The tensilon challenge test is used to diagnose which condition?

• A. myasthenia gravis
• B. multiple sclerosis
• C. guillain-barré syndrome
• D. amyotrophic lateral sclerosis

Answer: (A)

This test hinges on how neuromuscular transmission responds to a cholinesterase inhibitor. In myasthenia gravis, autoimmune attack reduces the number of functional acetylcholine receptors at the neuromuscular junction, causing weakness that worsens with activity. Administering a short-acting acetylcholinesterase inhibitor like edrophonium briefly increases acetylcholine at the junction, allowing more receptors to be activated and producing a noticeable, temporary improvement in strength. That improvement supports the diagnosis of myasthenia gravis.

In the other conditions—such as multiple sclerosis, Guillain–Barré syndrome, or amyotrophic lateral sclerosis—weakness arises from central or peripheral nerve demyelination or motor neuron loss, not from a deficit at the neuromuscular junction. Increasing acetylcholine won’t provide meaningful, lasting improvement there, so the test isn’t diagnostic for those disorders.