Abstract

Intracranial pressure is the tension recorded within the skull vault as exerted on the brain by the CSF and blood. Increased intracranial pressure (ICP) means greater than normal pressure on the brain. It results from a greater volume of fluid or swelling of the brain. Raised ICP has a wide variety of aetiologies. The body adjusts to these changes to return the pressure to normal. If the pressure isn’t kept at a normal level and keeps rising, it can cause very serious problems because the brain can’t work normally. The main aim in the management of these patients is to prevent secondary injury to the brain. Detection of elevated ICPs can be achieved through non-invasive and invasive methods. We are describing the currently available non-invasive methods of ICP measurement and their limitations.

A basic understanding of the physiology of intracranial pressure helps determine appropriate diagnostics and correct interventions. Ultrasonography of ONSD shows a high diagnostic accuracy for ICP, with high pooled sensitivity and specificity. A systematic review by Koziarz et al. reported a sensitivity of 97% and specificity of 86% for ONSD measured via ultrasound in predicting increased ICP. However, this review included both adult and paediatric populations. Transcranial Doppler is a commonly used tool in Neurocritical care to measure CBF in various conditions (e.g. vasospasm in subarachnoid haemorrhage, traumatic brain injury, acute ischemic stroke, and brain stem death) by imaging middle cerebral artery using the temporal window, and a pulsatility index can be derived to indirectly detect ICP changes. The American Academy of Neurology (AAN) Report of the Therapeutics and Technology Assessment Subcommittee states that TCD can accurately identify acute MCA occlusions with a sensitivity, specificity, PPV, and NPV higher than 90%. Invasive ICP monitoring by EVD is also easily available. A reliable, non-invasive neuroimaging technique to accurately detect ICP could revolutionize the clinical approach to critically ill patients.