Rehabilitative Soft Exoskeleton for Rodents

Robotic exoskeletons provide programmable, consistent and controllable active therapeutic assistance to patients with neurological disorders. Here we introduce a prototype and preliminary experimental evaluation of a rehabilitative gait exoskeleton that enables compliant yet effective manipulation of the fragile limbs of rats. To assist the displacements of the lower limbs without impeding natural gait movements, we designed and fabricated soft pneumatic actuators (SPAs). The exoskeleton integrates two customizable SPAs that are attached to a limb. This configuration enables a 1 N force load, a range of motion exceeding 80 mm in the major axis, and speed of actuation reaching two gait cycles/s. Preliminary experiments in rats with spinal cord injury validated the basic features of the exoskeleton. We propose strategies to improve the performance of the robot and discuss the potential of SPAs for the design of other wearable interfaces

Hybrid peripheral-spinal neuroprosthesis for refined motor execution after paralysis

Spinal cord injury (SCI) disrupts the communication between the brain and the spinal circuits responsible for movement, thereby causing severe motor deficits. Current strategies to restore function to paralyzed limbs have separately investigated electrical stimulation of the spinal cord or of the peripheral neuromuscular system. Various neuromodulation strategies, for instance electrical epidural stimulation (EES) of the spinal cord, reactivate spinal circuits below the lesion and enable the generation of locomotor activity. EES targets muscle synergies rather than specific muscles or joints, and can therefore be limited by low selectivity. Accessing distal muscles individually is key to restore refined movement. Peripheral nerve stimulation (PNS) offers this possibility by selectively recruiting fibers innervating distinct muscles. Here, I developed a hybrid electrical stimulation paradigm, concomitantly targeting the spinal cord and the peripheral nerves for a global activation of coordinated multi-joint leg movements and a selective activation of distal muscles respectively. This approach combines two highly complementary stimulation paradigms into one refined neuroprosthetic system that could improve functional restoration after paralysis. The first part of this work addressed the validation of intraneural electrodes for selective and stable PNS. Albeit highly promising, incomplete characterization of long-term usability and biocompatibility has so far restricted their widespread use. To bridge this gap, I conducted a longitudinal assessment and comprehensively characterized their functional properties in light of their bio-integration in rats. Results showed that i) stimulation thresholds increased moderately during one month after implantation and then stabilized, ii) these changes correlated with progressive implant encapsulation, and iii) selectivity in muscle recruitment was retained in spite of the encapsulation, permitting precise control over ankle kinematics in anesthetized experiments. Overall, these results demonstrated the potential for long-term usability of intraneural implants. In the second part of this work, I developed and characterized a hybrid PNS-EES paradigm that concomitantly stimulated the spinal cord and the sciatic nerves in rat models of severe SCI, and validated it in a pilot study with a human SCI. I showed that i) muscle recruitment obtained by EES and PNS was highly complementary, ii) PNS enabled controllable adjustments in leg movements during locomotion, and iii) the hybrid PNS-EES paradigm permitted refined movements that increased functionality during locomotion in rats and a human pilot subject. This thesis provides evidence about the long-term functionality of intraneural implants and demonstrates their potential for stable interfacing with peripheral nerves. The hybrid PNS-EES paradigm reveals how the complementarity of both strategies effectively improved functional outcomes for paralyzed lower limbs. These findings open promising perspectives for the development of hybrid neuroprosthetic systems to restore functional and refined movements to paralyzed limbs

Medical students’ perceptions and coping strategies during the first wave of the COVID-19 pandemic: studies, clinical implication, and professional identity

Background: The unfolding of the COVID-19 pandemic during spring 2020 has disrupted medical education worldwide. The University of Geneva decided to shift on-site classwork to online learning; many exams were transformed from summative to formative evaluations and most clinical activities were suspended. We aimed to investigate the perceived impact of those adaptations by the students at the Faculty of Medicine.Methods: We sent an online self-administered survey to medical students from years 2 to 6 of the University of Geneva, three months after the beginning of the pandemic. The survey explored students’ main activities during the first three months of the pandemic, the impact of the crisis on their personal life, on their training and on their professional identity, the level of stress they experienced and which coping strategies they developed. The survey consisted of open-ended and closed questions and was administered in French.Results: A total of 58.8% of students responded ( n  = 467) and were homogeneously distributed across gender. At the time of the survey, two thirds of the participants were involved in COVID-19-related activities; 72.5% voluntarily participated, mainly fueled by a desire to help and feel useful. Many participants (58.8%) reported a feeling of isolation encountered since the start of the pandemic. Main coping strategies reported were physical activity and increased telecommunications with their loved ones. Most students described a negative impact of the imposed restrictions on their training, reporting decreased motivation and concentration in an unusual or distraction-prone study environment at home and missing interactions with peers and teachers. Students recruited to help at the hospital in the context of increasing staff needs reported a positive impact due to the enriched clinical exposure. Perceived stress levels were manageable across the surveyed population. If changed, the crisis had a largely positive impact on students’ professional identity; most highlighted the importance of the health care profession for society and confirmed their career choice. Conclusion: Through this comprehensive picture, our study describes the perceived impact of the pandemic on University of Geneva medical students, their training and their professional identity three months after the start of the pandemic. These results allowed us to gain valuable insight that reinforced the relevance of assessing the evolution of the situation in the long run and the importance of developing institutional support tools for medical students throughout their studies.</p