ABSTRACT
Diffused axonal damage or injury (DAD or DAI) is an interruption of axon-neuron connectivity as a result of brain trauma, resulting in temporal or permanent neurologic dysfunction. DAD is present in as much as 50% of admissions for traumatic brain injury (TBI). Axonal damage and disconnection, although diffused, is not homogeneous, therefore, some areas of the brain are more commonly affected than others, such as the brainstem, cortical white matter, and corpus callosum. With brain trauma, the structural breakdown of axons occurs as a result of acceleration/deceleration and the propagation of shearing, rotational, and kinetic forces acting directly through the brain following the impact (primary axotomy), along with the action of many secondary metabolic, electrochemical, and inflammatory processes (secondary axotomy) initiated by the primary mechanistic event. Pathologic features of DAD may vary from the presence of "retraction balls" or axonal swelling at the cortical white matter, corpus callosum, brainstem, and cerebellum through a hemorrhagic lesion of corpus callosum, intraventricular hemorrhage, and/or lesions of the rostral brainstem. Data in the clinical setting are mostly evaluated on qualitative grounds (CT, MRI), which may miss significant and critical pathologic elements that are important to forecast outcome. With improvements in imaging technologies, radiographic analysis of the brain followingTBI has also improved outcome prediction.
