Correlation between Invasive and Non-Invasive techniques of ICP measurements in patients with Hydrocephalus: A Prospective Observational study

Hydrocephalus is an active distension of the ventricular system of the brain related to the inadequate passage of CSF from its point of production within the ventricular system to its point of absorption into the systemic circulation. ICP can be defined as the pressure inside the cranial vault and is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimetres of mercury (mmHg) and at rest, is normally 7–15 mmHg for a supine adult. The gold standard method of ICP measurement is the Intraventricular catheter based system, but its use has been limited because of complications, cost limiting factors and the requirement of trained personnel to insert the catheter. Thus, non-invasive methods of ICP measurements come into focus which includes Optic Nerve Sheath Diameter measurement using an USG, various methods to estimate PI using TCD/TCCD and the calculation of Npi using a pupilometer. Individually these modalities have their fallacies and the correlation of their combined estimations have not been reliably assessed so far. In our designed study, we will be focusing on mainly ONSD, (PI)Pulsatility index measured by TCD and NPi- Neurological Pupillary index (measured by pupillometer) and their correlations among themselves and with ventricular opening pressure (Invasive intraventricular ICP measurement). We hypothesize that the Combined measurement of PI, ONSD and Npi will have the best correlation with Invasive ICP (Ventricular opening pressure), and it can be used to estimate ICP in hydrocephalus patients with reliable accuracy.