Quantitative Sensory Testing Reveals Evidence of Altered Pain Processing in Paget's Disease of Bone.

Pain is the most common symptom of Paget's disease of bone (PDB), but its underlying mechanisms are poorly understood. Notably, bone pain does not correlate well with metabolic activity or treatment response. This study aimed to assess whether sensory processing is altered in skin overlying Pagetic bone using quantitative sensory testing (QST). We conducted a cross-sectional study of 156 people with PDB attending secondary care referral centres in the UK. We conducted quantitative sensory testing of the skin overlying affected sites and compared the data with unaffected sites as a control. The modalities used were hot and cold rollers, pinprick, vibration and von-Frey filaments to test both spinothalamic and lemniscal pathways. There was a consistent trend for sensory perception to be increased over affected sites versus control sites in the study population. The differences were significant for vibration detection threshold (p = 0.009), pain threshold (p = 0.010) and both single and multiple pinprick testing methods (both p < 0.001). Subgroup analysis revealed similar trends when analysis was restricted to those with pain thought to be due to bone deformity or increased metabolic activity and those with and without musculoskeletal pain. Sensory processing is altered in skin overlying Pagetic bone, independent of current pain symptoms. We speculate that this may be due to abnormalities of bone shape, bone structure or metabolic abnormalities in the affected bone. The mechanisms are unclear but deserve further study.