Question

A 35-year-old female has proximal weakness of muscles, ptosis and easy fatiguability. The best test to diagnose her condition is:

• A. Muscle biopsy
• B. CPK
• C. Edrophonium test
• D. EMG

Hint:

A drug that boosts acetylcholine briefly reverses ptosis and weakness.

Answer 1

The Correct Option is C

A young woman whose muscles tire quickly, whose eyelids droop and whose weakness is proximal and fluctuating is pointing strongly toward myasthenia gravis, a failure of transmission across the neuromuscular junction caused by antibodies against acetylcholine receptors. Because the problem is too little effective acetylcholine signalling, a drug that boosts acetylcholine should temporarily reverse the signs. That is exactly what the edrophonium test does, by briefly blocking the enzyme that breaks down acetylcholine, it raises transmitter levels at the junction, and within seconds the ptosis lifts and strength improves before fading again. This dramatic transient response confirms the junctional nature of the disease and is the best diagnostic choice here. Tests aimed at the muscle itself, such as creatine kinase or muscle biopsy, stay normal because the muscle fibres are intact. Electromyography can show decremental responses but is not the single best listed answer for this textbook presentation. The edrophonium test wins.
\[\boxed{\text{Edrophonium test}}\]