The influence of neural factors on secondary conditions such as pain and fatigue in persons living with spinal cord injury

Abstract

This study aimed to determine the nature of the interaction between pain and fatigue, their associations with disrupted autonomic activity in SCI, and the wider psychosocial context. Participants included 45 adults with SCI (21 tetraplegia, 24 paraplegia), and 44 able-bodied (AB) controls. Pain and fatigue measures, socio-demographic, injury and psychosocial factors, Heart Rate Variability (HRV) and eye blink variables were assessed. Multivariate analyses of variance (MANOVA) and post hoc protected t-tests were used to determine differences in variables. Pearson’s correlation analysis was used to determine the relationships between factors. Repeated measures MANOVA was used to determine changes in variables during a fatigue intervention using the Osler Maintenance of Wakefulness test. While all groups fatigued at a similar rate during the fatigue intervention, increases in fatigue, due to high baseline levels, was most severe for the tetraplegia group. Using HRV measures, those with tetraplegia had lowered sympathetic activity. There were no differences found in parasympathetic activity between the groups, or in the time and non-linear domains in the pre and post intervention phases. In the frequency domain, changes in ratio of low and high frequency components (LF/HF) and LF power were associated with fatigue. Results indicate that strategies that maintain or increase sympathetic tone, while maintaining appropriate sympathovagal balance may help reduce fatigue in SCI. Pain intensity remained high during the intervention and was associated with fatigue for the SCI group. Pain intensity correlated with neuropathic pain, and negative mood indicating that psychological coping strategies for pain may improve psychological outcomes. Pain interference correlated with musculo-skeletal pain, incomplete injury, and years since injury. Increasing age correlated with reduced autonomy and social participation, confidence in managing pain and daily activities. Overall there were little group differences in personality traits, resilience, and general self-efficacy.