Chronic Subdural Haemorrhage 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. [Please download the PDF file if you are unable to view the image below.] Content serves as a guide only. Seek the advice of your doctor for more details Information correct as of December 2020 Reproduced with permission from the National Neuroscience Institute (NNI)