Session: Research Posters

Paper Number: 166685

Prolonged Exposure to Microgravity Increases Susceptibility to Traumatic Brain Injury 

With increasing duration of spaceflight (potentially leading to semi-permanent off-world habitation), the health complications associated with long-term exposure to microgravity should be investigated. Spaceflight Associated Neuro-Ocular Syndrome (SANS) is a group of neurological and ocular effects resulting from prolonged exposure to microgravity, characterized by significant fluid shifts into the cranium and an upward shift of the brain relative to the skull. This syndrome is recognized by NASA, and is known to impair cognitive ability and motor function. SANS-related changes to the brain’s size and position in the cranium may exacerbate known injury mechanics, but its effect on susceptibility to traumatic brain injury have yet to be studied. Using a biofidelic human body model (THuMS) along with a structural finite element analysis software (LS-Dyna), we tested this hypothesis in two parts: first, we applied boundary conditions to the FE model to replicate the positional/geometric changes to brain tissue from SANS, second, the SANS-altered FE models were subjected to a variety of potentially injurious loads (direct impacts and inertial events). The SANS features to be replicated included the upward migration of cerebrospinal fluid (CSF), the enlargement of ventricular spaces, and elevation of intracranial pressure. To achieve this, a thermal expansion was added to the third and lateral ventricles (15%) and the head model was subjected to an upward gravity load of 1G.  This model effectively reproduced the effects of SANS, including some subtle details. For example, a slight but measurable narrowing to the central sulcus is also evident in the microgravity-analog FEM model, qualitatively corroborated by MRI data collected by Roberts et. al. For the injury analysis, an unmodified THuMS model was used as a control for each injury event. Results demonstrated that, when subject to an impact or inertial event, the SANS-modified models experienced larger stresses and strains than the control models, signifying an increased risk of traumatic brain injury. This was evident in the increase of each of the selected injury prediction criteria from the baseline to SANS-altered models. Specifically, while Cumulative Strain Damage Measure (CSDM) levels remain non-injurious according to the collected injury tolerance levels, Maximum Principal Strain (MPS) levels changed classification from ‘non-injurious’ to ‘injurious’ (MPS>0.24) in all four injury events (8 m/s parietal impact, 20 m/s parietal impact, 10G impulse, 20G impulse) due to SANS boundary conditions. From this, we conclude that the potential for an individual to experience a brain injury during an event such as an impact or spacecraft landing may be drastically increased as a result of the pre-strained brain tissue. This data serves as a preliminary study into the effects of microgravity on susceptibility to traumatic brain injury. As the promise of creating a spacefaring society becomes more realistic, steps must be taken to mitigate the effects of long-term microgravity exposure on susceptibility to traumatic brain injury. 

Presenting Author: Yooyeon Jung University of North Florida

Presenting Author Biography: Yooyeon Jung is a Master's of Science candidate in Mechanical Engineering at University of North Florida. With a Bachelor's of Science in Biology from Florida State University, Jung aims to integrate the two disciplines with her research in 3D modeling of anatomical structures from radiographic images. Jung currently investigates the change in susceptibility to traumatic brain injury from prolonged exposure to microgravity by evaluating the structural changes detected between pre and post space flight MRIs. In industry, Jung works in engineering applications in healthcare through various projects at Johnson & Johnson MedTech.

Authors:

Ryan Baskerville University of North Florida
Yooyeon Jung University of North Florida
Alexandra Schönning University of North Florida
Jutima Simsiriwong University of North Florida
Grant Bevill University of North Florida