A soft supernumerary hand for rehabilitation in sub acute stroke: a pilot study on spasticity

See this research for my shouting below: The absolute stupidity of stroke leadership keeps showing in all its glory.

Effect of resisted exercise on muscular strength, spasticity and functionality in chronic hemiparetic subjects: a systematic review 2009

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A soft supernumerary hand for rehabilitation in subacute stroke: a pilot study on spasticity

Carlo Trompetto University of Genova Manuel G. Catalano Fondazione Istituto Italiano di Tecnologia Alessandro Farina IRCCS Ospedale Policlinico San Martino Giorgio Grioli (  giorgio.grioli@iit.it ) Fondazione Istituto Italiano di Tecnologia Laura Mori University of Genova Andrea Ciullo Fondazione Istituto Italiano di Tecnologia Matteo Pittaluga IRCCS Ospedale Policlinico San Martino Martina Rossero Fondazione Istituto Italiano di Tecnologia Luca Puce University of Genova Antonio Bicchi Fondazione Istituto Italiano di Tecnologia Research Article Keywords: Posted Date: February 24th, 2022 DOI: https://doi.org/10.21203/rs.3.rs-1369771/v1 License:   This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Page 2/13 

 

Abstract 

In sub-acute stroke patients, task-specific training is the most effective rehabilitation treatment for the upper limb. However, in those patients with severe paresis and initial spasticity, task-specific training could increase the risk to develop severe spasticity in the following months.(You're completely wrong there and your mentors and senior researchers don't know that? God almighty, what the fuck do stroke researchers know?) Four sub-acute patients, at high risk of developing spasticity, underwent task-specific training using a supernumerary, aesthetically and functionally anthropomorphic, soft robotic hand (SoftHand-X), driven by the residual movements of the patient's paretic hand. A 1-year follow up was done. All subjects presented a remarkable recovery of upper limb function. No worsening of spasticity was found. The proposed SoftHand-X-based rehabilitation technique for task-specific training in sub-acute stroke patients does not increase the risk of developing severe spasticity. Introduction Stroke is the leading cause of disability in western society [1]. Six months after stroke, approximately 50% of patients remain with a chronic reduction of arm function [2]. That reduces their independence and quality of life significantly [3]. Therefore, improving upper limb function is a core element of stroke rehabilitation. The natural course of clinical recovery after stroke reflects the ability of the neuronal network to adapt plastically to injury [4]. Observational studies show that recovery is more rapid during the first month after stroke, and motor function typically reaches a plateau within three months [5]. Compelling evidence state that the first three months after stroke (acute and sub-acute phases) may represent a critical window for rehabilitation to maximize recovery of body functions and activities [6, 7]. It is widely accepted that upper limb motor training should draw inspiration from the principles of motor learning to promote neural plasticity and functional improvement. According to these principles, repetitive and intensive functional tasks should be used, including grasping exercises (task-specific training) [8]. Task-specific training has been proven to speed up the process of motor recovery in post-stroke patients [9]. Therefore, delivering task-specific training within the first three months after stroke is crucial to promote upper limb functional recovery. Unfortunately, muscle hypertonia begins to appear in the same first three months after the stroke when rehabilitation could obtain its best since the plastic mechanisms underlying the recovery of function are most active. Secondary soft tissue changes in muscles, tendons, and ligaments can cause what is usually referred to as intrinsic hypertonia [10]. However, compelling evidence shows that increased stretch reflex activity partially causes velocity-dependent hypertonia [11] (i.e. an increase in muscle tone that becomes more apparent with more rapid stretching movements) in the overwhelming majority of stroke patients. Velocity-dependent hypertonia includes both spasticity and spastic dystonia. Spasticity is due to stretch reflex exaggeration. Moreover, Patients affected by spastic dystonia cannot relax their muscles, Page 3/13 which spontaneously contract at rest [12]. On the contrary, in healthy subjects, the stretch reflex cannot be evoked during muscle tone assessment [13]. At its onset, which usually happens in the first few weeks after stroke, hypertonia is generally mild and does not cause disability. While the prevalence of muscle hypertonia peaks at four weeks after stroke, the number of patients with severe muscle hypertonia continues to increase during the first year [14]. At one year after stroke, severe spastic dystonia of fingers, wrist, and elbow flexors can hinder function, and result in pain and complications, requiring chronic treatment with botulinum toxin. The association between muscle hypertonia and severe motor impairment in the first three months after stroke is an important predictor of the possible development of severe hypertonia one year after stroke [15]. Patients