What does a negative straight leg raise (SLR) test in a sitting position, but a positive straight leg raise (SLR) test in a supine position, indicate?

From the Guidelines

A negative straight leg raise test while sitting but positive while lying down typically indicates a non-organic or inconsistent neurological finding, suggesting that the pain may not be due to true nerve root compression or sciatica. This discrepancy is crucial in clinical practice as it may point towards symptom magnification, psychological factors influencing pain perception, or malingering, which are important considerations for treatment planning. The straight-leg-raise test, as described in the guideline evidence from the American College of Physicians and the American Pain Society 1, is a procedure used to passively stretch the sciatic nerve and elicit symptoms suggesting nerve root tension. A positive test is usually considered reproduction of the patient’s sciatica when the leg is raised between 30 and 70 degrees. However, the inconsistency between the sitting and supine positions may indicate complex origins of pain beyond simple nerve compression, possibly involving central sensitization or psychosocial factors.

Key points to consider in interpreting this test result include:

• The patient's symptoms and medical history, to differentiate between organic pathology and non-organic factors in back pain.
• The possibility of Waddell's sign, which is sometimes used by clinicians to help distinguish between these factors.
• The importance of a comprehensive treatment approach that addresses not only the physical aspects of pain but also potential psychological and social factors.
• The guideline evidence from 1 emphasizes the importance of considering neurogenic claudication, nonspecific low back pain, radiculopathy, sciatica, and spinal stenosis in the diagnosis and treatment of low back pain, highlighting the complexity of diagnosing and managing back pain.

In clinical practice, this inconsistency should prompt a more detailed evaluation of the patient's condition, considering both the physical and psychological aspects of their pain, and potentially leading to a more holistic treatment plan that addresses all relevant factors contributing to their symptoms.

From the Research

Straight Leg Raise (SLR) Test Results

• A negative SLR test in a sitting position, but a positive SLR test in a supine position, may indicate lumbar disc herniation with nerve root compression, as the supine SLR test has been found to be more sensitive in reproducing leg pain than the seated SLR test in patients with signs and symptoms consistent with lumbar radiculopathy and MRI evidence of nerve root compression 2.
• The difference in results between the sitting and supine positions may be due to the fact that the supine SLR test applies more traction to the nerve roots, making it more likely to reproduce leg pain in patients with lumbar disc herniation 3, 2.
• However, it's also possible that the results may be influenced by other factors, such as the patient's age, sex, and disk level, as these factors have been found to affect the results of the SLR test 4.
• The SLR test, whether performed in a sitting or supine position, is a useful tool for diagnosing lumbar disc herniation, but it should be used in conjunction with other diagnostic tests, such as MRI, to confirm the diagnosis 3, 4, 2.
• The results of the SLR test should be interpreted with caution, as they may be influenced by various factors, including the patient's condition, the examiner's technique, and the test's limitations 5, 6.

Comparison of SLR Test Positions

• The supine SLR test has been found to be more sensitive than the seated SLR test in patients with lumbar disc herniation 2.
• However, the seated SLR test may be less recognizable and less likely to be exploited by malingering patients, making it a useful alternative to the supine SLR test 5.
• The results of the SLR test in the sitting and supine positions have been found to be equivalent, suggesting that patients with a positive test should have similar angles in both positions 5.

Diagnostic Implications

• A positive SLR test in the supine position, but a negative test in the sitting position, may indicate a more severe case of lumbar disc herniation with nerve root compression, as the supine SLR test is more sensitive in reproducing leg pain in these patients 2.
• The results of the SLR test should be interpreted in conjunction with other diagnostic tests, such as MRI, to confirm the diagnosis of lumbar disc herniation 3, 4, 2.