A number of factors that include age, the presence of enthesitis, and depressive symptoms may be associated with neuropathic pain in ankylosing spondylitis, according to a study published in Clinical Rheumatology.
In the cross-sectional study, patients with ankylosing spondylitis (n=105) underwent a clinical assessment that included use of the Bath Ankylosing Spondylitis Disease Activity Index to evaluate disease activity and the presence enthesitis, uveitis, fibromyalgia, and current peripheral arthritis.
Anteroposterior pelvic radiographs were used to evaluate radiographic changes in hip joints, and the modified Stoke Ankylosing Spondylitis Spine Score was used to evaluate osteoproliferative changes in the cervical and lumbar spine.
Study participants were asked to fill out the painDETECT questionnaire, the Beck Depression Inventory, and the Euro Quality of Life questionnaire. PainDETECT scores ≤12 indicated a low probability of neuropathic pain (<15% probability; nociceptive pain; n=68). Those with PainDETECT scores between 13 and 18 were categorized as having mixed pain (n=22), and those with PainDETECT scores ≥19 were classified as having neuropathic pain (probability >90%; n=15).
Participants categorized as having neuropathic or mixed pain were found to have a higher incidence of peripheral arthritis (P =.001) and enthesitis (P =.005), a greater prevalence of concomitant fibromyalgia (P =.02), and higher modified Stoke Ankylosing Spondylitis Spine Score (P =.001) compared with patients with nociceptive pain. Patients in the neuropathic pain group had the highest pain scores (current, worst, and average), as assessed with the visual analog scale. They also had the highest Bath Ankylosing Spondylitis Disease Activity Index, depression scores, and the lowest quality of life scores (assessed with the 5-level Euro Quality of Life index).
The small sample size and the use of patient self-reports to categorize pain represent study limitations.
“[O]ur study demonstrated a neuropathic pain component in patients [with ankylosing spondylitis] and its association with various disease-related variables, including high disease activity, radiographic progression, enthesitis, peripheral arthritis, depression, and poor quality of life,” concluded the study authors. “Further studies on the interaction between the nervous and immune system are needed to understand complicated pain mechanism and improve treatment outcome in patients with [ankylosing spondylitis].
Choi J-H, Lee S-H, Kim H-R, Lee K-A. Association of neuropathic-like pain characteristics with clinical and radiographic features in patients with ankylosing spondylitis [published online April 30, 2018]. Clin Rheumatol. doi: 10.1007/s10067-018-4125-z