who in the first three months after stroke present such clinical association represent a real challenge for neurorehabilitation. In order to facilitate sensory-motor recovery, it is essential to treat them with task-specific training, including grasping exercises. Obviously, due to the severe motor deficit, such patients can perform task-specific training only in an assisted manner, that is, with the help of the physiotherapist. That is especially true for hand movements since the motor deficit is usually more pronounced in the distal muscles. On the other hand, there is the concern, deeply felt by physiotherapists, that in such patients the execution of repeated and intense grasping exercises may aggravate hypertonia in flexor muscles of the wrist and fingers [16]. Indeed, in subacute stroke patients with severe-moderate upper limb impairment, it has been reported a muscle tone increase after rehabilitation treatment [17]. Robotics is a promising approach to poststroke rehabilitation. It may be used to deliver or enhance taskspecific training [18]. Robots for upper limb training can be differentiated into exoskeletons and endeffector robots. While exoskeletons control one or more joints of the paretic limb by means of torque actuators, end-effector robots guide only the most distal part of the paretic limb. A recent meta-analysis states that, in comparison with non-robotic treatment, robotic rehabilitation of the upper limb produces a positive effect on motor control and muscle strength of the paretic limb, but a negative effect on hypertonia [19]. Besides exoskeletons and end-effector robots, supernumerary Robotic Limbs (SRLs) represent a new frontier in robotics. They constitute a new type of wearable robot, which augment the human body by providing additional robotic limbs or fingers. Unlike exoskeletons, supernumerary robotic limbs do not request any joint-to-joint alignment. Moreover, they do not force the user to follow a specific trajectory with their own body parts. SRLs have been initially proposed for industrial purposes to improve users' ergonomics and enhance their capabilities [20, 21]. More recently, SRLs have been used in chronic stroke patients for compensating their missing abilities and counter learned non-use [22, 23]. To date, SRLs have never been used in post-acute stroke patients to promote neural plasticity and functional improvement. This pilot study represents the first attempt to use a supernumerary robotic hand in patients with subacute stroke (see Fig. 1). Patients with severe hand weakness and initial hypertonia were enrolled, therefore being at high risk of developing severe hypertonia of wrist and fingers flexors in the following months. In our protocol, full finger extension of the robotic hand was activated by the patients through Page 4/13 their residual, albeit minimal, active extension of fingers or wrist, while the patients were required to relax their muscles to achieve full flexion of the robotic fingers. Our idea is that, following this protocol, patients could be able to perform task-specific training including grasping exercises, which is known to promote motor recovery, without any overt activation of flexor muscles of fingers and wrist, whose intensive and repetitive activation could favor the development of severe hypertonia in the following months. Moreover, the visual input provided by the robotic hand could activate the mirror neuron system of the affected hemisphere, which is thought to play an important role in motor learning and rehabilitation [24]. This can be compared to the classic Mirror Therapy, widely used in post-stroke rehabilitation, which is based on the movements of the unaffected hand reflected on a mirror placed in the patient's midsagittal plane to provide the illusion of movement of the affected hand [25]. The advantage of our new approach could consist in the fact that the movement, albeit assisted, is induced by the voluntary activation of the affected hemisphere. Our idea can also be compared with the use of immersive or non-immersive virtual reality (VR) for stroke rehabilitation, which has been demonstrated effective in combination with conventional therapy [26, 27]. In our case, the positive effects of the reinforcement of the visual input in causal association with the motor commands, at the basis of VR therapy, could be further strengthened by the matching residual kinaesthetic feedback from the patient’s arm. Furthermore, the actual possibility to perform functional tasks in the real world could provide positive motivational reinforcement. The first aim of this pilot study is to assess the short-term and long-term effects of this novel rehabilitative approach on the muscle tone of wrist and fingers flexor muscles. Accordingly, the primary outcome is the clinical assessment of muscle tone using the Modified Ashworth Scale (MAS). The secondary outcome is the EMG assessment of spasticity and spastic dystonia. The second aim is to evaluate the feasibility of the treatment by investigating patients’ compliance. Our hypothesis is that the proposed treatment does not worsen hypertonia. If this hypothesis were confirmed, then we could plan a randomized controlled trial in patients with subacute stroke to evaluate the effectiveness of the treatment with the robotic hand on functional recovery. Results In compliance