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Network connectivity predicts effectiveness of responsive neurostimulation in focal epilepsy
网络连通性可预测反应性神经刺激对局灶性癫痫的疗效

Joline M. Fan, Anthony T. Lee, Kiwamu Kudo, Kamalini G. Ranasinghe, Hirofumi Morise, Anne M. Findlay, Heidi E. Kirsch, Edward F. Chang, Srikantan S. Nagarajan, Vikram R. Rao
Joline M. Fan, Anthony T. Lee, Kiwamu Kudo, Kamalini G.Ranasinghe, Hirofumi Morise, Anne M. Findlay, Heidi E. Kirsch, Edward F. Chang, Srikantan S. Nagarajan, Vikram R. Rao

Network connectivity predicts effectiveness of responsive neurostimulation in focal epilepsy
网络连通性可预测反应性神经刺激对局灶性癫痫的疗效

OJoline M. Fan,' Anthony T. Lee, Kiwamu Kudo,, 4 - Kamalini G. Ranasinghe, '
OJoline M. Fan、' Anthony T. Lee、 Kiwamu Kudo、, 4 - Kamalini G.Ranasinghe, '
Hirofumi Morise, Anne M. Findlay, Heidi E. Kirsch, Edward F. Chang,
Hirofumi Morise, Anne M. Findlay, Heidi E. Kirsch, Edward F. Chang、
Srikantan S. Nagarajan and Vikram R. Rao"*
Srikantan S. Nagarajan 和 Vikram R. Rao "*

\author{ \作者{
  • Co-senior authors.  共同第一作者
    See Hitten Zaveri (https://doi.org/10.1093/braincomms/fcac114) for a scientific commentary on this article.
    关于这篇文章的科学评论,请参阅 Hitten Zaveri ( https://doi.org/10.1093/braincomms/fcac114)。

