Lumbar Nerve Root Lesion Patterns

Procedure

Patient prone. Bend the knee towards the buttock; if no symptoms appear, gently extend the hip while stabilising the pelvis. Compare with the other side.

Positive Finding

Reproduction of the familiar pain in the front of the thigh or groin. A quadriceps stretch alone does not count.

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

Tensions the femoral nerve and the L2–L4 roots. A positive test points to an upper lumbar root rather than L5 or S1. A negative test does not rule an upper root out. 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 sits upright at the edge of the plinth, hands behind the back. In sequence: slump the thoracic and lumbar spine, flex the neck, extend the knee on the tested side, then dorsiflex the ankle. Stop at the first symptoms. Then ask the patient to lift the head and note any change.

Positive Finding

The patient's familiar leg symptoms reproduced in the slumped position and eased when the neck is released.

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

A positive slump with relief on neck release suggests the leg pain comes from irritable neural tissue. It does not identify the root level; use the neurological examination for that. 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, legs straight, no pillow under the head. Lift the symptomatic leg slowly with the knee straight until symptoms appear. Note the angle and where the symptoms are felt, then add ankle dorsiflexion.

Positive Finding

The patient's familiar leg pain, usually below the knee, reproduced as the leg is raised and increased by ankle dorsiflexion. A posterior thigh stretch alone does not count.

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

Tensions the L5 and S1 roots most. A negative SLR makes a disc herniation compressing a lower lumbar root less likely. A positive SLR supports nerve-root irritation; the neurological examination points to the level. 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. Lift the unaffected leg with the knee straight while the patient reports any symptoms in the painful leg.

Positive Finding

Reproduction of the familiar radiating pain in the symptomatic leg when the opposite leg is raised.

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

Usually negative, so a negative result rules little out. When positive, a disc herniation compressing a lower lumbar root is much more likely. 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. Palpate the paraspinal area at each lumbar level and tap gently over each spinous process.

Positive Finding

Local tenderness, or pain spreading into the leg, at one level.

Interpretation

Nerve roots lie deep inside the foramen and cannot be palpated. Local tenderness is common in back pain and does not identify the level of a root lesion; the neurological examination and imaging do that.

Procedure

Test strength by myotome (hip flexion L2–3, knee extension L3–4, ankle dorsiflexion L4, big-toe extension and hip abduction L5, plantarflexion S1), light-touch and pin-prick sensation by dermatome, and the patellar (L4) and Achilles (S1) reflexes, comparing both sides.

Positive Finding

Weakness, altered sensation or a reduced reflex that fits one nerve root and matches the leg pain.

Interpretation

The pattern of deficits suggests the root involved: for example, a reduced patellar reflex and weak knee extension point to L4, weak big-toe extension and hip abduction to L5, and a reduced Achilles reflex with weak plantarflexion to S1. Overlap between roots is common. A normal examination does not exclude root compression. 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.