Electromyography and Neuromuscular Disorders

Electromyography and Neuromuscular Disorders......Page 2
Copyright Page......Page 5
Foreword......Page 6
Preface to the Third Edition......Page 7
Preface to the Second Edition......Page 8
Preface to the First Edition......Page 10
Dedication......Page 11
Acknowledgments......Page 12
Localization of the Disorder is the Major Aim of the Electrodiagnostic Study......Page 13
Neuropathic Localization......Page 14
Assessment of the Temporal Course can Often be Made......Page 15
Neuromuscular Junction Localization......Page 16
Cardinal Rules of Nerve Conduction Studies and Electromyography......Page 17
Anatomy......Page 20
Physiology......Page 22
Classification......Page 26
Recording......Page 28
Suggested Readings......Page 30
Motor Conduction Studies......Page 31
Duration......Page 32
Conduction Velocity......Page 33
Peak Latency......Page 34
Conduction Velocity......Page 35
Lesions Proximal to the Dorsal Root Ganglion Result in Normal Sensory Nerve Action Potentials......Page 36
Proximal Stimulation: Normal Temporal Dispersion and Phase Cancellation......Page 37
Mixed Conduction Studies......Page 38
Use Supramaximal Stimulation......Page 39
Neuropathic Lesions......Page 40
Axonal Loss......Page 41
Demyelination......Page 43
Conduction Block......Page 44
Suggested Readings......Page 47
4 Late Responses......Page 48
F Response......Page 49
F Response Procedure......Page 50
The F Estimate......Page 52
H Reflex......Page 53
Axon Reflex......Page 56
Suggested Readings......Page 58
Blink Reflex Procedure......Page 59
Patterns of Abnormalities......Page 61
Suggested Readings......Page 63
Normal Neuromuscular Junction Physiology......Page 64
Modeling Slow Repetitive Nerve Stimulation......Page 65
Repetitive Nerve Stimulation in the Electromyography Laboratory......Page 67
Exercise Testing in the Electromyography Laboratory......Page 68
Stimuli must be Supramaximal......Page 69
Nerve Selection......Page 70
Decrement and Increment Calculation......Page 71
Repetitive Nerve Stimulation Protocol......Page 72
Suggested Readings......Page 73
Routine Ulnar Conduction Study: Pseudo-Conduction Block between the Wrist and Below-Elbow Sites......Page 74
Ulnar Conduction Study: Proximal Martin–Gruber Anastomosis and Pseudo-Conduction Block between the Below-Elbow and Above-Elbow Sites......Page 75
Ulnar Conduction Study Recording the First Dorsal Interosseous: Pseudo-Conduction Block between the Wrist and Below-Elbow Sites......Page 76
Routine Median Motor Study: Increased Compound Muscle Action Potential Amplitude Proximally......Page 77
Martin–Gruber Anastomosis and Carpal Tunnel Syndrome: Positive Proximal Deflection (“Dip”) and Factitiously Fast Conduction Velocity......Page 78
Needle Electromyography and Martin–Gruber Anastomosis......Page 79
Miscellaneous Anatomic Variations......Page 80
Suggested Readings......Page 82
Temperature......Page 83
Age......Page 85
Electrode Impedance and Noise......Page 86
Filters......Page 87
Stimulus Artifact......Page 88
Cathode Position: Reversing Stimulator Polarity......Page 89
Co-stimulation of Adjacent Nerves......Page 91
Electrode Placement for Motor Studies......Page 93
Antidromic versus Orthodromic Recording......Page 94
Distance between Recording Electrodes and Nerve......Page 95
Distance between Active and Reference Recording Electrodes......Page 96
Limb Position and Distance Measurements......Page 98
Limb Position and Waveform Morphology......Page 100
Suggested Readings......Page 101
9 Basic Statistics for Electrodiagnostic Studies......Page 102
Bayes’ Theorem and the Predictive Value of a Positive Test......Page 105
Multiple Tests and the Increasing Risk of False Positives......Page 107
Suggested Readings......Page 108
Key Points:......Page 109
Stimulation Sites:......Page 110
Key Points:......Page 111
Key Points:......Page 112
Stimulation Sites:......Page 113
Key Points:......Page 114
Stimulation Sites:......Page 115
Distal Distance:......Page 116
Distal Distance:......Page 117
Key Points:......Page 119
Stimulation Sites:......Page 120
Stimulation Site:......Page 121
Distal Distance:......Page 122
Key Points:......Page 123
Upper Extremity......Page 124
Craniobulbar......Page 126
Stimulation Sites:......Page 127
Key Points:......Page 128
Key Points:......Page 131
Distal Distance:......Page 132