    }
Responsive neurostimulation is a promising treatment for drug-resistant focal epilepsy; however, clinical outcomes are highly variable across individuals. The therapeutic mechanism of responsive neurostimulation likely involves modulatory effects on brain networks; however, with no known biomarkers that predict clinical response, patient selection remains empiric. This study aimed to determine whether functional brain connectivity measured non-invasively prior to device implantation predicts clinical response to responsive neurostimulation therapy. Resting-state magnetoencephalography was obtained in 31 participants with subsequent responsive neurostimulation device implantation between 15 August 2014 and 1 October 2020. Functional connectivity was computed across multiple spatial scales (global, hemispheric, and lobar) using pre-implantation magnetoencephalography and normalized to maps of healthy controls. Normalized functional connectivity was investigated as a predictor of clinical response, defined as percent change in self-reported seizure frequency in the most recent year of clinic visits relative to pre-responsive neurostimulation baseline. Area under the receiver operating characteristic curve quantified the performance of functional connectivity in predicting responders ( reduction in seizure frequency) and non-responders ( . Leave-one-out cross-validation was furthermore performed to characterize model performance. The relationship between seizure frequency reduction and frequency-specific functional connectivity was further assessed as a continuous measure. Across participants, stimulation was enabled for a median duration of 52.2 (interquartile range, 27.0-62.3) months. Demographics, seizure characteristics, and responsive neurostimulation lead configurations were matched across 22 responders and 9 non-responders. Global functional connectivity in the alpha and beta bands were lower in non-responders as compared with responders (alpha, ; beta, ). The classification of responsive neurostimulation outcome was improved by combining feature inputs; the best model incorporated four features (i.e. mean and dispersion of alpha and beta bands) and yielded an area under the receiver operating characteristic curve of . The leave-one-out cross-validation analysis of this four-feature model yielded a sensitivity of , specificity of , positive predictive value of , and negative predictive value of . Global functional connectivity in alpha band correlated with seizure frequency reduction (alpha, ). Global functional connectivity predicted responder status more strongly, as compared with hemispheric predictors. Lobar functional connectivity was not a predictor. These findings suggest that non-invasive functional connectivity may be a candidate personalized biomarker that has the potential to predict responsive neurostimulation effectiveness and to identify patients most likely to benefit from responsive neurostimulation therapy. Follow-up large-cohort, prospective studies are required to validate this biomarker. These findings furthermore support an emerging view that the therapeutic mechanism of responsive neurostimulation involves network-level effects in the brain.
反应性神经刺激是治疗耐药性局灶性癫痫的一种很有前景的方法;然而,不同个体的临床结果差异很大。反应性神经刺激的治疗机制可能涉及对大脑网络的调节作用;然而,由于没有预测临床反应的已知生物标志物,患者的选择仍然是经验性的。本研究旨在确定在设备植入前进行的非侵入性脑功能连接测量是否能预测反应性神经刺激疗法的临床反应。在2014年8月15日至2020年10月1日期间,对31名随后植入反应性神经刺激设备的参与者进行了静息态脑磁图测量。利用植入前脑磁图计算了多个空间尺度(全局、半球和脑叶)的功能连通性,并与健康对照组的脑磁图进行归一化处理。归一化功能连通性作为临床反应的预测因子进行了研究,临床反应定义为最近一年门诊中自我报告的癫痫发作频率相对于反应前神经刺激基线的百分比变化。接收器操作特征曲线下面积量化了功能连通性在预测应答者( ,癫痫发作频率减少)和非应答者( ,癫痫发作频率减少)方面的性能。此外,还进行了留空交叉验证,以确定模型的性能。癫痫发作频率减少与频率特异性功能连通性之间的关系作为连续测量指标得到了进一步评估。所有参与者接受刺激的中位持续时间为 52.2 个月(四分位间范围为 27.0-62.3 个月)。22 名应答者和 9 名无应答者的人口统计学特征、癫痫发作特征和应答神经刺激导联配置相匹配。与应答者相比,非应答者α和β波段的整体功能连接性较低(α, ;β, )。通过组合特征输入,神经刺激反应性结果的分类得到了改善;最佳模型包含四个特征(即阿尔法和贝塔波段的平均值和离散度),接收者操作特征曲线下的面积为 。对这一四特征模型进行一出交叉验证分析得出的灵敏度为 ,特异性为 ,阳性预测值为 ,阴性预测值为 。阿尔法波段的全局功能连通性与癫痫发作频率降低相关(阿尔法, )。与半球预测因子相比,全局功能连通性对反应者状态的预测更强。 脑叶功能连通性不是一个预测指标。这些研究结果表明,非侵入性功能连接可能是一种候选的个性化生物标志物,有可能预测反应性神经刺激的有效性,并识别出最有可能从反应性神经刺激治疗中获益的患者。要验证这一生物标志物,还需要进行大队列、前瞻性的随访研究。这些发现进一步支持了一种新的观点,即反应性神经刺激的治疗机制涉及大脑中的网络级效应。
1 Department of Neurology and Weill Institute for Neurosciences, University of California San Francisco, San Francisco, CA, USA
1 美国加利福尼亚州旧金山,加州大学旧金山分校神经病学系和威尔神经科学研究所
2 Department of Neurosurgery, University of California San Francisco, San Francisco, CA, USA
2 美国加利福尼亚州旧金山加利福尼亚大学旧金山分校神经外科系
3 Medical Imaging Center, Ricoh Company, Ltd., Kanazawa, Japan
3 日本金泽理光株式会社医学影像中心
4 Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, USA
4 美国旧金山加州大学放射学和生物医学成像系
Correspondence to: Joline M. Fan, MD, MS
通讯作者:Joline M. Fan, MD, MSJoline M. Fan, MD, MS
University of California, San Francisco
加州大学旧金山分校
Department of Neurology and Weill Institute for Neurosciences
神经病学系和威尔神经科学研究所
505 Parnassus Ave, Box 0114
San Francisco, CA 94158, USA
美国加利福尼亚州旧金山 94158
E-mail: joline.fan@ucsf.edu
电子邮件: joline.fan@ucsf.edu
Keywords: RNS system; neuromodulation; imaginary coherence; functional connectivity; magnetoencephalography
关键词RNS 系统;神经调节;假想相干性;功能连接;脑磁图
Abbreviations: antiseizure medication; area under the receiver operating characteristic curve; functional connectivity; false discovery rate; intracranial electroencephalography; interquartile range; leave-one-out cross-validation; magnetoencephalography; negative predictive value; non-responder; positive predictive value; responder; receiver operating characteristic; region of interest; responsive neurostimulation; standard deviation; seizure onset zone
缩写: 抗癫痫药物; 接收者操作特征曲线下面积; 功能连通性; 假发现率; 颅内脑电图; 四分位数间范围; 一出交叉验证; 脑磁图; 阴性预测值; 无反应者; 阳性预测值; 有反应者; 接收者操作特征; 感兴趣区; 有反应的神经刺激; 标准偏差; 癫痫发作区

