Quantitative assessment of upper limb motor impairments in people with neurological diseases

Individuals with neurological diseases often exhibit upper limb (UL) motor deficits, which can compromise their ability to perform basic activities of daily living (ADL). The clinical assessment of these impairments is commonly performed by clinicians using tests and scales that are not suitable to adequately characterize UL alterations in terms of duration, velocity and kinematics of a performed movement. However, in recent times, the research on motor dysfunctions has been taking advantage of the possibilities offered by quantitative motion analysis techniques (e.g. motion capture systems and wearable inertial sensors) which are able to provide objective information regarding UL movement abilities during the performance of functional tasks. The aim of this thesis was to define and validate an experimental approach, based on the use of optoelectronic stereophotogrammetry, aimed to obtaining quantitative information about the kinematics of a specific functional motor task (hand to mouth, HTM) that are fully representative of important ADLs such as feeding and drinking. In particular, the study was focused on the assessment of the main spatio-temporal and kinematic parameters of the HTM task, providing in this way information about movement quality in order to better understand the control characteristics of impairment. Moreover, on the basis of the kinematic data associated with the main UL joint movements, a specific synthetic index (Arm Profile Score, APS) was formulated following an approach similar to the one that previously proposed to characterize the gait kinematics in a range of neurological conditions. In this way, the whole kinematic pattern can be summarized by a single value that can be easily interpreted by physicians (i.e. the larger the value, the more distant the movement pattern from those of unaffected individuals). Experimental tests were performed in samples of individuals with Multiple Sclerosis (MS, n = 30), Parkinson’s disease (PD, n = 16) and Dementia with Lewy Bodies (DLB, n = 10) and in 56 age- and gender-matched individuals (HC), who underwent a 3D kinematic evaluation of the HTM task using a motion capture system. A range of spatial-temporal parameters (e.g. total and phases’ duration of the movement, velocity of the hand) and joint kinematics were calculated as well as the APS score. Differences between groups were investigated using one-way MANOVA, while a correlation analysis was performed to assess the existence of a possible relationship with clinical tests and/or disability level assessed by specialized neurologists. The results obtained suggest that the analysis of HTM task is suitable to objectively characterize UL functional motor performance. Moreover, the APS score succeeded in discriminating abnormal kinematic patterns with respect to a physiological movement. Furthermore, the existence of significant relationships between the synthetic indexes and the clinical scales scores (i.e. Expanded Disability Scale Score, EDSS, for MS, Hoehn & Yahr, H&Y, scale and Unified Parkinson’s Disease Rating Scale, UPDRS, for basal ganglia disorders) suggests that these are suitable to represent the peculiar UL alterations associated with each condition. Thus, the use of quantitative synthetic measures is an effective way to quantify overall UL functions and compare motor impairments between clinical groups, features that are undetectable by standard clinical tests. In summary, the quantitative assessment of UL impairments in people with neurological diseases during a functional task may effectively support and integrate the clinical evaluation through an accurate description of the movement features. This technique appears able to play an important role in supporting physicians in monitoring the individual’s deficit progression and in planning suitable interventions for managing UL movement disorders.