Influence of gravity for optimal head positions in the treatment of head injury patients

Brain edema is a major neurological complication of traumatic brain injury (TBI), commonly including a pathologically increased intracranial pressure (ICP) associated with poor outcome. In this study, gravitational force is suggested to have a significant impact on the pressure of the edema zone in the brain tissue and the objective of the study was to investigate the significance of head position on edema at the posterior part of the brain using a finite element (FE) model. A detailed FE model including the meninges, brain tissue and a fully connected cerebrospinal fluid (CSF) system was used in this study. Brain tissue was modelled as a poroelastic material consisting of an elastic solid skeleton composed of neurons and neuroglia, permeated by interstitial fluid. The effect of head positions (supine and prone position) due to gravity was investigated for a localized brain edema at the posterior part of the brain. The water content increment at the edema zone remained nearly identical for both positions. However, the interstitial fluid pressure (IFP) inside the edema zone decreased around 15% by having the head in a prone position compared with a supine position. The decrease of IFP inside the edema zone by changing patient position from supine to prone has the potential to alleviate the damage to central nervous system nerves. These observations indicate that considering the patient's head position during intensive care and at rehabilitation might be of importance to the treatment of edematous regions in TBI patients.