Graphical Abstract 图表摘要

31 Patients with presurgical magnetoencephalography, undergo chronic Responsive neurostimulation therapy
31 手术前接受脑磁图检查的患者,接受慢性反应性神经刺激治疗
  1. Compute functional connectivity and normalize to healthy cohort
    计算功能连通性,并与健康队列标准化
  1. Compare responders and non-responders
    比较应答者和非应答者

3) Classification and comparison of functional connectivity with seizure frequency
3) 功能连通性与癫痫发作频率的分类和比较

Depicting truncated methodology and findings. Thirtyne patients underwent presurgical magnetoencephalography (MEG) evaluation prior to responsive neurostimulation (RNS) implantation. First, resting-tate functional connectivity was computed based on presurgical MEG and normalized to healthy individuals. Second, averaged functional connectivity between RNS responders and non-esponders were compared. Third, the classification performance using functional connectivity and the relationship between seizure reduction and functional connectivity were evaluated.
描述截断的方法和研究结果。三十名患者在接受反应性神经刺激(RNS)植入手术前接受了脑磁图(MEG)评估。首先,根据手术前的脑磁图计算静息态功能连接,并与健康人进行归一化。其次,比较 RNS 响应者和非响应者之间的平均功能连接。第三,评估了使用功能连通性进行分类的性能以及癫痫发作减少与功能连通性之间的关系。

