30 year old woman with proximal muscle weakness – Medicine MCQ

A 30 year old woman presented to the OPD with proximal muscle weakness, ptosis and easy fatigability. Which of following is the most sensitive test to arrive at a diagnosis?
A. Single fiber electromyography
B. Muscle biopsy
C. Measurement of creatinine phosphokinase levels
D. Edrophonium test

Correct answer : A. Single fiber electromyography

Myasthenia gravis – Reversal of ptosis after edrophonium test

• The history and clinical features are suggestive of myasthenia gravis.
• Single fiber electromyography is the most sensitive test for the diagnosis of myasthenia gravis
• Detection of acetylcholine receptor antibodies is the most specific test
• If single fiber electromyography is not given among the options, the next best choice is edrophonium test

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