Neuro-fuzzy modeling of multi-field surface neuroprostheses for hand grasp

154 p.Las neuroprótesis aplican pulsos eléctricos a los nervios periféricos con el objetivo de sustituir funciones motrices/sensoriales perdidas, dando asistencia e influyendo positivamente en la rehabilitación motriz de personas con disfunciones motrices causadas por trastornos neurológicos. La complejidad de la neuroanatomía del antebrazo y la mano, su dimensionalidad, las diversas tareas no-cíclicas, la variabilidad de movimientos entre sujetos y la reducida selectividad de las neuroprótesis superficiales, ha dado lugar al diseño de un número reducido de neuroprótesis orientadas a agarres básicos. La posibilidad de hacer más selectiva la estimulación mediante los electrodos multi-campo, junto con el conocimiento sobre la incomodidad y los movimientos que genera la aplicación de la estimulación eléctrica funcional (FES por sus siglas en inglés) en miembro superior, podrían ser base fundamental para el desarrollo de neuroprótesis de agarre más avanzadas. La presente tesis describe un análisis de incomodidad como resultado de FES en el miembro superior, y propone modelos neuro-difusos para neuroprótesis de agarre tanto para personas sanas como para personas con trastornos neurológicos. El conocimiento generado respecto a la incomodidad puede ser utilizado como guía para desarrollar aplicaciones de FES de miembro superior más cómodas. Del mismo modo, los modelos propuestos en esta tesis pueden ser utilizados para apoyar el diseño y la validación de sistemas de control avanzados en neuroprótesis dirigidas a la función de agarre.Tecnalia; Intelligent Control Research Grou

Stimulation discomfort comparison of asynchronous and synchronous methods with multi-field electrodes

Functional Electrical Stimulation (FES) is a technique that consists on applying electrical current pulses to artificially activate motor nerve fibers and produce muscle contractions to achieve functional movements. The main applications of FES are within the rehabilitation field, in which this technique is used to aid recovery or to restore lost motor functions. People that benefit of FES are usually patients with neurological disorders which result in motor dysfunctions; most common patients include stroke and spinal cord injury (SCI). Neuroprosthesis are devices that have their basis in FES technique, and their aim is to bridge interrupted or damaged neural paths between the brain and upper or lower limbs. One of the aims of neuroprosthesis is to artificially generate muscle contractions that produce functional movements, and therefore, assist impaired people by making them able to perform activities of daily living (ADL). FES applies current pulses and stimulates nerve fibers by means of electrodes, which can be either implanted or surface electrodes. Both of them have advantages and disadvantages. Implanted electrodes need open surgery to place them next to the nerve root, so these electrodes carry many disadvantages that are produced by the use of invasive techniques. In return, as the electrodes are attached to the nerve, they make it easier to achieve selective functional movements. On the contrary, surface electrodes are not invasive and are easily attached or detached on the skin. Main disadvantages of surface electrodes are the difficulty of selectively stimulating nerve fibers and uncomfortable feeling perceived by users due to sensory nerves located in the skin. Electrical stimulation surface electrode technology has improved significantly through the years and recently, multi-field electrodes have been suggested. This multi-field or matrix electrode approach brings many advantages to FES; among them it is the possibility of easily applying different stimulation methods and techniques. The main goal of this thesis is therefore, to test two stimulation methods, which are asynchronous and synchronous stimulation, in the upper limb with multi-field electrodes. To this end, a purpose-built wrist torque measuring system and a graphic user interface were developed to measure wrist torque produced with each of the methods and to efficiently carry out the experiments. Then, both methods were tested on 15 healthy subjects and sensitivity results were analyzed for different cases. Results show that there are significant differences between methods regarding sensation in some cases, which can affect effectiveness or success of FES.Tecnalia and Fundación Iñaki Goenag

Stimulation Discomfort Comparison of Asynchronous and Synchronous Methods with Multi-Field Surface Electrodes

Functional Electrical Stimulation (FES) is a technique that artificially stimulates motor nerves in order to restore motor/sensory functions for assistive and therapeutic applications. Recently, multi-field surface electrodes for transcutaneous electrical stimulation have been suggested to overcome problems of single channel surface stimulation. This study compares sensation perceived by 15 healthy subjects on upper limb when two different stimulation methods are applied by means of multi-field electrodes. Asynchronous and synchronous stimulation methods are compared for four different cases: activation of two neighbor fields, three neighbor fields, two distant fields and three distant fields. Two descriptors rated from 1 to 5 are used to describe discomfort: superficial discomfort and deep discomfort. Results expressed no differences in superficial discomfort for any case, but showed significant differences in deep discomfort for distant field activations. In these cases, synchronous stimulation resulted in higher perceived deep discomfort than asynchronous stimulation and affected its efficacy

