Hyperperfusion syndrome is a complication of carotid artery stenting (CAS) that leads to a poor outcome. Therefore, prevention of hyperperfusion syndrome is important in the perioperative management of CAS. We performed CAS under general anesthesia with both proximal balloon protection and distal filter protection. We used the Invos system to monitor regional cerebral oxygen saturation (rSO
2) for 2 days after CAS. Although the Invos system provides continuous and less-invasive monitoring, rSO
2 values may be influenced by the patient's respiratory or circulatory conditions. In this study, we compared perioperative rSO
2 monitoring and single-photon emission computed tomography (SPECT) imaging, and report the efficacy of rSO
2 monitoring in predicting hyperperfusion syndrome.
Methods: SPECT was performed before and one day after CAS; rSO
2 monitoring was continuously performed from immediately before induction of general anesthesia until two days after CAS.
Results: In total, 44 patients underwent 49 CAS operations at our institution between January 2012 and December 2013. One patient who did not undergo SPECT imaging 1 day after CAS was excluded. The median age of all patients was 74 years and 88% patients were male. One patient experienced asymptomatic subarachnoid hemorrhage after CAS. According to the SPECT imaging results, hyperperfusion phenomenon was diagnosed in 4 patients, in 3 of whom the increase in the ratio of rSO
2 on balloon deflation was above 0.2 and the decrease in ratio of rSO
2 on balloon inflation was below 0.15. In one of these 4 patients, compared to the preoperative status, the difference between ipsilateral rSO
2 and contralateral rSO
2 increased by more than 5% after CAS.
Conclusion: A change in the rSO
2 ratio by proximal balloon protection could be one of the indices of hyperperfusion phenomenon. In some cases, rSO
2 monitoring alone may not detect hyperperfusion. Therefore, another method such as SPECT imaging may be used in combination with rSO
2 to detect hyperperfusion syndrome after CAS.
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