EMG Primer : A Guide to Practical Electromyography and Electroneurography

In the last twenty years electromyography and electro­ neurography have earned a secure position amongst methods of electrophysiological investigation; indeed, it is no longer possible to think of neurological diagnosis with­ out them. In particular, it is in the early recognition of peri­ pheral neuromuscular disorders that these techniques are so dependable and objective. The present text may be thought of as an introduction to method and to diagnostic application, and it should be of value to the physician both in hospital and in his practice. The authors have thought it best to omit discussion of basic scientific problems, which may be found in the neurophysiological literature. Munich, Spring 1974 A. Schrader v Contents 1. 1 Anatomical Foundations . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. 1. 1. The Motor Unit. . . . . . . . . . . . . . . . . . . . . . . 1 1. 1. 2. Structure of the Peripheral Nerve . . . . . . . 1 1. 1. 3. The Neuromuscular Junction . . . . . . . . . . . . . . . 1 1. 2 Electrophysiological Foundations . . . . . . . . . . . . . . . . . . 2 1. 2. 1. Origin of Muscle Action Potentials. . . . . . . . . . . . 2 1. 2. 2. Conduction in the Peripheral Nerve. . . . . . . . . . . . 3 1. 2. 2. 1. Stimulation: Basic Considerations. . . . . . . . . . . . . 3 1. 2. 2. 2. Form, Duration and Amplitude of Action Potentials. . . 4 a) Evoked Muscle Action Potentials . . . . . . . . . . . 4 b) Nerve and Sensory Action Potentials. . . . . . . . . 4 c) Reflex Potentials . . . . . . . . . . . . . . . . . . . . 5 2. 1. Technical Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. 1. 1. Structure and Function of the Machine. . . . . . . . . . 6 2. 1. 1. 1. The Structure of an Electromyograph. . . . . . . . . . 6 2. 1. 1. 2. The EMG Amplifier. . . . . . . . . . . . . . . . . . . . 7 2. 1. 1. 3. Supplementary Measuring Methods in Electrom- graphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.1 Anatomical Foundations.- 1.1.1. The Motor Unit.- 1.1.2. Structure of the Peripheral Nerve.- 1.1.3. The Neuromuscular Junction.- 1.2 Electrophysiological Foundations.- 1.2.1. Origin of Muscle Action Potentials.- 1.2.2. Conduction in the Peripheral Nerve.- 1.2.2.1. Stimulation: Basic Considerations.- 1.2.2.2. Form, Duration and Amplitude of Action Potentials.- a) Evoked Muscle Action Potentials.- b) Nerve and Sensory Action Potentials.- c) Reflex Potentials.- 2.1. Technical Foundations.- 2.1.1. Structure and Function of the Machine.- 2.1.1.1. The Structure of an Electromyograph.- 2.1.1.2. The EMG Amplifier.- 2.1.1.3. Supplementary Measuring Methods in Electromyography.- a) The Stimulator and the Latency Measuring Device.- b) The Delay Line.- c) The Averager.- d) The Digital Averager.- 2.2. Electrodes.- 2.2.1. Main Groups.- a) Electrodes for Action Potential Recording.- b) Electrodes for Stimulation.- c) Earth Electrodes.- 2.2.2. Areas of Use.- 2.2.3. Treatment and Care of Electrodes.- 3.1. General Section.- 3.1.1. The Normal Electromyogram.- 3.1.1.1. Methods of Recording.- a) With Surface Electrodes.- b) With Needle Electrodes.- 3.1.1.2. Procedure in the Electromyographical Examination.- 3.1.1.3. Elements of the Needle Myogram.- a) Spontaneous Activity.- b) Activity During Voluntary Innervation.- 3.1.1.4. Methods of Registration.- a) Optical.- b) Acoustical.- 3.1.2. The Normal Electroneurogram.- 3.1.2.1. The Motor Electroneurogram.