How old are isodense subdural haematomas?
They vary depending on the physiology of the patient and the make up of the blood, but generally 1 - 2 weeks old.
What can be done to confirm this finding?
Giving contrast will allow you to visualise pial vessels as well as render the cortex somewhat hyperdense.
There is generalised fullness to the brain with little if any sulcal CSF visible over the convexities. There cortex is poorly visualised and appears thickened in parts.