Leuthardt Eric C, Miller Kai, Anderson Nicholas R, Schalk Gerwin, Dowling Joshua, Miller John, Moran Daniel W, Ojemann Jeff G
Department of Neurological Surgery, University of Washington School of Medicine, Harborview Medical Center, Seattle, Washington, USA.
Neurosurgery. 2007 Apr;60(4 Suppl 2):260-70; discussion 270-1. doi: 10.1227/01.NEU.0000255413.70807.6E.
Electrocortical stimulation (ECS) has been well established for delineating the eloquent cortex. However, ECS is still coarse and inefficient in delineating regions of the functional cortex and can be hampered by after-discharges. Given these constraints, an adjunct approach to defining the motor cortex is the use of electrocorticographic signal changes associated with active regions of the cortex. The broad range of frequency oscillations are categorized into two main groups with respect to the sensorimotor cortex: low and high frequency bands. The low frequency bands tend to show a power reduction with cortical activation, whereas the high frequency bands show power increases. These power changes associated with the activated cortex could potentially provide a powerful tool in delineating areas of the motor cortex. We explore electrocorticographic signal alterations as they occur with activated regions of the motor cortex, as well as its potential in clinical brain mapping applications.
We evaluated seven patients who underwent invasive monitoring for seizure localization. Each patient had extraoperative ECS mapping to identify the motor cortex. All patients also performed overt hand and tongue motor tasks to identify associated frequency power changes in regard to location and degree of concordance with ECS results that localized either hand or tongue motor function.
The low frequency bands had a high sensitivity (88.9-100%) and a lower specificity (79.0-82.6%) for identifying electrodes with either hand or tongue ECS motor responses. The high frequency bands had a lower sensitivity (72.7-88.9%) and a higher specificity (92.4-94.9%) in correlation with the same respective ECS positive electrodes.
The concordance between stimulation and spectral power changes demonstrate the possible utility of electrocorticographic frequency alteration mapping as an adjunct method to improve the efficiency and resolution of identifying the motor cortex.
电皮质刺激（ECS）已被广泛用于描绘明确的皮质。然而，ECS在描绘功能皮质区域时仍然粗糙且效率低下，并且可能受到后放电的阻碍。鉴于这些限制，定义运动皮质的一种辅助方法是利用与皮质活跃区域相关的皮质电图信号变化。就感觉运动皮质而言，广泛的频率振荡可分为两个主要组：低频带和高频带。低频带往往随着皮质激活而显示功率降低，而高频带则显示功率增加。这些与激活皮质相关的功率变化可能为描绘运动皮质区域提供一个强大的工具。我们探讨了运动皮质激活区域出现的皮质电图信号改变及其在临床脑图谱应用中的潜力。
我们评估了7例接受侵入性监测以定位癫痫发作的患者。每位患者都进行了术中ECS图谱绘制以识别运动皮质。所有患者还执行了明显的手部和舌部运动任务，以确定与定位手部或舌部运动功能的ECS结果在位置和一致程度方面相关的频率功率变化。
低频带在识别与手部或舌部ECS运动反应相关的电极时具有较高的敏感性（88.9 - 100%）和较低的特异性（79.0 - 82.6%）。高频带与相同的各自ECS阳性电极相关时具有较低的敏感性（72.7 - 88.9%）和较高的特异性（92.4 - 94.9%）。
刺激与频谱功率变化之间的一致性表明，皮质电图频率改变图谱作为一种辅助方法，可能有助于提高识别运动皮质的效率和分辨率。
