Contribution of neurogenic mechanisms to the pathogenesis of chronic joint pain

Abstract

Objective: to study the contribution of neurogenic mechanisms to the pathogenesis of chronic pain in patients with rheumatoid arthritis (RA), knee osteoarthritis (OAk) and ankylosing spondylitis (AS). To evaluate the effectiveness of an anticonvulsants in complex therapy of RA and OAk.Patients and methods. The study included 518 patients, 208 (40.2%) had definite RA, 160 (30.9%) had OAk and 150 (28.9%) had AS. All patients were rheumatologically and neurologically examined to determine the state of the somatosensory system; DN4 and Pain DETECT questionnaires were used to diagnose pain descriptors characteristic of neuropathic and nocyplastic pain; visual analogue scale (VAS) was used for pain intensity at rest assessment; algometry – for detecting secondary hyperalgesia. Functional, affective disorders and quality of life were assessed as well. Moreover, efficacy of the anticonvulsant in the complex therapy of RA and OAk was evaluated.Results and discussion. 49.5% of RA patients had neuropathic pain. It has been statistically significantly shown that older patients with a long history of the disease, advanced X-ray stage and high level of anxiety and depression experience neuropathic pain more frequently. Disease activity and ESR level did not affect the severity of the neuropathic component of pain. In 37.5% of OAk cases, signs of nociplastic pain were observed. Patients in this group were in pain according to VAS, worse functional state and quality of life, as well as a higher level of anxiety, the differences were statistically significant. 12.7% of AS patients had nociplastic pain. There was no association with the age and duration of the disease. Higher levels of disease activity, pain and depression and worse functional abilities were observed when nociplastic pain was present. The effectiveness of anticonvulsant is demonstrated in the complex therapy of chronic articular pain in RA and OAk, which confirms the role of central sensitization in the pathogenesis of pain in these diseases.Conclusion. Chronic pain in RA, OAk and AS patients in some cases has mixed nature, both inflammatory and neurogenic mechanisms (neuropathic and nociplastic) are involved. It is necessary to examine patients to identify the neuropathic component of pain, which will improve pain control and ensure a holistic approach to therapy. In patients with RA and OAk, having a mixed nature of pain, complex treatment, containing a central action drug from a group of anticonvulsants, is more effective compared with standard anti-inflammatory therapy.