The intracranial pressure (ICP) has three components: an arterial vascular component; a cerebrospinal fluid (CSF) circulatory component; and a venous outflow component. More generally, multiple variables such as the arterial pulsatile pressure, autoregulation and cerebral venous outflow all contribute to the vascular component. Intracranial compliance is a concept often associated with CSF storage. Measurement of brain compliance is classically performed using a CSF bolus injection. In sedated patients with TBI, continuous ICP monitoring is recommended, and can only be achieved by direct invasive measurement. The gold standard for ICP monitoring is a catheter inserted into the lateral ventricle and connected to an external pressure transducer. Cerebral perfusion pressure (CPP)-oriented therapy has been introduced to decrease the risk of ischaemia in post-injury care. Intracranial pressure waveforms include distinct periodic components: heart pulse waves, respiratory waves and quasi-periodic slow vasogenic waves.