Background Chronic pain is the most typical clinical presentation of rheumatoid arthritis (RA) and osteoarthritis (OA). Suggest that the pain in RA and OA has mixed nature and includes nociceptive, neuropathic and psychogenic components (1,2).
Objectives To study neuropathic pain (NP) in patients with RA and OA.
Methods We recruited 183 patients with RA (male:female ratio 1:10) aged 18-60 years (average age 46±11.8) and 80 female patients with knee osteoarthritis (kOA) aged 45-65 years (average age 59±5) admitted to the Institute of Rheumatology. RA mean duration 9.03±7.6 years and mean duration of kOA was 9±6.5 years. Patients with chronic knee pain had OA Kellgren-Lawrence severity grade II-III. All patients underwent rheumatological and neurological examination. Patients were divided into two groups: patients with DN4 score>4 (with NP) and DN4 score<4 (no evident NP).
Results 78 (43%) patients with active RA and 24 (30%) patients with kOA presented with NP. In the kOA group the presence of NP features was correlated with higher pain intensity, WOMAC index and significantly correlated with higher level of anxiety. Patients with NP had more diffuse hyperalgesia to mechanical stimuli compared to controls, no other somatosensory defects were found. Patients with NP and RA were older (50.1±9.4 vs. 44.4±12.8 years), had longer disease duration (10.7±8.2 years vs. 7.9±7.1 years) with a higher clinical stage (stage 3-4 92%, stage 2-3 68%) and R-stages (stage 3-4 73%, stage 2-3 84%) (p<0.05). We found no significant differences between the two groups in RA activity (DAS28 score) or quality of life. Neurologic findings in patients were characterized by the presence of polyneuropathy (distal senso-motor) - 62%, tunnel neuropathy - 9%, multiple mononeuropathy - 21%, cervical myelopathy – 3%, and their combinations - 3%.
Conclusions This study has demonstrated the mixed nature of chronic pain, neuropathic pain detected in 43% patients with RA and 30% with OA. Identification of neuropathic mechanisms of pain has important practical implications and opens new therapeutic perspectives for comprehensive treatment of the painful syndrome in RA and kOA.
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Schaible HG, Ebersberger A, Von Banchet GS. Mechanisms of pain in arthritis. Ann N Y Acad Sci 2002:966:343-354.
Disclosure of Interest None declared