Negative neurodynamic tests do not exclude neural dysfunction in patients with entrapment neuropathies.
Baselgia L., Bennett DL., Silbiger RM., Schmid AB.
To examine differences in somatosensory phenotypes of patients with positive and negative neurodynamic tests and compare these to healthy controls.case-control study SETTING: University department PARTICIPANTS: Fifty-three patients with electrodiagnostically confirmed carpal tunnel syndrome (CTS) and 26 healthy controls participated in this study. Patients with CTS were sub-grouped according to the results of the upper limb neurodynamic tests (ULNT) biasing the median nerve into patients with positive (ULNT(pos)) or negative (ULNT(neg)) neurodynamic tests.NA MAIN OUTCOME MEASURE: All participants underwent quantitative sensory testing in the median innervated territory of their hand.Only 46% of patients with CTS had positive neurodynamic tests. No differences were identified between groups for pain thresholds (p>0.247). However, CTS patients had increased mechanical (p<0.0001) and thermal detection thresholds (p<0.0001) compared to healthy controls. ULNT(neg) patients had a more pronounced vibration detection deficit (mean (SD): 7.43 (0.59)) compared to healthy controls (7.89 (0.22), p=0.001). Interestingly, warm detection was the only domain differentiating ULNT(pos) (mean degrees Celsius (SD): 4.03 (2.18)) and ULNT(neg) groups (6.09 (3.70), p=0.032), with ULNT(neg) patients demonstrating increased loss of function.Patients with normal neurodynamic tests seem to have a more severe dysfunction of the unmyelinated fibre population. Our findings suggest that neurodynamic tests should not be used in isolation to judge neural involvement. Rather, they should be interpreted in the context of loss of function tests of the small fibre domain.