Effect of cervical contralateral lateral flexion on displacement and strain in the median nerve and flexor digitorum superficialis at the wrist during the ULNT1-Cadaveric study

Introduction: A key issue in neurodynamic testing is whether a manoeuvre designed to produce differential biomechanical behaviour (structural differentiation) of nerve compared to adjacent muscle is mechanically accurate. The aim of this study was to investigate the capacity of cervical contralateral lateral flexion to produce differential biomechanical behaviour of the median nerve at the wrist (mechanical specificity) in relation to the adjacent muscle (flexor digitorum superficialis) at different ranges of upper limb neurodynamic test 1 in cadavers. Material and methods: A cross-sectional study was carried out. In fresh frozen cadavers, with microstrain devices and Vernier calipers, strain and excursion in the median nerve and flexor digitorum superficialis muscle were measured during cervical contralateral lateral flexion at 0 degrees, 30 degrees, 60 degrees and 90 degrees of elbow flexion of the upper limb neurodynamic test 1. Results: The cervical movement resulted in proximal excursion and significant changes in strain in the median nerve at 0 degrees, 30 degrees and 60 degrees of elbow flexion during the upper limb neurodynamic test 1 (p < 0.05). In contrast, the structural differentiation manoeuvre did not affect the strain nor the excursion in the muscle at any position of the elbow (p > 0.05). Conclusion: Adding CCLF to each ULNT1 median elbow angle increased strain and created proximal excursion of the median nerve at the wrist. Neck movement produced no changes in strain nor excursion of the flexor digitorum superficialis. This study adds to evidence that, in certain circumstances, neck movement may be used in differentiation of nerve and muscle disorders in the wrist.