Variations in Information Flow Patterns Following Intracranial Hypertensive Events in Traumatic Brain Injured Patients

Intracranial hypertension is an acute, life-threatening neurological condition that can lead to high risk of mortality. Its prompt identification and timely management are key to functional recovery and resuscitation of the patient. The objective of the present study is to propose quantitative measures for the early assessment of intracranial hypertensive (IH) episodes in traumatic brain injured (TBI) patients and to explore the association between intra-individual variability and IH events. To achieve this, we identified fifty-nine IH events in twelve TBI patients, and analyzed intracranial pressure (ICP), mean arterial pressure (MAP) and heart rate (HR). The notion of Granger causal (GC) analysis was adopted to quantify the bi-directional information flow patterns among ICP, MAP and HR. Additionally, the coefficient of variations of GC values was estimated to quantify intra-individual variations. The present study shows that GC values of ICP-to-MAP, MAP-to-ICP and HR-to-ICP decrease during an IH event while the GC value of HR-to-MAP increases during an IH event. Moreover, it was also observed that TBI patients show more inconsistency during ICP elevations. Our findings suggest that directional communications across cardiovascular (MAP and HR) and cerebrovascular (ICP) mechanisms are associated with the onset of intracranial hypertension. These derived GC measures may also be utilized as functional bio-markers in physiological diagnostics.