Maria Chiara Carboncini

Arm rehabilitation with a robotic exoskeleleton in Virtual Reality

Several studies demonstrate the importance of an early, constant and intensive rehabilitation following cerebral accidents. This kind of therapy is an expensive procedure in terms of human resources and time, and the increase of both life expectance of world population and incidence of stroke is making the administration of such therapies more and more important. The development of new robotic devices for rehabilitation can help to reduce this cost and lead to new effective therapeutic procedures. In this paper we present an exoskeleton for the robotic-assisted rehabilitation of the upper limb. This article describes the main issues in the design of an exoskeletal robot with high performance, in terms of backdrivability, low inertia, large workspace isomorphic to the human arm and high payload to weight ratio. The implementation of three different robotic schemes of therapy in virtual reality with this exoskeleton, based on an impedance control architecture, are presented and discussed in detail. Finally the experimental results of a preliminary evaluation of functionality of the system carried out on one patient are presented, and compared with the performance in the execution of the exercise obtained with healthy volunteers. Moreover, other preliminary results from an extended pilot clinical study with the L-Exos are reported and discussed.

A force-feedback exoskeleton for upper-limb rehabilitation in virtual reality

This paper presents the design and the clinical validation of an upper-limb force-feedback exoskeleton, the L-EXOS, for robotic-assisted rehabilitation in virtual reality VR. The L-EXOS is a five degrees of freedom exoskeleton with a wearable structure and anthropomorphic workspace that can cover the full range of motion of human arm. A specific VR application focused on the reaching task was developed and evaluated on a group of eight post-stroke patients, to assess the efficacy of the system for the rehabilitation of upper limb. The evaluation showed a significant reduction of the performance error in the reaching task paired t-test, p < 0.02.

Positive effects of robotic exoskeleton training of upper limb reaching movements after stroke

This study, conducted in a group of nine chronic patients with right-side hemiparesis after stroke, investigated the effects of a robotic-assisted rehabilitation training with an upper limb robotic exoskeleton for the restoration of motor function in spatial reaching movements. The robotic assisted rehabilitation training was administered for a period of 6 weeks including reaching and spatial antigravity movements. To assess the carry-over of the observed improvements in movement during training into improved function, a kinesiologic assessment of the effects of the training was performed by means of motion and dynamic electromyographic analysis of reaching movements performed before and after training. The same kinesiologic measurements were performed in a healthy control group of seven volunteers, to determine a benchmark for the experimental observations in the patients’ group. Moreover degree of functional impairment at the enrolment and discharge was measured by clinical evaluation with upper limb Fugl-Meyer Assessment scale (FMA, 0–66 points), Modified Ashworth scale (MA, 0–60 pts) and active ranges of motion. The robot aided training induced, independently by time of stroke, statistical significant improvements of kinesiologic (movement time, smoothness of motion) and clinical (4.6 ± 4.2 increase in FMA, 3.2 ± 2.1 decrease in MA) parameters, as a result of the increased active ranges of motion and improved co-contraction index for shoulder extension/flexion. Kinesiologic parameters correlated significantly with clinical assessment values, and their changes after the training were affected by the direction of motion (inward vs. outward movement) and position of target to be reached (ipsilateral, central and contralateral peripersonal space). These changes can be explained as a result of the motor recovery induced by the robotic training, in terms of regained ability to execute single joint movements and of improved interjoint coordination of elbow and shoulder joints.

Cross-correlation time-frequency analysis for multiple EMG signals in Parkinson's disease: a wavelet approach

Using a wavelet analysis approach, it is possible to investigate better the transient and intermittent behavior of multiple electromyographic (EMG) signals during ballistic movements in Parkinsonian patients. In particular, a wavelet cross-correlation analysis on surface signals of two different shoulder muscles allows us to evidence the related unsteady and synchronization characteristics. With a suitable global parameter extracted from local wavelet power spectra, it is possible to accurately classify the subjects in terms of a reliable statistic and to study the temporal evolution of the Parkinsons disease level. Moreover, a local intermittency measure appears as a new promising index to distinguish the low-frequency behavior from normal subjects to Parkinsonian patients.

A pilot clinical study on robotic assisted rehabilitation in VR with an arm exoskeleton device

The development of new robotic devices for rehabilitation can lead to new and more efficient therapeutic procedures. Moreover, the use of VR-based scenarios in which patients perform rehabilitation exercises dramatically increases the patients¿ motivation and thus the final therapy outcome. In this paper preliminary results of a pilot study carried out with an exoskeleton for the robotic assisted rehabilitation of the upper limb are presented. The paper briefly describes the main kinematic and mechanical features of the exoskeleton system, showing its peculiar characteristics which make it useful for rehabilitation purposes. The implementation of three different robotic schemes of therapy in virtual reality with this exoskeleton, based on an impedance control architecture, are presented and discussed in detail. Finally, qualitative and quantitative results obtained in a 6 week pilot study with three chronic stroke patients are reported.

The relation between EMG activity and kinematic parameters strongly supports a role of the action tremor in parkinsonian bradykinesia

The kinematics characteristics of an upper arm extension of large amplitude (90°) performed in the horizontal plane and the simultaneous activity of the shoulder muscles were recorded in 12 parkinsonian patients and in six normal control subjects. The movement, triggered by an acoustic “go” signal, was preceded by an isometric adduction.

