Straight Leg Raise Test

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Background

The Straight Leg Raise (SLR) test is a commonly used test to identify an impairment in the sciatic nerve. It have also specific importance in detecting disc herniation and neural compression. It can also classify as a neurodynamic evaluation test as it can detect excessive nerve root tension or compression.

Variations of the SLR test:

Laseagues test: This knee is flexed slightly to

Bragards test:

Chris

The SLR test (SLR) also know as Lasègue sign, as positive when there is a sensation of pain by applying pressure to the Piriformis muscle and his tendon, particularly when the hip is flexed at an angle of 90 degrees and the knee is extended.The pain or tenderness is often localized in the vicinity of the greater sciatic notch.

Technique

The straight leg raise is a passive test. Each leg is tested individually with the unaffected leg being tested first. When performing the SLR test, the patient is positioned in supine without a pillow under his/her head, the hip medially rotated and adducted, and the knee extended. With the patient in supine, the clinician stands at the tested side with the distal hand around the patient's heel and proximal hand on patient's distal thigh(anterior) to maintain knee extension. The clinician lifts the patient's leg by the posterior ankle while keeping the knee in a fully extended position. The clinician continues to lift the patient's leg by flexing at the hip until the patient complains of pain or tightness in the back or back of the leg. Then the clinician slowly lowers the leg until the pain or tightness resolves, at which point he puts the ankle in dorsiflexion and will have the patient to flex the neck

Straight Leg Raise Test video provided by Clinically Relevant

Interpretation

• If symptoms are primarily back pain, it is most likely the result of a disc herniation applying pressure on the anterior theca of the spinal cord, or the pathology causing the pressure is more central. "Back pain only" patients who have a disc prolapse have smaller, more central prolapses.
• If pain is primarily in the leg, it is more likely that the pathology causing the pressure on neurological tissue(s) is more lateral.
• Disc herniations or pathology causing pressure between the two extremes are more likely to cause pain in both areas.

Reasoning

• Neurologic pain which is reproduced in the leg and low back between 30-70 degrees of hip flexion is suggestive of lumbar disc herniation at the L4-S1 nerve roots.
• Pain at less than 30 degrees of hip flexion might indicate acute spondyloithesis, gluteal abscess, disc protrusion or extrusion, tumor of the buttock, acute dural inflammation, a malingering patient, or the sign of the buttock.
• Pain at greater than 70 degrees of hip flexion might indicate tightness of the hamstrings, gluteus maximus, or hip capsule, or pathology of the hip or sacroiliac joints.

Sensitizing Maneuvers

After the elicitation of symptoms, the examiner can slowly and carefully lower the leg until the patient no longer feels pain or tightness. Next, either the patient is asked to bring his or her chin to the chest, or the examiner may dorsiflex the patient's foot, or both actions may be done simultaneously; however, foot dorsiflexion is most commonly performed first. Both maneuvers are considered to be provocative or sensitizing tests for neurological tissue.

Pain that increases with neck flexion or foot dorsiflexion or both indicates stretching of the dura mater of the spinal cord or a lesion within the spinal cord (e.g. disc herniation, tumor, or meningitis)

Pain that does not increase with neck flexion may indicate a lesion in the hamstring area (tight hamstrings) or in the lumbosacral or sacro-iliac joint.

• Inclusion of neck flexion in the SLR is documented as Hyndman's sign, Brudzinski's Sign, Linder's Sign, or the Soto-Hall test.
• Inclusion of ankle dorsiflexion in the SLR is documented as Lasegue's test or Bragard's test.
• Inclusion of great toe extension in the SLR (instead of ankle dorsiflexion) is documented as Sicard's Test.

Modifications

Modifications to the Straight Leg Raise test can be used to stress different peripheral nerves to a greater degree; these are referred to as SLR tests with a particular nerve bias.

SLR test and its Modifications

	SLR (BASIC)	SLR2	SLR3	SLR4	CROSS LEG SLR 5
HIP	Flexion and adduction	Flexion	Flexion	Flexion and medial Rotation	Flexion
KNEE	Extension	Extension	Extension	Extension	Extension
ANKLE	Dorsiflexion	Dorsiflexion	Dorsiflexion	Plantar flexion	Dorsiflexion
FOOT	------	Eversion	Inversion	Inversion	-------
TOES	------	Extension	-----	------	------
NERVE BIAS	Sciatic Nerve and Tibial Nerve	Tibial Nerve	Sural Nerve	Common Peroneal Nerve	Nerve Root (Disc Prolapse)

Evidence

1. A Cross-sectional study by Boyd and Villa (2012)  examined normal asymmetries between limbs in healthy, asymptomatic individuals during SLR testing and the relationship of various demographic characteristics. The authors concluded that Overall range of motion during SLR was related to sex, weight, BMI and activity level, which is likely reflected in the high variability documented. We can be 95% confident that inter-limb differences during SLR neurodynamic testing fall below 11 degrees in 90% of the general population of healthy individuals. In addition, inter-limb differences were not affected by demographic factors and thus may be a more valuable comparison for test interpretation.
2. Rabin et al. has shown sensitivty of the SLR test to be .67
3.  Deville et al. found the specificity to be .26 .
4. A systematic review of the Clinical utility of SLR by Scaia V, Baxter D and Cook C (2012) investigated the diagnostic accuracy of a finding of pain during the straight leg raise test for lumbar disc herniation, lumbar radiculopathy, and/or sciatica.The authors concluded that Variability in reference standard may partly explain the inconsistencies in the diagnostic accuracy findings. Further, pain that is not specific to lumbar radiculopathy, such as that associated with hamstring tightness, may also lead to false positives for the SLR; and may inflate the sensitivity of the test.
5. Diagnostic Test accuracy review (Cochrane Meta analysis)  assessed the performance of tests performed during physical examination (alone or in combination) to identify radiculopathy due to lower lumbar disc herniation in patients with low-back pain and sciatica. The review included 16 cohort studies (median N = 126, range 71 to 2504) and three case control studies (38 to100 cases). Only one study was carried out in a primary care population. Most studies assessed the Straight Leg Raising (SLR) test. In surgical populations, characterized by a high prevalence of disc herniation (58% to 98%), the SLR showed high sensitivity (pooled estimate 0.92, 95% CI: 0.87 to 0.95) with widely varying specificity (0.10 to 1.00, pooled estimate 0.28, 95% CI: 0.18 to 0.40). Results of studies using imaging showed more heterogeneity and poorer sensitivity. The crossed SLR showed high specificity (pooled estimate 0.90, 95% CI: 0.85 to 0.94) with consistently low sensitivity (pooled estimate 0.28, 95% CI: 0.22 to 0.35). Combining positive test results increased the specificity of physical tests, but few studies presented data on test combinations.The authors of the meta analysis conclude that When used in isolation, current evidence indicates poor diagnostic performance of most physical tests used to identify lumbar disc herniation. However, most findings arise from surgical populations and may not apply to primary care or non-selected populations. Better performance may be obtained when tests are combined.