Introduction 导言

Of the 46 million people worldwide with active epilepsy, approximately one-third have seizures that are incompletely controlled with medications. For many of these individuals with drug-resistant epilepsy, surgical resection of seizureproducing brain tissue has the potential to yield seizure freedom. However, resection may not be feasible in patients with multiple seizure foci or seizures that arise from critical brain regions. In these cases, implanted neurostimulation devices, such as the responsive neurostimulation (RNS®) system, represent promising treatment alternatives. In a recent prospective study, treatment with the RNS system demonstrated progressive clinical benefit with a median reduction in seizure frequency of after nine years.
在全球 4600 万活动性癫痫患者中, ,约有三分之一的癫痫发作无法完全通过药物控制。对于其中许多耐药癫痫患者来说,手术切除产生癫痫发作的脑组织有可能使他们摆脱癫痫发作。 然而,对于有多个癫痫发作灶或癫痫发作来自重要脑区的患者来说,切除手术可能并不可行。在这种情况下,植入式神经刺激装置(如反应性神经刺激 (RNS®) 系统)是一种很有前景的替代治疗方法。在最近的一项前瞻性研究中,使用 RNS 系统进行治疗显示出了渐进的临床疗效,九年后癫痫发作频率的中位数减少了
Although median outcomes in clinical trials are encouraging, response to RNS therapy is highly variable across individuals. While over a third of patients experience dramatic improvement with reductions in seizure frequency exceeding , nearly a quarter of patients are non-responders, exhibiting seizure frequency reduction. Owing to a lack of methods to prognosticate even such extreme outcomes, patient selection for RNS in contemporary practice is largely empiric. Indeed, response does not appear to depend on age at seizure onset, seizure onset zone (SOZ) location, brain imaging abnormalities, or the number of seizure foci. Similar to all invasive therapies, implantation of the RNS system is associated with morbidity for patients and substantial costs to the medical system. The desire to minimize ineffective implants creates a critical need for biomarkers that reveal which patients are most and least likely to benefit from RNS therapy.
尽管临床试验的中位结果令人鼓舞,但不同患者对 RNS 治疗的反应却千差万别。虽然超过三分之一的患者病情得到显著改善,癫痫发作频率减少超过 ,但近四分之一的患者无应答,癫痫发作频率减少 由于缺乏方法来预测即使是如此极端的结果,因此在当代的临床实践中,RNS 患者的选择在很大程度上是经验性的。 事实上,反应似乎并不取决于癫痫发作时的年龄、癫痫发作区(SOZ)位置、脑成像异常或癫痫发作灶的数量。 与所有侵入性疗法类似,植入 RNS 系统也会给患者带来发病率,并给医疗系统带来巨大成本。 为了尽量减少无效植入,亟需生物标志物来揭示哪些患者最有可能或最不可能从 RNS 治疗中获益。
Recently, electrographic biomarkers of clinical response have been identified in RNS system electrocorticograms and in pre-implant intracranial electroencephalography (iEEG). These biomarkers derive from invasive recordings and spatially restricted sampling of the epileptogenic network, limiting their clinical utility. An ideal biomarker would be measurable non-invasively, before device implantation, and would not depend on the specific brain regions sampled by intracranial electrodes.
最近,在 RNS 系统皮层电图 和植入前颅内脑电图 (iEEG) 中发现了临床反应的电图生物标志物。 这些生物标记源于侵入性记录和致痫网络的空间受限取样,限制了其临床实用性。理想的生物标志物应该是在设备植入前就能进行非侵入性测量,并且不依赖于颅内电极采样的特定脑区。
Physiological mechanisms underlying the efficacy of RNS are incompletely understood, however, given the protracted time course of clinical response, they likely involve plasticity and gradual restructuring of the epileptogenic network. Growing evidence for network-level effects of chronic neurostimulation suggests that intrinsic network connectivity may mediate the effects of neurostimulation and help determine the potential for long-term evolution of the network. As such, we hypothesized that different patterns of network functional connectivity, readily assayed by resting-state magnetoencephalography (MEG), may confer differential susceptibility to chronic neurostimulation and thereby help predict the effectiveness of RNS therapy. To test this hypothesis, we examined a retrospective cohort of patients treated with the RNS system and evaluated their clinical outcomes in relation to resting-state FC measured by MEG prior to device implantation.
目前对 RNS 疗效的生理机制尚不完全清楚, ,但鉴于临床反应的时间过程较长,这些机制很可能涉及可塑性和致痫网络的逐步重组。 越来越多的证据表明,慢性神经刺激的网络级效应 表明,内在的网络连通性可能会介导神经刺激的效应,并有助于确定网络长期演变的潜力。因此,我们假设,不同的网络功能连通性模式很容易通过静息态脑磁图(MEG)进行评估,它们可能会对慢性神经刺激产生不同的易感性,从而有助于预测 RNS 治疗的效果。为了验证这一假设,我们对接受 RNS 系统治疗的患者进行了回顾性队列研究,并评估了他们的临床疗效与设备植入前 MEG 测量的静息态 FC 的关系。

