Electrodiagnostic Findings in Neuromuscular Disorders

2018 ◽  
Author(s):  
Bashar Katirji
Keyword(s):  
Neuromuscular Junction ◽  
Peripheral Nerve ◽  
Myasthenia Gravis ◽  
Nerve Conduction ◽  
Neuromuscular Disorders ◽  
Nerve Conduction Studies ◽  
Anterior Horn Cell ◽  
Peripheral Neuropathies ◽  
Peripheral Nerve Lesions ◽  
Myasthenic Syndrome

Neuromuscular disorders are often classified into four major categories: anterior horn cell disorders, peripheral neuropathies, neuromuscular junction disorders and myopathies. This chapter discusses the electrodiagnostic and clinical EMG findings in these various neuromuscular disorders. Peripheral neuropathies are subdivided into focal mononeuropathies, radiculopathies, plexopathies and generalized peripheral polyneuropathies. Focal peripheral nerve lesions and generalized peripheral polyneuropathies may be axonal or demyelinating, and manifest quite distinctly on nerve conduction studies. Neuromuscular junction disorders may be presynaptic, as seen with the Lambert-Eaton myasthenic syndrome, or postsynaptic, as seen with myasthenia gravis.

Specialized Electrodiagnostic Studies

2018 ◽  
Author(s):  
Bashar Katirji
Keyword(s):  
Neuromuscular Junction ◽  
Peripheral Nerve ◽  
Nerve Stimulation ◽  
Nerve Conduction ◽  
Nerve Conduction Studies ◽  
Single Fiber ◽  
Repetitive Nerve Stimulation ◽  
Myasthenic Syndrome ◽  
Basic Concepts ◽  
Trigeminal Nerves

In addition to nerve conduction nerve studies and needle EMG, the clinical EMG study include more specialized examinations Some of the tests, such as the F waves and H reflexes are now often used as part of the routine nerve conduction studies. Others are utilized for specific indications: Repetitive nerve stimulation and single fiber EMG are used predominantly in patients with suspected neuromuscular junction disorders such as myasthenia gravis, Lambert-Eaton myasthenic syndrome or botulism; the blink reflexes are used in patients with disorders of the facial and trigeminal nerves as well as brainstem conditions. This chapter covers the late responses, including the F waves, H reflexes and blink reflexes and their applications in the diagnosis of peripheral nerve disorders. This is a followed by a discussion of the basic concepts of slow and rapid repetitive nerve stimulation and single fiber EMG, as well as their applications in the diagnosis of neuromuscular junction disorders.

scholarly journals Presynaptic Paraneoplastic Disorders of the Neuromuscular Junction: An Update

2021 ◽  
Vol 11 (8) ◽  
pp. 1035
Author(s):  
Maria Pia Giannoccaro ◽  
Patrizia Avoni ◽  
Rocco Liguori
Keyword(s):  
Potassium Channels ◽  
Neuromuscular Junction ◽  
Calcium Channels ◽  
Myasthenia Gravis ◽  
Neuromuscular Transmission ◽  
Voltage Gated ◽  
Voltage Gated Calcium Channels ◽  
Immune Mediated ◽  
Recent Developments ◽  
Myasthenic Syndrome

The neuromuscular junction (NMJ) is the target of a variety of immune-mediated disorders, usually classified as presynaptic and postsynaptic, according to the site of the antigenic target and consequently of the neuromuscular transmission alteration. Although less common than the classical autoimmune postsynaptic myasthenia gravis, presynaptic disorders are important to recognize due to the frequent association with cancer. Lambert Eaton myasthenic syndrome is due to a presynaptic failure to release acetylcholine, caused by antibodies to the presynaptic voltage-gated calcium channels. Acquired neuromyotonia is a condition characterized by nerve hyperexcitability often due to the presence of antibodies against proteins associated with voltage-gated potassium channels. This review will focus on the recent developments in the autoimmune presynaptic disorders of the NMJ.

