**Question:** Test used for prolapsed lumbar intervertebral disc is-

A. Discography
B. X-ray
C. MRI
D. Electromyography (EMG)

**Core Concept:**
The correct test for diagnosing a prolapsed lumbar intervertebral disc involves pinpointing the source of back pain and neurological deficits caused by the herniated disc. Discography, X-ray, MRI, and EMG are imaging and diagnostic techniques used in clinical practice.

**Why the Correct Answer is Right:**
A) Discography: This diagnostic test involves injecting contrast medium into the lumbar intervertebral disc under fluoroscopic guidance. If the pain reproduces the patient's symptoms, it confirms the diagnosis of a herniated disc. Discography is more specific but less sensitive than MRI and CT scans.

**Why Each Wrong Option is Incorrect:**
B) X-ray: Though X-rays can detect bone abnormalities, they are inadequate for diagnosing soft tissue issues like a herniated disc. The low contrast resolution and lack of soft tissue detail prevent accurate diagnosis.

C) MRI: Magnetic resonance imaging is highly sensitive for detecting disc abnormalities, including herniations. However, MRI is not the best test for confirming the pain originates from the herniated disc, as it does not directly test the disc itself.

D) Electromyography (EMG): EMG assesses the function of the nerves and muscles. While it can detect nerve root compression, it is not the primary test for diagnosing a lumbar disc herniation. EMG is primarily used to evaluate peripheral nerve function.

**Clinical Pearl:**
In clinical practice, the most reliable diagnostic test for a lumbar disc herniation involves a combination of history, physical examination, and MRI findings. Confirming the pain originating from the herniated disc usually requires a targeted diagnostic test like discography, which directly assesses the affected disc. MRI is crucial for visualizing the disc herniation but does not directly evaluate the disc.