Neuroimmunology of Traumatic Brain Injury: A Longitudinal Study of Interdependency of Inflammatory Markers and Heart Rate Variability in Severe Traumatic Brain Injury

The aim of the present study is to evaluate the interdependency between heart rate variability (HRV) and inflammatory markers in patients with severe traumatic brain injury (TBI). A prospective exploratory study was done with a sample size of 89 patients. HRV of these patients was recorded using a telemetric device. The recordings were made on day 1 of the patients' admission into the intensive care unit followed by serial recordings on day 3 and day 10. Serum samples of the patients were also collected on these days for analysis of interleukin (IL)-1, IL-6, IL-10, and tumor necrosis factor alpha levels using enzyme-linked immunosorbent assay kits. The outcome assessment was done using the Disability Rating Scale at discharge and Glasgow Outcome Scale-Extended at 6 months post-trauma. The data were analyzed by grouping the patients on based on mortality and outcome. In the present study, there was significant subclinical autonomic dysfunction in patients with severe TBI. Among the serum cytokines, levels of IL-10 had a significant impact on outcome. An increase in IL-10 levels correlated with the unfavorable outcome. This study highlights the association between the HRV parameters and immune response. The timely management of both autonomic and immune dysfunction in patients with severe TBI may have an impact in preventing the secondary injury process.