THU0572 THE ROLE OF PRESSURE PAIN THRESHOLD IN A REHABILITATIVE APPROACH TO ANALYZE PAIN PROCESSING MECHANISM IN HAND OSTEOARTHRITIS PATIENTS: A PILOT STUDY.
Authors: P. Pedersini, R. La Touche, E. A. Sanchez Romero, J. H. Villafañe
Journal: Annals of the Rheumatic Diseases (2020)

Background: The hand pain experienced by patients with hand osteoarthritis (OA) is often accompanied by hypersensitivity and sings of peripheral and central sensitization 1 . The European League Against Rheumatism (EULAR) published a systematic literature review that summarized the current non-pharmacological, pharmacological and surgical approaches for the management of hand OA 2 . The identified review did not consider interventions that specifically targeted reducing pain sensitivity. A reliable method to assess the presence of hypersensitivity is the pressure pain threshold (PPT) 3 . During the rehabilitation management considering the pain mechanism involved could be an important factor to address more effective treatments 4 . Objectives: The aim of the present study was to investigate the role of pain processing mechanism in patients with hand OA through PPT and using a specific functional Magnetic Resonance Imaging (fMRI). Methods: 20 patients with hand OA and 20 healthy controls, aged 50 to 90 years, were recruited. Pressure pain threshold (PPT) was assessed bilaterally over the hand, on the C5-C6 zigoapophyseal joint, median, ulnar, radial nerves, and anterior tibial muscle by a blinded assessor respect to the condition of the subjects 3 . In five participants for each group, PPT over the hand was assessed neurophysiologically by advanced modalities including functional MRI to analyze the pain mechanisms related to hand OA 5 . Results: The results showed that PPTs were significantly lower over the hand and the median, ulnar, radial nerves (P&lt;0.05), but not over the C5-C6 zigoapophyseal joint and anterior tibial (P&gt;0.05) in OA patients as compared to healthy controls. Both groups demonstrated activation of the thalamus, frontal and somatosensory cortex area during PPT over the hand, although the total brain area activated in OA patients was greater than in control participants. Conclusion: Patients with hand OA shown features of altered pain mechanism that were evident both in PPTs measures than using functional MRI. PPT is a useful marker in detecting pain sensitivity in hand OA and could be used in future pain studies to evaluate pain modulation strategies. References: [1]Villafañe JH, Valdes K, Pedersini P, Berjano P. Osteoarthritis: a call for research on central pain mechanism and personalized prevention strategies. Clin Rheumatol . August 2018. [2]Kroon FPB, Carmona L, Schoones JW, Kloppenburg M. Efficacy and safety of non-pharmacological, pharmacological and surgical treatment for hand osteoarthritis: a systematic literature review informing the 2018 update of the EULAR recommendations for the management of hand osteoarthritis. RMD Open . 2018;4(2):e000734. [3]Pedersini P, Negrini S, Cantero-Tellez R, Bishop MD, Villafañe JH. Pressure algometry and palpation of the upper limb peripheral nervous system in subjects with hand osteoarthritis are repeatable and suggest central changes. J Hand Ther . January 2019. [4]O’Leary H, Smart KM, Moloney NA, Blake C, Doody CM. Pain sensitization associated with nonresponse after physiotherapy in people with knee osteoarthritis. Pain . 2018;159(9):1877-1886. [5]Sofat N, Smee C, Hermansson M, et al. Functional MRI demonstrates pain perception in hand osteoarthritis has features of central pain processing. J Biomed Graph Comput . 2013;3(4). Disclosure of Interests: None declared