The neuroscience behind the injury.

A traumatic brain injury begins with a mechanical force — impact, whiplash, or blast — that causes the brain to accelerate, decelerate, or rotate inside the skull. Axons stretch and shear at the microscopic level, a process called diffuse axonal injury.

Within minutes, a cascade of neurochemical changes follows: excess glutamate release, calcium influx, mitochondrial dysfunction, and inflammatory response. This "secondary injury" can persist for months — which is why symptoms often worsen weeks after the initial event.

Standard imaging looks for blood and swelling. But most mild TBI damage is microstructural — invisible without diffusion tensor imaging or advanced volumetric analysis.