Department of Neurosurgery, Osaka University Medical School, Suita, Osaka, Japan.
J Neurosurg. 2010 Mar;112(3):528-38. doi: 10.3171/2009.7.JNS09239.
Event-related cerebral oscillatory changes reflect regional brain activation. In a previous study, the authors proposed a new method to determine language dominance: examine frontal oscillatory changes during silent reading by using synthetic aperture magnetometry (SAM). The authors' aims in the present study were to establish a normal template for this method, to confirm the results of their previous study with a larger patient population, and to evaluate their method with respect to language localization.
A statistical group analysis of 14 healthy volunteers was conducted to establish a normal control. Language dominance and localization were then evaluated in a larger population of 123 consecutive patients. Study participants were instructed to silently read 100 visually presented words. Using SAM, the spatial distribution of the oscillatory changes was obtained as the Student t statistic by comparing the current density for each voxel between 1 second before and 1 second after each word presentation. Group analyses of the healthy volunteers were performed using statistical nonparametric mapping. Language dominance in the patients was determined according to the laterality index (LI) calculated using peak t values of the left and right frontal desynchronizations. Language dominance was prospectively assessed, and the results were compared with those of the Wada test (63 patients). Language localization results were quantitatively compared with those of stimulation mapping (17 patients).
Group analysis of the healthy volunteers indicated beta to low gamma band desynchronization in the left frontal area and alpha to beta desynchronization in the left parietotemporal areas. In patients, the frontal language areas were detected in 118 persons (95.9%). Lateralization of beta or low gamma desynchronization in the inferior or middle frontal gyri corresponded well with language dominance. The introduction of the LI resulted in a quantitative evaluation of language dominance, whose results were concordant with those of the Wada test in 51 (85.0%) of 60 cases. The distance between the estimated frontal language areas and stimulation-positive sites was 6.0 +/- 7.1 mm (mean +/- SD).
This study is the first in which magnetoencephalography (MEG) was used to determine language dominance in a large population, and the results were compared with those of the Wada test. Moreover, language localization results obtained using MEG were compared with those obtained by invasive mapping. The authors' method, which is based on neuromagnetic oscillatory changes, is a new approach for noninvasively evaluating the frontal language areas, a procedure that has been problematic using MEG dipole methods. Synthetic aperture magnetometry is a noninvasive alternative to Wada testing for language dominance and helps to determine stimulation sites for invasive mapping.
事件相关的大脑振荡变化反映了区域大脑激活。在之前的一项研究中，作者提出了一种新的方法来确定语言优势：通过使用合成孔径磁成像（SAM）检查默读期间的额部振荡变化。作者在本研究中的目的是为该方法建立一个正常模板，用更大的患者群体确认他们之前的研究结果，并评估他们的方法在语言定位方面的应用。
对 14 名健康志愿者进行统计组分析以建立正常对照。然后，对 123 例连续患者的更大人群进行语言优势和定位评估。研究参与者被指示默读 100 个视觉呈现的单词。使用 SAM，通过比较每个体素在每个单词呈现前 1 秒和后 1 秒的电流密度，获得振荡变化的空间分布作为学生 t 统计量。对健康志愿者的组分析使用统计非参数映射进行。根据左、右额去同步化的峰值 t 值计算的侧化指数（LI），确定患者的语言优势。前瞻性评估语言优势，并将结果与瓦达测试（63 例）进行比较。对刺激映射（17 例）的语言定位结果进行定量比较。
健康志愿者的组分析表明，左侧额区的β至低频γ带去同步化和左侧顶颞区的α至β去同步化。在患者中，118 人（95.9%）检测到额叶语言区。下或中额回β或低频γ去同步化的侧化与语言优势吻合良好。引入 LI 可对语言优势进行定量评估，其结果与 60 例中的 51 例（85.0%）瓦达测试结果一致。估计的额叶语言区与刺激阳性部位之间的距离为 6.0 +/- 7.1mm（平均值 +/- SD）。
这是首次使用脑磁图（MEG）在大人群中确定语言优势的研究，并与瓦达测试的结果进行了比较。此外，还比较了使用 MEG 获得的语言定位结果与使用侵袭性映射获得的结果。作者的方法基于神经磁振荡变化，是一种无创评估额叶语言区的新方法，这一过程使用 MEG 偶极子方法存在问题。合成孔径磁成像（SAM）是瓦达测试语言优势的替代方法，有助于确定侵袭性映射的刺激部位。
