Lasegue's sign

Lasegue's symptom is used to assess irritation of the sciatic nerve (nervus ischiadicus), lower lumbar, and upper sacral nerve roots. The symptom is named after the French clinician Charles Lasegue, whose pupil described the maneuver and named it after his teacher.

Performance
The examiner grabs the patient's lower limb by the calcaneus and lifts it off the mat, while the knee is in extension. The limit is, if possible, flexion in the hip at an angle of 90 °. The lower limb should be medially rotated. If no symptoms occur, it joins the dorsal flexion leg maneuver, which tightens the sciatic nerve more. If dorsiflexion does not allow the tension of the back group of muscles, we reduce the angle of inclination in the hip by 5 ° and try dorsiflexion again.

Test positivity and differential diagnostics
The test is positive if you experience severe back pain or radicular pain in the lower limb. A positive test may indicate sciatic nerve irritation or lumbosacral nerve roots irritation.

Differential diagnostics of the positive test includes:
 * disk protrusion with nerve root oppression below L4
 * meningism
 * intraspinal lesions such as tumor below L4
 * hip or proximal femur malignancy or osteomyelitis
 * spondylitis ankylosans
 * fractures of the sacrum
 * piriformis muscle syndrome (accounts for 6% of low back pain cases, is one of the forms of back pain)