Mechanics of Mild Traumatic Brain Injury

Investigators: Philip V. Bayly, Guy M. Genin

Mild traumatic brain injury (MTBI), including concussion, is the most prevalent form of head injury. It is estimated that over 300,000 concussions occur annually in the US as a result of participation in sports. Moderate to severe brain injury has long been known to lead to permanent cognitive impairment. Studies suggest that repeated mild traumatic brain injury can also lead to significant long-term cognitive decline. In boxers, dementia pugilistica is associated with a history of blows to the head, and professional soccer players who have repeatedly headed a soccer ball reportedly exhibit similar symptoms.

A number of fundamental questions remain open in the understanding of MTBI. Neither the threshold of force or acceleration required to cause concussion nor the exact mechanism of injury is known. People who have sustained one or more concussions are at increased risk for future concussion. The effects of concussion and repeated mild traumatic injury (shaking, e.g.) in the developing brain remain to be determined. Impact to the skull clearly leads to deformation and damage of brain matter, but specific pathways and injury thresholds are not yet available.

The problem revolves around three core issues:

(1) What are the forces on and accelerations of the skull during events associated with mild brain injury?
(2) What are the associated dynamic strain fields in the brain?
(3) How does straining relate to cellular and tissue injury?

Representative projects:

• Measurement of linear and angular head acceleration during soccer heading. In these studies, the kinematics of the human subject’s head is completely characterized with high temporal resolution, using an array of tri-axial accelerometers.
  
  
  Representative Publications:
  • R. S. Naunheim, P. V. Bayly, J. Standeven, J. S. Neubauer, L. M. Lewis, G. M. Genin. " Linear and Angular Accelerations of the Human Head during Heading of a Soccer Ball. "   Medicine and Science in Sports and Exercise 2003 Aug.
  
  
• Measurement and prediction of intracranial strain during mild head injury.
  • MR tagging and imaging techniques are under development for measurement of the strain fields in the brain during closed-head injury. Click here for more information.
    
    
    Representative Publications:
    • P.V. Bayly, S. Ji, V. Song, R.J. Okamoto, P.G. Massouros, G.M. Genin. " Measurement of Intra-cranial Strain in Physical Models of Brain Injury. "   To appear. 2003.
    
    
  • Analytical modeling of the response of the brain to inertial loading. The objective of these analyses is to derive scaling laws that show how brain injury in animal models relates to humans, and that reveal the relative importance of loading parameters, material parameters, and structural parameters in the brain's response to inertial loading.
    
    
    Representative Publications:
    • P.G. Massouros, G.M. Genin. " An analytical model of the brain subjected to periodic acceleration. "   To appear. 2003.