while the other training group practiced gait tasks in combination with cognitive tasks (integrated). Participants received six weeks of training, twice a week in the presence of a physiotherapist and twice a week unsupervised. Before the intervention, DT performance was tested twice before and after a six week control period (test 1 and test 2). Effects of training on DT performance were assessed immediately after the intervention (test 3) and after 12 weeks of follow-up (test 4). The primary outcome was DT gait velocity during the Stroop task, which was an untrained task. Both training strategies proved to be effective in improving DT gait outcomes after training and no differences between strategies could be found. Training did not only improve trained dual tasks, but effects also transferred to untrained tasks and were retained at 12-weeks of follow-up. A second important finding was that fall risk did not increase during and after DT training. Effects on DT cognitive outcomes however were less consistent.In study five, we examined which factors determined DT training effects. Comparable to study 2, motor and cognitive factors, which were assessed at baseline, determined the training effects. Better DT performance before training related to less improvement after training, probably indicating that less room for improvement was available in these patients. Better cognitive performance on the ScopaCog related to larger effects from training, especially in the integrated task training group.In conclusion, this thesis provided insight into general mechanisms of dual tasking in PD and also generated a better understanding into the specific mechanisms underlying DT training interventions in people with PD. We found that DT measures can be used reliably in people with PD and are mostly determined by single-task performance and a test of executive function. Both consecutive and integrated strategies of DT training can be used effectively and safely in a large sample of people with early to mid stage PD. The effects suggested that task automatization, as well as a degree of task integration is possible in this patient group. The findings of this thesis offer new avenues for further research into the concept of dual tasking and DT training in PD and offer a framework for implementing DT interventions in clinical practice.
Choose an application
In België hebben 8.3 per 1000 levend geboren kinderen een aangeboren hartaandoening, wat gelijklopend is met het voorkomen in de westerse wereld. Vroeger leefden slechts weinig kinderen met ernstige hartaandoeningenlang. In de voorbije decennia echter hebben verbeterde chirurgische technieken en medische opvolging de overleving veranderd en meer en meer patiënten bereiken nu de volwassenheid met een levensverwachting die dichtbij het normale ligt. De eerste studies met betrekking tot aangeboren hartaandoeningen waren vooral gericht op de behandeling van de hartafwijking en de beperkingen op het niveau van het hart. Recent hebben studies echter gefocust op kwaliteit van leven, met inbegrip van de huidige inspanningsstatus bij kinderen, adolescenten en volwassenen. Met dit doctoraatsonderzoek wouden we tot een beter begrip komen van parameters, determinanten, met inbegrip van fysieke activiteit, en de prognostische waardevan de inspanningstolerantie bij volwassenen met een aangeboren hartafwijking. Onze resultaten tonen een verlaagde inspanningscapaciteit, die sterker verlaagd is bij patiënten met meer complexe onderliggende hartdefecten. Verder toonden we aan dat de verminderde inspanningstolerantie niet alleen het gevolg is van beperkingen in het hart, maar ook van fysieke activiteitsniveaus die lager liggen dan bij de gemiddelde bevolking enlager dan aanbevolen. Verder toonden we aan dat een verminderde inspanningscapaciteit geassocieerd is met een hoger risico voor cardiovasculaire aandoeningen, cardiovasculaire behandelingen waarvoor ziekenhuisopnamenoodzakelijk is, en overlijden. Daarom willen we de mogelijke voordelenvan fysieke activiteit voor deze patiëntenpopulatie benadrukken, aangezien deze al een verhoogd risico voor secundair cardiovasculair lijden kent. We geloven dat het aanbevolen is om volwassen patiënten met aangeboren hartaandoeningen actief te informeren, aan te moedigen en te begeleiden naar meer fysieke activiteit binnen de beperkingen van hun hartaandoening. Inspanningstraining zal vermoedelijk positieve effecten hebben op de inspanningscapaciteit, de gezondheidsstatus en de lange termijn prognose van deze patiënten. In Belgium, the birth prevalence of congenital heart disease is 8.3 per1000 live births, which is in line with the prevalence in the western world. Long-term survival of patients with severe congenital heart disease used to be poor. In the last decades, however, improved surgical techniques and medical follow-up have changed the outcome and more and more patients reach adulthood with a life expectancy close to normal. The early studies on congenital heart disease focused on treatment of the heart defect and limitations within the heart, however in recent years studieshave focused on quality of life, including the current exercise status in children, adolescents and adults. With this doctoral research we wanted to come to a better understanding of measures, determinants, including physical activity behaviour, and the prognostic value of exercise tolerance in adults with congenital heart disease. Our results documented a reduced exercise capacity, which is more severe in patients with more complex underlying cardiac abnormalities. We furthermore documented that the reduced exercise tolerance was not only related with heart disease related impairments, but also with physical activity levels that were lower in comparison with the general population and lower then recommended. Moreover, we showed that a reduced exercise capacity is related with a higher risk for cardiovascular diseases, cardiovascular interventions requiring hospitalisation and death. We therefore emphasize on the potential benefits of physical activity for this patient population at high riskof secondary cardiovascular disease. We believe that it seems recommended to actively inform, encourage and guide adult patients with congenital heart disease to be more physically active within the limits of their cardiac condition. Exercise training will probably have beneficial effects on the patient's actual exercise capacity, perceived health status, and long term prognosis.
