In a recent teaching course for residents, I was asked to clarify the confusion in the textbooks over the different eponymous names related to the root tension signs (passive straight leg raising / SLR test). Different textbooks use these names interchangeably — for example, a popular book by Bruce Reider mentions the forced dorsiflexion manoeuvre as the Lasègue's test. I'd recommend avoiding eponymous names for these signs altogether, given the confusion. Nevertheless, the medical history behind these root tension signs is fascinating.
Many attribute the first description of the passive SLR to Ernst Charlie Lasègue, a professor of medicine in Paris. In his 1864 paper he described a syndrome of radicular pain sometimes associated with muscle atrophy — but he did not describe the leg-raising test itself.
The SLR test was actually published in 1881 by Lasègue's 30-year-old student J.J. Forst (not Frost) as his doctoral thesis. Forst acknowledged that his teacher was the discoverer of this phenomenon and dedicated his thesis to Lasègue in addition to his parents. Forst described two components of the test: the leg-raising test with knee extension, and the relief of pain on knee flexion (the verification/control test). Most descriptions of the original Lasègue test forget to mention this second control test.
Both Lasègue and Forst got the explanation of the test wrong — they thought it was due to pressure of the hamstrings on the sciatic nerve rather than stretch of the nerve itself. Three years later, in 1884, another Frenchman, Beurmann, disproved Forst's thesis using a cadaver model, concluding correctly that lifting the leg stretches the sciatic nerve and that muscles play no role in compressing it.
Interestingly, another physician arrived at this test independently: Laza K. Lazarević, personal physician to the Serbian King, published a description of this test in a Serbian-language medical journal a year before Forst's thesis (1880). He later described it more elaborately in a German-language journal (1884), comparing the sciatic nerve stretch to the strings of a violin. He measured the distance from his own PSIS to the heel — 103 cm supine, 111 cm at maximum SLR — concluding the 8 cm increase was responsible for the nerve stretch.
Lazarević may have published it first, but Lasègue's name stuck and became popular — he was better known, being a pupil of the famous neurologist Armand Trousseau.
Modifications of the passive SLR were later described. The crossed SLR (well-leg SLR) was first described by Polish neurologist J. Fajersztajn (1867–1935) in 1901, who showed via cadaver dissection that traction on one sciatic nerve pulled the dural sac caudally and ipsilaterally, displacing and stretching the contralateral roots. Fajersztajn also described, in the same 1901 paper, that pain during the Lasègue test worsened with forced dorsiflexion of the ankle — though this manoeuvre is usually attributed to Karl Bragard (1890–1973), who published it later in 1928. So the forced-dorsiflexion qualifying test is called the Bragard test, even though Fajersztajn described it first.
Classically, both Fajersztajn and Bragard performed forced dorsiflexion at the point pain begins. We usually practice a modification: the leg is lowered slightly until pain is relieved, and forced dorsiflexion then reproduces the pain (first described by A.J. Mester in 1942) — this improves the specificity of the passive SLR.
Worth remembering: these tests were described before the "dynasty of the disc." From 1920 to the mid-1930s, sciatica was attributed to neoplastic processes; surgeries with lesions diagnosed as enchondromas and chondromas were, in retrospect, disc herniations. Most credit goes to Mixter and Barr (1934, NEJM) for linking sciatica with intervertebral disc prolapse — though almost five years earlier, the famous Walter E. Dandy had a lesser-known description of the same association.
Hope this was interesting! If you have comments or interesting additions to this story, please share them.
Further reading:
Karbowski, K., Radanov, B. (1995). The History of the Discovery of the Sciatica Stretching Phenomenon. Spine 20(11), 1315-1317.
HALL, G. (1930). Neurologic Signs and Their Discoverers. JAMA 95(10), 703.
Weinstein, J., Burchiel, K. (2009). Dandy's disc. Neurosurgery 65(1), 201-205.
WOODHALL, B., HAYES, G. (1950). The Well-Leg-Raising Test of Fajersztajn in the Diagnosis of Ruptured Lumbar Intervertebral Disc. JBJS 32(4), 786-792.
Neurological Eponyms by Peter J. Koehler, George W. Bruyn, John M. S. Pearce, Oxford University Press.