Intracranial Pressure Monitoring Modalities

Abstract

Intracranial pressure (ICP) monitoring is a fundamental component of neurocritical care, particularly in patients with severe traumatic brain injury, in whom intracranial hypertension can reduce cerebral perfusion, worsen secondary brain injury, and increase the risk of neurological deterioration and death. Clinical manifestations of raised ICP, such as pupillary abnormalities and abnormal motor posturing, may appear late; therefore, objective monitoring is essential for early detection and treatment guidance. Invasive techniques, including external ventricular drains and intraparenchymal monitors, provide direct and continuous ICP measurements. External ventricular drainage is regarded as the reference standard because it permits both pressure monitoring and therapeutic cerebrospinal fluid drainage, whereas intraparenchymal devices are easier to insert but cannot be re-zeroed after placement and may develop measurement drift. also invasive techniques are associated with complications such as infection, hemorrhage, obstruction, malposition, and mechanical failure. These limitations have encouraged the use of non-invasive methods, particularly transcranial Doppler ultrasonography, which evaluates cerebral blood-flow velocities and pulsatility index as indirect indicators of downstream cerebrovascular resistance and ICP. Other non-invasive modalities include optic nerve sheath diameter ultrasonography, neuroimaging, and tympanic membrane displacement. This review summarizes the principles, advantages, limitations, complications, and clinical applications of invasive and non-invasive ICP monitoring modalities, with particular emphasis on transcranial Doppler and pulsatility index interpretation.