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Medicine

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Neurology

Question
4 out of 15
 

The most sensitive test for the diagnosis of myasthenia gravis is: (AIPG 2009)



A Elevated serum ACh-receptor binding antibodies.

B Repetitive nerve stimulation test.

C Positive edrophonium test.

D Measurement of jitter by single fibre electromyography.

Ans. D

Measurement of jitter by single fibre electromyography.

Diagnostic studies

1. Administration of intravenous edrophonium (a short-acting cholinesterase inhibitor) usually produces a transient improvement in strength in patients suffering from myas­thenia gravis.

Extra edge: (Ref. Hari- 18th ed., pg- 3481)

The edrophonium test is now reserved for patients with clinical findings that are suggestive of MG but who have negative antibody and electrodiagnostic test results. False-positive tests occur in occasional patients with other neurologic disorders, such as amyotrophic lateral sclerosis, and in placebo-reactors.

2). Repetitive nerve stimulation studies can demonstrate a decremental response of the compound muscle action potential.

a. Acetylcholine receptor antibodies can be detected in the blood of 80%-90% of patients.

b. A thoracic CT or MRI scan shows a thymoma, if present.

c. EMG is the most sensitive & most specific test.

Neurology Flashcard List

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