Many brain conditions require the pressure inside the skull to be measured in order to gather important information for diagnostics and to adjust the required treatment effectively to the patient’s needs. The pressure inside the skull is referred to as intracranial pressure (ICP) and is usually measured in mmHG (mmHG - millimetres of mercury). The pressure unit cmH₂O or centimetres of water column is also used on occasion (1 mmHg is equal to 1.36 cmH₂O). ICP is currently measured using a variety of different systems, each of which offers various properties and comes with their own challenges. Patients can expect a great deal from today’s technical standards.