Stimulation Sites:......Page 133
Key Points:......Page 134
Key Points:......Page 135
Nerve Conduction Studies of the Lower Extremity: Normal Adult Values......Page 136
Equipment......Page 137
Typical Needle Electromyography Examination (Box 12–1)......Page 139
Cross-section Anatomy Key Points:......Page 141
Cross-section Anatomy Key Points:......Page 144
Cross-section Anatomy Key Points:......Page 148
Cross-section Anatomy Key Points:......Page 151
Cross-section Anatomy Key Points:......Page 154
Cross-section Anatomy Key Points:......Page 157
Cross-section Anatomy Key Points:......Page 160
Cross-section Anatomy Key Points:......Page 164
Cross-section Anatomy Key Points:......Page 167
Cross-section Anatomy Key Points:......Page 170
Cross-section Anatomy Key Points:......Page 173
Cross-section Anatomy Key Points:......Page 176
Cross-section Anatomy Key Points:......Page 179
Cross-section Anatomy Key Points:......Page 182
Cross-section Anatomy Key Points:......Page 186
Cross-section Anatomy Key Points:......Page 190
Cross-section Anatomy Key Points:......Page 193
Cross-section Anatomy Key Points:......Page 197
Cross-section Anatomy Key Points:......Page 200
Cross-section Anatomy Key Points:......Page 203
Cross-section Anatomy Key Points:......Page 206
Cross-section Anatomy Key Points:......Page 209
Cross-section Anatomy Key Points:......Page 212
Cross-section Anatomy Key Points:......Page 216
Cross-section Anatomy Key Points:......Page 221
Cross-section Anatomy Key Points:......Page 225
Cross-section Anatomy Key Points:......Page 229
Morphology......Page 232
Firing Characteristics......Page 235
Endplate Spikes (“Nerve Potentials”)......Page 236
Fibrillation Potentials......Page 237
Positive Sharp Waves......Page 238
Myotonic Discharges......Page 240
Fasciculation Potentials......Page 241
Myokymic Discharges......Page 242
Neuromyotonic Discharges......Page 243
Suggested Readings......Page 246
Physiology......Page 247
Morphology......Page 248
Duration......Page 249
Polyphasia, Serrations, and Satellite Potentials......Page 250
Stability......Page 251
Firing Pattern (Activation, Recruitment, Interference Pattern)......Page 252
Acute Axonal Loss......Page 255
Chronic Axonal Loss......Page 256
Neuromuscular Junction Disorders......Page 257
Suggested Readings......Page 259
Axonal Loss Lesions......Page 261
Demyelinating Lesions......Page 262
Axonal Loss: Acute......Page 264
Axonal Loss: Chronic......Page 265
Demyelination (Slowing and Conduction Block): Single Distal Lesion......Page 266
Myopathic Lesions......Page 267
Myopathy: Chronic with Denervating Features......Page 268
Central Nervous System Lesions......Page 269
Mononeuropathy: Non-localizing......Page 270
Polyneuropathy: Asymmetric Axonal......Page 271
Plexopathy......Page 272
Motor Neuron Disease......Page 273
Myopathy: Distal......Page 274
Myopathy with Myotonic Discharges......Page 275
Localizing a Mononeuropathy by Needle EMG: Issues and Limitations......Page 276
Anatomy......Page 279
Clinical......Page 281
Etiology......Page 283
Nerve Conduction Studies......Page 284
Median Second Lumbrical-versus-Ulnar Interossei Distal Motor Latencies......Page 286
Inching across the Wrist and Palmar Stimulation......Page 287
Wrist-to-Palm versus Palm-to-Digit Sensory Conduction Velocity (Segmental Sensory Conduction Studies across the Wrist)......Page 289
Electromyographic Approach......Page 292
Special Situation: EDX Studies after Carpal Tunnel Release......Page 293
Suggested Readings......Page 300
Etiology......Page 301
Ligament of Struthers Entrapment......Page 302
Anterior Interosseous Nerve Syndrome......Page 303
Nerve Conduction Studies......Page 304
Electromyographic Approach......Page 305
Suggested Readings......Page 309
Anatomy......Page 310
Clinical......Page 311
Differential Diagnosis......Page 313
Nerve Conduction Studies......Page 314
Differential Slowing: Flexed versus Extended Elbow Conduction Techniques......Page 316
Short Segment Incremental Studies (“Inching”)......Page 317
Recording the First Dorsal Interosseous......Page 318
Mixed and Sensory Nerve Conductions......Page 319
Dorsal Ulnar Cutaneous Sensory Study......Page 320
Nerve Conduction Study Pitfalls......Page 322
Electromyographic Approach......Page 323
Suggested Readings......Page 329
Clinical......Page 331
Differential Diagnosis......Page 333
