REIDER PART 2
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356 Chapter 9 Lumbar Spinc

maximal hip flexion is reachcd or the patient asks the examiner to stop owing to pain (Fig. 9-25). The angle formed by the lower limb and the examination table at the point of maximal elevation is noted, and the procedurę is repeated with the opposite limb.

In a normal patient, straight-leg raising of 70° to 90° should be possible and may be accompanied by a feeling of tightness in the posterior thigh. In the presence of sci-atica, the angle of hip flexion is reduced and the patient reports shooting pain radiating down the posterior thigh and often into the lower leg along the distribution of the sciatic nerve. Straight-leg raising stretches the L5 and SI nerve roots 2 mm to 6 mm, but it puts lit tle tension on the morę proximal nerve roots. An abnormal straight-leg raising test, therefore, suggests a lesion of either the L5 or the SI nerve root. Beyond 70° of hip flexion, deformation of the sciatic nerve occurs beyond the spine. Sciatic pain that is reproduced only with hip flexion beyond 70°, therefore, suggests the possibility of sciatic nerve com-pression outside the spinał canal. If the patient with lim-ited straight-leg raising reports tightness in the posterior thigh rather than sciatica, hamstring tightness is the probable cause. Hamstring tightness may be associatcd with a wide variety of conditions, including spondyloly-sis. Lasegue’s test, discussed later, does not exaccrbatc the discomfort of hamstring tightness the way it exacerbatcs sciatica. Recent studies have confirmed that the straight-leg raise test is extremely sensitive (0.9) but rather less specific (0.26) for confirming the presence of a com-pressed or irritated lumbar nerve root.

Crossed Straight-Leg Raising Test Performing the straight-leg raising test on the sidc opposite that of the sciatica is callcd the crossed straight-leg raising test. For example, if a patient complains of right-sided sciatica, the examiner performs a straight-leg raising test on the patients left side. If this maneuver reproduces or exacerbates the patienfs right-sided sciatica, the result is extremely sensitive and specific for a herniated L5-S1 or L4-L5 lumbar disk. The crossed straight-leg raising test is less sensitive (.29) but morę specific (.88) than the straight-leg raising test for confirming a compressed or irritated lumbar nerve root.

Lasegue’s Test

Lasegue’s test is a progression of the straight-leg raising test. To perform Lasegue’s test, the examiner carries out the straight-leg raising test, pausing when the patient complains of reproduction of his or her typical sciatic pain. While maintaining the degree of hip flexion at which sciatic pain is induced, the examiner passively dor-siflexes the foot of the leg being raised (Fig. 9-26). This maneuver further deforms the sciatic nerve. If the patients radicular pain is exacerbated, the diagnosis of sciatica isstrengthened. Lasegues test may also reproduce radicular pain in some cases of lumbar disk herniation in which the straight-leg raising test is otherwise negative. The results of both the straight-leg raising test and the Lasćgue test are abnormal in most cases of lumbar disk herniation, however. The sensitivity of Lasegues test is reported to be 0.7.

Figurę 9-25. Straight-leg raising test.

Figurę 9-26. Lasegues test.