Stefano Viscuso

Primary sensory and motor cortex activities during voluntary and passive ankle mobilization by the SHADE orthosis

This study investigates cortical involvement during ankle passive mobilization in healthy subjects, and is part of a pilot study on stroke patient rehabilitation. Magnetoencephalographic signals from the primary sensorimotor areas devoted to the lower limb were collected together with simultaneous electromyographic activities from tibialis anterior (TA). This was done bilaterally, on seven healthy subjects (aged 29 ± 7), during rest, left and right passive ankle dorsiflexion (imparted through the SHADE orthosis, O‐PM, or neuromuscular electrical stimulation, NMES‐PM), and during active isometric contraction (IC‐AM). The effects of focussing attention on ankle passive movements were considered. Primary sensory (FSS1) and motor (FSM1) area activities were discriminated by the Functional Source Separation algorithm. Only contralateral FSS1 was recruited by common peroneal nerve stimulation and only contralateral FSM1 displayed coherence with TA muscular activity. FSM1 showed higher power of gamma rhythms (33–90 Hz) than FSS1. Both sources displayed higher beta (14–32 Hz) and gamma powers in the left than in the right hemisphere. Both sources displayed a bilateral reduction of beta power during IC‐AM with respect to rest. Only FSS1 beta band power reduced during O‐PM. No beta band modulation was observed of either source during NMES‐PM. Mutual FSS1‐FSM1 coherence in gamma2 band (61–90 Hz) showed a slight trend towards an increase when focussing attention during O‐PM. Somatosensory and motor counterparts of lower limb cortical representations were discriminated in both hemispheres. SHADE was effective in generating repeatable dorsiflexion and inducing primary sensory involvement similarly to voluntary movement. Hum Brain Mapp, 2010.

Passive ankle dorsiflexion by an automated device and the reactivity of the motor cortical network

Gait impairment is an important consequence of neurological disease. Passive mobilization of the affected lower limbs is often prescribed in order to safeguard tissue properties and prevent circulatory sequelae during paresis. However, passive movement could play a role also in stimulating cortical areas of the brain devoted to the control of the lower limb, so that deafferentation and learned non-use can be contrasted. The purpose of the present work is to investigate cortical involvement during active and passive movements of the ankle joint, in an attempt to gain deeper insight in the similarities between these two conditions. A wearable device to mobilize the ankle joint was implemented utilizing rotary shape memory alloy actuators. The technical characteristics of this actuator make it very compatible with the tight limitations on electromagnetic noise imposed by diagnostic instrumentation. Eleven healthy volunteers took part in the pre-clinical phase of the study. According to the protocol, brain activity was recorded by 165-channel magnetoencephalography (MEG) under three different conditions: rest, active dorsiflexion of the ankle and passive mobilization of the same joint. The acquired data were processed to obtain cortical ERD/ERS (Event Related Desynchronization/ Synchronization) maps, which were then compared. The results of this analysis show that there are similar patterns of activity between active and passive movement, particularly in β band, in the contralateral primary sensorimotor, dorsal premotor and supplementary motor areas. This result, albeit obtained from healthy subjects, might suggest that passive motion provides somatosensory afferences that, to some extent, are processed in a similar manner as for voluntary control. Should this evidence be confirmed by further experiments on neurological patients, it could support the prescription of passive exercise as a surrogate of active workout, at least, so long as patients are paretic.