- Stimulation and Recording.- The Normal Examination Procedure.- Registration and Evaluation.- 3.1.2.2. The Sensory Electroneurogram.- The Normal Examination Procedure.- Registration and Evaluation.- The Examination in Children.- Repetitive Stimulation.- 3.1.3. The Pathological Electromyogram.- 3.1.3.1. Lesions of the Lower Motor Neurone.- a) Fasciculation Potentials.- b) Fibrillation Potentials and Positive Sharp Waves.- Pathological Changes in the Pattern on Voluntary Effort.- a) Reduction of the Interference Pattern.- b) Changes in Motor Unit Action Potential Form.- c) Discharge Frequency.- 3.1.3.2. EMG in Primary Muscle Disease.- Spontaneous Activity.- Pathological Changes in the Pattern on Voluntary Effort.- a) Changes in Motor Unit Action Potential Form.- b) Discharge Frequency.- 3.1.3.3. The EMG in Metabolic Electrolyte Disturbances.- 3.1.3.4. The EMG in Centrally-Determined Movement Disturbances.- 3.1.4. The Pathological Electroneurogram.- 3.1.4.1. The Pathological Motor Electroneurogram.- 3.1.4.2. The Pathological Sensory Electroneurogram.- 3.1.5. Disorders of the Neuromuscular Junction.- 3.2. Special Section (Diagnosis).- 3.2.1. Peripheral Neurogenic Diseases.- 3.2.1.1. General Aspects.- 3.2.1.2. Anterior Horn Cell Diseases.- a) Generalised Anterior Hom Cell Diseases.- b) Local Disorders of Anterior Horn Cells: Poliomyelitis.- Syringomyelia.- 3.2.1.3. Root Lesions.- a) The Intervertebral Disc.- b) Cervical ‘Whiplash’ Injury.- c) Polyradiculitis (Guillain-Barré).- d) Other Varieties of Root Lesion.- 3.2.1.4. Plexus Lesions.- 3.2.1.5. Local Lesions of the Peripheral Nerve.- a) Neuronotmesis.- b) Axonotmesis.- c) Neurapraxia.- d) Reinnervation.- Compressive Neuropathy.- a) Carpal Tunnel Syndrome.- b) Cubital Sulcus Syndrome.- c) Chronic Compressive Neuropathies of the Lower.- d) Radial Nerve (“Saturday Night Palsy”) Limb.- Idiopathic Facial Nerve Palsy (Bell’s).- Trigeminal Neuropathy.- Polyneuropathies.- Peroneal Muscular Atrophy.- 3.2.2. Primary Muscle Disease.- 3.2.2.1. Progressive Muscular Dystrophy (Duchenne).- 3.2.2.2. InflammatoryMuscle Disease (Myositis and Polymyositis).- 3.2.2.3. Late-Onset Myopathies.- 3.2.2.4. Hereditary Distal Myopathy (Welander).- 3.2.2.5. Myotonia.- 3.2.3. Secondary Myopathies.- 3.2.4. Myasthenic Syndromes.- 3.2.4.1. Myasthenia Gravis.- 3.2.4.2. Symptomatic Myasthenia.- 3.2.5. Electrolyte Disturbances.- 3.2.6. Myxoedema.- 3.2.7. Tetanus.- 3.2.8. Centrally-Determined Disturbances of Movement.- 3.2.8.1. Spasticity.- 3.2.8.2. Rigidity.- 3.2.8.3. Tremor.- a) Rest Tremor in Extrapyramidal Disease.- b) Intention Tremor.- 3.2.8.4. Torticollis.- 3.2.9. EMG, ENG and the “Floppy Infant” Syndrome.- 3.2.9.1. Peripheral Neurogenic Lesions.- 3.2.9.2. Myogenic Pareses.- 3.2.9.3. Centrally-Determined Disturbances of Movement.- 4.0. EMG of the Extraocular Muscles.- 4.1. Myopathies.- a) Oligo-Symptomatic Form of Ocular Myositis.- b) Acute Exophthalmic Myositis.- c) Ocular Muscle Dystrophy.- d) Endocrine Ocular Myopathy.- e) Ocular Myotonia.- f) Ocular Myasthenia.- 4.2. Peripheral Neurogenic Paresis.- 4.3. Centrally-Determined Disturbances of Movement.- 5.0. Possibilities of Error in the EMG.- 5.1. Possibilities of Error in the ENG.- a) Motor Electroneurogram.- b) Sensory Electroneurogram.- 6.0. Short Introduction to an EMG Examination.- 7.0. Index of Important Terms in Clinical EMG.- 8.0. Index of Important Technical Terms and Abbreviations.- 9.0. Selected Bibliography.- 10.0. Subject Index.