Median nerve stiffness with three movement sequences of the upper limb neurodynamic test 1: An ultrasound shear-wave elastography study.

Background: During the Upper Limb Neurodynamic Test 1 (ULNT1) joint movement order can be varied to improve its diagnostic accuracy. However, nerve behavior with neurodynamic sequences still requires in vivo research.

Objective: To quantify differences in median nerve (MN) stiffness measuring shear-wave velocity (SWV) with ultrasound elastography during three sequences of the ULNT1.

Design: Cross-sectional study.

Methods: MN SWV was measured in 35 asymptomatic subjects at the wrist and elbow at the initial and final position (P1) of the standard (ULNT1-STD), proximal-to-distal (ULNT1-PROX) and distal-to-proximal (ULNT1-DIST) sequences of the ULNT1.

Results: Significantly different increases at P1 in nerve stiffness occurred between sequences and locations (p < 0.001). At the wrist, the ULNT1-PROX produced the smallest increase (44.32% ± 44.06, SWV: 4.49 ± 0.95 m/s), the ULNT1-STD produced a larger increase (82.13% ± 45.36, SWV: 5.67 ± 0.79 m/s, p < 0.001) and the ULNT1-DIST produced the largest (92.90% ± 55.37, SWV: 5.97 ± 0.79 m/s, p < 0.001). Differences between the ULNT1-DIST and ULNT1-STD did not reach significance. At the elbow, the ULNT1-PROX showed a 119.92% ± 53.51 increase (SWV: 4.08 ± 0.84 m/s), the ULNT1-DIST a 134.84% ± 53.83 (SWV: 4.34 ± 0.77 m/s), and the ULNT1-STD a 113.30% ± 59.28 (SWV: 3.98 ± 1.04 m/s). No significant differences were found among the sequences.

Conclusion: The ULNT1-STD and ULNT1-DIST showed greater increases at MN stiffness at the wrist compared to the ULNT1-PROX. This supports a basis for future investigation of the mechanisms of neurodynamic testing in which emphasizing anatomical locations for improving diagnostic efficacy might be applied.