Design and implementation of a portable amagnetic shape memory rotary actuator

Actuators based on standard technologies often do not comply with environmental constraints on electromagnetic noise. Even though shape memory actuators are not ferromagnetic, activation by Joule’s effect poses a question about magnetic compatibility. This article presents a new concept design of a rotary actuator based on a double coil of NiTi wire, which permits to abate dramatically the electromagnetic fields generated. A particular implementation of the idea was devised as a case study to investigate feasibility. The desired torque and stroke were 83 N cm and 40°, respectively, and mechanical tests confirmed that a maximal stroke of 38° can be achieved for resisting torques ranging from 33 to 122 N cm. The built prototype proved appropriate to respond to the needs of a neuroscience study requiring mobilization of the ankle. So, this device was tested during measurement of brain activity in healthy subjects with both magnetoencephalography and functional magnetic resonance imaging, that is, diagnostic equipment with very demanding constraints on electromagnetic noise. Neither magnetoencephalography signals nor the functional magnetic resonance imaging images were affected by any electromagnetic noise or artifacts, allowing for further analysis and extraction of neurological features. Besides the discussed uses, this type of actuator could find an application in several fields, such as biomedical, robotic, aerospace, or automotive.

Shape Memory Actuators for Medical Rehabilitation and Neuroscience

Actuators based on shape memory alloys (SMA) proved to be particularly advantageous with respect to other actuation technologies when they are embedded in applications requiring strict compliance to a set of compatibility (e.g. mechanical, biological, weight, ...) and environmental constraints. Most noteworthy are the uses in miniaturised components, lightweight systems, sensing-actuating systems (e.g. actuators interacting with changing environmental variables), low-noise or low-impact appliances (e.g. actuators with reduced interaction with the environment) and self-sensing controllable devices. With particular regard to these preferred applications, SMA can also play a role in solving specific actuation problems in the fields of Medical Rehabilitation and Neuroscience. The main characteristics expected of SMA actuators for these fields are light weight and portability; self-adjustment to evolving needs; applicability of actuation in shielded environments (with bioimaging and diagnostic devices: magnetic resonance imaging (MRI, fMRI), magnetoencephalography (MEG), and the like).

Assessment of the Peripheral Performance and Cortical Effects of SHADE, an Active Device Promoting Ankle Dorsiflexion

Acute post-stroke rehabilitation protocols include passive mobilisation as a means to prevent contractures, but this technique could also help preserve neuromuscular activation patterns through proprioceptive information. This paper presents SHADE, an active orthosis that provides repetitive passive motion to a flaccid ankle by using shape memory alloy wire actuators. SHADE was studied to assess the promoted passive range of motion (PROM), acceptability and cortical effects. PROM and tolerability was assessed on 3 acute post-stroke patients (58±5y/o) by means of optoelectronic cinematic analysis. EEG/MEG instrumentation was utilised to evaluate sensorimotor cortical involvement during passive mobilization induced by SHADE in 7 healthy subjects (30.3±6.9y/o). These data were compared with voluntary movement (VM). SHADE produced good mobilisation across the available PROM (typically, from 5° plantarflexion to 15° dosiflexion). Acceptability in patients was also good. Suitable functional sources were identified for the primary sensorimotor areas. Cortico-muscular coherence was high not only in primary motor but also in primary somatosensory cortex. The cerebral involvement in these regions during the use of SHADE was similar to VM and significantly different from rest. This suggests that passive stimulation with SHADE could have clinical implications in supporting recovery of active functionality in stroke patients.

WO02 Cortical correlate of passive mobilisation of the ankle joint by means of the SHADE orthosis

WO02 Cortical correlate of passive mobilisation of the ankle joint by means of the SHADE orthosis Simone Pittaccio 1, Filippo Zappasodi 2, Stefano Viscuso 1, Francesca Mastrolilli 3 , Matilde Ercolani 3, Francesco Passarelli 3 , Franco Molteni 4, Paolo Maria Rossini 5, Franca Tecchio 6 1CNR-IENI, Unità di Lecco, Italy; 2CNR-ISTC, Unità MEG, Ospedale Fatebenefratelli, Isola Tiberina, Rome, Italy; 3AFaR, Ospedale Fatebenefratelli, Isola Tiberina, Rome, Italy; 4Ospedale Valduce, Clinica Villa Beretta, Costamasnaga, Italy; 5Dept. of Neurology, ‘Campus Bio-Medico’ University, Rome, Italy; 6IRCCS San Raffaele, Tosinvest Sanità, Cassino, Italy

