From inverted pendulum to N-link chain: inertial sensors-based assessment of movement kinematics and dynamics for functional evaluation and rehabilitation

Despite several clinical tests that have been developed to qualitatively describe complex motor tasks by functional testing, these methods often depend on clinicians' interpretation, experience and training, which make the assessment results inconsistent, without the precision required to objectively assess the effect of the rehabilitative intervention. A more detailed characterization is required to fully capture the various aspects of motor control and performance during complex movements of lower and upper limbs. The need for cost-effective and clinically applicable instrumented tests would enable quantitative assessment of performance on a subject-specific basis, overcoming the limitations due to the lack of objectiveness related to individual judgment, and possibly disclosing subtle alterations that are not clearly visible to the observer. Postural motion measurements at additional locations, such as lower and upper limbs and trunk, may be necessary in order to obtain information about the inter-segmental coordination during different functional tests involved in clinical practice. With these considerations in mind, this Thesis aims: i) to suggest a novel quantitative assessment tool for the kinematics and dynamics evaluation of a multi-link kinematic chain during several functional motor tasks (i.e. squat, sit-to-stand, postural sway), using one single-axis accelerometer per segment, ii) to present a novel quantitative technique for the upper limb joint kinematics estimation, considering a 3-link kinematic chain during the Fugl-Meyer Motor Assessment and using one inertial measurement unit per segment. The suggested methods could have several positive feedbacks from clinical practice. The use of objective biomechanical measurements, provided by inertial sensor-based technique, may help clinicians to: i) objectively track changes in motor ability, ii) provide timely feedback about the effectiveness of administered rehabilitation interventions, iii) enable intervention strategies to be modified or changed if found to be ineffective, and iv) speed up the experimental sessions when several subjects are asked to perform different functional tests.

Movement Analysis by means of inertial sensors: from bench to bedside

in the everyday clinical practice. Having this in mind, the choice of a simple setup would not be enough because, even if the setup is quick and simple, the instrumental assessment would still be in addition to the daily routine. The will to overcome this limit has led to the idea of instrumenting already existing and widely used functional tests. In this way the sensor based assessment becomes an integral part of the clinical assessment. Reliable and validated signal processing methods have been successfully implemented in Personal Health Systems based on smartphone technology. At the end of this research project there is evidence that such solution can really and easily used in clinical practice in both supervised and unsupervised settings. Smartphone based solution, together or in place of dedicated wearable sensing units, can truly become a pervasive and low-cost means for providing suitable testing solutions for quantitative movement analysis with a clear clinical value, ultimately providing enhanced balance and mobility support to an aging population.

Protocollo semplificato per lo studio cinematico dell'arto superiore: individuazione di indici di normalita nel movimento di "reaching"

L'esigenza di poter usufruire in clinica di uno strumento per l'analisi cinematica dell'arto superiore altamente attendibile che fornisca dati clinicamente validi e facili da interpretare e rapidamente applicabile dal personale medico competente, ha posto le basi per la realizzazione del modello che in questa tesi viene proposto. L'obiettivo è stato definire un metodo di misura per l'analisi delle traiettorie dell'arto superiore basato su un modello di markerizzazione che sia clinicamente attuabile e descriva la catena completa dell'estremità superiore interessata nel gesto di “reaching” indipendentemente dalla patologia.

Tra pacifismo e ambientalismo: il Nuclear Freeze Movement e la risposta dell'amministrazione Reagan

Negli anni Ottanta si assiste tanto nel vecchio quanto nel nuovo continente alla rinascita del movimento antinucleare. Mentre in Europa l’origine di questa ondata di proteste antinucleari è collegata alla “doppia decisione” NATO del 1979, negli Stati Uniti la genesi si colloca nel contesto dalla mobilitazione dei gruppi ambientalisti in seguito all’incidente alla centrale nucleare di Three Mile Island. Dopo l’elezione di Ronald Reagan, alle proteste contro le applicazioni pacifiche dell’atomo si affiancarono quelle contro la politica nucleare del Paese. La retorica di Reagan, il massiccio piano di riarmo, unitamente al rinnovato deteriorarsi delle relazioni tra USA e URSS contribuirono a diffondere nell’opinione pubblica la sensazione che l’amministrazione Reagan, almeno da un punto di vista teorico, non avesse escluso dalle sue opzioni il ricorso alle armi nucleari nel caso di un confronto con l’URSS. I timori legati a questa percezione produssero una nuova ondata di proteste che assunsero dimensioni di massa grazie alla mobilitazione provocata dalla Nuclear Weapons Freeze Campaign (NWFC). Il target della NWFC era l’ampio programma di riarmo nucleare sostenuto da Reagan, che secondo gli attivisti nucleari, in un quadro di crescenti tensioni internazionali, avrebbe fatto aumentare le possibilità di uno scontro atomico. Per evitare lo scenario dell’olocausto nucleare, la NWFC proponeva «un congelamento bilaterale e verificabile del collaudo, dell’installazione e della produzione di armi nucleari». L’idea del nuclear freeze, che era concepito come un passo per fermare la spirale del riarmo e tentare successivamente di negoziare riduzioni negli arsenali delle due superpotenze, riscosse un tale consenso nell’opinione pubblica americana da indurre l’amministrazione Reagan a formulare una risposta specifica. Durante la primavera del 1982 fu, infatti, creato un gruppo interdipartimentale ad hoc, l’Arms Control Information Policy Group, con il compito di arginare l’influenza della NWFC sull’opinione pubblica americana e formulare una risposta coerente alle critiche del movimento antinucleare.

