THU0572 THE ROLE OF PRESSURE PAIN THRESHOLD IN A REHABILITATIVE APPROACH TO ANALYZE PAIN PROCESSING MECHANISM IN HAND OSTEOARTHRITIS PATIENTS: A PILOT STUDY.

Abstract

Background:The hand pain experienced by patients with hand osteoarthritis (OA) is often accompanied by hypersensitivity and sings of peripheral and central sensitization1. 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 OA2. 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 treatments4.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 subjects3. 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 OA5.Results:The results showed that PPTs were significantly lower over the hand and the median, ulnar, radial nerves (P<0.05), but not over the C5-C6 zigoapophyseal joint and anterior tibial (P>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.