Introduction: Cerebral hyperperfusion syndrome (CHS) is a devastating complication after carotid revascularization procedure such as carotid angioplasty and stenting (CAS). Although there is no reliable predictor of CHS after CAS, it is believed CHS is caused by impaired cerebral autoregulation (CA). However, there is no study using CA assessment as a predictor of the occurrence of CHS after CAS.
Hypothesis: Impaired preoperative CA index is associated with occurrence of CHS after CAS.
Methods: 17 patients with 70-95% stenosis of internal carotid artery who were scheduled to have CAS were enrolled. All patients had dynamic CA assessment 1 day before CAS by analyzing the relationship between the blood pressure of peripheral artery and the flow of stenotic internal carotid artery. Two dynamic CA indexes were measured: time domain analysis (mean pressure-flow correlation coefficient index, Mx) and frequency domain analysis (phase difference at 0.05-0.15Hz measured by a nonlinear analytic method based on Hilbert-Huang transform). In addition, magnetic resonance perfusion image with arterial spin labeling (MR-ASL) was done at 1 day before CAS as baseline, and was followed at 1 and 3 days after CAS to assess the temporal change of cerebral blood flow (CBF). The definition of hyperperfusion is 100% increase of CBF in MR-ASL compared to baseline.
Results: 1 patient developed CHS after CAS, whose Mx is 0.68; and 1 patient was found to have asymptomatic hyperperfusion after CAS, whose Mx is 0.58. The other 15 patients have no hyperperfusion after CAS, and their CBF after CAS did not change significantly compared to baseline (P=0.312 and 0.286 on day 1 and day 3 after CAS, respectively) The average Mx between patients with and without hyperperfusion are significant different (0.16±0.24 vs. 0.63±0.07, p=0.025). The average phase difference between patients with and without hyperperfusion are not different (32.5±11.1 vs. 28.2±19.8, p=0.307).
Conclusions: Impaired preoperative dynamic CA using time domain analysis (Mx) is associated with cerebral hyperperfusion status after CAS. Therefore, preoperative dynamic CA is a potential screening tool to improve the safety of CAS.