Dorsal Ulnar Cutaneous Sensory Study......Page 334
Median Second Lumbrical versus Ulnar Interossei Distal Motor Latencies......Page 335
Short Segment Incremental Studies......Page 336
Comparison of the Various Electrophysiologic Tests in Ulnar Neuropathy at the Wrist......Page 337
Electromyographic Approach......Page 338
Suggested Readings......Page 342
Anatomy......Page 343
Radial Nerve between the Spiral Groove and the Bifurcation near the Elbow......Page 344
Deep Branch......Page 345
Posterior Interosseous Neuropathy......Page 346
Differential Diagnosis......Page 347
Nerve Conduction Studies......Page 348
Anatomic Considerations of Some Radial-Innervated Muscles on Needle EMG......Page 351
Suggested Readings......Page 357
Anatomy......Page 358
Peroneal Neuropathy at the Fibular Neck......Page 360
Etiology......Page 361
Nerve Conduction Studies......Page 362
Electromyographic Approach......Page 363
Suggested Readings......Page 368
Clinical......Page 369
Differential Diagnosis......Page 370
Nerve Conduction Studies......Page 371
Electromyographic Approach......Page 372
Suggested Readings......Page 376
Clinical......Page 377
Nerve Conduction Studies......Page 378
Electromyographic Approach......Page 380
Suggested Readings......Page 383
Trigeminal Nerve......Page 384
Facial Neuropathy......Page 386
Trigeminal Neuropathy......Page 387
Nerve Conduction Studies......Page 388
Nerve Conduction Studies and Blink Reflex......Page 389
Electromyographic Approach......Page 390
Suggested Readings......Page 395
Key Question No. 1: What is the Temporal Course and Progression of the Polyneuropathy (Acute, Subacute, Chronic; Progressive, Stepwise, Relapsing/Remitting)?......Page 396
Key Question No. 2: Which Fiber Types are Involved (Motor, Large Sensory, Small Sensory, Autonomic)?......Page 397
Key Question No. 3: What is the Pattern of the Polyneuropathy (Distal Dying Back [Distal-To-Proximal Gradient], Short Nerves, Multiple Nerves; Symmetry, Asymmetry)?......Page 398
Key Question No. 5: Is there a Family History of Polyneuropathy?......Page 399
Key Question No. 6: Is there a History of Medical Illness or are there Signs Suggesting A Medical Illness Associated with Polyneuropathy?......Page 400
Special Situations in Axonal Polyneuropathy: The Use of the Sural/Radial Amplitude Ratio in Mild Polyneuropathy......Page 401
Diabetes......Page 402
Demyelinating Polyneuropathy......Page 403
Guillain–Barré Syndrome (GBS)......Page 404
Electrophysiology......Page 405
Charcot–Marie–Tooth Neuropathy......Page 406
Electrophysiology......Page 407
Multifocal Motor Neuropathy with Conduction Block......Page 408
Electrophysiologic Evaluation of Polyneuropathy......Page 409
Nerve Conduction Studies......Page 410
Electromyographic Approach......Page 411
Suggested Readings......Page 427
Classic Amyotrophic Lateral Sclerosis......Page 429
Primary Lateral Sclerosis......Page 430
Cervical/Lumbar Stenosis......Page 431
Inclusion Body Myositis......Page 432
Nerve Conduction Studies......Page 433
Electromyographic Approach......Page 437
Suggested Readings......Page 442
28 Atypical Motor Neuron Disorders......Page 444
West Nile Encephalitis......Page 445
Familial Amyotrophic Lateral Sclerosis (FALS)......Page 446
Hereditary Spastic Paraplegia......Page 447
Adult Polyglucosan Body Disease......Page 448
Monomelic Amyotrophy......Page 449
Delayed Radiation-Induced Motor Neuron Syndrome......Page 450
Nerve Conduction Studies......Page 451
Electromyographic Approach......Page 452
Suggested Readings......Page 459
Etiology......Page 460
Nerve Conduction Studies......Page 461
Superficial Peroneal SNAP and L5 Radiculopathy: the Rare Exception......Page 464
Electromyographic Approach......Page 466
Time Course in Radiculopathy......Page 467
If the Sensory Nerve Root is Predominantly Affected, the Electromyographic Study will be Normal......Page 469
Abnormal Paraspinal Muscles are Useful in Identifying a Radiculopathy but Not the Segmental Level of the Lesion......Page 470
There is no Difference between a Radiculopathy/Polyradiculopathy and Focal/Diffuse Motor Neuron Disease on the Electromyographic Study......Page 472
Fibrillation Potentials in the Paraspinal Muscles do not Necessarily Imply Radiculopathy......Page 473
In the Elderly, it may not be Possible to Differentiate a Mild Chronic Distal Polyneuropathy from Mild Chronic Bilateral L5–S1 Radiculopathies......Page 474
