====== Lasègue’s sign ======

AKA [[straight leg raising]] (SLR) test. Helps differentiate [[sciatica]] from [[pain]] due to
[[hip]] pathology. 

===== Test =====
With patient [[supine]], raise afflicted limb by the [[ankle]] until the pain is elicited
((Dyck P. Lumbar Nerve Root: The Enigmatic
Eponyms. Spine. 1984; 9:3–6)) 
(should occur at < 60°, tension in nerve increases little above this angle). A positive test consists of leg pain or paresthesias in the distribution of pain (back pain alone does not qualify). The patient may also extend the hip (by lifting it off table) to reduce the angle. Although not part of Lasègue’s sign, ankle dorsiflexion with SLR usually augments pain due to nerve root compression. SLR primarily tenses L5 and S1, L4 less so, and more proximal roots very little. Nerve-root compression produces a positive Lasègue’s sign in ≈ 83% of cases
((Lewis PJ, Weir BKA, Broad R, et al. Long-Term Prospective Study of Lumbosacral Discectomy. J Neurosurg. 1987; 67:49–53))
(more likely to be positive in patients < 30 yrs of age with HLD
((Spangfort EV. The Lumbar Disc Herniation. A
Computer-Aided Analysis of 2,504 Operations.
Acta Orthop Scand. 1972; 142:1–93))). 
May be positive in lumbosacral plexopathy. Note: flexing both [[thigh]]s with the knees extended (“long-sitting” or sitting knee extension) may be tolerated further than flexing the single symptomatic side alone
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[[Lasègue's sign]] was named after [[Charles Lasègue]] (1816-1883).

In [[1864]] Lasègue described the signs of developing low back pain while straightening the knee when the leg has already been lifted. In [[1880]] Serbian doctor Laza Lazarević described the straight leg raise test as it is used today, so the sign is often named Lazarević's sign in Serbia and some other countries.
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see [[Femoral nerve stretch test]]