Background: Evidence to support the assumptions that underpin the upper limb neurodynamic test 1 [ULNT] for median nerve is limited and inconclusive. The ULNT 1 is a part of orthopaedic clinical examination that clinicians use to assess the mechanosensitivity of major nerve trunks and their central connections in neurogenic type musculoskeletal pain conditions, e.g. post whiplash injury. The test assumes a pathophysiological relationship between restriction of nerve movement and increased nerve tension and strain, both potentially contributing to increased sensory response (e.g. pain) that coincides with a decrease in elbow extension motion and increased flexor muscle activation. Evidence of this relationship in a symptomatic population, and involving measurements of nerve movement (in-vivo) is lacking. Using dynamic ultrasound imaging (DUI), nerve movement can be computed to validate ULNT 1 in a symptomatic population. Purpose(s): The study evaluated the construct validity of the ULNT 1 using correlation between test components, including median nerve movement measurement in vivo. Potential clinical benefits include clarity of reasoning to justify clinicians' use of the test for patients, and supportive evidence for constructs used to interpret the test. Method(s): Construct validity design using correlation between estimates of median nerve movement, pain, Brachialis muscle activity and elbow extension in n=22 chronic Whiplash Associated Disorder(WAD)II [19 females, 3 males], mean age(SD) = 26(7) years. Arm starting and ending position replicated the ULNT 1. Pain response was recorded on a VAS scale. EMG of Brachialis muscle activity was captured alongside DUI images of median nerve longitudinal movement. Elbow extension motion was measured bilaterally at limits of pain [P2] or available range [R2] and side differences were computed. Pearson product moment correlation coefficient [denoted by r] was used to measure correlation between the ULNT 1 test constructs. Result(s): The results demonstrate a statistically significant, strong and positive association between median nerve movement and elbow ROM(r = 0.6), pain (r = 0.7). However, there was a statistically non-significant, weak and positive association between Brachialis muscle activity and pain response (r = 0.1), median nerve movement (r = 0.2), and elbow ROM (r = 0.1). Conclusion(s): The study provides further evidence to justify current clinical practice of using pain response and elbow extension ROM to interpret ULNT 1 when assessing chronic musculoskeletal pain conditions. Further, the result supports use of nerve movement data as an additional construct to interpret ULNT 1. This information was previously unknown in the ULNT 1 literature and therefore merit dissemination to assist translation into clinical practice. However, poor correlation between Brachialis muscle activity and other constructs of ULNT 1 challenge current practice of using a patient's muscle resistance to interpret the test. Implications: Physiotherapists can interpret ULNT 1 using constructs of pain, elbow extension ROM, and nerve movement measurement, but should apply caution when relying on muscle resistance to interpret the test.
Edeni, K., Ringdal, H., Karanasios, S., Heneghan, N., & Rushton, A. (2015). Validity of upper limb neurodynamic test using median nerve movement, elbow extension, pain response, brachialis muscle activity in chronic wad. Physiotherapy, 101, e340. https://doi.org/10.1016/j.physio.2015.03.547