Neurophysiological assessments for peripheral nerve injury

2021 ◽  
pp. 261-263
Author(s):  
Arup Mallik
Keyword(s):  
Peripheral Nerve ◽  
Nerve Injury ◽  
Nerve Conduction ◽  
Peripheral Nerve Injury ◽  
Nerve Conduction Studies ◽  
Anatomical Distribution

Neurophysiology is a useful investigation to assess peripheral nerve injury. It consists of nerve conduction studies and electromyography, providing information on anatomical distribution of the lesion (pre/postganglionic, single/multiple nerves), whether the lesion is primarily demyelinating or axonal, and whether the lesion is in continuity, as well as the overall prognosis.

Repetitive Nerve Stimulation Studies

2016 ◽  
pp. 328-346
Author(s):  
Kathleen D. Kennelly
Keyword(s):  
Neuromuscular Junction ◽  
Nerve Stimulation ◽  
Nerve Conduction ◽  
Neuromuscular Transmission ◽  
Repetitive Stimulation ◽  
Nerve Conduction Studies ◽  
Clinical Correlation ◽  
Repetitive Nerve Stimulation ◽  
Anatomy And Physiology

Repetitive stimulation is a technique that evaluates the function of the neuromuscular junction. It is important not only in the detection, clarification, and follow-up of neuromuscular junction diseases, but also in excluding these disorders in patients with symptoms of fatigue, vague weakness, diplopia, ptosis, and malaise, or with objective weakness of uncertain origin. The technique requires knowledge of the physiology and pathophysiology of neuromuscular transmission and the basic techniques of nerve conduction studies. This chapter includes a brief review of the anatomy and physiology of the neuromuscular junction as it applies to repetitive stimulation, a detailed discussion of the technique, the pitfalls that can occur if not carried out correctly, criteria used to classify the results as normal or abnormal, the patterns of abnormalities that can be seen, and the clinical correlation of those abnormalities with the various different disorders of neuromuscular transmission.

A 46-Year-Old Man with Double Vision and Proximal Leg Weakness

2016 ◽  
Author(s):  
Jeffrey A. Cohen ◽  
Justin J. Mowchun ◽  
Victoria H. Lawson ◽  
Nathaniel M. Robbins
Keyword(s):  
Neuromuscular Junction ◽  
Myasthenia Gravis ◽  
Clinical Picture ◽  
Double Vision ◽  
Junction Conditions ◽  
Antibody Testing ◽  
Tumor Surveillance ◽  
Difficult Condition ◽  
Leg Weakness ◽  
Myasthenic Syndrome

Lambert-Eaton myasthenic syndrome (LEMS) can be a difficult condition to diagnose. In this chapter, the clinical picture and characteristics are discussed. The pathophysiology is also reviewed. Features to distinguish LEMS from more common neuromuscular junction conditions such as myasthenia gravis are reviewed. We review features that distinguish between idiopathic and paraneoplastic forms, and we discuss the importance of tumor surveillance. Antibody testing and the correct electrodiagnostic strategy are presented. Treatment of LEMS is outlined.Lambert-Eaton syndrome (LES) is a difficult condition to diagnose. The unique clinical picture and its characteristics are discussed. This is especially true in the patient without a diagnois of cancer. Antibody testing and the correct electrodiagnostic strategy are presented. Treatment of LES is outlined.

Peripheral Nerve Ultrasound and Short-Segment Nerve Conduction Studies Before and After Ulnar Nerve Decompression

2016 ◽  
Vol 35 (6) ◽  
pp. 1367-1368
Author(s):  
Jonathan K. Smith ◽  
Matthew E. Miller ◽  
David E. Reece ◽  
Yin-Ting Chen ◽  
Mark E. Landau
Keyword(s):  
Peripheral Nerve ◽  
Ulnar Nerve ◽  
Nerve Conduction ◽  
Nerve Conduction Studies ◽  
Nerve Ultrasound ◽  
Short Segment ◽  
Nerve Decompression ◽  
Before And After
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