Choose an application
In life, performance of everyday activities always requires some degree of trunk control. The development of trunk control is a complex process and therefore vulnerable for adverse conditions during early life. Cerebral palsy (CP) is defined as a group of disorders of the development of movement and posture, causing activity limitations that are attributed to non-progressive disturbances occurring in the developing fetal and infant brain. Empirical findings show that children with CP often have impaired trunk control, which affects their ability to maintain a stable position in sitting and standing as well as their performance of functional activities such as reaching and walking. This may in turn impact on the independency and quality of life of these children. However, despite its clinical relevance, current insights into trunk deficits in children with CP is limited, which can be partially explained by a paucity of available measurement tools for both clinical and objective evaluation of trunk control. Adequate assessment is necessary to gain a thorough understanding of their movement deficits, and to provide a sound base for well-targeted treatment planning. At the start of this doctoral project, a comprehensive clinical measurement scale to evaluate both static and dynamic aspects of trunk control and their relation to functional activities was nonexistent. Moreover, whilst three-dimensional (3D) movement analysis has proven a suitable method to obtain a detailed and objective description of upper and lower limb movements in children with CP, its application for trunk movement analysis remained very limited. The few available methods to assess trunk kinematics were dissimilar with regard to the biomechanical model, marker sets, calculation procedures and study population. The scope of this doctoral project was to contribute to the understanding of impaired trunk control in children with CP. The first part of this doctoral project focused on the development of a clinical and an objective measurement method for trunk control in children with CP (Chapters 1 and 2). In the second part, we aimed to gain insights into clinical and objective parameters of impaired trunk control (Chapters 3 and 4), and into the functional relationship between the trunk and the lower limbs during gait (Chapter 5).The first part of this doctoral project addressed the need for appropriate measurement tools for trunk control evaluation in children with CP. A review of the literature revealed a lack of a suitable clinical measurement tool for trunk evaluation in children with CP. In stroke rehabilitation, the Trunk Impairment Scale (TIS) appeared a promising tool to measure both static and dynamic aspects of trunk control in sitting. However, the specific clinical features of impaired trunk control in children with CP necessitated the development of a new scale, based on the TIS, the Trunk Control Measurement Scale (TCMS) (Chapter 1). The TCMS assesses trunk control in sitting and consists of three subscales. The first subscale static sitting balance measures static trunk control during movements of upper and lower limbs. The other two subscales selective movement control and dynamic reaching, evaluate dynamic aspects of trunk control, i.e. active trunk movements within and beyond the base of support. The psychometric properties of the TCMS were evaluated in 26 children with spastic CP and 30 typically developing (TD) children between 8 and 15 years. Results showed excellent inter-rater and test-retest reliability. Also, several aspects of validity (internal consistency, construct validity, discriminant ability) of the TCMS were established. These findings support the use of the TCMS as an evaluative tool.Besides the evaluation of trunk control in sitting, we were also interested to study trunk movements during functional activities, such as gait. Despite the additional value of 3D movement analysis in the assessment of pathological movement patterns, no suitable model to study trunk movements in children with CP was available in literature. Therefore, a biomechanical model was composed for evaluation of head and trunk kinematics during gait in children with CP (Chapter 2). This model consists of five rigid segments, i.e. head, thorax, pelvis, shoulder line and spine. Reliability of the model was verified in 10 children with spastic diplegia between 5 and 15 years. Results showed overall good reliability of all segments within one session and over time, except for the head due to standardization difficulties. Range of motion (ROM) was found the most reliable parameter. The findings of this study provided a sound base for the clinical utility of the model.The second part of this doctoral project was set out to improve our understanding of trunk deficits in children with spastic CP, by use of the previously developed methodology. In Chapter 3, clinical characteristics of impaired trunk control were investigated with the TCMS in a large cohort of children with spastic CP (N=100). Also, differences in these characteristics between subgroups, based on topography (hemiplegia, diplegia, quadriplegia) and severity of the functional impairment (GMFCS levels I-IV), were studied. Results showed clearly impaired trunk control in children with spastic CP, however to a various extent, depending on the topography and severity of the functional impairment. Children with hemiplegia and diplegia mainly showed impaired dynamic trunk control, while children with quadriplegia showed distinct deficits in both static as well as dynamic trunk control. Marked differences were found between GMFCS levels, with larger deficits found in more severely impaired children. These findings provided first specific guidelines for targeted treatment interventions to improve trunk control.Chapter 4 aimed to identify objective parameters of impaired trunk control during gait. Head and trunk kinematic parameters were compared between 20 children with spastic diplegia and 20 age-matched TD children. Children with CP were divided into two subgroups according to their GMFCS level (I-II). Discrete (ROM, mean position) and continuous kinematic parameters (waveforms) were compared between groups. Additionally, a newly developed measure for the overall trunk deficit during gait, the Trunk Profile Score (TPS), was proposed. This index reflects the magnitude of deviation of trunk motion relative to a norm-based dataset of TD children. Results indicated clear head and trunk