Useless. Survivors don't want predictions, they want concrete results that cure or prevent cerebral damage from stroke. Do the research that GETS THERE! I see nothing here that suggests testing to see if the Circle of Willis is complete and then you wouldn't need this work. But obviously since I'm not medically trained, I know nothing, so don't listen to me. The stroke rates after carotid endarterectomy are too high for me, so I'd test to see if the Circle of Willis is complete and if so then close up the offending artery so it can never throw a clot. My right carotid artery completely closed up after my stroke and thus I didn't have to worry about it. Now collaterals have formed around it. I never had any issues from lack of blood flow with only three arteries feeding my Circle of Willis.
Application of quantitative electroencephalography in predicting early cerebral ischemia in patients undergoing carotid endarterectomy
Guanxu Zhao†, 
Lei Zhao
Shuai Feng
Tianlong Wang- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University, Beijing, China
Background: Quantitative electroencephalography (QEEG) has emerged as a promising monitoring method in cerebral ischemia, but the feasibility of QEEG in intraoperative cerebral perfusion-related ischemia monitoring is still uncertain. The purpose of this study was to investigate the value of QEEG monitoring in Carotid Endarterectomy (CEA) and the thresholds for intraoperative cerebral perfusion-related ischemia monitoring.
Methods: Sixty-three patients who underwent carotid endarterectomy with continuous Transcranial Doppler ultrasound (TCD) monitoring and QEEG monitoring at Xuanwu Hospital Capital Medical University from January 2021 to August 2021 were enrolled in this study. Each patient received total intravenous anesthesia. Middle cerebral artery blood flow velocity (V-MCA) was obtained by TCD. Relative alpha percentage (RA) and alpha-delta ratio (ADR) were obtained by QEEG monitoring. Patients were divided into ischemic and non-ischemic groups using a decline of more than 50% in the V-MCA monitored by TCD as the gold standard.
Results: Of the 63 patients, twenty patients were divided into the ischemic group, and forty-three patients into the non-ischemic group. Ipsilateral post-clamp RA and ADR values of QEEG were decreased for all patients in the ischemic group. The optimal threshold for RA and ADR to predict cerebral ischemia was a 14% decrease from baseline (sensitivity 90.0%, specificity 90.7%, Kappa value 0.786), a 21% decrease from baseline (sensitivity 85.0%, specificity 81.4%, Kappa value 0.622), respectively, indicated by TCD monitoring.
Conclusions: Our study demonstrated that QEEG is a promising monitoring method undergoing CEA under general anesthesia and has good consistency with TCD.
Introduction
Worldwide, ischemic stroke accounts for about 68% and hemorrhagic stroke about 32%, while in China, the proportion of ischemic stroke is even more significant with 84%. Stroke is the second leading cause of death worldwide and the first leading cause of death in China (1–4). Stroke imposes a heavy burden on patients, families, and society. Therefore, prevention and treatment of stroke are of great importance.
About 10–20% of stroke is caused by carotid artery diseases, so timely intervention is crucial for the secondary or even primary prevention of stroke. Among the many factors leading to stroke, the degree of carotid artery stenosis is the most important determinant. Carotid endarterectomy (CEA) is a surgical method for reconstructing carotid blood flow and reducing the risk of stroke by removing calcified plaques inside vessels. Previous studies have confirmed that CEA has high benefits for patients with non-disabling stroke and severe carotid artery stenosis (70–99%), as well as patients with recent hemispheric and retina-related transient ischemic attack (TIA) (5–8). Although there are benefits for patients with severe stenosis, CEA requires temporary blocking of blood flow in one side of the carotid artery, which will lead to a significant reduction of cerebral blood flow at the clamping side of the hemisphere during CEA, and even ischemic stroke and other neurological adverse events. Previous studies have shown that 30 days perioperative stroke rates after CEA range between 2 and 6% (5, 9, 10). These make the benefits of patients dependent on the perioperative safety of CEA. In order to reduce the incidence of neurological adverse events during CEA and maximize the benefit of patients, intraoperative cerebral perfusion-related ischemia monitoring is essential. Intraoperative monitoring (IOM) can guide the surgeon to optimize surgical strategy and provide recommendations for shunting.
Many centers have used transcranial doppler (TCD) for IOM due to its convenient and non-invasive characteristics. However, TCD monitored the brain region with the middle cerebral artery as the blood supply and lack of monitoring in other areas. Besides, some patients don't have the appropriate temporal insonation window to be monitored with TCD. In recent years, Quantitative EEG (QEEG) has been attracting more and more attention as a new monitoring method (11, 12). QEEG uses Fourier transforms to quantify the raw EEG based on its amplitude, power, frequency, and rhythmicity to show numerical values, ratios or percentages, and a graphical display array or trend. It is now possible to calculate the ratio or percentage of α, β, θ, and δ power in a particular frequency band, such as relative alpha percentage (RA) and alpha-delta ratio (ADR), and these values can be compared between different regions, such as electrode pair channels. RA is the power of α wave as a percentage of power in 1–20 Hz band. ADR is the ratio of α wave power to δ wave power. Compared with raw EEG, one advantage of QEEG is that it allows for a more visual display of cerebral perfusion monitoring, another is that QEEG can monitor the whole brain perfusion, rather than only partial brain areas as TCD and cerebral oxygenation do. Laman et al. analyzed the value of QEEG parameters such as spectral edge frequency (SEF) and relative band power in predicting shunt in CEA. Kamitaki et al. evaluated the value of QEEG according to the responses of different QEEG parameters after carotid artery clamping during CEA under general anesthesia. Both of them obtained good results (13, 14). However, the two studies were retrospective, using EEG data from a database, and in Kamitaki's study, the grouping of patients is a subjective judgment by EEG physicians. At present, no specific threshold for QEEG changes in CEA has been proposed and there is no study on the combination of QEEG and TCD for cerebral perfusion during CEA.
The aim of the present study was to use a combination of QEEG and TCD to evaluate the feasibility of the new QEEG monitoring to monitor cerebral perfusion status during CEA, reducing the incidence of perioperative cerebral ischemia events.
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