1Department of Neurological Surgery and.
2Biomagnetic Imaging Laboratory, Department of Radiology and Biomedical Imaging, University of California, San Francisco, California.
J Neurosurg. 2020 Apr 3;134(3):1102-1112. doi: 10.3171/2020.1.JNS192267. Print 2021 Mar 1.
Gliomas are intrinsic brain tumors with the hallmark of diffuse white matter infiltration, resulting in short- and long-range network dysfunction. Preoperative magnetoencephalography (MEG) can assist in maximizing the extent of resection while minimizing morbidity. While MEG has been validated in motor mapping, its role in speech mapping remains less well studied. The authors assessed how the resection of intraoperative electrical stimulation (IES)-negative, high functional connectivity (HFC) network sites, as identified by MEG, impacts language performance.
Resting-state, whole-brain MEG recordings were obtained from 26 patients who underwent perioperative language evaluation and glioma resection that was guided by awake language and IES mapping. The functional connectivity of an individual voxel was determined by the imaginary coherence between the index voxel and the rest of the brain, referenced to its contralesional pair. The percentage of resected HFC voxels was correlated with postoperative language outcomes in tasks of increasing complexity: text reading, 4-syllable repetition, picture naming, syntax (SYN), and auditory stimulus naming (AN).
Overall, 70% of patients (14/20) in whom any HFC tissue was resected developed an early postoperative language deficit (mean 2.3 days, range 1-8 days), compared to 33% of patients (2/6) in whom no HFC tissue was resected (p = 0.16). When bifurcated by the amount of HFC tissue that was resected, 100% of patients (3/3) with an HFC resection > 25% displayed deficits in AN, compared to 30% of patients (6/20) with an HFC resection < 25% (p = 0.04). Furthermore, there was a linear correlation between the severity of AN and SYN decline with percentage of HFC sites resected (p = 0.02 and p = 0.04, respectively). By 2.2 months postoperatively (range 1-6 months), the correlation between HFC resection and both AN and SYN decline had resolved (p = 0.94 and p = 1.00, respectively) in all patients (9/9) except two who experienced early postoperative tumor progression or stroke involving inferior frontooccipital fasciculus.
Imaginary coherence measures of functional connectivity using MEG are able to identify HFC network sites within and around low- and high-grade gliomas. Removal of IES-negative HFC sites results in early transient postoperative decline in AN and SYN, which resolved by 3 months in all patients without stroke or early tumor progression. Measures of functional connectivity may therefore be a useful means of counseling patients about postoperative risk and assist with preoperative surgical planning.
神经胶质瘤是一种内在的脑肿瘤，其特征是弥漫性白质浸润，导致短程和长程网络功能障碍。术前脑磁图（MEG）可以帮助最大限度地扩大切除范围，同时最大限度地降低发病率。MEG 已在运动映射中得到验证，但其在言语映射中的作用仍研究较少。作者评估了通过 MEG 识别的术中电刺激（IES）阴性、高功能连接（HFC）网络部位的切除如何影响语言表现。
26 例患者接受了术前语言评估和胶质瘤切除术，这些患者在清醒语言和 IES 映射的指导下进行了手术，在这些患者中获得了静息状态、全脑 MEG 记录。通过索引体素与大脑其余部分之间的虚相干确定单个体素的功能连接，以其对侧体素为参考。切除 HFC 体素的百分比与术后语言任务的复杂程度相关：文本阅读、4 音节重复、图片命名、句法（SYN）和听觉刺激命名（AN）。
总体而言，70%（14/20）切除任何 HFC 组织的患者（平均 2.3 天，范围 1-8 天）术后出现早期语言缺陷，而未切除 HFC 组织的患者中只有 33%（2/6）（p=0.16）。当按切除的 HFC 组织量分叉时，切除 HFC 组织>25%的患者（3/3）在 AN 中均出现缺陷，而切除 HFC 组织<25%的患者中只有 30%（6/20）（p=0.04）。此外，AN 和 SYN 下降的严重程度与 HFC 部位切除百分比之间存在线性相关（p=0.02 和 p=0.04，分别）。术后 2.2 个月（范围 1-6 个月），所有患者（9/9）除 2 例因术后早期肿瘤进展或累及下额枕束的中风而外，HFC 切除与 AN 和 SYN 下降之间的相关性均已解决（p=0.94 和 p=1.00，分别）。
使用 MEG 的功能连接虚相干测量能够识别低级别和高级别神经胶质瘤内和周围的 HFC 网络部位。切除 IES 阴性的 HFC 部位会导致术后早期短暂的 AN 和 SYN 下降，所有患者在没有中风或早期肿瘤进展的情况下，在 3 个月内恢复。功能连接的测量值因此可能是向患者提供术后风险咨询的有用手段，并有助于术前手术计划。
