**Abstract**

In the last decades, the development of new noninvasive technologies in critical care allowed physicians to continuously monitor clinical parameters, aggregating important information that has been previously inaccessible or restricted due to the invasiveness of the existing techniques. The aim of this chapter is to present noninvasive methods in use on intensive care units (ICU) for brain injured patients monitoring, collaborating to the diagnosis and follow-up, aiding medical teams to achieve better outcomes.

**Keywords:** noninvasive methods, brain injury, monitoring, ICP pulse waveform, ICPwf, US optic nerve sheath diameter, ONSD, CT scan optic nerve sheath diameter, MRI optic nerve sheath diameter, near-infrared spectroscopy, NIRS, transcranial Doppler, TCD