Methods 方法

Study cohort 研究队列

All patients who had MEG imaging and were subsequently implanted with the RNS system (NeuroPace, Inc., Mountain View, CA) between 15 August 2014 and 1 October 2020 at UCSF Medical Center were considered for inclusion in this study. Two patients were excluded because they were seizure-free after implantation and RNS stimulation was never enabled. One patient was excluded due to stimulation-related side effects, preventing stimulation from being enabled as intended. The remaining patients were analyzed in this study. In addition, a subgroup analysis was performed on a subset of patients who did not undergo concurrent resective surgery . An intention-to-treat analysis was furthermore performed on all patients , including the three patients who were excluded in the primary analysis due to stimulation not being enabled or not active on both leads.
所有在 2014 年 8 月 15 日至 2020 年 10 月 1 日期间在加州大学旧金山分校医疗中心接受 MEG 成像检查并随后植入 RNS 系统(NeuroPace, Inc., Mountain View, CA)的患者 都被考虑纳入本研究。有两名患者因植入后无癫痫发作且从未启用 RNS 刺激而被排除在外。一名患者因与刺激相关的副作用而被排除在外,导致刺激无法如期启用。本研究对其余患者 进行了分析。此外,还对未同时接受切除手术的患者进行了亚组分析 。此外,还对所有患者进行了意向治疗分析 ,包括在主要分析中因刺激未启用或双侧导联均未激活而被排除在外的三名患者。
Age-matched healthy controls were recruited from the community with eligibility criteria including normal cognition, normal MRI, and absence of neurological or psychiatric illness. Data collection and analysis of MEG and RNS data were approved by the UCSF Institutional Review Board Committee, and all patients provided written consent for the analyses performed in this study.
年龄匹配的健康对照组 从社区招募,资格标准包括认知正常、磁共振成像正常、无神经或精神疾病。MEG 和 RNS 数据的收集和分析已获得加州大学旧金山分校机构审查委员会的批准,所有患者都对本研究中的分析提供了书面同意。

Magnetoencephalography data acquisition and preprocessing
脑磁图数据采集和预处理

All participants in the epilepsy cohort underwent a , clinically indicated routine EEG/MEG recording in the UCSF Biomagnetic Imaging Laboratory, using a whole-head MEG system (CTF, Port Coquitlam, British Columbia, Canada) comprising 275 axial gradiometers. Fiducial coils over the nasion and bilateral preauricular points were used to align the head position within the sensory array and to co-register MEG data with an individual's brain MRI. Age-matched controls underwent a shorter MEG recording session lasting 5 . All participants were required to be awake and interactive immediately prior to the recording session. Participants were then instructed to rest quietly in the scanner with eyes closed during the recording. MEG recording sessions were performed while the participants were on their normal antiseizure medications (ASMs); participants who were cognitively altered from their baseline or who had a seizure before or during MEG recording were not included in this study.
癫痫队列中的所有参与者都在加州大学旧金山分校生物磁成像实验室(UCSF Biomagnetic Imaging Laboratory)接受了由 275 个轴向梯度仪组成的全头 MEG 系统(CTF,加拿大不列颠哥伦比亚省高贵林港) 、临床指示的常规 EEG/MEG 记录。鼻翼和双侧耳前点上的靶线圈用于对准感觉阵列中的头部位置,并将 MEG 数据与个人的脑核磁共振成像共同注册。年龄匹配的对照组进行了一次较短的 MEG 记录,持续时间为 5 。记录前,所有参与者都必须保持清醒并进行互动。然后,参与者被要求在记录期间闭眼在扫描仪中安静休息。MEG 记录过程是在参试者正常服用抗癫痫药物 (ASM) 的情况下进行的;在 MEG 记录之前或期间出现认知改变或癫痫发作的参试者不包括在本研究中。
Raw EEG/MEG traces were parsed into 15 s epochs. Each segment was directly visualized, and any segments with movement/electrical artifact or epileptiform discharges were removed from the data set. The first six epochs to represent an awake, artifact-free and epileptiform discharge-
原始的 EEG/MEG 曲线被解析为 15 秒的时间片段。每个片段都被直接可视化,任何有运动/电伪影或痫样放电的片段都会从数据集中删除。前六个时程代表一个清醒的、无 伪影和癫痫样放电的时程。

free resting state were included in the analysis. The epochs were concatenated to achieve a 90 s time series representing the resting state. Prior work has demonstrated that of resting-state data reliably achieves stationarity. In select patients, a dual signal subspace project filter was used to remove metallic artifact from non-cranial implants. Source reconstruction was performed using an adaptive beamforming method to determine the voxel level time series from the sensor time series.
自由静息状态也包括在分析中。将 epochs 连接起来,得到一个代表静息状态的 90 秒时间序列。先前的研究表明, ,静息状态数据能可靠地实现静止性。 在选定的患者中,使用双信号子空间项目滤波器去除非颅内植入物的金属伪影。 使用自适应波束成形方法 进行信号源重建,以确定传感器时间序列的体素水平时间序列。

