Amplitude of Tissue Oxygenation Index Change Predicts Cerebral Hyperperfusion Syndrome During Carotid Artery Stenting

Objective Hyperperfusion syndrome (HPS) after carotid artery stenting (CAS) is a rare but serious complication. HPS is associated with preoperative hemodynamic impairment as the result of poor collateral flow and intraoperative cerebral ischemia. Filter-type embolic protection devices maintain anterograde carotid flow during CAS and prevent HPS somewhat. The early treatment of patients undergoing CAS and at risk for HPS is essential. Near-infrared spectroscopy allows noninvasive, real-time measurement of frontal lobe regional cerebral O 2 saturation (TOI; tissue oxygenation index). Methods The perioperative amplitude of TOI was monitored in 130 patients undergoing CAS while using a filter-type embolic protection device. Patients were divided retrospectively into good ( n  = 110) and poor/no crossflow groups ( n  = 20), and we compared the amplitude of the TOI change, correlation with ipsilateral regional cerebral blood flow, and clinical results. Results The incidence of HPS was significantly greater in the poor/no crossflow group ( P  = 0.019). In 2 patients with HPS, the amplitude of the TOI change was V-shaped, with a decrease after postdilatation and an increase above baseline 5 minutes after reperfusion. The TOI/baseline ratio was significantly decreased after internal carotid artery occlusion for postdilatation in the ipsilateral hemisphere in the poor/no crossflow group ( P P  = 0.002, r = 0.613, P Conclusions The amplitude of the TOI change measured by near-infrared spectroscopy was an excellent predictor of cerebral HPS after CAS.