‘Central sensitization’ in chronic neck/shoulder pain

Background and purpose: ‘Central sensitization’ (CS) may play a major role in maintaining several chronic pain conditions. CS has been proposed to play a significant role in a range of musculoskeletal pain conditions, such as trapezius myalgia, fibromyalgia, temporomandibular disorders, and low back pain. Whether CS varies over time within an individual is not known. This study evaluated (1) whether there is an intraindividual association between clinical pain and signs of CS, and (2) whether there is an inter-individual association between clinical pain and signs of CS. Methods: Twenty-seven sedentary workers (19 women, 8 men) with varying neck/shoulder pain participated in a pre-test and in two test sessions. On one of the test sessions the subjects had weak (or no) clinical pain (weak-pain day). On the other test session the subjects had stronger clinical pain (strong-pain day). As an indicator of ‘central sensitization’, we assessed the area of secondary pinprick hyperalgesia (tested by 84.4 g/mm2 Von Frey hairs) in response to a first-degree burn to the volar fore-arm (contact heat, 46°C, 5 min). While in the lab, the subjects’ current clinical pain intensity (0–10 cm VAS) and distribution was assessed (PINTlab and PDISTlab ). The subjects also rated their pain...