Robotic assisted rehabilitation in Virtual Reality with the L-EXOS.

This study presents the evaluation results of a clinical trial of robotic-assisted rehabilitation in Virtual Reality performed with the PERCRO L-Exos (Light-Exoskeleton) system, which is a 5-DoF force-feedback exoskeleton for the right arm. The device has demonstrated itself suitable for robotic arm rehabilitation therapy when integrated with a Virtual Reality (VR) system. Three different schemes of therapy in VR were tested in the clinical evaluation trial, which was conducted on a group of nine chronic stroke patients at the Santa Chiara Hospital in Pisa-Italy. The results of this clinical trial, both in terms of patients performance improvements in the proposed exercises and in terms of improvements in the standard clinical scales which were used to monitor patients receovery are reported and discussed. The evaluation both pre and post-therapy was carried out with both clinical and quantitative kinesiologic measurements. Statistically significant improvements were found in terms of Fugl-Meyer scores, Ashworth scale, increments of active and passive ranges of motion of the impaired limb, and quantitative indexes, such as task time and error.

Cortical source of blink-related delta oscillations and their correlation with levels of consciousness.

Recently, blink‐related delta oscillations (delta BROs) have been observed in healthy subjects during spontaneous blinking at rest. Delta BROs have been linked with continuous gathering of information from the surrounding environment, which is classically attributed to the precuneus. Furthermore, fMRI studies have shown that precuneal activity is reduced or missing when consciousness is low or absent. We therefore hypothesized that the source of delta BROs in healthy subjects could be located in the precuneus and that delta BROs could be absent or reduced in patients with disorders of consciousness (DOC). To test these hypotheses, electroencephalographic (EEG) activity at rest was recorded in 12 healthy controls and nine patients with DOC (four vegetative states, and five minimally conscious states). Three‐second‐lasting EEG epochs centred on each blink instance were analyzed in both time‐ (BROs) and frequency domains (event‐related spectral perturbation or ERSP and intertrial coherence or ITC). Cortical sources of the maximum blink‐related delta power, corresponding to the positive peak of the delta BROs, were estimated by standardized Low Resolution Electromagnetic Tomography. In control subjects, as expected, the source of delta BROs was located in the precuneus, whereas in DOC patients, delta BROs were not recognizable and no precuneal localization was possible. Furthermore, we observed a direct relationship between spectral indexes and levels of cognitive functioning in all subjects participating in the study. This reinforces the hypothesis that delta BROs reflect neural processes linked with awareness of the self and of the environment. Hum Brain Mapp 34:2178–2189, 2013.

Blink-related delta oscillations in the resting-state EEG: A wavelet analysis

Over the past decades, many studies have linked the variations in frequency of spontaneous blinking with certain aspects of information processing and in particular with attention and working memory functions. On the other hand, according to the theory postulated by Crick and Koch, the actual function of primary consciousness is based on the reciprocal interaction between attention and working memory in the automatic and serial mode. The purpose of this study was to investigate for electrophysiological correlates compatible with the cognitive nature of spontaneous blinking, by using the EEG recordings obtained in a group of seven healthy volunteers while they rested quietly though awake, with their eyes open, but not actively engaged in attention-demanding goal-directed behaviours. The global wavelet analysis - at total of 189 three-second EEG epochs time-locked to the blink - revealed an increase in the delta band signal corresponding to the blink. In particular, a reconstruction of the EEG signal by means of inverse-wavelet transform (IWT) showed a blink-related P300-like wave at mid-parietal site. We assumed this phenomenon to represent an electrophysiological sign of the automatic processing of contextual environmental information. This might play a role in maintaining perceptive awareness of the environment at a low level of processing, while the subject is not engaged in attention-demanding tasks but rather introspectively oriented mental activities or free association(s).

Higher level gait disorders in subcortical chronic vascular encephalopathy: a single photon emission computed tomography study

BACKGROUND the so-called higher level gait disorders include several types of gait disorders in which there are no major modifications in strength, tone, sensitivity, coordination and balance. Brain activation sites related to walking have been investigated using SPECT in humans. The aim of the study was to investigate brain activation during walking in subjects with high-level gait disorders due to chronic subcortical vascular encephalopathy. SUBJECTS twelve patients with a chronic vascular encephalopathy were enrolled in the study. Seven subjects had apraxic gait while in the other five the gait was normal. All patients had undergone a recent cerebral magnetic resonance that revealed diffused chronic ischemic lesions within the white matter. METHODS all 12 patients underwent a regional cerebral blood flow (rCBF) brain SPECT study with (99m)Tc-Bicisate on two separate days and under two different conditions: at rest (baseline) and while walking (functional). RESULTS the rCBF increase induced by the treadmill test (functional-baseline), bilaterally in the medial frontal gyrus and in the anterior lobes of the cerebellum, resulted significantly (P < 0.001) lower in patients with gait apraxia versus those without it. CONCLUSIONS this study of the brain with SPECT records the areas of perfusion deficit that appear in apraxic subjects when they walk, compared with the recordings obtained with the same investigation performed at rest.