Fig. 1

The line and the two sites. This supposed line, which is shown with a green and yellow border line, includes the bilateral temporal lines, coronal suture, and parietooccipital sulcus in the sagittal MRI. The upper part was near the parietal lobe, with little muscle attached. As the midline of the dura is not easy to watertight suture, little muscle is covered, and it is difficult to apply a compression bandage. Therefore, we named it “parietal site”, which is shown in the figure. The subdural CSF can more easily flow to the subcutaneous tissue and form SFC and not STH. The lower part is far away from the top of the head and with thick muscle attachment, which could be compression bandaged. It is similar to having a sporting hairband on your head. Therefore, we named it “Sports hair band site” in this study, which is shown in figure with green colour. The subdural fluid has difficulty flowing through the dura and muscle to the subcutaneous tissue. This means that it is easier to form STH than SFC