Mechanical Redesign and Implementation of Intuitive User Input Methods for a Hand Exoskeleton Informed by User Studies on Individuals with Chronic Upper Limb Impairments

Individuals with upper limb motor deficits due to neurological conditions, such as stroke and traumatic brain injury, may exhibit hypertonia and spasticity, which makes it difficult for these individuals to open their hand. The Hand Orthosis with Powered Extension (HOPE) Hand was created in 2018. The performance of the HOPE Hand was evaluated by conducting a Box and Blocks test with an impaired subject. Improvements were identified and the HOPE Hand was mechanically redesigned to increase the functionality in performing grasps. The original motor configuration was reorganized to include active thumb flexion and extension, as well as thumb abduction/adduction. An Electromyography (EMG) study was conducted on 19 individuals (10 healthy, 9 impaired) to evaluate the viability of EMG device control for the specified user group. EMG control, voice control, and manual control were implemented with the HOPE Hand 2.0 and the exoskeleton system was tested for usability during a second Box and Blocks test

Design and effectiveness evaluation of mirror myoelectric interfaces: a novel method to restore movement in hemiplegic patients

The motor impairment occurring after a stroke is characterized by pathological muscle activation patterns or synergies. However, while robot-aided myoelectric interfaces have been proposed for stroke rehabilitation, they do not address this issue, which might result in inefficient interventions. Here, we present a novel paradigm that relies on the correction of the pathological muscle activity as a way to elicit rehabilitation, even in patients with complete paralysis. Previous studies demonstrated that there are no substantial inter-limb differences in the muscle synergy organization of healthy individuals. We propose building a subject-specific model of muscle activity from the healthy limb and mirroring it to use it as a learning tool for the patient to reproduce the same healthy myoelectric patterns on the paretic limb during functional task training. Here, we aim at understanding how this myoelectric model, which translates muscle activity into continuous movements of a 7-degree of freedom upper limb exoskeleton, could transfer between sessions, arms and tasks. The experiments with 8 healthy individuals and 2 chronic stroke patients proved the feasibility and effectiveness of such myoelectric interface. We anticipate the proposed method to become an efficient strategy for the correction of maladaptive muscle activity and the rehabilitation of stroke patients.This study was funded by the Baden-Württemberg Stiftung (GRUENS ROB-1), the Deutsche Forschungsgemeinschaft (DFG, Koselleck), the Fortüne-Program of the University of Tübingen (2422-0-0), and the Bundes Ministerium für Bildung und Forschung BMBF MOTORBIC (FKZ 13GW0053), AMORSA (FKZ 16SV7754), Gipuzkoa Regional Government (INKRATEK), Ministry of Science of the Basque Country (Elkartek: EXOTEK). A. Sarasola-Sanz’s work was supported by La Caixa-DAAD scholarship and N. Irastorza-Landa’s work by the Basque Government and IKERBASQUE, Basque Foundation for Science, Bilbao, Spain

Does the score on the mrc strength scale reflect instrumented measures of maximal torque and muscle activity in post‐stroke survivors?

It remains unknown whether variation of scores on the Medical Research Council (MRC) scale for muscle strength is associated with operator‐independent techniques: dynamometry and surface electromyography (sEMG). This study aimed to evaluate whether the scores of the MRC strength scale are associated with instrumented measures of torque and muscle activity in post-stroke survivors with severe hemiparesis both before and after an intervention. Patients affected by a first ischemic or hemorrhagic stroke within 6 months before enrollment and with complete paresis were included in the study. The pre‐ and post‐treatment assessments included the MRC strength scale, sEMG, and dynamometry assessment of the triceps brachii (TB) and biceps brachii (BB) as measures of maximal elbow extension and flexion torque, respectively. Proprioceptive‐based training was used as a treatment model, which consisted of multidirectional exercises with verbal feedback. Each treatment session lasted 1 h/day, 5 days a week for a total 15 sessions. Nineteen individuals with stroke participated in the study. A significant correlation between outcome measures for the BB (MRC and sEMG p = 0.0177, ϱ = 0.601; MRC and torque p = 0.0001, ϱ = 0.867) and TB (MRC and sEMG p = 0.0026, ϱ = 0.717; MRC and torque p = 0.0001, ϱ = 0.873) were observed post intervention. Regression models revealed a relationship between the MRC score and sEMG and torque measures for both the TB and BB. The results confirmed that variation on the MRC strength scale is associated with variation in sEMG and torque measures, especially post intervention. The regression model showed a causal relationship between MRC scale scores, sEMG, and torque assessments

Developing Predictive Models for Upper Extremity Post–Stroke Motion Quality Estimation Using Decision Trees and Bagging Forest

