Phase-II Clinical Validation of a Powered Exoskeleton for the Treatment of Elbow Spasticity

Abstract

Introduction: Spasticity is a typical motor disorder in patients affected by stroke. Typically post-stroke rehabilitation consists of repetition of mobilization exercises on impaired limbs, aimed to reduce muscle hypertonia and mitigate spastic reflexes. It is currently strongly debated if the treatment's effectiveness improves with the timeliness of its adoption; in particular, starting intensive rehabilitation as close as possible to the stroke event may counteract the growth and postpone the onset of spasticity. In this paper we present a phase-II clinical validation of a robotic exoskeleton in treating subacute post-stroke patients.Methods: Seventeen post-stroke patients participated in 10 daily rehabilitation sessions using the NEUROExos Elbow Module exoskeleton, each one lasting 45 min: the exercises consisted of isokinetic passive mobilization of the elbow, with torque threshold to detect excessive user's resistance to the movement. We investigated the safety by reporting possible adverse events, such as mechanical, electrical or software failures of the device or injuries or pain experienced by the patient. As regards the efficacy, the Modified Ashworth Scale, was identified as primary outcome measure and the NEEM metrics describing elbow joint resistance to passive extension (i.e., maximum extension torque and zero-torque angle) as secondary outcomes.Results: During the entire duration of the treatments no failures or adverse events for the patients were reported. No statistically significant differences were found in the Modified Ashworth Scale scores, between pre-treatment and post-treatment and between post-treatment and follow-up sessions, indicating the absence of spasticity increase throughout (14 days) and after (3–4 months follow-up) the treatment. Exoskeleton metrics confirmed the absence of significant difference in between pre- and post-treatment data, whereas intra-session data highlighted significant differences in the secondary outcomes, toward a decrease of the subject's joint resistance.Conclusions: The results show that our robotic exoskeleton can be safely used for prolonged sessions in post-stroke and suggest that intensive early rehabilitation treatment may prevent the occurrence of spasticity at a later stage. Moreover, the NEEM metrics were found to be reliable compared to the Modified Ashworth Scale and sensitive to revealing intra-session changes of elbow resistance to passive extension, in agreement with clinical evidences.

A Review on Design of Upper Limb Exoskeletons

“…In a later version, bio-inspired morphological characteristics were introduced by adding the compliance in the mechanical design using nonlinear elastic elements and custom-made torsional springs [97]. NEUROExos was developed by carefully analyzing the neuro-scientific motion requirement, and later, it was used in several experimental studies to cure neurological disorders [68].…”

Robotic Assistance for Upper Limbs May Induce Slight Changes in Motor Modules Compared With Free Movements in Stroke Survivors: A Cluster-Based Muscle Synergy Analysis

“…In fact, the focus is to coordinate distal joints (the elbow and wrist) properly in order to proceed correctly toward the target (the mouth), also emphasizing the role of proprioceptive feedback in relation to the motor output. The main requirement of the task involves flexing the elbow against gravity, so spasticity or strength deficits on the elbow agonist muscles (such as the biceps or triceps) can drastically interfere with performance during its execution (Bohannon et al, 1991 ; Crea et al, 2017 ; Posteraro et al, 2017 ). Elbow flexion is coupled with an internal rotation and slight elevation of the shoulder.…”

A Novel Generation of Ergonomic Upper-Limb Wearable Robots: Design Challenges and Solutions

“…From the kinematic variables recorded from the sensing apparatus, considering only the extension phase (all the participants had spasticity on the elbow flexors), the torque exerted at the maximum extension angle (MET) and the angle correspondent to a null exerted torque (ZTA) were extracted as indicators of the resistance to the movement. 38 The absence of mechanical or electrical failures, damages to the device, or undesired effects on the patients during the entire duration of the treatment demonstrated the safety of the device for treating patients with different body sizes and motor impairments for long periods. This behavior suggested that a treatment program provided with this device in the early post-stroke phase could contribute to the spasticity prevention.…”