A magnetically quasi-transparent tool for ankle passive mobilization in investigations on cortical involvement using MEG

Passive mobilization of the paretic limbs is commonly part of standard care in the first stages after stroke, but at this moment it is not clear whether this can positively impact brain reorganization and functional recovery. Applying passive mobilization during MEG measurements poses the question of finding a way to provide repeatable cycles of movement without interfering too much with the biosignal acquisition. This paper presents SHADE, an active orthosis that promotes ankle dorsiflexion and fulfils these requirements by using shape memory alloy wire actuators. These alloys are very deformable at room temperature but can recover large deformations and generate considerable forces when heated above a characteristic temperature. Heating is provided by Joule’s effect, cooling by natural convection. Since current is provided by a dc-generator, only limited and easily removable magnetic noise is produced. SHADE was tested in a MEG shielded room to evaluate both orthosis performance and sensorimotor cortical involvement during passive mobilization induced in 7 healthy subjects (30.3±6.9y/o). The measurements could be cleaned from any noise produced by SHADE and suitably analyzed to describe the activation patterns of primary sensorimotor areas devoted to the ankle control. The cerebral involvement in these regions during the use of SHADE was significantly different from rest. This suggests that passive stimulation with SHADE could have clinical implications and possibly a role in the recovery of active functionality in stroke patients.

Devices for Rehabilitation Applications

Recent research is showing that Shape Memory Alloys (SMA) can be advantageously employed for a number of applications in Rehabilitation Medicine and the related field of Neuroscience. This innovative use of SMA was investigated with the specific aim of improving the treatment approach to neurological patients with sequelae from stroke, traumatic brain injury, cerebral palsy, etc. Several examples of devices built for this purpose will be presented together with an outline of the reasons why the shape-memory and pseudoelastic effects can be regarded as interesting resources on account of scientific, technical and clinical reasons. In particular the design and functioning of an SMA-based ankle exerciser and pseudoelastic repositioning splints for the upper and lower limbs will be discussed in relation with results of neurophysiologic and clinical tests. The main observations so far suggest that this type of devices is able to support patients’ physical rehabilitation by adapting to changing conditions and needs during functional recovery. Furthermore, due to their improved tolerability relative to traditional treatments SMA devices can be used for longer times and tend to produce interesting effects in the control of spastic syndromes.

Digital Image-Based Method for Quality Control of Residual Bending Deformation in Slender Pseudoelastic NiTi Devices

Pseudoelastic NiTi-based devices are often required to recover their shape repeatedly and their working performance can be judged from the amount of residual deformation after use. The quality problem in this respect can even be removed from fatigue life or safety issues and impact on the functional and aesthetic value of the product. While linear deformation can be appreciated quantitatively in a straightforward manner, the bending strains are more difficult to assess directly. We devised a very simple digital image-based method to measure the residual bending deformation by comparison of the pristine shape of the device with the one resulting from bending and free recovery. The program was written in LabView and is capable of reporting about the deflection and location of strain concentration along slender pseudoelastic elements in a semi-quantitative way appropriate for quality sample checks. The method is semi-automatic and provides a user-friendly interface for the operator. Apart from simple shapes like straight wires and ribbons, the method was tested on devices as complex as spectacles frames. This application is particularly interesting, where shape recovery and functional and aesthetic value are tightly linked, and deformation by severe handling is a typical effect of use.

Pseudoelastic Hinges Promoting Muscle “Creep” as Opposed to Relaxation for the Rehabilitation of Spastic Syndromes

The evolution of spastic pathologies as a consequence of brain damage is a complex phenomenon involving disuse, immobility and brain tissue remodeling [1]. The vicious circle leading to a worsening of the patients’ status proceeds through muscle shortening by contractures, disruption of the normal reflex behaviour and sensory disturbances. A way to prevent chronicity of major consequences could be to favour mobility and any residual use of the affected limb.Copyright