Acute Subdural Haemorrhage: Occurs immediately after a head injury, resulting in thick bleeding that may require urgent evacuation via craniotomy.
Chronic Subdural Haemorrhage: A slow “ooze” following minor head trauma. It is an inflammatory process involving repeated healing and bleeding over a long period.
Patients with chronic haemorrhages may tolerate larger volumes of blood before showing symptoms, but significant “mass effect” or midline shift requires neurosurgical intervention.