Which response to a Tensilon test confirms a diagnosis of myasthenia gravis?

• A. Improvement of symptoms
• B. Worsening symptoms
• C. No change
• D. Immediate relief lasting hours

Answer: (A)

The test looks for a temporary boost in neuromuscular transmission after increasing acetylcholine at the junction. In myasthenia gravis, there are fewer functional acetylcholine receptors, so boosting acetylcholine helps the remaining receptors work longer and strengthens muscle contraction briefly. If symptoms improve after administering the drug, that positive response supports a diagnosis of MG. The effect is short-lived because the medication is rapidly cleared, lasting only minutes, not hours. Worsening symptoms or no change would not indicate MG, and an improvement lasting hours would be inconsistent with the short-acting drug.