Somatosensory Profiles in Patients with non Specific Neck Arm Pain with and without positive Neurodynamic Tests

Despite normal neurological bedside and electrodiagnostic, some patients with non-specific neck arm pain (NSNAP) have heightened nerve mechanosensitivity upon neurodynamic testing [1, 2]. It remains however unclear whether this is associated with a minor nerve injury. The aim of this study was to evaluate potential differences in somatosensory function among patients with unilateral NSNAP with and without positive neurodynamic tests and healthy controls. Quantitative sensory testing was performed in 40 patients with unilateral NSNAP; 23 with positive upper limb neurodynamic tests (ULNTPOS) and 17 with negative neurodynamic tests (ULNTNEG). The protocol comprised thermal and mechanical detection and pain thresholds as well as mechanical pain sensitivity, wind-up ratio and dynamic mechanical allodynia. All parameters were measured in the maximal pain area on the affected side as well as over the corresponding area on the unaffected side. Symptom severity, functional deficits, psychological parameters, quality of life and sleep disturbance were also recorded. Fifty-seven percent of patients with NSNAP had positive neurodynamic tests despite normal bedside neurological integrity tests and nerve conduction parameters. Clinical profiles did not differ between patient groups. Somatosensory profiling revealed a more pronounced loss of function phenotype in ULNTPOS patients compared to healthy controls. Hyperalgesia (cold, heat and pressure pain) was present bilaterally in both NSNAP group. The ULNTNEG subgroup represented an intermediate phenotype between ULNTPOS patients and healthy controls in both thermal and pressure pain thresholds as well as mechanical detection thresholds. In conclusion, heightened nerve mechanosensitivity was present in over half of patients with NSNAP. Our data suggest that NSNAP presents as a spectrum with some patients showing signs suggestive of a minor nerve dysfunction. [1] Elvey RL. Physical evaluation of the peripheral nervous system in disorders of pain and dysfunction. J Hand Ther 1997;10:122-129. [2] van der Heide B, Bourgoin C, Eils G, Garnevall B, Blackmore M. Test-retest reliability and face validity of a modified neural tissue provocation test in patients with cervicobrachial pain syndrome. J Man Manip Ther 2006;14:30-36