Development of a Metric for Predicting Brain Strain Responses Using Head Kinematics

Area of Science:

• Biomechanics
• Neuroscience
• Mechanical Engineering

Background:

• Diffuse brain injuries result from excessive brain deformation, primarily due to rapid head rotation.
• Current brain injury metrics often fail to accurately represent the physics of brain deformation across various impact conditions.
• There is a need for a more effective and universally applicable brain injury assessment tool.

Purpose of the Study:

• To develop a novel brain injury metric, the universal brain injury criterion (UBrIC), based on a second-order mechanical system.
• To correlate rotational head kinematics with established strain-based brain injury metrics, such as maximum principal strain (MPS) and cumulative strain damage measure (CSDM).
• To establish UBrIC's applicability across a wide range of head impact kinematics encountered in automotive crashes and sports.

Main Methods:

• Developed UBrIC using a second-order mechanical system model.
• Related rotational head kinematics to MPS and CSDM.
• Validated UBrIC by comparing its predictions to MPS and CSDM from 1600 head impacts simulated using two finite element (FE) brain models.

Main Results:

• UBrIC demonstrated the highest correlation with the FE brain models compared to existing metrics.
• The new metric performed better than existing metrics across most simulated impact conditions.
• UBrIC offers a reliable measurement for brain injury assessment in diverse head impact scenarios.

Conclusions:

• UBrIC provides a more effective and broadly applicable method for assessing brain injury severity.
• The metric can inform the design of protective gear, such as helmets, and injury countermeasures.
• Further research is needed to incorporate validated strain-based injury risk functions into UBrIC for comprehensive human injury risk assessment.