RecruitingDevice studyCorrelation Between Noninvasive Blood Vessel Functionality Parameters and Cerebral Hemodynamics in Neurocritical Care PatientsThe purpose of this clinical research project is to employ Mespere LifeSciences NeurOs Cerebral Oximetry system, equipped with noninvasive sensors approved by the FDA, to monitor and investigate the correlation within a cohort of patients suffering from traumatic brain injury (TBI), stroke, brain tumor, and brain bleeding. This study aims to investigate and establish the correlation between blood vessel functionality parameters-specifically, Vasodilation/Constriction Index (VDC), Vascular Resistance Index (VR), and Volume Reactivity Index (VRx)-with the crucial physiological indicators, Intracranial Pressure (ICP) and Mean Arterial Pressure (MAP). By doing so, the investigators seek to address fundamental questions surrounding cerebral hemodynamics and autoregulation in various neurological conditions.