Positioning and design by computed tomography imaging in neuroendoscopic surgery of patients with chronic subdural hematoma

Figure 1 Head computed tomography imaging and surgical design. A: On the thickest layer of the hematoma cavity in the computed tomography (CT) image, make a straight line perpendicular to brain surface, which cross the skull at point A' at the inner side and point B' at the outer side. At the edge of the hematoma at the layer, find points C' and D' with distance to A' and B' equal to the thickness of the hematoma, respectively. Connect and extend C'A' and D'A', which intersect at points E' and F' with the surface of the skull, respectively; B: Axial CT scan showing septated right chronic subdural hematoma with two clear compartments. Small blue arrows indicate the membrane to be opened; C: Axial CT scan showing the range of bone window; and D: Axial CT scan showing the postoperative intracranial conditions. CT: Computed tomography.