What is diffuse axonal injury?

• A. Shearing injury where brain tissues respond differently to trauma -> compromising cellular membranes
• B. Localized contusion at site of impact
• C. Epidural hematoma due to arterial rupture
• D. Hemorrhage in the ventricles

Answer: (A)

Diffuse axonal injury happens when rapid head movement creates shear forces that tear and disrupt axons across the white matter, especially at gray–white matter junctions, the corpus callosum, and brainstem. This widespread axonal damage interrupts neural connectivity and axonal transport, often leading to immediate coma or prolonged unconsciousness rather than a single focal lesion. The description here captures that idea of a shear injury causing disruption to axons and membranes, which is what DAI is. By contrast, a localized contusion is a focal bruise at the impact site, an epidural hematoma comes from arterial rupture forming a space-occupying bleed between skull and dura, and hemorrhage in the ventricles refers to bleeding within the brain’s ventricles. DAI is about diffuse, network-wide injury rather than a solitary hematoma or focal contusion.