Paradox pain sensitivity using cuff pressure or algometer testing in patients with hemophilia.

Introduction: Pain is a common comorbidity in patients with hemophilia (PwH) due to hemophilic arthropathy. This study aims to explore pain sensitivity in PwH methodologically investigating in cuff pressure testing compared to algometer testing.

Methods: 37 PwH and 35 healthy control subjects (Con) enrolled in this study. Joint health status was assessed. Subjective pain was evaluated using numeric rating scales. Pain sensitivity was measured with pressure algometry and cuff pressure algometry. Pressure pain thresholds of the algometer (PPT_a) were measured at knee, ankle joints, and forehead. Subsequently, thresholds of cuff pressure were measured at the left and right lower legs (PPT_cuff). In both, lower values represent higher pain sensitivity.

Results: PwH exerted a worse joint health status than Con. Pain sensitivity was higher in PwH compared to Con as PPT_a of the knee and ankle joints were lower in PwH. No difference was observed in PPT_a at the forehead. Contrastingly, lower pain sensitivity was detected in PwH by higher PPT_cuff values compared to Con in both legs.

Conclusion: While PPT_a of the knee and ankle joints are lower in PwH, PPT_cuff are higher in PwH compared to Con. This reveals a paradox situation, highlighting that PwH experience local, joint- and hemophilic arthropathy-related pain, whereas pain sensitivity of non-affected soft tissue structures is lower. The reasons explaining the PPT_cuff results remain elusive but might be explained by coping strategies counteracting chronic joint pain, resulting in lower sensitivity at non-affected structures.