Marco Molinari

Rehabilitation of gait after stroke: a review towards a top-down approach

This document provides a review of the techniques and therapies used in gait rehabilitation after stroke. It also examines the possible benefits of including assistive robotic devices and brain-computer interfaces in this field, according to a top-down approach, in which rehabilitation is driven by neural plasticity.The methods reviewed comprise classical gait rehabilitation techniques (neurophysiological and motor learning approaches), functional electrical stimulation (FES), robotic devices, and brain-computer interfaces (BCI).From the analysis of these approaches, we can draw the following conclusions. Regarding classical rehabilitation techniques, there is insufficient evidence to state that a particular approach is more effective in promoting gait recovery than other. Combination of different rehabilitation strategies seems to be more effective than over-ground gait training alone. Robotic devices need further research to show their suitability for walking training and their effects on over-ground gait. The use of FES combined with different walking retraining strategies has shown to result in improvements in hemiplegic gait. Reports on non-invasive BCIs for stroke recovery are limited to the rehabilitation of upper limbs; however, some works suggest that there might be a common mechanism which influences upper and lower limb recovery simultaneously, independently of the limb chosen for the rehabilitation therapy. Functional near infrared spectroscopy (fNIRS) enables researchers to detect signals from specific regions of the cortex during performance of motor activities for the development of future BCIs. Future research would make possible to analyze the impact of rehabilitation on brain plasticity, in order to adapt treatment resources to meet the needs of each patient and to optimize the recovery process.

EMG patterns during assisted walking in the exoskeleton

Neuroprosthetic technology and robotic exoskeletons are being developed to facilitate stepping, reduce muscle efforts, and promote motor recovery. Nevertheless, the guidance forces of an exoskeleton may influence the sensory inputs, sensorimotor interactions and resulting muscle activity patterns during stepping. The aim of this study was to report the muscle activation patterns in a sample of intact and injured subjects while walking with a robotic exoskeleton and, in particular, to quantify the level of muscle activity during assisted gait. We recorded electromyographic (EMG) activity of different leg and arm muscles during overground walking in an exoskeleton in six healthy individuals and four spinal cord injury (SCI) participants. In SCI patients, EMG activity of the upper limb muscles was augmented while activation of leg muscles was typically small. Contrary to our expectations, however, in neurologically intact subjects, EMG activity of leg muscles was similar or even larger during exoskeleton-assisted walking compared to normal overground walking. In addition, significant variations in the EMG waveforms were found across different walking conditions. The most variable pattern was observed in the hamstring muscles. Overall, the results are consistent with a non-linear reorganization of the locomotor output when using the robotic stepping devices. The findings may contribute to our understanding of human-machine interactions and adaptation of locomotor activity patterns.

Effects of robotic guidance on the coordination of locomotion

BackgroundFunctional integration of motor activity patterns enables the production of coordinated movements, such as walking. The activation of muscles by weightened summation of activation signals has been demonstrated to represent the spatiotemporal components that determine motor behavior during walking. Exoskeleton robotic devices are now often used in the rehabilitation practice to assist physical therapy of individuals with neurological disorders. These devices are used to promote motor recovery by providing guidance force to the patients. The guidance should in principle lead to a muscle coordination similar to physiological human walking. However, the influence of robotic devices on locomotor patterns needs still to be characterized. The aim of this study was to analyze the effect of force guidance and gait speed on the modular organization of walking in a group of eight healthy subjects.MethodA group of healthy subjects walked on a treadmill with and without robotic aiding at speeds of 1.5, 2.0 and 2.5 Km/h. The guidance force was varied between 20%, 40%, 70% and 100% level of assistance. EMG recordings were obtained from seven leg muscles of the dominant leg and kinematic and kinetic features of the knee and hip joints were extracted.ResultsFour motor modules were sufficient to represent the variety of behavioral goals demanded during robotic guidance, with similar relationships between muscle patterns and biomechanical parameters across subjects, confirming that the low-dimensional and impulsive control of human walking is maintained using robotic force guidance. The conditions of guidance force and speed that maintained correct and incorrect (not natural) modular control were identified.ConclusionIn neurologically intact subjects robotic-guided walking at various force guidance and speed levels does not alter the basic locomotor control and timing. This allows the design of robotic-aided rehabilitation strategies aimed at the modulation of motor modules, which are altered in stroke.

The spinal cord independence measure: how much change is clinically significant for spinal cord injury subjects

Abstract Purpose: To calculate the clinical significance of the SCIM III according to distribution-based approaches. Method: Retrospective review of the charts of 255 patients with registration of the total SCIM and of the four subscales. Clinical significance was calculated per several distribution-based approaches. The calculated clinical significance was compared with improvements by the patients to determine the percentage of patients who achieved significant improvement. Results: An improvement of at least 4 points of the total SCIM is needed to obtain a small significant improvement and of 10 points to obtain a substantial improvement. Based on these results, the percentages of patients who achieved an improvement varied from 60% to 100%. Conclusions: The results provide benchmarks for clinicians and researchers to interpret whether patients’ change score on the SCIM III can be interpreted as true or clinically meaningful and to make clinical judgments about the patients’ progress. Implications for Rehabilitation An improvement of at least four points of the total SCIM is needed to obtain a small significant improvement and of 10 points to obtain a substantial improvement. The results provide benchmarks for clinicians and researchers to interpret whether patients’ change score on the SCIM III can be interpreted as true or clinically meaningful and to make clinical judgments about the patients’ progress.

