Lorenzo Garavaglia

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.

Can passive mobilization provide clinically-relevant brain stimulation? A pilot eeg and nirs study on healthy subjects

Lower limb rehabilitation is a fundamental part of post-acute care in neurological disease. Early commencement of active workout is often prevented by paresis, thus physical treatment may be delayed until patients regain some voluntary command of their muscles. Passive mobilization of the affected joints is mostly delivered in order to safeguard tissue properties and shun circulatory problems. The present paper investigates the potential role of early passive motion in stimulating cortical areas of the brain devoted to the control of the lower limb. An electro-mechanical mobilizer for the ankle joint (Toe-Up!) was implemented utilizing specially-designed shape-memory-alloy-based actuators. This device was constructed to be usable by bedridden subjects. Besides, the slowness and gentleness of the imparted motion, make it suitable for patients in a very early stage of their recovery. The mobilizer underwent technical checks to confirm reliability and passed the required safety tests for electric biomedical devices. Four healthy volunteers took part in the pre-clinical phase of the study. The protocol consisted in measuring of brain activity by EEG and NIRS in four different conditions: rest, active dorsiflexion of the ankle, passive mobilization of the ankle, and assisted motion of the same joint. The acquired data were processed to obtain maps of cortical activation, which were then compared. The measurements collected so far show that there is a similar pattern of activity between active and passive/assisted particularly in the contralateral premotor areas. This result, albeit based on very few observations, might suggest that passive motion provides somatosensory afferences that are processed in a similar manner as for voluntary control. Should this evidence be confirmed by further trials on healthy individuals and neurological patients, it could form a basis for a clinical use of early passive exercise in supporting central functional recovery.

Applications of Shape Memory Alloys for Neurology and Neuromuscular Rehabilitation

Shape memory alloys (SMAs) are a very promising class of metallic materials that display interesting nonlinear properties, such as pseudoelasticity (PE), shape memory effect (SME) and damping capacity, due to high mechanical hysteresis and internal friction. Our group has applied SMA in the field of neuromuscular rehabilitation, designing some new devices based on the mentioned SMA properties: in particular, a new type of orthosis for spastic limb repositioning, which allows residual voluntary movement of the impaired limb and has no predetermined final target position, but follows and supports muscular elongation in a dynamic and compliant way. Considering patients in the sub-acute phase after a neurological lesion, and possibly bedridden, the paper presents a mobiliser for the ankle joint, which is designed exploiting the SME to provide passive exercise to the paretic lower limb. Two different SMA-based applications in the field of neuroscience are then presented, a guide and a limb mobiliser specially designed to be compatible with diagnostic instrumentations that impose rigid constraints in terms of electromagnetic compatibility and noise distortion. Finally, the paper discusses possible uses of these materials in the treatment of movement disorders, such as dystonia or hyperkinesia, where their dynamic characteristics can be advantageous.

Two single cases treated by a new pseudoelastic upper-limb orthosis for secondary dystonia of the young

The study proposes a new treatment for dystonia based on a dynamic wearable orthosis equipped with metallic materials of non-linear mechanical characteristics. Two boys with upper-limb dystonia were enrolled, as well as six healthy children. Fully-customised devices were made for the patients. They used the orthosis for one month and their performances were evaluated before and after the treatment. The assessment was done with clinical scales (Modified Ashworth Score, Melbourne Upper Limb Assessment, PedsQL), interviews and optoelectronic kinematic analysis. Normal kinematics was obtained from the healthy group for comparison. Kinematic analysis showed modifications in motor patterns for both patients, with increases in the ranges of motion of initially stiff segments, improvements in posture, emergence of multi-joint strategies. Clinical scales did not always show similar trends in the two cases. The changes in control strategies could be linked to the force field dynamically applied by the device and appear to be learnable. This interpretation will be further tested with larger groups and longer treatments.

Pilot study of the cortical correlates and clinical effects of passive ankle mobilisation in children with upper motorneuron lesions.

Upper motoreuron lesions (UML) affects people of all ages and conditions and is a major cause of disability in the young. Whereas active exercise is recognised as paramount to restore the lost motor functions, passive mobilisation of the affected limbs is regarded as a means to safeguard muscular tissue properties during a period of disuse and lack of voluntary control, which often characterises the acute and sub-acute phases. The purpose of the present work is to study the cortical reactivity in UML patients who are treated for two weeks with a robotic passive ankle mobiliser, and the clinical effects of this treatment. The rationale is that, if passive mobilisation can affect positively the functional reorganisation at a cortical level, it could be proposed as a suitable tool to maintain afferentation and guide central nervous remapping, thus bridging the period of time when active exercise is impossible due to acute paresis. Preliminary results on 7 patients (aged 15.35±4.36) showed that this therapy is very well tolerated and suggest that its application could specifically improve ankle PROM and plantarflexor muscle length. EEG data showed improved desynchronisation in at least one frequency band in 3 patients of the study, thus confirming the effects of passive mobilisation on the cortical re-organisation of some patients having UML.

Dynamic Splints, Functionally-Customized With Nitinol, Can Reduce Joint Rigidity in Pediatric Subjects With Spasticity

Neuromuscular diseases as a consequence of brain damage are complex phenomena involving disuse, immobility, brain tissue remodeling and cortical function remapping. They may have various causes and strike any part of the population. The vicious circle leading to a worsening of the patients’ conditions proceeds through muscle shortening by contractures, disruption of the normal reflex behavior and sensory problems, development of spasticity [1]. Physical rehabilitation alone or in association with surgery or pharmacological treatments can be useful in limiting those degenerations. Besides manual rehabilitation, splints and braces are prescribed to control the limb posture and obtain stretching of the muscles. The role of those orthoses is to maintain the paretic limb in a set ‘physiological’ position and let it relax into that posture, in an attempt to reduce muscle rigidity and contractures. However applying a fixed constraint to the limb and waiting for relaxation to take place, may cause discomfort, pain, skin rash, and sundry different complications [2]. Also, any residual voluntary movement is prevented by a fixed-angle splinting. In addition, all these negative characteristics limit tolerability and daily application times. This work presents a different way to promote limb repositioning, based on the application of NiTi-alloy-based dynamic splints, which favor mobility and any residual use of the affected limb. Furthermore it suggests that application of mild contact forces prolonged in time has the advantage of feeling less painful and uncomfortable for the patients, improving overall treatment tolerability.Copyright

A New Device for an Early Rehabilitation of the Ankle Joint and its Effects on Brain Activation: A NIRS and EEG Study

The ankle joint is a fundamental element in the biomechanical system of locomotion. When its functions are impaired, due to neurological insult such as brain trauma or a stroke, severe disability and loss of personal independence may ensue. For this reason, great care is given to the physical rehabilitation of the lower limb. On the other hand, it is often the case that only a limited amount of time can be specifically devoted to the ankle joint manipulation during routine rehabilitation sessions. Furthermore, early initiation of active workout may be impossible for patients showing paresis; even passive exercise is often delivered to a minimal degree while the general conditions of the patients impose that they are kept bedridden. The delay in commencing rehabilitation may have negative consequences in terms of detrimental changes in tissue properties, deafferentation through lack of proprioceptive stimulation, learned non-use, and, ultimately, spastic paresis [1].Copyright

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