Quantifying cerebral autoregulation following endovascular thrombectomy using wavelet transformation

Cerebral autoregulation (CA) is essential for protecting the brain against harmful fluctuations in cerebral blood flow (CBF) and may be severely impaired in acute ischemic stroke (AIS) patients. Continuous wavelet transform (CWT) is a robust method for quantifying CA. However, data on CWT-based metrics following endovascular thrombectomy (EVT) remain limited. Therefore, we aimed to characterize CA using CWT in AIS patients after EVT.

We performed a prospective observational study recruiting patients with anterior circulation AIS treated with EVT. Continuous bilateral middle cerebral artery (MCA) blood flow velocities were obtained by transcranial doppler ultrasound (TCD) and synchronized with arterial blood pressure (ABP). CWT-derived Synchronization index gamma (SI) was calculated in the very-low frequency range (0.005-0.08 Hz). The primary outcome was an unfavorable clinical outcome at 90-days (modified Rankin Scale 3-6). Secondary outcomes were early neurological recovery, Alberta Stroke Program Early CT Score (ASPECTS), MRI-based infarct volume, and intracranial hemorrhage.

A total of 20 patients were included in the primary outcome analysis. There was no statistically significant difference in median Synchronization index gamma (SI) between patients with unfavorable clinical outcomes compared to patients with favorable clinical outcomes (0.61 ±0.15 vs. 0.41 ±0.20, p = 0.055). Patients who failed to achieve early neurological recovery had higher median SI compared to others (0.63 ±0.14 vs. 0.36 ±0.17, p = 0.005). Median SI was inversely correlated with ASPECTS, indicating impaired CA in larger infarcts (Spearman's rho = -0.52, p = 0.043).

CWT is a viable method for evaluating CA after EVT and may provide important information on early cerebral hemodynamics following arterial recanalization.