Evidence of Spinal Cord Hyperexcitability as Measured With Nociceptive Flexion Reflex (NFR) Threshold in Chronic Lateral Epicondylalgia With or Without a Positive Neurodynamic Test

There is emerging evidence of altered pain signal processing as a likely underlying mechanism in chronic lateral epicondylalgia (LE), yet this remains to be assessed. Furthermore, it has been proposed that neurodynamic tests reflect nociceptive withdrawal responses. Therefore, the objective was to improve our understanding of spinal cord excitability as measured by nociceptive flexion reflex (NFR) threshold in chronic LE with and without a positive neurodynamic test. NFR threshold, pain-free grip, and pressure pain threshold were measured in 30 LE participants and 31 healthy controls. Test of neural tissue involvement (using upper limb neural tension, radial bias) was used to differentiate LE participants with or without a positive neurodynamic test. There were significant differences in NFR threshold between the control and LE with or without a positive neurodynamic test (F[2,54] = 5.68, P = .006), after adjusting for age, sex, pain rating at NFR threshold, and reflex size (NFR interval peak z score). The mean differences (95% confidence interval) in NFR threshold between the control and LE with or without a positive neurodynamic test were 3.74 mA (.637, 6.84) and 3.38 mA (.0245, 6.74) respectively.PerspectiveThe results suggest evidence of spinal cord hyperexcitability, particularly sensory hypersensitivity, in LE with or without a positive neurodynamic test. Our data appear to support the hypothesis that continued peripheral afferent stimulation results in facilitation of nociceptive pathways in this patient population.