Cerebral Microvascular Injury in Traumatic Brain Injury

Traumatic cerebral vascular injury (TCVI) is a frequent, perhaps universal, feature after traumatic brain injury (TBI) and may be responsible for some TBI-related chronic disability. Because there are multiple pharmacologic and non-pharmacologic therapies that promote vascular health, TCVI is an attractive target for therapeutic intervention after TBI. The cerebral microvasculature (CMV) is a component of the neurovascular unit (NVU) coupling neuronal metabolism with local cerebral blood flow. The NVU participates in the pathogenesis of TBI, either directly from physical trauma or as part of the cascade of secondary injury that occurs after TBI. Pathologically, there is extensive microvascular injury in humans and experimental animals, identified with either conventional light microscopy or ultrastructural examination. It is seen in acute and chronic TBI and even described in chronic traumatic encephalopathy (CTE). Non-invasive, physiologic measures of cerebral microvascular function show dysfunction after TBI in humans and experimental animal models of TBI. These include imaging sequences Arterial Spin Labeling (ASL), Transcranial Doppler, Near InfraRed Spectroscopy (NIRS), etc. Understanding the pathophysiology of TCVI, a relatively under-studied component of TBI, has promise for developing novel TBI therapies.