Prevention of secondary damage is an important goal in the treatment of severe neurological conditions, such as major head trauma or stroke. However, there is currently a lack of non-invasive methods for monitoring cerebral physiology. Diffuse optical methods have been proposed as an inexpensive, non-invasive bedside monitor capable of providing neurophysiology information in neurocritical patients. However, the reliability of the technique to provide accurate longitudinal measurement during the clinical evolution of a patient remains largely unaddressed. Here, we report on the translation of a hybrid diffuse optical system combining frequency domain diffuse optical spectroscopy (FD-DOS) and diffuse correlation spectroscopy (DCS) for real-time monitoring of cerebral physiology in a neuro intensive care unit (neuro-ICU). More specifically, we present a case study of a patient admitted with a high-grade aneurysmal subarachnoid hemorrhage, who was monitored throughout hospitalization. We show that the neurophysiological parameters measured by diffuse optics at the bedside are consistent with the clinical evolution of the patient at all the different stages following its brain lesion. These data provide support for clinical translation of DOS/DCS as a useful biomarker of neurophysiology in the neuro-ICU, particularly in locations where other clinical resources are limited.

Abstract:Atherosclerotic disease has been associated with increased risk of severe neurovascular consequences including transient ischemic attacks, ischemic strokes, and even mortality. Following the onset of carotid stenosis, the brain undergoes different compensatory mechanisms to provide adequate perfusion in order to maintain brain metabolism. In this study, we employed near-infrared spectroscopy (NIRS) to better comprehend how carotid stenosis affects cerebral hemodynamics, both at rest and during activity. Eighteen patients diagnosed with atherosclerotic disease were recruited for a protocol consisting of resting state and vasoreactivity testing performed with breath holding. Although the breath holding challenge induced global vasodilation in all patients, the extent of dilation varied according to the level of stenosis. Patients diagnosed with carotid stenosis have impaired hemodynamic response, with a median 77% vasoreactivity in the hemisphere ipsilateral to the stenotic vessel when compared to the healthy hemisphere. Hemodynamics of these patients differed at rest, with 33% fewer network links in the hemisphere ipsilateral to the stenosis than the healthy hemisphere. On the other hand, hemodynamic patterns were more heterogeneous with patients diagnosed with a carotid occlusion, which correlates with the opening of collateral circulation. Overall, our results suggest that NIRS can open new directions to the investigation of the effects of cerebrovascular atherosclerotic disease.

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