Case to Ponder 79 Answer: Acute subdural, petechial haemorrhages and early diffuse axonal injury

 Radiology Level: FRCR, FRCS, MRCP, ABR, EDiR, Radiology Mid-Level ++

The appearances here are of a severe intracranial injury.

The most apparent findings are those of small foci of high attenuation occuring at the grey-white matter interface. The most notable of these is in the right parietal region and in the left frontal region. These reflect small foci of acute diffuse axonal injury that occur in closed brain trauma due to shearing forces from deceleration-accelaration. Typically CT underestimates the severity of these injuries in the acute phase identifying the haemorrhagic but not the non-haemorrhagic injuries. MRI is more sensitive in this regard. If CT is repeated, typically after 24 hours, more areas are involved and areas of hypodensity tend to appear around the areas of focal bleeds. An area to pay particular attention to, particularly on sagittal reconstructions is the corpus callosum. Involvement of this area results in an even worse prognosis.

Whenever one sees haemorrhage intracranially it is important to review all areas for further haemorrhage. In this case we can see that there is increased density related to the tentorium cerebelli. This is asymmetrically more prominent on the left. These findings can be confirmed on coronal imaging but are diagnostic of an acute subdural haemorrhage over the tent.

Further subtle findings may be present including minor swelling of the sulci over the left vertex and questionably small areas of inter-sulcal linear high attenuation that may indicate limited subarachnoid blood in the right vertex.

Such cases indicate the need for careful review of all compartments for haemorrhage in acute head trauma. Although such cases may have minimal radiological CT findings they portend a very poor prognosis with evolution of findings over the first 24 hours.