Suggested Readings......Page 479
Anatomy......Page 480
Clinical......Page 481
Lower Trunk Plexopathy......Page 482
Neoplasms and Other Mass Lesions......Page 483
Delayed Radiation Injury......Page 484
Thoracic Outlet Syndrome......Page 485
Nerve Conduction Studies......Page 486
Electromyographic Approach......Page 489
Neurogenic Thoracic Outlet Syndrome......Page 490
Suggested Readings......Page 498
Clinical......Page 499
Electrodiagnosis......Page 501
Anatomy......Page 502
Electrodiagnosis......Page 503
Clinical......Page 504
Clinical......Page 505
Clinical......Page 506
Electrodiagnosis......Page 507
Suggested Readings......Page 511
Obturator Nerve......Page 513
Clinical......Page 514
Retroperitoneal Hemorrhage......Page 515
Tumors and Other Mass Lesions......Page 517
Postpartum Plexopathy......Page 518
Lateral Femoral Cutaneous Neuropathy (Meralgia Paresthetica)......Page 519
Nerve Conduction Studies......Page 520
Electromyographic Approach......Page 521
Normal Paraspinal Muscles on EMG do not Exclude a Radiculopathy......Page 522
If the Lesion is Acute, the Study may be Normal......Page 523
Suggested Readings......Page 529
Clinical......Page 530
Etiology......Page 532
Piriformis Syndrome......Page 533
Nerve Conduction Studies......Page 534
Special Studies in Suspected Piriformis Syndrome......Page 535
Electromyographic Approach......Page 536
Suggested Readings......Page 540
Myasthenia Gravis......Page 541
Clinical......Page 542
Nerve Conduction Studies......Page 543
Electromyography......Page 544
Single-fiber Electromyography......Page 545
Electrophysiologic Evaluation......Page 547
Clinical......Page 549
Electrophysiologic Evaluation......Page 550
Congenital Myasthenic Syndromes......Page 551
Suggested Readings......Page 559
35 Myopathy......Page 561
Clinical......Page 562
Electromyographic Approach......Page 563
Spontaneous Activity in Myopathies......Page 564
Motor Unit Action Potential Analysis in Myopathies......Page 565
Single-fiber Electromyography in Myopathy......Page 566
Polymyositis and Dermatomyositis......Page 567
Critical Illness Myopathy......Page 568
Suggested Readings......Page 573
Muscle Cooling......Page 575
Prolonged Exercise Test......Page 576
Myotonic Dystrophy......Page 578
Clinical......Page 579
Electrophysiologic Evaluation......Page 581
Electrophysiologic Evaluation......Page 582
Electrophysiologic Examination......Page 583
Paramyotonia Congenita......Page 584
Clinical......Page 585
Electrophysiologic Examination......Page 586
Electrophysiologic Examination......Page 587
Other Conditions Associated with Myotonia......Page 588
Suggested Readings......Page 593
Differential Diagnosis of Neurologic Weakness in the ICU......Page 595
Electrodiagnostic Studies in the Intensive Care Unit: Technical Issues......Page 597
Low or Absent Motor Responses with Normal Sensory Responses......Page 599
Decreased Activation......Page 601
Nerve Conduction and Electromyographic Protocol in the Intensive Care Unit......Page 602
Phrenic Motor Study......Page 603
Suggested Readings......Page 604
Maturation Issues......Page 605
Technical Issues......Page 607
Approach to the Child as a Patient......Page 608
Goals of the Pediatric Electrodiagnostic Examination......Page 610
Suggested Readings......Page 611
Basics of Electricity......Page 612
Ohm’s Law......Page 613
Kirchhoff’s Laws......Page 614
Resistors in Parallel......Page 615
Direct Current and Alternating Current......Page 616
Capacitance......Page 617
Inductance......Page 619
Waveforms, Frequency Analysis, and Filtering......Page 620
Low-Frequency (High-Pass) Filters......Page 621
High-Frequency (Low-Pass) Filters......Page 622
Practical Implications for Electrodiagnostic Studies......Page 623
Electrical Issues......Page 626
Central Lines and Electrical Wires......Page 628
Implanted Pacemakers and Cardioverter-Defibrillators......Page 629
Pneumothorax......Page 630
Bleeding......Page 631
Coexistent Medical Conditions......Page 632
Needle Electromyography and Patients at Risk of Bleeding......Page 633
Infection......Page 634
Suggested Readings......Page 635
Palmar Mixed Nerve Studies......Page 637
Phrenic Motor Study*......Page 638
Motor Studies......Page 639
Late Responses*......Page 640
Mean Motor Unit Action Potential Duration Based on Age and Muscle Group......Page 641