Widespread Pressure Pain Hyperalgesia in Chronic Nonspecific Neck Pain with Neuropathic Features: A Descriptive Cross-Sectional Study

Background: Neck pain has an elevated prevalence worldwide. Most people with neck pain are diagnosed as nonspecific neck pain patients. Poor recovery in neck disorders, as well as high levels of pain and disability, are associated with widespread sensory hypersensitivity. Nevertheless, there is controversy regarding the presence of widespread hyperalgesia in chronic nonspecific neck pain (CNSNP); this lack of agreement could be due to the presence of different pathophysiological mechanisms in CNSNP. Objectives: To determinate differences in pressure pain thresholds (PPTs) over extracervical and cervical regions, and differences in cervical range of motion (ROM) between patients with CNSNP with and without neuropathic features (NF and No-NF, respectively). In addition, this study expected to observe correlations in these 2 types of CNSNP of psychosocial factors with PPTs and with cervical ROM separately. Study Design: Descriptive, cross-sectional study. Setting: A hospital physiotherapy outpatient department. Methods: This research involved 53 patients with CNSNP that had obtained a Self-completed Leeds Assessment of Neuropathic Symptoms and Signs pain scale (S-LANSS) score >= 12 (pain with NF, NF group); 54 that had obtained a S-LANSS score < 12 (pain with No-NF, No-NF group), and 53 healthy controls (control group, CG). Measures included: PPTs (suboccipital muscle, upper fibers trapezius muscle, lateral epicondyle, and anterior tibial muscle), cervical ROM (flexion, extension, rotation, and latero-flexion), pain intensity (Visual Analog Scale [VAS]), neck disability index (NDI), kinesiophobia (Tampa Scale of Kinesiophobia-11 [TSK-11]), and Pain Catastrophizing Scale (PCS). Results: A statistically significant effect was observed for the group factor in all assessed measures (P < 0.01). Both CNSNP groups showed statistically significant differences compared to the CG for PPTs in the cervical region (suboccipital and upper fibers trapezius muscles), but only the NF group demonstrated statistically significant differences for PPTs in the lateral epincondyle and anterior tibial muscle when compared to the CG or No-NF group. The largest statistically significant correlation found in the NF group was between PPT in the anterior tibial muscle and TSK-11 (r = -0.372; P < 0.01), while in the No-NF group it was between PPT in the suboccipital muscle and NDI (r = -0.288; P < 0.05). Statistically significant differences were found between the 2 CNSNP groups and CG in all cervical ROMs, but not between both CNSNP groups. The largest statistically significant correlation observed in the NF group was between cervical total rotation and TSK-11 (r = -0.473; P < 0.01), while in the No-NF group it was between cervical total latero-flexion and PCS (r = -0.532; P < 0.01). Limitations: Although the S-LANSS scale has been validated as a screening tool for pain with NF, currently there is no "gold standard," so these findings should be interpreted with caution. Conclusions: Widespread pressure pain hyperalgesia was detected in patients with CNSNP with NF, but not in patients with CNSNP with No-NF. Patients with CNSNP presented bilateral pressure pain hyperalgesia over the cervical region and a decreased cervical ROM compared to healthy controls. However, no differences were found between the 2 CNSNP groups. These findings suggest differences in the mechanism of pain processing between patients with CNSNP with NF and No-NF.