Cerebellar contribution to feedforward control of locomotion.

The cerebellum is an important contributor to feedforward control mechanisms of the central nervous system, and sequencing—the process that allows spatial and temporal relationships between events to be recognized—has been implicated as the fundamental cerebellar mode of operation. By adopting such a mode and because cerebellar activity patterns are sensitive to a variety of sensorimotor-related tasks, the cerebellum is believed to support motor and cognitive functions that are encoded in the frontal and parietal lobes of the cerebral cortex. In this model, the cerebellum is hypothesized to make predictions about the consequences of a motor or cognitive command that originates from the cortex to prepare the entire system to cope with ongoing changes. In this framework, cerebellar predictive mechanisms for locomotion are addressed, focusing on sensorial and motoric sequencing. The hypothesis that sequence recognition is the mechanism by which the cerebellum functions in gait control is presented and discussed.

Cognitive aspects: sequencing, behavior, and executive functions

The question posed today is not whether the cerebellum plays a role in cognition, but instead, how the cerebellum contributes to cognitive processes, even in the developmental age. The central role of the cerebellum in many areas of human abilities, motor as well as cognitive, in childhood as well as in adulthood, is well established but cerebellar basic functioning is still not clear and is much debated. Of particular interest is the changing face of cerebellar influence on motor, higher cognitive, and behavioral functioning when adult and developmental lesions are compared. The idea that the cerebellum might play quite different roles during development and in adulthood has been proposed, and evidence from experimental and clinical literature has been provided, including for sequencing, behavioral aspects, and executive functions Still, more data are needed to fully understand the changes of cerebrocerebellar interactions within the segregated loops which connect cerebrum and cerebellum, not only between childhood and adulthood but also in health and disease.

Exoskeletons for Over-Ground Gait Training in Spinal Cord Injury

Spinal cord injury (SCI) is a traumatic event with a global incidence of 23 cases per million, representing 180,000 cases per annum worldwide. Recovery of locomotion is a main priority for spinal cord-injured patients. In addition to overcoming the obvious mobility and social issues related to the inability to stand or walk, regular ambulation may profoundly combat secondary medical problems associated with lack of weight-bearing activity in SCI patients. Lower limb exoskeletons (EXOs) may be devised as an ambulation device, as a rehabilitation tool or may be aimed at allowing both objectives living. Regarding rehabilitation, it is worth noticing that EXOs also provide a perfect environment for precise assessing of rehabilitation protocols and effects. Different is the case of EXO for mobility, where the old wheelchair is still largely winning the challenge: existing exoskeletons have limitations with respect to affordability, size, weight, speed, and efficiency, which may reduce their functional application. In all functional areas (velocity, safety, portability, acceptance as well as autonomy in the ADL) none of today EXOs can compete with the performances of an average wheelchair. However, EXO usage requires learning, and brain changes associated with tool usage introduce the human in the loop concept, a key aspect of clinical relevance for EXO usage. At present, interesting data on the biological mechanisms and rehabilitation relevance of embodiment are providing hints for guiding rehabilitation. In this chapter, these challenges will be presented from a clinical rehabilitation perspective and expectations and critics discussed.

Approach to Gait and Balance Rehabilitation in Spinal Cord Injury

In 1700 BC, the Edwin Smith Papyrus, an ancient Egyptian medical text, described spinal cord injury (SCI) as an “ailment not to be treated.” (Silva et al. in Progress in neurobiology 2014;114:25–57, [1]) SCI can actually be defined as a lesion that occurs in any portion of the spinal cord and results in complete or incomplete impairment of motor, sensory and autonomic functions below the level of the injury [1]. The aetiology of SCI may be traumatic (TSCI) or non-traumatic (NTSCI).

Walking Assistance of Subjects with Spinal Cord Injury with an Ankle Exoskeleton and Neuromuscular Controller

This work was devoted to preliminary test the Achilles ankle exoskeleton and its NeuroMuscular Controller (NMC) with a test pilot affected by incomplete spinal cord injury. The customization of the robot controller, i.e. a subject-specific tailoring of the assistance level, was performed and a 10-session training to optimize human-robot interaction was finalized. Results demonstrated that controller tuning was in line with the functional clinical assessment. NMC adapted to the variable walking speed during the training and the test pilot was successfully trained in exploiting robotic support and also improved his performance in terms of walking speed and stability. After the training, a higher speed could also be achieved during free walking and hence a slight unexpected rehabilitation effect was evidenced.

Training Balance Recovery in People with Incomplete SCI Wearing a Wearable Exoskeleton

Improving stability of people wearing a lower extremity Wearable Exoskeleton (WE) is one of the biggest challenges in the field. The goal of this preliminary study was to improve balance recovery from perturbations in people with incomplete Spinal Cord Injury (SCI) assisted by a WE with specifically developed balance controller. The WE has actuated ankle and knee joints, which were controlled by using a body sway-based balance controller. Two test pilots participated in 5 training sessions, devoted to enhance the use of the robot, and in pre/post assessments. Their balance during quiet standing was perturbed through pushes in forward direction.