Which imaging will show objective functional localization and severity?

• A. Electromyography and Nerve Conduction Velocity
• B. Magnetic Resonance Imaging
• C. Lumbar X-rays
• D. Computed Tomography Scan

Answer: (A)

Functional localization and severity come from tests that measure how nerves and muscles actually work, not just what they look like on pictures. Electromyography and nerve conduction studies provide objective data on nerve impulse transmission and muscle electrical activity. Nerve conduction studies quantify how fast and how strongly impulses travel along a nerve (conduction velocity, amplitudes, latencies), while electromyography records muscle activity at rest and during contraction, revealing spontaneous activity and recruitment patterns. Together, they can pinpoint where a lesion lies along the motor unit—whether at the level of the motor neuron, nerve root, peripheral nerve, neuromuscular junction, or muscle—and gauge how severely function is affected by the abnormality (e.g., demyelination vs axonal loss). Imaging methods like MRI, X-ray, or CT show anatomy and structural changes but don’t directly assess nerve or muscle function, so they don’t provide the same objective measure of localization and severity.