Figure 53-3 Intracranial pressure-volume relationship. The horizontal portion of the curve indicates that initially there is some latitude for compensation in the face of an expanding intracranial lesion. This compensation is accomplished largely by displacement of cerebrospinal fluid (CSF) and venous blood from the intracranial to the extracranial spaces. Once the compensatory latitudes are exhausted, small increments in volume result in large increases in intracranial pressure with the associated hazards of herniation or decreased cerebral perfusion pressure (CPP) resulting in ischemia.