How does neuromodulation improve outcomes after traumatic brain injury?*

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. A particularly dire complication following TBI is cerebral edema (i.e., brain tissue swelling) which increases the risk of death tenfold. Recent studies indicate that neuromodulation (specifically, electrical stimulation of cranial nerves) reduces brain edema and improves cognitive outcomes. However, the underlying mechanisms of this reduced secondary injury are not well-understood. We have recently shown that acute post-TBI edema results from suppression of fluid transport through the glymphatic system (a waste clearance pathway involving cerebrospinal fluid flow through the brain). In this talk, we will present preliminary data suggesting that neuromodulation reduces brain edema by restoring extracellular fluid transport via the glymphatic system. Our results have important implications that may lead to novel therapeutic approaches to TBI.