What test measures how fast electrical signals travel through a nerve?

• A. Nerve Conduction Velocity Test
• B. EMG Test
• C. Spinal Tap
• D. CT Scan

Answer: (A)

Measuring how fast electrical signals travel through a nerve is done with a nerve conduction study. In this test, a small electrical stimulus is applied to a nerve at one point and the resulting response is recorded farther along the same nerve. By looking at how long the signal takes to travel between the two points and the distance between them, you get the conduction velocity. Healthy nerves with intact myelin transmit impulses quickly, while nerves that have demyelination slow down the signal, which shows up as a reduced conduction velocity. This helps differentiate types of nerve injury—for example, demyelinating problems tend to slow conduction velocity, whereas axonal problems might reduce the signal's strength (amplitude) rather than its speed. Other options assess different things: EMG examines electrical activity in muscles, not how fast nerves conduct signals; a spinal tap analyzes cerebrospinal fluid; a CT scan images anatomy. So the test that measures how fast electrical signals travel through a nerve is the nerve conduction velocity test.