[Cerebral Hemodynamics and Metabolism: A Practical Guide for Neurosurgeons]

Cerebral hemodynamics and metabolism are central to neurosurgical decision-making and directly influence management in cerebrovascular disease, revascularization, and perioperative care. Powers'classification offers a physiological basis for hemodynamic ischemia, and quantitative positron emission tomography remains the gold standard for evaluating cerebral blood flow, cerebral blood volume, oxygen extraction fraction, and the cerebral metabolic rate of oxygen. Single photon emission computed tomography with acetazolamide, computed tomography/magnetic resonance perfusion, and arterial spin labeling have improved clinical accessibility and allow assessment of cerebrovascular reserve, time-to-peak, mean transit time, and time-to-maximum. In acute ischemic stroke, perfusion imaging has advanced treatment selection from a time-based to a tissue-based paradigm, supporting thrombectomy in patients with large ischemic cores. Post-recanalization phenomena, including hyperperfusion and no-reflow, illustrate the complexity of microcirculatory dynamics. Perfusion studies also inform decisions in bypass surgery and carotid revascularization. For neurosurgeons, understanding these modalities and their complementary interpretations is essential for safe and effective practice. Future integration of imaging metrics with physiological data through artificial intelligence may facilitate patient-specific strategies, standardized protocols, multicenter validation, and ultimately reduce complications while improving outcomes.