Comparison of longitudinal sciatic nerve movement with different mobilization exercises: an in vivo study utilizing ultrasound imaging.

STUDY DESIGN Controlled laboratory study using a single-group, within-subjects comparison. OBJECTIVES To determine whether different types of neural mobilization exercises are associated with differing amounts of longitudinal sciatic nerve excursion measured in vivo at the posterior midthigh region. BACKGROUND Recent research focusing on the upper limb of healthy subjects has shown that nerve excursion differs significantly between different types of neural mobilization exercises. This has not been examined in the lower limb. It is important to initially examine the influence of neural mobilization on peripheral nerve excursion in healthy people to identify peripheral nerve excursion impairments under conditions in which nerve excursion may be compromised. METHODS High-resolution ultrasound imaging was used to assess sciatic nerve excursion at the posterior midthigh region. Four different neural mobilization exercises were performed in 31 healthy participants. These neural mobilization exercises used combinations of knee extension and cervical spine flexion and extension. Frame-by-frame cross-correlation analysis of the ultrasound images was used to calculate nerve excursion. A repeated-measures analysis of variance and isolated means comparisons were used for data analysis. RESULTS Different neural mobilization exercises induced significantly different amounts of sciatic nerve excursion at the posterior midthigh region (P<.001). The slider exercise, consisting of the participant performing simultaneous cervical spine and knee extension, resulted in the largest amount of sciatic nerve excursion (mean ± SD, 3.2 ± 2.0 mm). The amount of excursion during the slider exercise was slightly greater (mean ± SD, 2.6 ± 1.5 mm; P = .002) than it was during the tensioner exercise (simultaneous cervical spine flexion and knee extension). The single-joint neck flexion exercise resulted in the least amount of sciatic nerve excursion at the posterior midthigh (mean ± SD, -0.1 ± 0.1 mm), which was significantly smaller than the other 3 exercises (P<.001). CONCLUSION These findings are consistent with the results of previous research that has examined median nerve excursion associated with different neural mobilization exercises. Such nerve excursion supports theories of nerve motion associated with cervical spine and extremity movement, as generalizable to the lower limb.