Repetitive nerve stimulation studies in the Lambert-Eaton myasthenic syndrome

1994 ◽  
Vol 17 (9) ◽  
pp. 995-1001 ◽  
Author(s):  
Richard W. Tim ◽  
Donald B. Sanders
Author(s):  
Bashar Katirji

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.


Author(s):  
Bashar Katirji

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.


Author(s):  
Bashar Katirji

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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