Transcutaneous FES-induced pain maps on post-stroke upper limb

Functional Electrical Stimulation (FES) is a technique to artificially stimulate motor nerves in order to restore motor/sensory functions for assistive and therapeutic applications. This preliminary study attempts to detect differences in the perception of transcutaneous FES in upper limbs. Three chronic stroke survivors participated in the study. Multi-field electrodes were used to selectively activate the targeted areas over the wrist-finger flexors, wrist-finger extensors, biceps, and triceps muscles. Results showed no significant correlation between the applied current and pain ratings. Differences in the rating of pain in different fields over the four targeted areas were observed. The initial results suggest that here is a common pattern to most subjects for each area of the upper limb

Uso de redes neuro-borrosas RFNN para la aproximación del comportamiento de una neuroprótesis de antebrazo en pacientes con daño cerebral

Las neuroprótesis son sistemas basados en la técnica de estimulación eléctrica funcional que provocan contracciones musculares mediante la excitación artificial de nervios periféricos, y son utilizadas para sustituir funciones motrices/sensoriales en aplicaciones tanto asistivas como terapéuticas. Este trabajo presenta la posibilidad de utilizar redes neuro-borrosas recurrentes para obtener modelos capaces de extraer las características principales del resultado de la aplicación de una neuroprótesis de miembro superior en distintos pacientes. Se ha entrenado una Recurrent Fuzzy Neural Network (RFNN) con datos reales obtenidos de pacientes crónicos de daño cerebral adquirido. Se han analizado distintas estrategias y estructuras y los resultados preliminares muestran la capacidad de estas redes de aprender las características principales de distintos sujetos y de proporcionar información fácilmente interpretable

A foot drop compensation device based on surface multi-field functional electrical stimulation—Usability study in a clinical environment

Functional electrical stimulation applies electrical pulses to the peripheral nerves to artificially achieve a sensory/motor function. When applied for the compensation of foot drop it provides both assistive and therapeutic effects. Multi-field electrodes have shown great potential but may increase the complexity of these systems. Usability aspects should be checked to ensure their success in clinical environments. We developed the Fesia Walk device, based on a surface multi-field electrode and an automatic calibration algorithm, and carried out a usability study to check the feasibility of integrating this device in therapeutic programs in clinical environments. The study included 4 therapists and 10 acquired brain injury subjects (8 stroke and 2 traumatic brain injury).The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Part of this study was supported by the European Regional Development Funds through the Interreg Sudoe Program, project SOE1/P1/F0370

Usability study of a device for compensation of foot drop based on FES and surface multi-field electrodes in a clinical environment

Functional Electrical Stimulation (FES) has shown successful assistive and rehabilitation effects in people affected by foot drop dysfunction caused by neurological disorders [1]. Still, FES-based foot drop devices are not present in regular therapy programs of many countries due to barriers caused by technological, usability or reliability issues [2]. FES devices based on surface multi-field electrodes bring new broader stimulation possibilities and features like compensation of eversion/inversion and thus, potentially increase the configuration options. In this study, the satisfaction and usability aspects of a multi-field based FES device were analyzed in a clinical environment. Method The FES device used in this study was the Fesia Walk device for compensation of foot drop, which is based on a multi-field surface electrode and an inertial sensor for gait phase detection. 10 acquired brain injury subjects in chronic stage and 4 therapists participated in the study. The therapists received a two-hour training session prior to the therapy sessions. Every subject was assigned to one therapist and received 3 sessions of habituation and 6 sessions of over ground walking with the Fesia Walk during three weeks. Both therapists and users were evaluated with the Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST). Additionally, the therapists were evaluated with the System Usability Scale (SUS). An individual interview was carried out with each of the participants. Results The device received good scores in both the QUEST and SUS scales, with mean scores of 4.14 out of 5 and 85.6 out of 100 respectively. Furthermore, most users and all therapists showed interest to continue using the device after the study. Discussion and conclusions This usability study indicated that it is possible to include surface multi-field based FES devices for the compensation of foot drop in practical therapeutic programs and that they can be used as regular tools by therapists in clinical environments

The Use of Functional Electrical Stimulation on the Upper Limb and Interscapular Muscles of Patients with Stroke for the Improvement of Reaching Movements: A Feasibility Study

