The Common vein Copyright 2010
Definition
Diffuse axonal injury is a widespread axonal injury in cerebral white matter as a result of head trauma.
The diffuse axonal injury results from an impact caused by inertial forces of acceleration and deceleration (shearing forces) in the white matter.
Macroscopically, hemorrhagic injury in the corpus callosum and/or the dorsolateral brainstem point towards the diagnosis. There can also be hemorrhages in the subcortical white matter of cerebral hemispheres and hippocampus.
Clinically, the spectrum is broad, extending from coma to concussion (which is a transient loss of consciousness, no more than 10 minutes, with anterograde and retrograde amnesia without microscopic structural damage).
In imaging, CT brain is widely used in the acute phase of trauma, because it allows signs to be seen much earlier. Focal hypodensities in the hemispheric white matter, brainstem and corpus callosum can be seen; petechial bleeding to large hematomas can be visualized in the subcortical white matter, corpus callosum and deep white matter. MRI further allows the visualization of multiple small ovoid foci of edema from axonal damage, appearing as hypointense signals in T2WI’s.
Treatment is limited, since the injury is not reversible; it aims to stabilize patiente and control intracranial pressure, if elevated.