The function of the brain is not checkable in comatose or sedated patients. Because secondary brain damage will often cause brain edema it is necessary to recognize the resulting increases in brain pressure. Therefore, measurement of intracranial brain pressure (ICP) is the standard monitoring procedure in neurological intensive care. The procedure with a small drill hole trepanation and the insertion of a micropressure sensor has a comparatively low complication rate and offers continuous monitoring with reliable values. Other neuro-monitoring procedures have not achieved the value of ICP measurement and only reflect changes in ICP with other measurement principles. ICP measurement is the procedure which is decisive for conservative measures in the intensive care unit to secure cerebral perfusion or indications for surgical treatment of brain edema. Central venous pressure, intra-abdominal pressure and positive end-expiratory pressure do not have a substantial influence on ICP.