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.

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.

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.

Case 24

2018 ◽  
Author(s):  
Bashar Katirji
Keyword(s):  
Botulinum Toxin ◽  
Neuromuscular Junction ◽  
Nerve Stimulation ◽  
Clostridium Botulinum ◽  
Anaerobic Bacteria ◽  
Neuromuscular Disorder ◽  
Repetitive Nerve Stimulation ◽  
Myasthenic Syndrome ◽  
High Index Of Suspicion ◽  
Foodborne Botulism

Botulism is an extremely rare neuromuscular disorder, caused by botulinum toxin which is produced by the anaerobic bacteria Clostridium botulinum. It has several forms: classic foodborne, infantile, wound, intestinal, and iatrogenic forms. The presentation is often acute and severe but may be occasionally subacute and moderate. The diagnosis may be difficult and requires a high index of suspicion. This case presents an adult with classic foodborne botulism and highlights the clinical and electrodiagnostic findings that distinguish this disorder from other neuromuscular junction disorders including myasthenia gravis and Lambert-Eaton myasthenic syndrome. Specifically, the findings on repetitive nerve stimulation are discussed and distinguished from the results seen in other neuromuscular junction disorders.

Case 21

2018 ◽  
Author(s):  
Bashar Katirji
Keyword(s):  
Differential Diagnosis ◽  
Neuromuscular Junction ◽  
Nerve Stimulation ◽  
Neuromuscular Disorder ◽  
Practical Approach ◽  
Repetitive Nerve Stimulation ◽  
Occult Malignancy ◽  
Myasthenic Syndrome ◽  
Distinguishing Features

Lambert-Eaton myasthenic syndrome is a rare yet very important neuromuscular disorder that may be difficult to confirm if not considered in the differential diagnosis. It is often misdiagnosed as myasthenic gravis or other nonspecific neuromuscular disorder. The electrodiagnostic findings in Lambert-Eaton myasthenic syndrome continue to be the cornerstone of the diagnosis. This case outlines the clinical and electrodiagnostic features of a patient with this syndrome and highlights the findings on repetitive nerve stimulation. It also discusses the practical approach in the search for occult malignancy. The distinguishing features among the various neuromuscular junction disorders are emphasized.

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