Mechanical characterization of the human pia-arachnoid complex

Area of Science:

• Biomechanics
• Neuroscience
• Medical Engineering

Background:

• Traumatic brain injury (TBI), including concussion, results from rapid head accelerations causing brain deformation.
• The pia-arachnoid complex (PAC) mediates energy transfer from impact to the brain.
• Previous computational models lacked human PAC mechanical data.

Purpose of the Study:

• To quantify the normal traction modulus of the human PAC in situ.
• To investigate the distribution of brain-skull stiffness.
• To correlate PAC mechanics with microstructural properties.

Main Methods:

• Utilized hydrostatic fluid pressurization and optical coherence tomography.
• Tested five post-mortem human subjects at multiple brain locations.
• Measured normal traction modulus and compared with microstructural data.

Main Results:

• The human PAC exhibits a linear material response to traction loading.
• Mean normal traction modulus is 12.6 ± 4.8 kPa.
• Modulus is 21% higher in superior brain regions than inferior regions.
• Positive correlations found between modulus and arachnoid membrane thickness/trabeculae volume fraction.

Conclusions:

• This is the first characterization of human PAC mechanics.
• Brain-skull interface stiffness is heterogeneous.
• Incorporating heterogeneous models may improve TBI injury prediction accuracy.