Measuring intracranial pressure by invasive, less invasive or non-invasive means: limitations and avenues for improvement

Abstract

Sixty years have passed since neurosurgeon Nils Lundberg presented his thesis about intracranial pressure (ICP) monitoring, which represents a milestone for its clinical introduction. Monitoring of ICP has since become a clinical routine worldwide, and today represents a cornerstone in surveillance of patients with acute brain injury or disease, and a diagnostic of individuals with chronic neurological disease. There is, however, controversy regarding indications, clinical usefulness and the clinical role of the various ICP scores. In this paper, we critically review limitations and weaknesses with the current ICP measurement approaches for invasive, less invasive and non-invasive ICP monitoring. While risk related to the invasiveness of ICP monitoring is extensively covered in the literature, we highlight other limitations in current ICP measurement technologies, including limited ICP source signal quality control, shifts and drifts in zero pressure reference level, affecting mean ICP scores and mean ICP-derived indices. Control of the quality of the ICP source signal is particularly important for non-invasive and less invasive ICP measurements. We conclude that we need more focus on mitigation of the current limitations of today’s ICP modalities if we are to improve the clinical utility of ICP monitoring.

Review: pathophysiology of intracranial hypertension and noninvasive intracranial pressure monitoring

“…This method was again validated initially against synthetic data before feasibility was demonstrated on two patients undergoing invasive ICP monitoring via EVD. In both patients, prediction accuracy increased after assimilating CBFV data into the model and the researchers obtained a prediction error for mean ICP of less than 2 mm Hg in each patient, within the clinically accepted standard [31,32,177]. However, significantly more work involving larger, heteregenous patient populations needs to be conducted in order to establish the efficacy of this method for ICP estimation.…”

“…As a result, LP is no longer recommended for use in diagnosing ICH in neurocritical care settings and is reserved more often for use in hydrocephalus and idiopathic intracranial hypertension [3,29]. Guidelines regarding the accuracy of invasive ICP measurement have been outlined by The American National Standards Institute (ANSI)/Association for the Advancement of Medical Instrumentation (AAMI) and specify that ICP in the range of 0 − 20 mm Hg should maintain an accuracy of ±2 mm Hg, while ICP > 20 mm Hg should not exceed 10% error [31,32]. The relationship between pressure and volume within the intracranial compartment.…”

“…Rather, noninvasive ICP estimation techniques could prove useful in scenarios such as prehospital triage and screening at-risk patients for potential invasive monitoring, and they should be evaluated in that context rather than as a potential replacement for invasive monitoring. The AAMI has stated that noninvasive ICP measurement differences of ±2 mm Hg for ICP between 0 and 20 mm Hg and ±10% for ICP > 20 mm Hg, relative to invasive measurement, are acceptable [32]. Though these standards appear to be quite strict given the significant advantages offered by noninvasive measurement, they reflect the potentially severe consequences of inaccurate ICP measurement on patient management.…”

“…These differences are likely due to baseline pressure errors (BPE), which are marked by a spontaneous shift or drift in baseline pressure. One study observed BPEs of a magnitude that could erroneously affect patient management in 9 of 16 patients [44], though the broader risk and prevalence of BPEs is currently unknown and requires further study [32]. Placement of intraparenchymal probes also involves a surgical procedure and as a result poses similar risks to EVD; however, placement of these probes is considered less invasive than EVDs, which require ventricular puncture, so the risk of severe complications is likely lower [32].…”

Sonographic Measurement of the Optic Nerve Sheath Diameter (ONSD) and Eyeball Transversal Diameter (ETD) in Benin Healthy African Adults

“…Neuroimaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI) and transcranial Doppler ultrasound allow a non-invasive diagnosis [2] [3] [4]. However, each of them has its limits [2] [5] [6]. As diagnosis alternative, optic nerve sheath diameter (ONSD) measuring, a relatively recent technique was developed [7] [8] [9].…”