Significant progress has been made in understanding the production,circulation, and absorption of CSF. In part because of autoregulation, rapid changes in arterial pressure produce parallel but significantly dampened changes in CSF pressure. Chronic arterial hypertension rarely affects ICP,but changes in venous pressure are transmitted directly into the CSF, taking precedence over arterial effects. An understanding of basic CSF physiology,particularly in relation to ICP homeostasis, is important for surgeons treating intracranial hypertension, low ICP pressure, and spontaneous,traumatic, or iatrogenic CSF leakages. The principles discussed in this article are valuable to remember when planning surgical procedures in the head and neck, both to prevent and to treat potential complications related to increased or decreased CSF pressure.