Traumatic Axonal Injury: Novel Insights Into Evolution and Identification

Abstract

Cover. (Bottom) An axial contour map (irregular green lines) of areas that are more than 2 standard deviations below normal white matter magnetization transfer ratio in the region of the splenium of the corpus callosum in a patient with traumatic brain injury. (Top) The approximate axial section is indicated (straight green line) on a normal sagittal T1 weighted magnetic resonance (MR) scan. Figure 1. Axial Diffusion TensorImaging. An area with vasogenic edema is visible in the left frontal lobe on the T2 weighted image (arrows). It is much less evident on the mean diffusion-weighted map of the same section, produced by averaging the diffusion-weighted images obtained in all 23 noncolinear directions of the diffusion gradients. The corresponding trace map shows increased diffusivity in the left frontal lobe (arrows). In the fractional anisotropy map of the same section decreased anisotropy is visible in the left anterior portion of the corpus callosum due to the presence of vasogenic edema (arrowhead). Diffusion anisotropy is also decreased in the anterior portion of the left internal and external capsules (arrow), although these regions are characterized by normal T2 and trace values. A box indicates the region of the spenium of the corpus callosum in which a detailed analysis was performed by overlaying contours that correspond to 2 standard deviations (SD) below normal white matter magnetization transfer ratio (MTR). Arrows indicate regions in which the MTR was more than 2 SD below normal in these two traumatic brain injury (TBI) cases. Both patients had cognitive impairments consistent with TBI.

Sport-Related Concussion in Children and Adolescents

“…61 CT is the test of choice to evaluate for intracranial hemorrhage during the first 24 to 48 hours after injury. 62,63 It is also a superior imaging modality for detection of skull fractures. 64 CT is faster, more cost-effective, and easier to perform than MRI.…”

Blast-Related Traumatic Brain Injury: What Is Known?

“…28 Impaired axonal transport leads to focal axonal swelling and (after several hours) may result in axonal disconnection. 29 The most common locations are the corticomedullary (gray matter-white matter) junction (particularly in the frontal and temporal areas), internal capsule, deep gray matter, upper brainstem, and corpus callosum (Figure 2, pink). 27 Magnetic resonance imaging (MRI) is more sensitive than computed tomography (CT) in detecting diffuse axonal injury.…”

“…27 Magnetic resonance imaging (MRI) is more sensitive than computed tomography (CT) in detecting diffuse axonal injury. 27,29 T2 weighted magnetic resonance (MR) images, especially fluid attenuated inversion recovery (FLAIR) images, are best for visualizing nonhemorrhagic lesions. Some studies indicate that diffusion weighted MR may be even more sensitive than T2 weighted for identifying edema.…”

Traumatic Axonal Injury: Atlas of Major Pathways

“…The most common type of injury, and the most likely injury to occur in mild TBI, is traumatic axonal injury (also called diffuse axonal injury). 18 While magnetic resonance imaging (MRI) is more sensitive than computed tomography (CT) in detecting this type of brain injury, even MRI is often negative. [18][19][20][21][22][23] In addition, some areas of injury may become less visible with time.…”

“…18 While magnetic resonance imaging (MRI) is more sensitive than computed tomography (CT) in detecting this type of brain injury, even MRI is often negative. [18][19][20][21][22][23] In addition, some areas of injury may become less visible with time. 21 In such cases, MRI in the subacute and chronic stages is less likely to be positive than if acquired immediately following injury.…”