Coupling Robot-aided assessment and surface electromyography to evaluate wrist and forearm muscles activity, muscle fatigue and its effect on proprioception

Sensorimotor functions and an intact neural control of muscles are essential for the effective execution of movements during daily living tasks. However, despite the ability of human sensorimotor system to cope with a great diversity of internal and external demands and constraints, these mechanisms can be altered as a consequence of neurological disorders, injuries or just due to excessive effort leading to muscle fatigue. A precise assessment of both motor and sensory impairment is thus needed in order to provide useful cues to monitor the progression of the disease in pathological populations or to prevent injuries in case of workers. In particular, considering muscle fatigue, an objective assessment of its manifestation may be crucial when dealing with subjects with neuromuscular disorders for understanding how specific disease features evolve over time or for testing the efficacy of a potential therapeutic strategy. Indeed, muscle fatigue accounts for a significant portion of the disease burden in populations with neuromuscular diseases but, despite its importance, a standardized, reliable and objective method for fatigue measurement is lacking in clinical practice. The work presented in this thesis investigates a practical solution through the use of a robotic task and parameters extracted by surface electromyography signals. Moreover, a similar approach that combines robot-mediated proprioception test and muscle fatigue assessment has been developed and used in this thesis to objectively investigate the influence of muscle fatigue on position sense. Finally, the effect of posture on muscle activity, from a perspective of injuries prevention, has been examined. Data on adults and children have been collected and quantitative and objective information about muscle activity, muscle fatigue and joint sensitivity were obtained gaining useful insight both in the clinical context and in the prevention of workplace injuries. A novel method to assess muscle fatigue has been proposed together with the definition of an easy readable indicator that can help clinicians in the assessment of the patient. As for the impact of fatigue on the sensorimotor system, results obtained showed a decrease in wrist proprioceptive acuity which led also to a decline in the performance of a simple tracing task. Regarding the adoption of different muscle strategies depending on postures, results showed that muscle activity of forearm muscles was overall similar regardless from the postures

Sustained Isometric Wrist Flexion and Extension Maximal Voluntary Contractions Similarly Impair Hand-Tracking Accuracy in Young Adults Using a Wrist Robot

Due to their stabilizing role, the wrist extensor muscles demonstrate an earlier onset of performance fatigability and may impair movement accuracy more than the wrist flexors. However, minimal fatigue research has been conducted at the wrist. Thus, the purpose of this study was to examine how sustained isometric contractions of the wrist extensors/flexors influence hand-tracking accuracy. While gripping the handle of a three-degrees-of-freedom wrist manipulandum, 12 male participants tracked a 2:3 Lissajous curve (±32° wrist flexion/extension; ±18° radial/ulnar deviation). A blue, circular target moved about the trajectory and participants tracked the target with a yellow circle (corresponding to the handle's position). Five baseline tracking trials were performed prior to the fatiguing task. Participants then exerted either maximal wrist extension or flexion force (performed on separate days) against a force transducer until they were unable to maintain 25% of their pre-fatigue maximal voluntary contraction (MVC). Participants then performed 7 tracking trials from immediately post-fatigue to 10 min after. Performance fatigability was assessed using various metrics to account for errors in position-tracking, error tendencies, and movement smoothness. While there were no differences in tracking error between flexion/extension sessions, tracking error significantly increased immediately post-fatigue (Baseline: 1.40 ± 0.54°, Post-fatigue: 2.02 ± 0.51°, P < 0.05). However, error rapidly recovered, with no differences in error from baseline after 1-min post-fatigue. These findings demonstrate that sustained isometric extension/flexion contractions similarly impair tracking accuracy of the hand. This work serves as an important step to future research into workplace health and preventing injuries of the distal upper-limb

Perspectives and Challenges in Robotic Neurorehabilitation

The development of robotic devices for rehabilitation is a fast-growing field. Nowadays, thanks to novel technologies that have improved robots' capabilities and offered more cost-effective solutions, robotic devices are increasingly being employed during clinical practice, with the goal of boosting patients' recovery. Robotic rehabilitation is also widely used in the context of neurological disorders, where it is often provided in a variety of different fashions, depending on the specific function to be restored. Indeed, the effect of robot-aided neurorehabilitation can be maximized when used in combination with a proper training regimen (based on motor control paradigms) or with non-invasive brain machine interfaces. Therapy-induced changes in neural activity and behavioral performance, which may suggest underlying changes in neural plasticity, can be quantified by multimodal assessments of both sensorimotor performance and brain/muscular activity pre/post or during intervention. Here, we provide an overview of the most common robotic devices for upper and lower limb rehabilitation and we describe the aforementioned neurorehabilitation scenarios. We also review assessment techniques for the evaluation of robotic therapy. Additional exploitation of these research areas will highlight the crucial contribution of rehabilitation robotics for promoting recovery and answering questions about reorganization of brain functions in response to disease

Effects of hemispheric stroke localization on the reorganization of arm movements within different mechanical environments

none8siThis study investigated how stroke’s hemispheric localization affects motor performance, spinal maps and muscle synergies while performing planar reaching with and without assistive or resistive forces. A lesion of the right hemisphere affected performance, reducing average speed and smoothness and augmenting lateral deviation in both arms. Instead, a lesion of the left hemisphere affected the aiming error, impairing the feedforward control of the ipsilesional arm. The structure of the muscle synergies had alterations dependent on the lesion side in both arms. The applied force fields reduced the differences in performance and in muscle activations between arms and among populations. These results support the hypotheses of hemispheric specialization in movement control and identify potential significant biomarkers for the design of more effective and personalized rehabilitation protocols.openPellegrino L.; Coscia M.; Pierella C.; Giannoni P.; Cherif A.; Mugnosso M.; Marinelli L.; Casadio M.Pellegrino, L.; Coscia, M.; Pierella, C.; Giannoni, P.; Cherif, A.; Mugnosso, M.; Marinelli, L.; Casadio, M