What physical exam finding is indicative of sciatica in patients with musculoskeletal back pain?

A positive straight leg raise (SLR) test is indicative of sciatica in patients experiencing musculoskeletal back pain because it specifically assesses for nerve root irritation, typically affecting the sciatic nerve. When the leg is raised while in a supine position, this maneuver stretches the sciatic nerve and can reproduce radicular symptoms such as pain, tingling, or numbness that radiates down the leg. In cases of sciatica, this response occurs due to underlying issues like a herniated disc or lumbar spine problems that compress the nerve roots.

Other options such as paraspinal tenderness, limited range of motion, and unequal femoral pulses do not specifically address the nerve-related symptoms that characterize sciatica. While paraspinal tenderness and limited range of motion can occur in various back conditions, they lack the specificity for identifying sciatica. Unequal femoral pulses may indicate vascular issues rather than neurological problems, which are central to the diagnosis of sciatica. Therefore, the positive SLR is a key indicator for diagnosing sciatic nerve involvement.