ASSOCIATION BETWEEN PAIN PHENOTYPES AND MOTOR ACTIVITIES IN INDIVIDUALS WITH SPINAL CORD INJURY

Abstract

BackgroundChronic pain affects 70% of individuals with spinal cord injury (SCI), and up to 53% of individuals with SCI experience neuropathic pain that leads to declines in their health and quality of life. Chronic pain can be categorized by phenotypes as neuropathic or nociceptive. Neuropathic pain arises due to nervous system dysfunction, and nociceptive pain originates in the musculoskeletal system in response to noxious stimuli. Moderate-to-vigorous intensity physical activity (MVPA) and virtual reality (VR) have been effective interventions for pain management, however, the circumstances in which these interventions are efficacious for individuals with SCI are not well understood. The objectives of this study were to: 1) investigate the relationships between MVPA and pain phenotypes, 2) investigate the relationships between VR and pain phenotypes, and 3) explore a practical method of measuring MVPA in individuals with SCI. MethodsFor the first objective, one week of physical activity data was collected in the community from 17 individuals with SCI, and daily pain ratings were obtained. Spearman’s correlation analyses were performed to analyze the relationships between MVPA levels and pain intensity. For the second objective, participants engaged in two bouts of immersive VR, and pain intensity was assessed at baseline and following each bout. Friedman analyses of variance tests were conducted to identify changes in pain intensity across VR exposure time in each pain phenotype. For the third objective, a comparison of summary measures for raw physical activity data was conducted. Spearman’s correlation was used to analyze the relationship between ActiGraph Activity Counts and Monitor Independent Movement Summary (MIMS) Units. ResultsIn neuropathic pain, MVPA and pain intensity are negatively correlated. In nociceptive pain, there was no significant correlation between MVPA and pain intensity. A decrease in neuropathic pain was achieved from VR, however no change in nociceptive pain intensity was observed. Total active minutes summarized from raw accelerometer data by Activity Counts and MIMS Units values were strongly correlated, but minutes of MVPA calculated by Activity Counts were only moderately correlated to minutes of MVPA calculated through personalized thresholds with MIMS Units. The responses to VR for each pain phenotype were different. A decrease in neuropathic pain was achieved within a five-minute bout, and this decrease was maintained at the end of both VR sessions, whereas no change in nociceptive pain level was observed. Lastly, Activity Counts and MIMS Units values were strongly correlated (r = 0.94, p < 0.001). Minutes of MVPA calculated by Activity Counts were moderately correlated (r = 0.44, p < 0.001) to minutes of MVPA calculated through personalized thresholds with MIMS Units. ConclusionPain in each phenotype responded differently to both motor activities that were evaluated. These results may assist in the development of personalized pain management approaches through targeted combinations of interventions. By utilizing data from free-living individuals with SCI in the community, the process of personalized thresholds is translatable and describes MVPA levels more accurately and comprehensively than what can be collected in a laboratory setting. This approach can be implemented to optimize MVPA recommendations for individuals with SCI who experience chronic pain.