deficits during gait in children with spastic diplegia, predominantly in more severely impaired children. ROM in the sagittal plane differentiated best between GMFCS levels. The results of this study further established the discriminant ability of the trunk model.The functional relation between trunk and lower limb motion during gait was further explored in Chapter 5. In particular, we wanted to investigate to what extent trunk deficits during gait reflected the presence of underlying impaired trunk control, or needed to be considered as compensatory movements induced by lower limb impairments. We therefore studied the relationship between trunk performance in sitting, measured with the TCMS, and trunk and lower limb kinematic parameters during gait in 20 children with spastic diplegia. Several meaningful correlations were found between TCMS scores and increased trunk deficits during gait, while lower limb and trunk deficits were only related to a limited extent. The findings of this exploratory study thus provided first evidence that the observed trunk deficits during gait should not be solely considered compensatory to lower limb impairments, but also partially reflect an underlying trunk deficit. More in-depth study on a larger cohort will provide a better understanding of underlying trunk deficits in children with CP, which may facilitate well-targeted therapy planning.In conclusion, this doctoral project made a fundamental contribution to the understanding of impaired trunk control in children with spastic CP by providing reliable, clinically feasible and comprehensive tools to assess trunk control in a clinical and biomechanical context. Further elaboration of the current methodology to other motor types and severity levels is recommended. Also, future research is needed to gain insights into the neurological determinants and early development of trunk control. These insights may provide valuable and specific clues for therapeutic interventions aimed at improvement of trunk control in children with CP, which may ultimately improve their functionality.
Choose an application
Patients with chronic obstruction pulmonary disease (COPD) present with respiratory symptoms and systemic manifestations including, but not limited to, muscle dysfunction, exercise intolerance, health status impairment and physical inactivity. These clinical features result in a deteriorating health condition with needed attention from health care providers. This PhD thesis has addressed some important aspects in the handling of patients with COPD patients, from the assessment of the rate of decline over time to interventions to reactivate patients.Quadriceps weakness is related to hospitalization and mortality of patients with COPD. Importantly, this dysfunction can be reverted by an adequately prescribed exercise training program. However, quadriceps muscle force is not often measured in pulmonary rehabilitation centers around the world. This may be partly explained due to the high cost of the gold standard device for this measure. We showed that a strain gauge is equally valid and reliable to measure isometric quadriceps force of patients with COPD. This is a simpler and cheaper alternative for the computerized dynamometry.The early detection of dysfunction is fundamental for secondary prevention. Therefore, we investigated the changes in systemic manifestations of COPD from an early diagnosis of mild to moderate airflow obstruction. Our cohort of subjects with airflow obstruction did not present a faster deterioration in maximal exercise outcomes compared to controls without airflow obstruction, with and without a smoking history. The findings of this longitudinal study adds new information to the literature about the effects of aging on exercise capacity in these cohorts. This was done by including both the traditional peak exercise measures and the efficiency slopes, relatively new outcomes which are less effort dependent. In the latter outcome (oxygen efficiency slope), subjects with airflow obstruction even deteriorated slower compared to controls.Similarly, health status of subjects with early airflow obstruction did not deteriorate faster than in control subjects. Acute respiratory exacerbations contributed to a faster deterioration in our cohort of interest. The absolute change in health status did not correlate well with changes in functional outcomes, which reinforces we cannot estimate health status based on the functional condition of a patient. When subjects with overall fast deterioration were singled out, they presented with characteristics that may be linked to an emphysematous phenotype. This may help to guide the selection of patients with mild disease at risk for rapid deterioration.Patients with more advanced disease, who remain symptomatic despite optimal pharmacotherapy, are referred to pulmonary rehabilitation. This comprehensive therapy does not result in enhanced physical activity in its current conventional form. We found that implementing a semi-automated telecoaching program after twelve weeks of pulmonary rehabilitation does increase the amount of physical activity in patients with COPD. This without changing other clinical outcomes, which are enhanced during the first three months of pulmonary rehabilitation alone. Therefore, combining both interventions for patients who improved their functional capacity seem to optimize the therapy.
Choose an application
Freezing of Gait (FOG) is a debilitating phenomenon, common in advanced Parkinson's Disease (PD). Developing FOG is a major risk for falls and is associated with higher anxiety and depression and reduced quality of life. The pathophysiology of FOG is poorly understood and prospective studies designed to explore the mechanisms of FOG development are scarce. Furthermore, given the partial response to medication, the role of preventative or remedial therapy is promising. This project contains two parts - the first a prospective study to investigate the markers of FOG development using a multi-level and multi-domain approach while the second part is a training study which will target a potential marker of FOG development i.e. gait asymmetry to examine whether split-belt training can remediate FOG behaviour as a proof of concept for clinical trials. We expect that this innovative study will provide much needed insights into the development of FOG as well as guide future research aiming to ameliorate the burden of patients with PD.
Listing 1 - 10 of 62 | << page >> |
Sort by
|