Beyond the brain: peripheral interactions following traumatic brain injury.

Traumatic brain injury (TBI) is a leading cause of death and disability, and there are currently no pharmacological treatments known to improve patient outcomes. Unquestionably contributing towards a lack of effective treatments is the highly complex and heterogenous nature of TBI. In this invited review associated with the International Neurotrauma Symposium in Melbourne we highlight the recent surge of research that has demonstrated various central interactions with the periphery as a potential major contributor towards this heterogeneity and in particular the breadth of research from Australia. We describe the growing evidence of how extracranial factors such as polytrauma and infection can significantly alter TBI neuropathology. In addition, we highlight how dysregulation of the autonomic nervous system and the systemic inflammatory response induced by TBI can have profound pathophysiological effects on peripheral organs such as the heart, lung, gastrointestinal tract, liver, kidney, spleen and bone. Collectively, this review firmly establishes TBI as a systemic condition. Furthermore, the central and peripheral interactions that can occur following TBI must be further explored and accounted for in the ongoing search for effective treatments.