Which physical finding indicates a herniated intervertebral disc at the L5 root?

A positive straight leg raise is a classic physical finding associated with a herniated intervertebral disc, particularly affecting the L5 nerve root. This test evaluates the tension on the sciatic nerve and its roots as the leg is raised while the patient is in a supine position. When a herniated disc compresses the L5 nerve root, lifting the leg often reproduces radicular pain, indicating the presence of nerve root irritation or compression. This response occurs due to the stretching of neural structures that can be exacerbated with certain positioning.

In contrast, lower back stiffness can be present in a variety of conditions and is not specific to a herniated disc. The diminished Achilles reflex tends to indicate S1 nerve root involvement rather than L5. Increased pain with neck flexion points to issues in the cervical spine rather than the lumbar region, further confirming that it does not relate to a herniated disc at the L5 root. Understanding these distinctions helps in recognizing the clinical significance of the positive straight leg raise in diagnosing L5 root herniation.