CT Scan Guidance

Click on the scans for more detailed views

Case 1 Normal Scan
Case 2 Acute subdural haematoma demonstrating midline shift
Midline shift > 5mm
Intracranial haematoma - non-evacuated
Cortical contusion > 1cm in diameter
Obliteration of the 3rd ventricle
Case 3 Acute subdural haematoma
Intracranial haematoma - non-evacuated
Case 4 Acute extradural haematoma
Intracranial haematoma - non-evacuated
Case 5 Diffuse axonal injury
One or more petechial haemorrhages within the brain
Case 6 Cerebral contusion
Cortical contusion > 1cm in diameter

Early Outcome Form Section 6 Head CT scan - subheadings

Obliteration of the third ventricle

The third ventricle is demonstrated well in Case One - Normal Scan. Here you can see that it is effectively a small cleft within the brain. If there is any pressure, or swelling of the brain, this is one of the first structures to disappear on the scan, as the walls of the cleft are pushed against each other. It is a sign of increased pressure within the head and can either result from a blood clot pressing on the brain, or of swelling of the brain itself.

Midline shift - Greater than 5mm

If you look at Case Two, you will see that we have drawn the midline using a series of yellow dots. You can do the same thing by using a ruler and joining the falx cerebri anteriorly and posteriorly, as labelled in Case One. The third ventricle and the septum between the frontal horns of the lateral ventricle should not deviate from the midline at all, although there may be slight variations less than 5mm. You can use the scale to the right hand side of each scan to work out if the shift is greater than 5mm.

Intracranial haematoma - Evacuated Often, when you look at a post operative scan, there is still residual blood clot. Even though an extradural, or subdural haematoma has been removed, one will often see evidence of a blood clot post operatively, which is hopefully much smaller and not causing pressure on the brain. It does, however, indicate that there has been evacuation of a significant intracranial haematoma. These cases should be classified as "Intracranial haematoma - Evacuated"

Intracranial haematoma -

This refers to blood clot lying either on the surface of the brain in the extradural, or subdural space, or, indeed, to haematomas within the brain substance itself. If these have not been removed surgically, then they should be classified as non-evacuated.
One, or more petechial haemorrhages within the brain.

This refers to very small haemorrhages seen as small, white dots on the scan. They usually occur at the interface between grey and white matter (See Case Five). Other classical sites are the dorsolateral quadrant of the midbrain and also the corpus callosum. They are an indicator of diffuse axonal injury, which is a form of severe primary injury to the brain. This usually carries quite a poor prognosis.

Scans provided by Mr Jonathan Wasserberg, Consultant Neurosurgeon;
Mr Bill Mitchell, Research Associate, Dept Neurosurgery, University of Birmingham.