Magnetoencephalography network functional connectivity
脑磁图网络功能连接

Utilizing the Brainnetome atlas, the voxel level time series was mapped onto 218 cortical, atlas-based parcellations or regions of interest (ROIs). Time series per ROI were band-pass filtered into the following frequency bands: delta , theta , alpha , beta , and low gamma . Using the FieldTrip MATLAB Toolbox and custom built MATLAB tools, FC between ROIs were computed based on imaginary coherence, an established spectral coherence measure that is robust to volume conduction effects. The 218 cortical ROI level spatial maps were reduced in resolution to 44 modular ROI level maps to increase the signal to noise ratio, giving rise to 990 functional connections, which includes the averaged imaginary coherence within each module. To accommodate for the diverse locations of seizure foci and the native neurophysiologic features of each region, the FC maps of participants were normalized to that of healthy controls by z-scoring the FCs of each modular ROI-ROI connection to the corresponding modular ROI-ROI connections from a healthy cohort (Supplementary Fig. 1, ). The normalization processing enabled the identification of relative increases or decreases in network connectivity compared with a common basis.
利用 Brainnetome 图集, ,将体素水平的时间序列映射到 218 个基于图集的皮层扇区或感兴趣区(ROI)上。每个 ROI 的时间序列都经过带通滤波,分为以下频段:delta 、theta 、alpha 、beta 和低伽马 。使用 FieldTrip MATLAB 工具箱 和定制的 MATLAB 工具,根据假想相干性计算 ROI 之间的 FC,假想相干性是一种成熟的频谱相干性测量方法,对容积传导效应具有鲁棒性。 为了提高信噪比,将 218 个皮层 ROI 级空间图的分辨率降至 44 个模块 ROI 级地图,从而得到 990 个功能连接,其中包括每个模块内的平均虚相干性。为了考虑到癫痫发作灶的不同位置和每个区域的原生神经生理学特征,通过对每个模块化ROI-ROI连接的FC与健康组群中相应模块化ROI-ROI连接的FC进行z-评分,将参与者的FC图归一化为健康对照组的FC图(补充图1, )。通过归一化处理,可以识别与共同基础相比网络连通性的相对增加或减少。
FC was computed for global and regional (hemispheric and lobar) spatial representations. Global FC was computed by averaging -scores across all ROI-ROI interactions, spanning the whole brain for each participant. Hemispheric FC was computed as the mean -score within the relevant hemisphere. The relevant hemisphere is determined by the location of the RNS leads, which are placed at the hypothesized SOZ and are thus a marker of the suspected SOZ. If RNS leads were placed bilaterally, the hemispheric FCs were averaged across both hemispheres. Lobar FC was computed as the mean -scores within the lobe containing the RNS lead. If RNS leads involved two lobes, then the FCs per lobe were averaged together for each patient. The relevant lobe and hemisphere for each patient were determined by evaluating post-implantation CT scans and identifying the locations of active leads connected to the device.
全球和区域(半球和脑叶)空间表征的FC均已计算。全局FC的计算方法是对所有ROI-ROI相互作用的平均 -scores,涵盖每个参与者的整个大脑。半球 FC 是根据相关半球内的平均 - score 计算得出的。相关半球由 RNS 导联的位置决定,RNS 导联放置在假设的 SOZ 上,因此是可疑 SOZ 的标记。如果 RNS 导联放置在双侧,则计算两个半球 FC 的平均值。脑叶 FC 计算为包含 RNS 导联的脑叶的平均 -scores。如果 RNS 导联涉及两个脑叶,则将每个患者每个脑叶的 FC 取平均值。每位患者的相关脑叶和半球是通过评估植入后的 CT 扫描并确定与设备连接的有源导线位置来确定的。

