Sensory hyperalgesia is characteristic of nonspecific arm pain: A comparison with cervical radiculopathy and pain-free controls

OBJECTIVES: Nonspecific arm pain (NSAP) is a common clinical entity, the pathophysiological mechanisms of which are poorly understood. The purpose of this study was to investigate sensory profiles in individuals with nonspecific arm pain compared with cervical radiculopathy and pain-free controls. METHODS: Forty office workers with NSAP, 17 people with cervical radiculopathy, and 40 pain-free controls were assessed by means of quantitative sensory testing (thermal and vibration detection thresholds; thermal and pressure pain thresholds), tests for neural tissue sensitivity, and questionnaires. Between-group comparisons were conducted using Kruskal-Wallis tests. An exploratory factor analysis was used to determine characteristic features in NSAP. RESULTS: Both patient groups demonstrated cold and pressure pain sensitivity (P<0.003; P<0.05) and neural tissue sensitivity (P<0.001). The NSAP group also demonstrated heat pain sensitivity (P<0.001). Both patient groups demonstrated hypoaesthesia to vibration thresholds (P<0.05), whereas thermal hypoaesthesia was only evident in the cervical radiculopathy group (P<0.05). Exploratory factor analysis revealed pressure and thermal pain sensitivity as the key characteristics of this NSAP group. DISCUSSION: Sensory profiles in NSAP and cervical radiculopathy differ. NSAP is characterized by widespread sensitivity to thermal and pressure pain in the absence of thermal hypoaesthesia, whereas cervical radiculopathy is characterized by the presence of thermal and vibratory hypoaesthesia as well as more localized cold and pressure pain sensitivity. The identification of widespread sensory hypersensitivity in NSAP has important implications for clinical decision making.