Functional Electrical Nerve Stimulation: A Way to Restore Lost Functions
Today electrical nerve and muscle stimulation has a broad field of application which includes the following: • cardiac pacemakers • phrenic pacemakers against respiratory insufficiency • motor nerve stimulation for the paralyzed • electrical stimulation f
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Electrical Nerve Stimulation Theory, Experiments and Applications
Springer-Verlag Wien GmbH
Univ.-Doz. Dipl.-Ing. Dr. Frank Rattay Technical University Vienna Austria
This work is subject to copyright. AlI rights are reserved, whether the whole or part of the material is concerned, specificalIy those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machines or similar means, and storage in data banks. © 1990 by Springer-Verlag Wien Originally published by Springer Vienna in 1990
Printed on acid-free paper
With 136 Figures
Cover-design: T. Erben, Wien
ISBN 978-3-211-82247-0 DOI 10.1007/978-3-7091-3271-5
ISBN 978-3-7091-3271-5 (eBook)
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PREFACE Functional electrical stimulation is the most important application in the field of clinical treatment with currents or magnetism. This technique generates artificially neural activity in order to overcome lost functions of paralyzed, incontinent, or sensory handicapped patients. Electricity and magnetism is also used in other cases, e.g., to stimulate bone growth or wound healing. In contrast to these applications, the basic mechanism of the artificial excitation of the nerve and the muscle fibers has become known in the last few years. Although many textbooks are concerned with the natural excitation process, information on the influence of an applied electric or magnetic field is lacking. This book, written for students and biomedical engineers, should close this gap and, furthermore, it should stimulate the desire to design new instrumentation using optimal strategies. That this book's English reads naturally, is due to the corrections of Kris Kingery and Robert Motz. I also wish to thank the many friends and students who have provided valuable hints, discussions and computations.
Vienna, September 1990
Frank Rattay
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CONTENTS ABBREVIATIONS AND SYMBOLS
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TABLE OF IMPORTANT CONSTANTS AND TYPICAL PARAMETERS
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1. FUNCTIONAL ELECTRICAL NERVE STIMULATION-
A WAY TO RESTORE LOST FUNCTIONS Introduction - historical remarks Electrical stimulation of nerve and muscle fibers The choice of electrodes Electrode processes and tissue damage during stimulation monophasic and biphasic signals Future developments
2. FUNCTIONAL DESIGN OF THE NERVOUS SYSTEM The elements of the neuron The non-myelinated fiber The myelinated fiber Branching of dentrites and axons 3. THE EXCITABILITY OF CELLS Bernstein's cell membrane concept Box 3.1 Nernst- and Goldman equations Ionic channels Box 3.2 Electric network for membranes The patch clamp 4. THE SPACE CLAMP EXPERIMENT OF HODGKIN AND HUXLEYNON-PROPAGATING ACTION POTENTIALS Measurement of the voltage-depending ionic membrane conductance Quantifying membrane conductances Table 4.1 Symbols, constants and units used in the Hodgkin-Huxley model Box 4.1 The Hodgkin Huxley equations The influence of temperature Stimulation with current impulses
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Contents
5. MODELING THE MEMBRANE A reduced Hodgkin Huxley model The Fitzhugh