Responsive neurostimulation outcomes
响应式神经刺激成果

Clinical outcomes were based on averaged patient-reported seizure frequency determined at the most recent clinic visit of two time-samplings performed across all patients between October 2020 through October 2021, to reduce the noise from single time-point measures. Only clinic visits that exceeded a minimum of 6 months after stimulation onset were included. Seizure frequency was quantified relative to their pre-implant baseline (average seizure frequency over the 3 months immediately preceding RNS system implantation). Two patients underwent resective surgery in the years following RNS implantation, due to persistent breakthrough seizures despite RNS therapy. For these two patients, seizure frequency was documented prior to the definitive resection, occurring 63.8 and 39.2 months after stimulation onset. Patient-reported seizure frequency is the most widely used metric to determine clinical response to RNS. For example, a participant who previously had seven seizures per week and now has three seizures per week is computed to have seizure frequency reduction, i.e. the difference between the current and baseline frequency divided by the baseline frequency. Categorical testing was performed based on the standard definitions of participants with reduction in seizure frequency as 'responders' and those with reduction in seizure frequency as 'non-responders'.
临床结果基于 2020 年 10 月至 2021 年 10 月期间对所有患者进行的两次时间取样中最近一次就诊时确定的患者报告的癫痫发作频率平均值,以减少单一时间点测量的噪声。仅纳入刺激开始后至少超过 6 个月的门诊。发作频率相对于植入前基线(植入 RNS 系统前 3 个月的平均发作频率)进行量化。有两名患者在植入 RNS 后的数年内接受了切除手术,原因是尽管接受了 RNS 治疗,但仍有持续的突破性癫痫发作。这两名患者的癫痫发作频率在明确的切除手术前均有记录,分别发生在刺激开始后的 63.8 个月和 39.2 个月。患者报告的癫痫发作频率是确定 RNS 临床反应最广泛使用的指标。 例如,一名参与者以前每周有 7 次癫痫发作,现在每周有 3 次,则计算 癫痫发作频率减少,即当前频率与基线频率之差除以基线频率。根据标准定义 进行分类测试,将癫痫发作频率减少 的参与者视为 "有反应者",将癫痫发作频率减少 的参与者视为 "无反应者"。

Statistical analysis 统计分析

The relationship between RNS outcomes and FC was assessed through both categorical and continuous statistical testing. The distributions of normalized imaginary coherence across all ROI-ROI interactions were obtained for each participant. Whole-brain spatial map visualizations depicted the mean imaginary coherence or -score for each ROI, i.e. the averaged interaction between the represented ROI and all other ROIs. To evaluate group-level statistics of imaginary coherence between responders and non-responders, statistical testing was performed using a linear mixed effects model (RStudio V 1.2.5033). The linear mixed effects model was performed for each frequency band and compared the -scored FCs between responders and non-responders with lobar ROI as a repeated measure. To account for multiple comparisons across frequency bands, we then applied a post hoc multiple comparison adjustment ( false discovery rate, FDR). Individual models were constructed for global and regional FC approaches.
通过分类和连续统计测试评估了 RNS 结果与 FC 之间的关系。每个受试者在所有 ROI-ROI 相互作用中的归一化假想相干性分布情况均已获得。全脑空间图可视化描述了每个ROI的平均假想相干性或 -score,即所代表的ROI与所有其他ROI之间相互作用的平均值。为了评估应答者和非应答者之间假想相干性的组级统计,使用线性混合效应模型(RStudio V 1.2.5033)进行了统计测试。线性混合效应模型针对每个频段进行,并比较 -评分的有反应者和无反应者的 FCs,以叶 ROI 作为重复测量。为了考虑各频段间的多重比较,我们进行了事后多重比较调整( false discovery rate, FDR)。我们为全局和区域 FC 方法分别建立了模型。
The distributions of ROI-ROI interactions were additionally represented by mean and SD. Receiver operating characteristic (ROC) curves were computed by sweeping through all classification thresholds to elucidate the decision boundary and trade-off between sensitivity and specificity. The area under the ROC curve (AUC) was calculated as a measure of binary classification performance aggregated across all thresholds. Confidence intervals were determined using 1000 bootstrap replicates. Multivariate logistic regression was used to combine multiple features into a classification model. Specifically, two logistic regression models were constructed to predict responder status using multivariate features of the mean FC of the alpha and beta bands (i.e. 2
此外,ROI-ROI 相互作用的分布还用平均值和标度表示。通过扫描所有分类阈值计算接收者操作特征曲线(ROC),以阐明决策边界以及灵敏度和特异性之间的权衡。计算 ROC 曲线下面积(AUC),以此衡量所有阈值的二元分类性能。置信区间是通过 1000 次引导复制确定的。 多变量逻辑回归用于将多个特征组合到分类模型中。具体来说,利用阿尔法和贝塔带平均 FC 的多变量特征(即 2)构建了两个逻辑回归模型来预测应答者状态。

