Self-reported somatosensory symptoms of neuropathic pain in fibromyalgia and chronic widespread pain correlate with tender point count and pressure-pain thresholds

Widespread pain and pain hypersensitivity are the hallmark of fibromyalgia, a complex pain condition linked to central sensitization. In this study the painDETECT questionnaire (PDQ), validated to identify neuropathic pain and based on pain quality items, was applied in a cross-sectional sample of patients with chronic widespread pain (CWP). The aims of the study were to assess the patient-reported sensory neuropathic symptoms by PDQ and to correlate these with tender point (TP) count and pressure-pain thresholds. Eighty-one patients (75 F, 6 M) with CWP (ACR-criteria) filled in the PDQ. Manual TP examination was conducted according to ACR guidelines. Computerized cuff pressure algometry was used for the assessment of pressure-pain detection thresholds (PDT, unit: kPa) and pressure-pain tolerance thresholds (PTT, unit: kPa). Mean TP count was 14.32 (range: 2-18), mean PDQ score 22.75 (range: 5-37). Mean PDT was 8.8 kPa (range: 2-36) and mean PTT 30.9 kPa (range: 4-85). Deep-tissue hyperalgesia was the predominant somatosensory symptom reported in 83%, but other neuropathic symptoms were also frequent, e.g. burning 51% and prickling 47%. Statistically significant correlations were found between PDQ score and TP count: r = 0.35 (p < 0.01), and PDQ score and PDT: r = 0.45 (p < 0.01), and PTT: r = 0.43 (p < 0.01). The study indicates that pain in CWP has neuropathic features, and that the presence and number of tender points are associated with neuropathic pain symptoms. A high mean PDQ score was found to correlate with TP count and pressure-pain thresholds. The PDQ may become a useful tool assisting in the identification of central sensitization in patients with CWP and in the future diagnostic assessment fibromyalgia.