Fluctuations in intracranial pressure can be estimated non-invasively using near-infrared spectroscopy in non-human primates

Abstract

Intracranial pressure (ICP) is typically measured invasively through a sensor placed inside the brain or a needle inserted into the spinal canal, limiting the patient population on which this assessment can be performed. Currently, non-invasive methods are limited due to lack of sensitivity and thus only apply to extreme cases of increased ICP, instead of use in general clinical practice. We demonstrate a novel application for near-infrared spectroscopy (NIRS) to accurately estimate ICP changes over time. Using a non-human primate (Rhesus Macaque) model, we collected optical data while we induced ICP oscillations at multiple ICP levels obtained by manipulating the height of a fluid column connected via a catheter to the lateral ventricle. Hemodynamic responses to ICP changes were measured at the occipital pole and compared to changes detected by a conventional intraparenchymal ICP probe. We demonstrate that hemoglobin concentrations are highly correlated with induced ICP oscillations and that this response is frequency dependent. We translated the NIRS data into non-invasive ICP measurements via a fitted non-parametric transfer function, demonstrating a match in both magnitude and time alignment with an invasively measured reference. Our results demonstrate that NIRS has the potential for non-invasive ICP monitoring.

Estimating intracranial pressure using pulsatile cerebral blood flow measured with diffuse correlation spectroscopy

“…Another significant advantage of diffuse optical methods, such as DCS, which measures changes in cerebral blood flow, is the sensitivity to the microvasculature, allowing for localized measurements as compared to global measurements using TCD. We have recently shown that a transfer function approach can translate oxygenated hemoglobin concentration changes measured with NIRS into changes in ICP [36].…”

Comparison of static and dynamic cerebral autoregulation under anesthesia influence in a controlled animal model

“…Derivatives of the above described static, dynamic, and pseudo-dynamic measurements have been proposed in order to reduce the need of invasive ICP sensors and improve reliability. Such methods often replace ICP or ABP with other hemodynamic measurements such as hemoglobin concentrations, tissue oxygenation or blood volume and summaries of them can be found elsewhere [15,[23][24][25], including non-invasive diffuse optical methods used in this article [26,27]. Despite many decades of research and a large variety of measurement methods, a consensus on the effectiveness and use of CA measurements to guide clinical treatment has not yet been reached.…”

Optical imaging and spectroscopy for the study of the human brain: status report

“…For example, changes in oxy- and deoxy-hemoglobin have qualitatively been shown to correlate with ICP, 506 and a transfer function approach has been used to relate slow changes in oxygenated hemoglobin concentration to changes in ICP. 507 More recently, quantitative estimation of ICP has been demonstrated using non-invasive DCS measurements of CBF waveform morphology combined with machine learning. These approaches have yielded excellent accuracy of in an animal model 508 and clinical populations of benign enlargement of subarachnoid spaces and traumatic brain injury.…”