Pain Characteristics Among Individuals with Duchenne Muscular Dystrophy According to Their Clinical Stage

Background: Assessment of pain is not routine, standardized, or well-understood in individuals with Duchenne muscular dystrophy (DMD), even though pain is a common problem reported by more than half of DMD patients. Previous studies in this area included multiple neuromuscular diseases with highly variable phenotypes. Therefore, our aim was to focus on DMD specifically and evaluate comprehensive pain characteristics according to the disease stages, from ambulatory to late non-ambulatory. Methods: This was a cross-sectional study conducted in an out-patient pediatric rehabilitation clinic. Participants were 148 males with confirmed DMD, 14.5±5.3 years of age. Face-to-face interviews were conducted using a structured questionnaire regarding pain frequency, duration, intensity, location, aggravating/relieving factors, pain interference (Brief Pain Inventory), pain quality (PainDETECT Questionnaire), and functional ability (DMD Functional Ability Self-Assessment Tool). Pain characteristics were analyzed according to the clinical stage: ambulatory (Amb), early non-ambulatory (ENA), and late non-ambulatory (LNA).Results: Of the 148 participants who completed the assessment, 66 (44.6%) reported pain during the previous 4 weeks. There were no differences in the pain duration or intensity among the three groups. Pain location (Amb: calf, ENA: knee, LNA: lumbosacral region), aggravating factor (Amb: ambulation, ENA: transfer, LNA: sitting), and relieving factor (Amb: rest and massage, ENA and LNA: positional change) differed according to the clinical stage. Individuals in the LNA stage reported an increase in the frequency of pain and number of pain sites. The effect of pain on mood was also found to be greater in the LNA group than in the other clinical stages. Conclusion: Pain characteristics including location, aggravating/relieving factors, pain frequency, and pain interference change as the disease progresses in patients with DMD. Clinicians could more efficiently and critically assess and manage the patients’ pain aspect, based on these findings.