Abstract TP81: Time-Domain Near-Infrared Spectroscopy in Acute Ischemic Stroke Patients

Background: cerebral microcirculation might reveal important prognostic information for acute ischemic stroke. Time-Domain Near-Infrared Spectroscopy (TD-NIRS) is an advanced optical technique that estimates quantitatively and non-invasively the oxygenation in microcirculation of cerebral outer layers at the bedside of the patient. We aimed to measure hemoglobin species and tissue oxygen saturation in acute ischemic stroke patients comparing them to controls according to brain areas and large vessel recanalization status. Methods: TD-NIRS measurements within 24 h of stroke onset (1 st time point) and after 24 h (2 nd time point) were performed on anterior circulation stroke patients classified as lacunar and recanalized or non-recanalized partial/total anterior circulation syndrome. Fiducial markers categorized the brain region below each TD-NIRS probe as ischemic or non-stroke areas. We evaluated the concentration of deoxyhemoglobin (HbR), oxyhemoglobin (HbO), total hemoglobin (HbT) and tissue oxygen saturation (StO 2 ) and assessed differences compared to control subjects and according to large vessel occlusion. Results: TD-NIRS measurements were performed on 47 acute ischemic stroke patients. At 1 st time point the ischemic area had higher HbR and HbT compared to controls in both recanalized (p=8.2·10 -4 ; p=0.03) and non-recanalized patients (p=4.9·10 -3 , p=0.03), but lower StO 2 only in recanalized patients (p=0.015). The ischemic area of recanalized patients had higher concentration of HbR, HbO, HbT compared to the ipsilateral non-stroke area (p=0.01; p=3.6·10 -3 ; p=2.0·10 -3 ). The same pattern was observed at 2 nd time point. Recanalized patients had lower mean StO 2 in the ipsilateral hemisphere compared to non-recanalized patients at both time points (p=0.016, p=0.011). Conclusions: TD-NIRS can be performed during routine Stroke Unit activity and it is able to detect significant differences in hemoglobin species in large vessels ischemic stroke patients compared to controls. Data suggest that StO 2 could serve as surrogate functional marker of the metabolic activity of the rescued brain tissue.