Acute subdural hematoma is the commonest hematoma of head injury. It is also the commonest space occupying lesion of the brain in head injury. It is also the only surgically treatable complication of head injury. As such, it is always important to exclude subdural hematoma in any patient with head injuries, especially when their conscious level deteriorates. Most subdural hematoma occurs soon after injury but some develop only hours or even 1-2 days after trauma, i.e. delayed subdural hematoma.

Subdural hematoma aetiologically is due to rupture of the bridging veins on the cerebral surface, which drain the surface vessels to the superior sagittal sinus. Therefore, it is found most often on the convexity surface.