Which term describes a diffuse injury to white matter due to shearing forces?

Which term describes a diffuse injury to white matter due to shearing forces?

• A. Diffuse axonal injury
• B. Coup/contrecoup
• C. Penetrating injury
• D. Epidural hematoma

Answer: (A)

Diffuse axonal injury describes widespread damage to white matter from rapid, twisting forces that shear axons as the head undergoes acceleration–deceleration. This mechanism disrupts the axonal cytoskeleton and axonal transport across many tracts, so the injury is diffuse rather than anchored to a single spot. Clinically, it often leads to immediate or prolonged coma because large networks of communication are disrupted, not just a localized lesion. On imaging, tiny hemorrhages and white‑matter changes are frequently seen at the gray–white junction and in the corpus callosum or brainstem, especially with advanced MRI sequences. Other injuries listed describe localized lesions: a coup/contrecoup injury is a focal contusion at the site of impact and opposite side from brain movement, a penetrating injury involves a foreign object entering the skull creating a focal tract, and an epidural hematoma is a focal arterial bleed between the skull and dura with mass effect. These do not capture the diffuse, shearing axonal disruption characteristic of diffuse axonal injury.

Diffuse axonal injury describes widespread damage to white matter from rapid, twisting forces that shear axons as the head undergoes acceleration–deceleration. This mechanism disrupts the axonal cytoskeleton and axonal transport across many tracts, so the injury is diffuse rather than anchored to a single spot. Clinically, it often leads to immediate or prolonged coma because large networks of communication are disrupted, not just a localized lesion. On imaging, tiny hemorrhages and white‑matter changes are frequently seen at the gray–white junction and in the corpus callosum or brainstem, especially with advanced MRI sequences.

Other injuries listed describe localized lesions: a coup/contrecoup injury is a focal contusion at the site of impact and opposite side from brain movement, a penetrating injury involves a foreign object entering the skull creating a focal tract, and an epidural hematoma is a focal arterial bleed between the skull and dura with mass effect. These do not capture the diffuse, shearing axonal disruption characteristic of diffuse axonal injury.