DAÑO AXONAL DIFUSO SECUNDARIO A TRAUMATISMO CRANEOENCEFÁLICO Neurología del paciente en situación critica ( Neurocríticos).
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It is a potentially difficult diagnosis to make on imaging alone, especially on CT as the finding can be subtle, however, it has the potential to result in severe neurological impairment.
The patients at risk of diffuse axonal injury belong to the same cohort as those who suffer traumatic brain injury and as such young men are very much over-represented.
Typically, patients who are shown to have diffuse axonal injury have loss of consciousness at the time of the accident. Post-traumatic coma may last a considerable time and is often attributed to coexistent more visible injury e. As such the diagnosis is often not suspected until later when patients fail to recover neurologically as expected.
Diffuse axonal injury is the result of shearing forces, typically from rotational acceleration most often a deceleration.
Diffuse axonal injury
In the majority of cases, these didusa result in damage to the cells and result in edema. Actual complete tearing of the axons is only seen in severe cases.
Diffuse axonal injury is characterised by multiple focal lesions with a characteristic distribution: Non-contrast CT of the brain is routine in patients presenting with head injuries. Unfortunately, it is not sensitive to subtle diffuse axonal injury and as such, some patients with relatively normal CT scans may have significant unexplained neurological deficit The appearance depends on whether or not the lesions are overtly hemorrhagic.
Hemorrhagic lesions will be hyperdense and range in size from a few millimetres to a few centimetres in diameter. Non-hemorrhagic lesions are hypodense. They typically become more evident over the first few days as edema develops around them. They may be associated with significant and disproportionate cerebral swelling. When lesions are hemorrhagic, and especially when they are large, then CT is quite sensitive.
As such, it is usually a safe assumption that if a couple of small hemorrhagic lesions are visible on CT, the degree of damage is much greater. MRI is the modality of choice for assessing suspected diffuse axonal injury even in patients with entirely normal CT of the brain MRI, especially SWI or GRE sequences, exquisitely sensitive to paramagnetic blood products may demonstrate small regions of susceptibility artefact at the grey-white matter junction, in the corpus callosum or the brain stem.
Diffuse axonal injury – Wikipedia
Some lesions may be entirely non-hemorrhagic even using high field difuas SWI sequences. Over the first few days, the degree of surrounding edema will typically increase, although by 3-months post-injury FLAIR changes will have largely resolved 7. In contrast, SWI changes will usually take longer to resolve, although by months post-injury there will have been substantial resolution 7.
This is to be expected as edema is faster to resolve than hemorrhage. Importantly, it should be noted, that even with high field strength modern scanners, the absence of findings does not categorically exclude the presence of axonal injury.
Diffuse axonal injury | Radiology Reference Article |
MRS can be of benefit in identifying patients with grade I injury which may be inapparent on other sequences. Features typically demonstrate elevation of choline peak and reduction of NAA 3. Unfortunately little can be done for patients with diffuse axonal injury other than trying to minimise secondary damage caused by cerebral edema, hypoxia, etc. Depending on the severity and distribution of injury dkfusa The amount of axonal injury in the brainstem is predictive of long-term vegetative state, whereas supratentorial injury can result in focal neurological or neuropsychiatric deficits 1.
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