The reconstruction of skeletal movement: the soft tissue artefact issue

In 3D human movement analysis performed using stereophotogrammetric systems and skin markers, bone pose can only be estimated in an indirect fashion. During a movement, soft tissue deformations make the markers move with respect to the underlying bone generating soft tissue artefact (STA). STA has devastating effects on bone pose estimation and its compensation remains an open question. The aim of this PhD thesis was to contribute to the solution of this crucial issue. Modelling STA using measurable trial-specific variables is a fundamental prerequisite for its removal from marker trajectories. Two STA model architectures are proposed. Initially, a thigh marker-level artefact model is presented. STA was modelled as a linear combination of joint angles involved in the movement. This model was calibrated using ex-vivo and in-vivo STA invasive measures. The considerable number of model parameters led to defining STA approximations. Three definitions were proposed to represent STA as a series of modes: individual marker displacements, marker-cluster geometrical transformations (MCGT), and skin envelope shape variations. Modes were selected using two criteria: one based on modal energy and another on the selection of modes chosen a priori. The MCGT allows to select either rigid or non-rigid STA components. It was also empirically demonstrated that only the rigid component affects joint kinematics, regardless of the non-rigid amplitude. Therefore, a model of thigh and shank STA rigid component at cluster-level was then defined. An acceptable trade-off between STA compensation effectiveness and number of parameters can be obtained, improving joint kinematics accuracy. The obtained results lead to two main potential applications: the proposed models can generate realistic STAs for simulation purposes to compare different skeletal kinematics estimators; and, more importantly, focusing only on the STA rigid component, the model attains a satisfactory STA reconstruction with less parameters, facilitating its incorporation in an pose estimator.

Eye movement and diffusion tensor imaging analysis of treatment effects in a Niemann-Pick Type C patient

New treatment options for Niemann-Pick Type C (NPC) have recently become available. To assess the efficiency and efficacy of these new treatment markers for disease status and progression are needed. Both the diagnosis and the monitoring of disease progression are challenging and mostly rely on clinical impression and functional testing of horizontal eye movements. Diffusion tensor imaging (DTI) provides information about the microintegrity especially of white matter. We show here in a case report how DTI and measures derived from this imaging method can serve as adjunct quantitative markers for disease management in Niemann-Pick Type C. Two approaches are taken--first, we compare the fractional anisotropy (FA) in the white matter globally between a 29-year-old NPC patient and 18 healthy age-matched controls and show the remarkable difference in FA relatively early in the course of the disease. Second, a voxelwise comparison of FA values reveals where white matter integrity is compromised locally and demonstrate an individualized analysis of FA changes before and after 1year of treatment with Miglustat. This method might be useful in future treatment trials for NPC to assess treatment effects.

Video-based quantification of body movement during social interaction indicates the severity of negative symptoms in patients with schizophrenia

In schizophrenia, nonverbal behavior, including body movement, is of theoretical and clinical importance. Although reduced nonverbal expressiveness is a major component of the negative symptoms encountered in schizophrenia, few studies have objectively assessed body movement during social interaction. In the present study, 378 brief, videotaped role-play scenes involving 27 stabilized outpatients diagnosed with paranoid-type schizophrenia were analyzed using Motion Energy Analysis (MEA). This method enables the objective measuring of body movement in conjunction with ordinary video recordings. Correlations between movement parameters (percentage of time in movement, movement speed) and symptom ratings from independent PANSS interviews were calculated. Movement parameters proved to be highly reliable. In keeping with predictions, reduced movement and movement speed correlated with negative symptoms. Accordingly, in patients who exhibited noticeable movement for less than 20% of the observation time, prominent negative symptoms were highly probable. As a control measure, the percentage of movement exhibited by the patients during role-play scenes was compared to that of their normal interactants. Patients with negative symptoms differed from normal interactants by showing significantly reduced head and body movement. Two specific positive symptoms were possibly related to movement parameters: suspiciousness tended to correlate with reduced head movement, and the expression of unusual thought content tended to relate to increased movement. Overall, a close and theoretically meaningful association between the objective movement parameters and the symptom profiles was found. MEA appears to be an objective, reliable and valid method for quantifying nonverbal behavior, an aspect which may furnish new insights into the processes related to reduced expressiveness in schizophrenia.