with the inclusion criteria, the 4 subjects enrolled were unable to grasp and release objects. Instead, using SoftHand-X, they became able to perform these tasks and could follow an intensive rehabilitation program focused on grasping and releasing objects of various shapes and sizes. None of the participants experienced any adverse effect during the 10 treatment sessions (5 days a week for 2 weeks). The feasibility of using SoftHand-X was assessed measuring the level of patients’ participation to the treatment, by means of the Pittsburgh scale [28]. The median scores recorded among the 4 patients was 6, meaning “excellent participation in all exercises with maximal efforts, finishing all exercises, and taking an active interest in exercises and/or future therapy sessions”. The possibility of treating these patients with an intensive protocol focused on grasping and releasing objects raises the issue of spasticity in flexor muscles of the wrist and fingers. In fact, these subjects at Page 5/13 baseline were at high risk of developing a disabling form of spasticity in the following months [15] and there is concern that intensive exercise of the distal flexor muscles involved in grasping tasks could facilitate this progression [16]. For this reason, we made sure that SoftHand-X was controlled only by the activation of extensor muscles. Figure 2 shows the clinical scores of the 4 patients evaluated at the 4 times points: just before the beginning of the treatment (T0), just after the last session (T1), 10 days after the last session (T2) and 1 year after stroke (T3). A mean improvement in the motor score of the Fugl-Meyer Assessment for upper extremity (FMA-UE) (17) of 11 points from T0 to T1, 7 points from T1 to T2 and 23.3 points from T2 to T3 was observed, with an improvement of the hand/wrist motor sub-score of 5.8 points from T0 to T1, 2.3 points from T1 to T2 and 13.3 points from T2 and T3. Moreover, patients were also characterized by an increase of Medical Research Council (MRC) scores indicating a progressive improvement (from T0 to T3) of strength in flexor-extensor muscles of the wrist and fingers. At T0, two patients (1 and 4) showed an MAS score of 1 (mild spasticity) in flexor muscles of both wrist and fingers, while the other 2 patients showed an MAS of 1 only in wrist flexors. A decrease of the MAS score from 1 to 0 (no spasticity) was observed at T1 and at T2 in all 4 patients. At T3, only in patient 3 a mild spasticity in wrist flexors (MAS 1) reappeared. EMG assessment of muscle tone (see Fig. 3) showed, at T0, a stretch reflex not preceded by a tonic muscle contraction in all 4 patients, thus indicating spasticity [12, 13]. In the first two patients, spasticity disappeared immediately after treatment (T1) and never returned (T2 and T3). In patient number 3, spasticity decreased after treatment (T1 and T2), while at the last evaluation (T3) it was slightly more intense than at baseline. Finally, in the last patient, spasticity disappeared immediately after treatment (T1), it reappeared 10 days after the end of treatment (T2), while it was not present at the last assessment (T3). Discussion These results state that our 4 patients presented a remarkable recovery of the motor function of the upper limb. At the end of the study, one year after stroke onset (T3), all had achieved excellent motor control of the upper limb, practically without any residual disability or with slight residual disability. Obviously, the data of this pilot study, carried out on 4 subjects and without a control group, do not allow us to say whether and to what extent the rehabilitation treatment contributed to the achievement of this positive outcome. However, the temporal course of spasticity (evaluated both clinically and neurophysiologically) shows that the rehabilitation treatment with SoftHand-X does not induce any worsening of spasticity, either in the short- or long-term, suggesting instead that such treatment may even improve spasticity. The main limitation of this study is the small sample size. However, our intention was to enroll a very homogenous group of patients, at high risk of developing severe hypertonia. Since no worsening of spasticity was observed, thus confirming our hypothesis, a randomized controlled trial in patients with sub-acute stroke can now be planned to evaluate the effectiveness of SoftHand-X on Page 6/13 functional recovery. Methods Participants According to the aim of this pilot study, inclusion criteria were: first-ever stroke, occurred no longer than 2 months before the enrolment ischemic or haemorrhagic lesions confirmed by computed tomography or magnetic resonance imaging severe weakness of the flexor-extensor muscles of the fingers, with inability to grasp objects ability to perform minimal active extension movements of the fingers or wrist, covering at least 5 degrees of the corresponding passive range of motion increased tone in flexor muscles of the fingers or wrist, defined as an MAS score higher than 0 no severe cognitive impairment (Mini Mental State Examination-MMSE- > 24 points) and no severe aphasia All 4 participants (Table 1) gave written informed consent to the study that was conformed to the Declaration of Helsinki and was approved by the ethical committee of “IRCCS-Ospedale Policlinico San Martino, Genova, Italia” (approval number 258REG2017).