This study aims to evaluate the diagnostic accuracy of the straight leg raise test in patients with suspected lumbosacral radicular pain. Lumbosacral radicular pain is often caused by lumbar disc herniation and may radiate from the lower back or buttock to the leg. Although the straight leg raise test is commonly used in clinical practice, its diagnostic performance has been reported to vary.

In this study, diagnostic transforaminal epidural steroid injection or selective nerve root block will be used as the reference standard. The sensitivity, specificity, likelihood ratios, and area under the curve of the straight leg raise test will be calculated. The findings may help guide clinicians in determining when the straight leg raise test is sufficient and when further diagnostic confirmation may be needed.

Low back pain is one of the leading causes of disability worldwide. Lumbosacral radicular pain is commonly caused by lumbar disc herniation and is characterized by pain radiating from the lower back or buttock to the leg in a dermatomal distribution. The straight leg raise test is a simple and widely used physical examination test for evaluating suspected lumbar radiculopathy; however, its diagnostic accuracy varies across studies.

This study aims to evaluate the diagnostic performance of the straight leg raise test in patients with suspected lumbosacral radicular pain. Diagnostic transforaminal epidural steroid injection or selective nerve root block will be used as the reference standard. Only technically selective injections performed without sedation and with a low volume of short-acting local anesthetic will be included in the analysis. The study will assess the sensitivity, specificity, likelihood ratios, and area under the curve of the straight leg raise test. The results may help clarify when the straight leg raise test is reliable on its own and when additional diagnostic confirmation may be needed for clinical decision-making.

Inclusion Criteria:

• Age between 18 and 65 years.
• Preliminary diagnosis of lumbar radicular pain based on medical history, physical examination, and lumbar magnetic resonance imaging.
• Patients scheduled to undergo transforaminal epidural injection targeting the L4, L5, or S1 nerve root.

Exclusion Criteria:

• Inability to access clinical or procedural records in the hospital system.
• Absence of available radiological records related to the target level, if required.
• Inability to provide reliable NRS or straight leg raise test assessment due to cognitive impairment or language barrier.
• Coagulopathy, defined as INR > 1.5 or platelet count < 80,000/mm³, or inability to discontinue anticoagulant or antiplatelet therapy when required.
• Local or systemic infection, or skin lesion at the planned injection site.
• Pregnancy or breastfeeding.
• Known severe hypersensitivity to iodinated contrast material or local anesthetics.
• Progressive neurological deficit or cauda equina syndrome.
• Bilateral or nearly bilateral pain with both sides being prominent and equivalent, or need for therapeutic injection at more than one level during the same session.
• Epidural injection with local anesthetic and/or steroid at the same level within the last 6 weeks.
• Active polyneuropathy or other diffuse neuropathies.
• Active radicular pain originating from nerve roots other than L4, L5, or S1.
• Requirement for mandatory sedation.

Adult patients aged 18 to 65 years with a preliminary diagnosis of lumbar radicular pain based on medical history, physical examination, and lumbar magnetic resonance imaging, who are scheduled to undergo transforaminal epidural injection targeting the L4, L5, or S1 nerve root, will be included in the study.