Stroke is one of the leading causes of long–term disability. Approximately twothirds of stroke survivors require long-term rehabilitation, which suggests the importance of understanding the post-stroke recovery process during his activities of daily living. This problem is formulated as quantifying and estimating the poststroke movement quality in real world settings. To address this need, we have developed an approach that quantifies physical activities and can evaluate the performance quality. Wearable accelerometer and gyroscope are used to measure the upper extremity motions and to develop a mathematical framework to objectively relates sensors’ data to clinical performance indices. In this article we employ two machine learning classification methods, Bootstrap Aggregating (Bagging) Forest and Decision Tree (DT), to relate the post-stroke kinematic data to quality of the corresponding motion. We then compare the accuracy of the resulted two prediction models using cross-validation approaches. Our findings indicate that Bagging forest approach is superior to the computationally simpler DTs for unstable data sets including those derived from stroke survivors in this project

Rehabilitation Outcome Following Acute Stroke: Considering Ideomotor Apraxia

Stroke is a leading cause of death and the leading cause of adult disability in the United States affecting approximately 795,000 people yearly. Stroke sequelae often span multiple domains, including motor, cognitive, and sensory subsystems. Impairments can contribute to difficulty participating in activities of daily living (ADLs) and translate into disability - a concern for patients and occupational therapists alike. The role of ideomotor apraxia (IMA) in stroke rehabilitation is unclear. Thus, the purpose of these two studies is to investigate stroke rehabilitation outcome while considering the presence of ideomotor apraxia. Stroke causes dysfunctional movement patterns arising from an array of potential etiologies. Agreement exists that understanding the patient's functioning serves as the basis for the rehabilitation process and it is insufficient for clinicians simply to determine functional movement problems without knowing how underlying impairments contribute. Stroke-induced paresis is a prevalent impairment and frequent target of traditional rehabilitation. Stroke rehabilitation often addresses paresis narrowly with little consideration for other stroke consequences. Ideomotor apraxia is one such disorder after stroke that could conceivably limit rehabilitation benefit of otherwise efficacious treatment interventions aimed at remediating paresis. This led us to an initial study of a subject who experienced a single left, ischemic stroke with paresis of his right upper extremity and comorbid ideomotor apraxia. The subject participated in combined physical and mental practice for six consecutive weeks to improve use of his right arm. After intervention, the subject demonstrated clinically significant improvements in functional performance of his more-affected right upper extremity and reported greater self-perception of performance. The subject continued to demonstrate improvements after four weeks with no intervention and despite persistent IMA. This single case report highlights the importance of recognizing that ideomotor apraxia does present after stroke, and traditional stroke rehabilitation efforts directed at paresis can be efficacious for subjects with IMA. Traditional beliefs suggested that ideomotor apraxia does not translate to disability in everyday life and that IMA resolves spontaneously. Despite accumulating evidence of the influence of IMA on functional ability, this topic remains relatively neglected. It is unclear how ideomotor apraxia affects the rehabilitation process. The second study reports rehabilitation outcomes of a group of subjects following acute stroke. The Florida Apraxia Battery gesture-to-verbal command test was used to detect IMA in subjects. Level of independence with a set of ADLs and motor impairment of the more-affected upper extremity was documented at admission and discharge. Study subjects participated in standard of care stroke rehabilitation in the inpatient rehabilitation units. A total of fifteen subjects who sustained a left hemisphere stroke participated in this study - ten with IMA and five without IMA. After rehabilitation, subjects with IMA improved ADL independence and displayed decreased motor impairment of their right upper extremity. Subjects with and without IMA exhibited comparable improvements in ADL independence, but subjects with IMA exhibited less ADL independence upon when compared to subjects without IMA. Additional findings suggested that subjects with IMA were not different with respect to motor impairments and length of stay; however, additional studies with larger sample sizes are needed. In summary, these two studies aid to elucidate the implications of ideomotor apraxia on traditional stroke rehabilitation efforts. Study subjects with ideomotor apraxia after acute stroke still derive benefit from traditional rehabilitation. Because traditional rehabilitation interventions narrowly target motor impairment, these findings support the need for considering IMA as a factor in developing interventions tailored to patients with IMA and possibly as a specific focus for interventions. A step toward addressing this need is to assess whether IMA is present after stroke on a regular basis. This work provides a framework for researchers and clinicians to investigate further how ideomotor apraxia translates into disability. These findings are important since consideration of ideomotor apraxia could influence selection and design of rehabilitation interventions to optimize patient daily functioning after stroke

Assessment of movement quality in robot- assisted upper limb rehabilitation after stroke: a review

