Washington University School of Medicine, Washington University in St. Louis, St. Louis, Missouri 63110, USA.
Neurosurgery. 2010 Feb;66(2):E407-9. doi: 10.1227/01.NEU.0000345352.13696.6F.
Electrocortical stimulation (ECS) has long been established for delineating eloquent cortex in extraoperative mapping. However, ECS is still coarse and inefficient in delineating regions of functional cortex and can be hampered by afterdischarges. Given these constraints, an adjunct approach to defining motor cortex is the use of electrocorticographic (ECoG) signal changes associated with active regions of cortex. The broad range of frequency oscillations are categorized into 2 main groups with respect to sensorimotor cortex: low-frequency bands (LFBs) and high-frequency bands (HFBs). The LFBs tend to show a power reduction, whereas the HFBs show power increases with cortical activation. These power changes associated with activated cortex could potentially provide a powerful tool in delineating areas of speech cortex. We explore ECoG signal alterations as they occur with activated region of speech cortex and its potential in clinical brain mapping applications.
We evaluated 7 patients who underwent invasive monitoring for seizure localization. Each had extraoperative ECS mapping to identify speech cortex. Additionally, all subjects performed overt speech tasks with an auditory or a visual cue to identify associated frequency power changes in regard to location and degree of concordance with ECS results.
Electrocorticographic frequency alteration mapping (EFAM) had an 83.9% sensitivity and a 40.4% specificity in identifying any language site when considering both frequency bands and both stimulus cues. Electrocorticographic frequency alteration mapping was more sensitive in identifying the Wernicke area (100%) than the Broca area (72.2%). The HFB is uniquely suited to identifying the Wernicke area, whereas a combination of the HFB and LFB is important for Broca localization.
The concordance between stimulation and spectral power changes demonstrates the possible utility of EFAM as an adjunct method to improve the efficiency and resolution of identifying speech cortex.
电皮质刺激（ECS）长期以来一直被用于在手术外映射中描绘语言皮质。然而，ECS 在描绘功能皮质区域方面仍然粗糙且效率低下，并且可能会受到后放电的阻碍。鉴于这些限制，定义运动皮质的辅助方法是使用与皮质活跃区域相关的皮质电图（ECoG）信号变化。与感觉运动皮质有关的宽频带频率振荡可分为 2 个主要组：低频带（LFB）和高频带（HFB）。LFB 往往表现出功率降低，而 HFB 则随着皮质激活而显示功率增加。与激活皮质相关的这些功率变化可能为描绘言语皮质区域提供有力工具。我们探讨了 ECoG 信号变化，因为它们与言语皮质的激活区域一起发生，并探讨了其在临床大脑映射应用中的潜力。
我们评估了 7 名接受癫痫定位侵入性监测的患者。每位患者均进行了手术外 ECS 映射以识别言语皮质。此外，所有患者都进行了显性言语任务，用听觉或视觉提示来识别与 ECS 结果位置和一致性程度相关的相关频率功率变化。
考虑到两个频带和两个刺激提示，电皮质频率改变映射（EFAM）在识别任何语言部位时的灵敏度为 83.9％，特异性为 40.4％。EFAM 在识别 Wernicke 区（100％）比识别 Broca 区（72.2％）更敏感。HFB 特别适合识别 Wernicke 区，而 HFB 和 LFB 的组合对于 Broca 定位很重要。
刺激与光谱功率变化之间的一致性表明 EFAM 作为一种辅助方法具有可能的实用性，可以提高识别言语皮质的效率和分辨率。
