Multidimensional analysis of the clinical spectrum and symptom burden of unexplained myofascial pain

Objective: Myofascial pain (MP) is a leading cause of disability globally. Pain quality and severity vary widely for people with MP, making it difficult to accurately assess the spectrum of symptoms and develop appropriate treatments. We assessed potential contributors to variability in the clinical spectrum of unexplained neck/shoulder pain and associated myofascial component(s). Design: Prospective cross-sectional study of adults reporting neck/shoulder pain and pain-free individuals. Outcomes Measures: Pain intensity and interference (PEG); Symptom burden measured using patient-reported outcomes and objective measures: pain catastrophizing (PCS); PROMIS physical function (PF); sleep disturbance; anxiety (GAD-2); depression (PHQ-2); hypermobility (Beighton/Brighton); Objective measures in the medial upper trapezius: pressure pain threshold (PPT) and quantitative sensory testing (QST). Results: Of the 96 adults recruited for the study, 82 had complete records (age 32.2 +/-13.1 years, 57% women). On physical exam, 23 were assessed to be in an active group (those with spontaneous MP without provocation), 38 in a latent group (those with MP upon provocation), and 21 in a normal group (no MP in neck and shoulder). The symptom burden explained 75% of the variance in PEG in the overall sample, 85% in the active group and 92% in the normal group. PF and PCS are key predictors of PEG. Network analysis identified unique symptom clusters in the active and latent groups. Conclusions: The symptom burden explains the variability in the clinical spectrum of pain intensity and interference in unexplained neck/shoulder MP. Network analysis can further improve clinical risk stratification. These findings represent a step towards an eventual goal of developing multidisciplinary clinical guidance for managing the whole patient, rather than the current emphasis on regional pain contributors in MP.