Central hypersensitivity - A model for persistent musculoskeletal pain in inflammatory bowel diseases

Pain is reported to affect over 70% of individuals with inflammatory bowel diseases (IBD), with abdominal and musculoskeletal (MSK) pain representing the most common complaints. MSK pain is typically considered within the narrow framework of inflammatory extraintestinal manifestations of IBD, resulting in a limited scope for the nature and underlying mechanisms participating in MSK pain experiences in this population. Symptoms related to central sensitization have recently demonstrated association with active IBD and worse MSK pain experiences, suggesting a potential roll for central mechanisms in MSK-related pain. Current literature exploring persistent pain in chronic inflammatory and MSK populations propose complex pain models comprised of dynamic nervous system relationships influenced by primary disease features and concomitant pain states, as well as affective and cognitive components. Nervous system contributions in the development and maintenance of persistent pain are postulated to include mechanisms of peripheral and central sensitization, changes in descending central modulation, as well as structural brain changes. These models go beyond current MSK pain models described in IBD literature, highlighting the need for new frameworks for considering MSK-related pain in IBD. Consequently, this paper proposes a broader theoretical model whereby central mechanisms, such as central sensitization and grey matter changes, as well as psychological and disease factors are suggested to modulate pain experiences in this population. Exploration of relationships within the proposed framework may provide not only a deeper understanding of the generation and maintenance of persistent MSK pain in IBD, but also highlight the need for new targeted management pathways in this population. This paper hypothesizes that exploration of central sensitization in IBD patients will demonstrate altered somatosensory functioning in patients with MSK pain, and that IBD activity and psychological factors will be associated with altered somatosensory functioning and worse pain experiences.