Introduction: Reaching movements in stroke patients are characterized by decreased amplitudes at the shoulder and elbow joints and greater displacements of the trunk, compared to healthy subjects. The importance of an appropriate and specific contraction of the interscapular and upper limb (UL) muscles is crucial to achieving proper reaching movements. Functional electrical stimulation (FES) is used to activate the paretic muscles using short-duration electrical pulses. Objective: To evaluate whether the application of FES in the UL and interscapular muscles of stroke patients with motor impairments of the UL modifies patients’ reaching patterns, measured using instrumental movement analysis systems. Design: A cross-sectional study was carried out. Setting: The VICON Motion System® was used to conduct motion analysis. Participants: Twenty-one patients with chronic stroke. Intervention: The Compex® electric stimulator was used to provide muscle stimulation during two conditions: a placebo condition and a FES condition. Main outcome measures: We analyzed the joint kinematics (trunk, shoulder, and elbow) from the starting position until the affected hand reached the glass. Results: Participants receiving FES carried out the movement with less trunk flexion, while shoulder flexion elbow extension was increased, compared to placebo conditions. Conclusion: The application of FES to the UL and interscapular muscles of stroke patients with motor impairment of the UL has improved reaching movements.This research has been supported by Spanish Ministry of Science project HYPER PROJECT (CONSOLIDER-INGENIO 2010) Hybrid Neuroprosthetic and Neurorobotic Devices for Functional Compensation and Rehabilitation of Motor Disorders. HYPER-CSD2009-00067

Stimulation discomfort comparison of asynchronous and synchronous methods with multi-field electrodes

Functional Electrical Stimulation (FES) is a technique that consists on applying electrical current pulses to artificially activate motor nerve fibers and produce muscle contractions to achieve functional movements. The main applications of FES are within the rehabilitation field, in which this technique is used to aid recovery or to restore lost motor functions. People that benefit of FES are usually patients with neurological disorders which result in motor dysfunctions; most common patients include stroke and spinal cord injury (SCI). Neuroprosthesis are devices that have their basis in FES technique, and their aim is to bridge interrupted or damaged neural paths between the brain and upper or lower limbs. One of the aims of neuroprosthesis is to artificially generate muscle contractions that produce functional movements, and therefore, assist impaired people by making them able to perform activities of daily living (ADL). FES applies current pulses and stimulates nerve fibers by means of electrodes, which can be either implanted or surface electrodes. Both of them have advantages and disadvantages. Implanted electrodes need open surgery to place them next to the nerve root, so these electrodes carry many disadvantages that are produced by the use of invasive techniques. In return, as the electrodes are attached to the nerve, they make it easier to achieve selective functional movements. On the contrary, surface electrodes are not invasive and are easily attached or detached on the skin. Main disadvantages of surface electrodes are the difficulty of selectively stimulating nerve fibers and uncomfortable feeling perceived by users due to sensory nerves located in the skin. Electrical stimulation surface electrode technology has improved significantly through the years and recently, multi-field electrodes have been suggested. This multi-field or matrix electrode approach brings many advantages to FES; among them it is the possibility of easily applying different stimulation methods and techniques. The main goal of this thesis is therefore, to test two stimulation methods, which are asynchronous and synchronous stimulation, in the upper limb with multi-field electrodes. To this end, a purpose-built wrist torque measuring system and a graphic user interface were developed to measure wrist torque produced with each of the methods and to efficiently carry out the experiments. Then, both methods were tested on 15 healthy subjects and sensitivity results were analyzed for different cases. Results show that there are significant differences between methods regarding sensation in some cases, which can affect effectiveness or success of FES.Tecnalia and Fundación Iñaki Goenag

Neuro-fuzzy modeling of multi-field surface neuroprostheses for hand grasp

154 p.Las neuroprótesis aplican pulsos eléctricos a los nervios periféricos con el objetivo de sustituir funciones motrices/sensoriales perdidas, dando asistencia e influyendo positivamente en la rehabilitación motriz de personas con disfunciones motrices causadas por trastornos neurológicos. La complejidad de la neuroanatomía del antebrazo y la mano, su dimensionalidad, las diversas tareas no-cíclicas, la variabilidad de movimientos entre sujetos y la reducida selectividad de las neuroprótesis superficiales, ha dado lugar al diseño de un número reducido de neuroprótesis orientadas a agarres básicos. La posibilidad de hacer más selectiva la estimulación mediante los electrodos multi-campo, junto con el conocimiento sobre la incomodidad y los movimientos que genera la aplicación de la estimulación eléctrica funcional (FES por sus siglas en inglés) en miembro superior, podrían ser base fundamental para el desarrollo de neuroprótesis de agarre más avanzadas. La presente tesis describe un análisis de incomodidad como resultado de FES en el miembro superior, y propone modelos neuro-difusos para neuroprótesis de agarre tanto para personas sanas como para personas con trastornos neurológicos. El conocimiento generado respecto a la incomodidad puede ser utilizado como guía para desarrollar aplicaciones de FES de miembro superior más cómodas. Del mismo modo, los modelos propuestos en esta tesis pueden ser utilizados para apoyar el diseño y la validación de sistemas de control avanzados en neuroprótesis dirigidas a la función de agarre.Tecnalia; Intelligent Control Research Grou