Which test is commonly used to diagnose myasthenia gravis?

• A. Electromyography
• B. Ice pack test
• C. Edrophonium (Tensilon) test
• D. Pulmonary function testing

Answer: (C)

A rapid, temporary improvement in muscle strength after a short-acting acetylcholinesterase inhibitor is what this test demonstrates. The Edrophonium (Tensilon) test uses edrophonium to briefly boost acetylcholine at the neuromuscular junction. In myasthenia gravis, where fewer functional acetylcholine receptors are available, this small, momentary increase in acetylcholine improves transmission and leads to a noticeable improvement in voluntary muscle strength. A positive, quick response supports the diagnosis.

Other tests provide useful information but aren’t as definitive on their own. Electromyography, especially repetitive nerve stimulation and single-fiber EMG, can show abnormal transmission and help confirm MG. The ice pack test is a simple bedside option for ocular MG, showing ptosis improvement with cooling, but it’s not a general diagnostic test. Pulmonary function testing doesn’t diagnose MG; it assesses respiratory muscle function to monitor disease impact and guide management.