​Chronic subdural haemorrhage (CSDH) is a collection of blood and fluid between the surface of the brain and its outermost covering known as the dura (Figure 1).

Small veins called “bridging veins” are located between the surface of the brain and the dura. A subdural haemorrhage can develop after a head injury where the veins can tear and bleed.

Small, repeated bleeds of veins within the fluid increases the amount of fluid around the brain as time passes. Symptoms usually occur weeks after the initial head injury.

Figure 1: Comparison of a normal brain scan and a patient with CSDH