These days, with a surge in skull base surgery and increased aggressiveness in resection of tumors earlier considered inoperable, the need for reliable means of brain monitoring becomes quite clear. This is especially true in cases involving major alteration of cerebral blood flow, as happens in resection, ligation, or occlusion of the internal carotid artery (ICA). I The possibility of preoperative assessment of brain circulatory reserves may allow the neurosurgeon to predict the necessity of shunting or bypassing the arterial flow to the brain. Although there is a commonly used way to simulate flow interruption-a temporary occlusion of ICA, prior to the operation-by itself it does not provide any quantitative data about brain circulation. For this reason, it was proposed that combining temporary occlusion with various imaging techniques such as positron emission tomography and single photon emission computed tomography, electroencephalography, transcranial Doppler ultrasonography, and others might meet this need. However, these methods do not give direct information about the sufficiency of brain respiration-its oxygen supply.For several years our group has been working with near-infrared spectroscopic evaluation of brain oxygenation-transcranial cerebral oximetry (TCCO). This technique is a useful, real-time, and reliable source of information about brain oxygenation in various neurosurgical situations, such as intraoperative monitoring of carotid endarterectomies and various intracranial procedures, evaluation of brain ischemia and vasospasm, and monitoring of endovascular procedures.In this article we report our preliminary experience using TCCO for preoperative assessment of patients undergoing surgery that may compromise ICA patency. 117Skull

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