Editing Diffuse axonal injury (section)

==Diagnosis==
[[File:Diffuse axonal injury- cMRT nach 3 Tagen.jpg|thumb|Diffuse axonal injury after a motorcycle accident. MRI after 3 days: on [[T1-weighted]] images the injury is barely visible. On the [[FLAIR]], [[Diffusion-weighted imaging|DWI]] and [[T2*-weighted]] images a small bleed is identifiable.]]
DAI is difficult to detect since it does not show up well on [[CT scan]]s or with other macroscopic imaging techniques, though it shows up microscopically.<ref name="Wasserman"/> However, there are characteristics typical of DAI that may or may not show up on a CT scan. Diffuse injury has more microscopic injury than macroscopic injury and is difficult to detect with CT and MRI, but its presence can be inferred when small bleeds are visible in the [[corpus callosum]] or the [[cerebral cortex]].<ref name="Crooks07">
{{cite journal | vauthors = Crooks CY, Zumsteg JM, Bell KR | title = Traumatic brain injury: a review of practice management and recent advances | journal = Physical Medicine and Rehabilitation Clinics of North America | volume = 18 | issue = 4 | pages = 681–710, vi | date = November 2007 | pmid = 17967360 | doi = 10.1016/j.pmr.2007.06.005 }}
</ref> MRI is more useful than CT for detecting characteristics of diffuse axonal injury in the subacute and chronic time frames.<ref name="Maas08">{{cite journal | vauthors = Maas AI, Stocchetti N, Bullock R | title = Moderate and severe traumatic brain injury in adults | journal = The Lancet. Neurology | volume = 7 | issue = 8 | pages = 728–41 | date = August 2008 | pmid = 18635021 | doi = 10.1016/S1474-4422(08)70164-9 | s2cid = 14071224 }}</ref> Newer studies such as [[Diffusion MRI#Diffusion tensor imaging|Diffusion Tensor Imaging]] are able to demonstrate the degree of white matter fiber tract injury even when the standard MRI is negative. Since axonal damage in DAI is largely a result of secondary [[biochemical cascade]]s, it has a delayed onset, so a person with DAI who initially appears well may deteriorate later. Thus injury is frequently more severe than is realized, and medical professionals should suspect DAI in any patients whose CT scans appear normal but who have symptoms like [[unconsciousness]].<ref name="Wasserman"/>

[[MRI]] is more sensitive than CT scans, but is still liable to [[false negative]]s because DAI is identified by looking for signs of [[edema]], which may not always be present.<ref name="Corbo"/>

DAI is classified into grades based on severity of the injury. In Grade I, widespread axonal damage is present but no focal abnormalities are seen. In Grade II, damage found in Grade I is present in addition to focal abnormalities, especially in the corpus callosum. Grade III damage encompasses both Grades I and II plus [[Anatomical terms of location#Directional terms|rostral]] [[brain stem]] injury and often tears in the tissue.<ref name="Bigler">{{cite journal | vauthors = Lees-Haley PR, Green P, Rohling ML, Fox DD, Allen LM | title = The lesion(s) in traumatic brain injury: implications for clinical neuropsychology | journal = Archives of Clinical Neuropsychology | volume = 18 | issue = 6 | pages = 585–94 | date = August 2003 | pmid = 14591433 | doi = 10.1016/S0887-6177(02)00155-5 | doi-access = free }}</ref>