van Putten Michel J A M, Peters Jurriaan M, Mulder Sandra M, de Haas Jan A M, Bruijninckx Cornelis M A, Tavy Dénes L J
Department of Neurology and Clinical Neurophysiology, Ziekenhuis Leyenburg, Leyweg 275, 2545 CH The Hague, The Netherlands.
Clin Neurophysiol. 2004 May;115(5):1189-94. doi: 10.1016/j.clinph.2003.12.002.
Carotid endarterectomy is a common procedure as a secondary prevention of stroke, and one of the early controversies in carotid surgery is centered around whether a shunt should be used during this procedure. Although various EEG parameters have been proposed to determine if the brain is at risk during carotid artery clamping, the common procedure is still the visual assessment of the EEG. We propose a brain symmetry index (BSI), that has been implemented as an on-line quantitative EEG parameter, as an additional criterion for shunt need in carotid endarterectomy.
The BSI captures a particular asymmetry in spectral power between the two cerebral hemispheres, and is normalized between 0 (perfect symmetry) and 1 (maximal asymmetry). The index was evaluated retrospectively in a group of 57 operations in which the EEG and the transcranial Doppler were used as criteria for shunt insertion. In addition, after online implementation of the algorithm, several patients have been evaluated prospectively.
If no visual EEG changes were detected, it was found that the change in BSI from baseline, DeltaBSI<or=0.03 in all patients. In none of these patients shunting was performed, except for 11 in whom shunting was advised based on changes in the transcranial Doppler signal. None of these patients suffered from neurological complications. In those operations with visual EEG changes during test-clamping and selective shunting, we found that DeltaBSI>or=0.06. In this group, one patient suffered from intraoperative stroke and one patient died, most likely from a hyperperfusion syndrome.
The BSI may assist in the visual EEG analysis during carotid endarterectomy and provides a quantitative measure for electroencephalographic asymmetry due to cerebral hypo-perfusion. In patients with a change in the BSI (DeltaBSI) smaller than 0.03 during test clamping, visual EEG analysis showed no changes, whereas if visual EEG analysis did warrant shunting, it was found that DeltaBSI>or=0.06.
颈动脉内膜切除术是预防中风的常见二级预防手术，颈动脉手术早期的争议之一集中在该手术过程中是否应使用分流管。尽管已经提出了各种脑电图参数来确定在颈动脉夹闭期间大脑是否处于危险中，但常见的做法仍是对脑电图进行视觉评估。我们提出了一种脑对称指数（BSI），它已被用作在线定量脑电图参数，作为颈动脉内膜切除术中分流需求的附加标准。
BSI捕捉两个大脑半球之间频谱功率的特定不对称性，并在0（完美对称）和1（最大不对称）之间进行归一化。该指数在一组57例手术中进行了回顾性评估，这些手术中脑电图和经颅多普勒被用作分流管插入的标准。此外，在算法在线实施后，对几名患者进行了前瞻性评估。
如果未检测到脑电图的视觉变化，发现在所有患者中，BSI相对于基线的变化，即DeltaBSI≤0.03。除了11名根据经颅多普勒信号变化建议进行分流的患者外，这些患者均未进行分流。这些患者均未出现神经并发症。在试验夹闭和选择性分流期间脑电图有视觉变化的手术中，我们发现DeltaBSI≥0.06。在该组中，一名患者发生术中中风，一名患者死亡，很可能死于高灌注综合征。
BSI可能有助于颈动脉内膜切除术期间的脑电图视觉分析，并为脑灌注不足引起的脑电图不对称提供定量测量。在试验夹闭期间BSI（DeltaBSI）变化小于0.03的患者中，脑电图视觉分析未显示变化，而如果脑电图视觉分析确实需要分流，则发现DeltaBSI≥0.06。
