Can cerebral near-infrared spectroscopy predict cerebral ischemic events in neurosurgical patients? A narrative review of the literature

Cerebral near-infrared spectroscopy (NIRS) is considered a valuable noninvasive modality for cerebral oxygenation monitoring during cardiovascular surgery and cardiac arrest. We assessed the capability of cerebral NIRS to predict cerebral desaturation and the related neurological outcomes in neurosurgical patients. A literature search in different electronic medical databases was performed from inception to January 2018. A total of 286 citations were found and finally 48 studies were retrieved, only 7 of these were eligible and included for review. A meta-analysis was not feasible because of high heterogeneity of patients' groups, different NIRS techniques used in the studies and different outcome criteria selected. The qualitative assessment showed controversial data on the threshold value of cerebral near-infrared spectroscopy used for detecting cerebral ischemia in neurosurgical patients. The evidence on the selected studies is not strong enough, at the moment, to recommend cerebral NIRS as a mandatory monitor to detect cerebral deoxygenation able to predict the future neurological outcome in neurosurgical patients. Further studies are needed to validate a threshold value for cerebral ischemia and the relationship between NIRS-detected cerebral desaturation and clinical outcome in the neurosurgical population.