Non-invasive assessment of intracranial biomechanics of the human brain

This review paper describes innovative methods and technology for non-invasive human brain physiological monitoring based on measuring the acoustic properties of the brain parenchyma. The clinical investigation of new technology shows the similarity between the invasively recorded intracranial pressure (ICP) and non-invasively recorded intracranial blood volume (IBV) pulse waves, slow waves and slow trends under intensive care unit (ICU) conditions. Also, the applicability of the non-invasive IBV slow wave monitoring technique for long-term non-invasive cerebrovascular autoregulation monitoring is supported by theoretical and experimental studies. The paper also describes a new absolute ICP measurement method which does not need calibration. The new method is based on a two-insonation depth transcranial Doppler (TCD) technique for absolute ICP and external absolute pressure aPe comparison using the eye artery (EA) as a natural ‘‘scales’’. The clinical study shows that it is possible to measure ICP non-invasively without calibration of the system.