Lumbar Nerve Root Lesion Patterns

Procedure

Patient prone or side-lying; examiner passively flexes the knee, bringing the heel toward the buttock to tension the femoral nerve. Assess for anterior thigh or inguinal pain.

Positive Finding

Reproduction of radicular pain in the anterior thigh, groin, or lower abdomen; increased pain with hip extension or lumbar extension component

Sensitivity / Specificity

Reference: Suri P, Rainville J, Katz JN, Jouve C, Hartigan C, Limke J, et al. The accuracy of the physical examination for the diagnosis of midlumbar and low lumbar nerve root impingement. Spine (Phila Pa 1976). 2011;36(1):63-73.

Interpretation

Positive finding suggests upper lumbar nerve root involvement (L2, L3, L4). Useful for identifying nerve tension in a different plane than SLR. May reproduce referred pain in non-radicular presentations. From 54 patients who ALL had nerve-root impingement on MRI (Suri 2011): 25 at L2–L4, 29 at L5/S1. So these figures show whether the test points to an upper lumbar root rather than a lower one. They do not show whether a nerve root is affected at all. A positive test points to L2–L4; a negative test does not rule an upper root out.

Procedure

Patient seated with spine flexed (slump); examiner flexes the patient's head and neck, then extends one knee while monitoring symptoms. Ankle dorsiflexion may be added.

Positive Finding

Radicular pain or tingling reproduction; symptom relief when the cervical or thoracic spine is extended (releasing nerve tension)

Sensitivity / Specificity

Reference: Majlesi J, Togay H, Unalan H, Toprak S. The sensitivity and specificity of the Slump and the Straight Leg Raising tests in patients with lumbar disc herniation. J Clin Rheumatol. 2008;14(2):87-91.

Interpretation

High sensitivity for nerve root involvement across lumbar, thoracic, and cervical levels. Moderate specificity; positive result suggests neural tension component but requires correlation with other findings. Useful screening tool. From one case-control study (Majlesi 2008) of 75 outpatients with back and/or leg pain: 38 had a disc herniation on MRI and 37 did not. The comparison patients had symptoms too, which is the fair comparison. But a herniation on MRI is not always the cause of the pain. In the same patients the straight leg raise scored 52% / 89%.

Procedure

Patient supine; examiner passively flexes the hip with knee extended until patient reports pain or reaches end of range. Note the angle of hip flexion at which symptoms begin.

Positive Finding

Reproduction of radicular pain (pain radiating below the knee) between 30–70° of hip flexion, or increased pain when dorsiflexing the ankle (Bragard test modification)

Sensitivity / Specificity

Reference: van der Windt DA, Simons E, Riphagen II, Ammendolia C, Verhagen AP, Laslett M, et al. Physical examination for lumbar radiculopathy due to disc herniation in patients with low-back pain. Cochrane Database Syst Rev. 2010.

Interpretation

Positive finding suggests nerve root tension, particularly L5 or S1 involvement. High sensitivity makes it useful for screening; specificity varies with patient population. False positives common with hamstring tightness alone. Pooled in a 2010 Cochrane review (van der Windt) from studies where surgery confirmed the diagnosis. Those patients were already selected for surgery (58–98% had a herniation), so specificity is poorly estimated, and sensitivity was lower in studies that used imaging or were done in primary care. A negative SLR makes a disc herniation causing leg pain less likely; a positive SLR on its own proves little.

Procedure

Patient supine; examiner passively flexes the contralateral (non-affected) hip and knee until pain or stretch is felt. Note whether ipsilateral radicular pain is reproduced.

Positive Finding

Reproduction of radicular pain on the affected side when the opposite leg is raised, typically indicating a central or posterolateral disc herniation

Sensitivity / Specificity

Reference: van der Windt DA, Simons E, Riphagen II, Ammendolia C, Verhagen AP, Laslett M, et al. Physical examination for lumbar radiculopathy due to disc herniation in patients with low-back pain. Cochrane Database Syst Rev. 2010.

Interpretation

High specificity indicates significant likelihood of nerve root compression (especially herniated nucleus pulposus). Low sensitivity means negative result does not exclude pathology. Most specific for central or contralateral disc herniation. Pooled in a 2010 Cochrane review (van der Windt), mostly from surgical populations. A positive crossed SLR makes a disc herniation more likely; because it is usually negative, a negative result does not rule one out.

Procedure

Patient prone or side-lying; examiner palpates along the paraspinal region at suspected nerve root levels and performs gentle percussion over spinous processes and transverse processes. Patient reports localized tenderness or referred radicular response.

Positive Finding

Localized tenderness over the intervertebral foramen region, segmental pain reproduction, or radiation of pain distally with percussion

Related reference: See current literature; standard palpation technique in orthopaedic clinical examination

Interpretation

Adjunctive test to localize anatomical level of involvement. Low diagnostic accuracy alone but useful for identifying the specific segmental level (L3/4, L4/5, L5/S1) when combined with neurological and imaging findings.

Procedure

Assess motor strength in key muscles (iliopsoas L2/3, quadriceps L3/4, ankle dorsiflexion L4/5, plantarflexion S1), dermatomes via light touch/pinprick, and deep tendon reflexes (patellar L4, Achilles S1).

Positive Finding

Motor weakness in a myotomal distribution, sensory loss in dermatomal pattern, or absent/diminished reflexes consistent with a specific nerve root level

Interpretation

Positive findings provide strong evidence of specific nerve root involvement and help confirm anatomical level of lesion. Absence of neurological deficit does not exclude nerve root lesion (particularly early or mild compression). Higher specificity for motor and reflex changes than sensory changes. This combines many separate checks (strength, reflexes, sensation), each with its own accuracy, so no single figure applies. In a 2010 Cochrane review most of these signs performed poorly on their own. For which root is involved, level-specific figures come from Suri 2011 (54 patients) — for example, a reduced patellar reflex pointed to L4 and weak hip abduction to L5.