Studies of stroke patients undergoing robot-assisted rehabilitation have revealed various kinematic parameters describing movement quality of the upper limb. However, due to the different level of stroke impairment and different assessment criteria and interventions, the evaluation of the effectiveness of rehabilitation program is undermined. This paper presents a systematic review of kinematic assessments of movement quality of the upper limb and identifies the suitable parameters describing impairments in stroke patients. A total of 41 different clinical and pilot studies on different phases of stroke recovery utilizing kinematic parameters are evaluated. Kinematic parameters describing movement accuracy are mostly reported for chronic patients with statistically significant outcomes and correlate strongly with clinical assessments. Meanwhile, parameters describing feed-forward sensorimotor control are the most frequently reported in studies on sub-acute patients with significant outcomes albeit without correlation to any clinical assessments. However, lack of measures in coordinated movement and proximal component of upper limb enunciate the difficulties to distinguish the exploitation of joint redundancies exhibited by stroke patients in completing the movement. A further study on overall measures of coordinated movement is recommended

Advancing the Functionality and Wearability of Robotic Hand Orthoses Towards Activities of Daily Living in Stroke Patients

Post stroke rehabilitation is effective when a large number of motor repetitions are provided to patients. However, conventional physical therapy or traditional desktop-size robot aided rehabilitation do not provide sufficient number of repetitions due to cost and logistical barriers. Our vision is to realize a wearable and functional hand orthosis that could be used outside of controlled, clinical settings, thus allowing for more training repetitions. Furthermore, if such a device can prove effective for Activities of Daily Living (ADLs) while actively worn, this can incentivize patients to increase its use, further enhancing rehabilitative effects. However, in order to provide such clinical benefits, the device must be completely wearable without obtrusive features, and intuitive to control even for non-experts. In this thesis, we thus focus on wearability, functionality, and intuitive intent detection technology for a novel hand robot, and assess its performance when used both as a rehabilitative device and an assistive tool. A fully wearable device must deliver meaningful manipulation capability in small and lightweight package. In this context, we investigate the capability of single-actuator devices to assist whole hand movement patterns through a network of exotendons. Our prototypes combine a single linear actuator (mounted on a forearm splint) with a network of exotendons (routed on the surface of a soft glove). We investigate two possible tendon network configurations: one that produces full finger extension (overcoming flexor spasticity) and one that combines proximal flexion with distal extension at each finger. In experiments with stroke survivors, we measure the force levels needed to overcome various levels of spasticity and to open the hand for grasping using the first of these configurations, and qualitatively demonstrate the ability to execute fingertip grasps using the second. Our results support the feasibility of developing future wearable devices able to assist a range of manipulation tasks. In order to further improve the wearability of the device, we propose two designs that provide effective force transmission by increasing moment arms around finger joints. We evaluate the designs with geometric models and experiment using a 3D-printed artificial finger to find force and joint angle characteristics of the suggested structures. We also perform clinical tests with stroke patients to demonstrate the feasibility of the designs. The testing supports the hypothesis that the proposed designs efficiently elicit extension of the digits in patients with spasticity as compared to existing baselines. With the suggested transmission designs, the device can deliver sufficient extension force even when the users have increased muscle tone due to fatigue. The vision of an orthotic device used for ADLs can only be realized if the patients are able to operate the device themselves. However, the field is generally lacking effective methods by which the user can operate the device: such controls must be effective, intuitive, and robust to the wide range of possible impairment patterns. The variety of encountered upper limb impairment patterns in stroke patients means that a single sensing modality, such as electromyography, might not be sufficient to enable controls for a broad range of users. To address this significant gap, we introduce a multimodal sensing and interaction paradigm for an active hand orthosis. In our proof-of-concept implementation, EMG is complemented by other sensing modalities, such as finger bend and contact pressure sensors. We propose multimodal interaction methods that utilize this sensory data as input, and show they can enable tasks for stroke survivors who exhibit different impairment patterns. We then assess the performance of the robotic orthosis for two possible roles: as a therapeutic tool that facilitates device mediated hand exercises to recover neuromuscular function, or as an assistive device for use in everyday activities to aid functional use of the hand. 11 chronic stroke (> 2 years) patients with moderate muscle tone (Modified Ashworth Scale ≤ 2 in upper extremity) engage in a month-long training protocol using the orthosis. Individuals are evaluated using standardized outcome measures, both with and without orthosis assistance. The results highlight the potential for wearable and user-driven robotic hand orthoses to extend the use and training of the affected upper limb after stroke. The advances proposed in this thesis have the potential to enable robotic based hand rehabilitation during daily activities (as opposed to isolated hand exercises with limited upper limb engagement) and over extended periods of time, even in a patient’s home environment. Numerous challenges must still be overcome in order to achieve this vision, related to design (compact devices with easier donning/doffing), control (robust yet intuitive intent inferral), and effectiveness (improved functionality in a wider range of metrics). However, if these challenges can be addressed, wearable robotic devices have the potential to greatly extend the use and training of the affected upper limb after stroke, and help improve the quality of life for a large patient population