features), as well as the mean and SD of alpha and beta FCs (i.e. 4 features). Using R (Rstudio V 1.2.5033), logistic regression models were constructed using the generalized linear model (glm) function with a binary outcome (i.e. setting family-type to binomial). Multivariate features were inputted as linear features for the binary outcome of responder or non-responder. Prediction scores were then obtained from the fitted logistic regression model via the predict.glm function.
特征),以及 alpha 和 beta FCs(即 4 个特征)的平均值和 SD 值。使用 R (Rstudio V 1.2.5033),利用广义线性模型 (glm) 函数构建二元结果的逻辑回归模型(即将家庭类型设置为二项式)。多变量特征作为线性特征输入,用于二元结果中的应答者或非应答者。然后通过 predict.glm 函数从拟合的逻辑回归模型中获得预测分数。
To assess further the logistic regression model performance, we performed leave-one-out cross-validation (LOOCV). The LOOCV was performed by splitting the observations into a training and testing set, in which all samples except for a single observation were used in the training set. The logistic regression model was constructed from the training set and tested on the single observation in the testing set. This process was iterated through all samples (e.g. 31 different models built on 30 samples), such that each sample served as the testing set. The accuracy, sensitivity, and specificity were computed. The optimal thresholds for class prediction were determined by maximizing the geometric mean of sensitivity and specificity. In addition, precision-recall curves were constructed based on LOOCV prediction scores and iterating across all classification thresholds to delineate the trade-off between precision and recall.
为了进一步评估逻辑回归模型的性能,我们进行了留一交叉验证(LOOCV)。LOOCV的方法是将观测数据分成训练集和测试集,其中训练集使用除单个观测数据外的所有样本。根据训练集构建逻辑回归模型,并在测试集中的单个观测值上进行测试。这一过程在所有样本中反复进行(例如,在 30 个样本中建立了 31 个不同的模型),因此每个样本都是测试集。计算准确率、灵敏度和特异性。通过最大化灵敏度和特异度的几何平均数,确定了类别预测的最佳阈值。此外,还根据 LOOCV 预测得分构建了精确度-召回率曲线,并在所有分类阈值之间进行迭代,以确定精确度和召回率之间的权衡。
Finally, a post analysis was performed to probe the association between mean/SD FC and RNS outcome as a continuous variable for frequency bands identified in the prior categorical analysis. The association was assessed using the Spearman rank correlation.
最后,针对先前分类分析中确定的频段,进行了 后分析,以探究作为连续变量的平均/标度 FC 与 RNS 结果之间的关联。相关性采用斯皮尔曼等级相关性进行评估。

Data Availability 数据可用性

The data that support the findings of this study are available from the corresponding author upon reasonable request.
支持本研究结果的数据可向相应作者索取。

Results 成果

Participant demographics and seizure characteristics
参与者的人口统计学特征和癫痫发作特征

Table 1 demonstrates demographics, seizure characteristics, and RNS lead configurations for all participants females), stratified by responder status. Mean age, duration of epilepsy, etiology, duration with RNS stimulation enabled, and baseline seizure frequency were not significantly different between responders and non-responders. There were no statistical differences in other characteristics, including seizure classification, lobar localization, RNS lead laterality, and prior or concurrent resection at the time of RNS implantation. In addition, there were no statistically significant differences between cohorts in the number or mechanism-of-action of ASMs used (Supplementary Fig. 2, Supplementary Table 1). One participant had bilateral mesial temporal lobe epilepsy. Indications for RNS in the other participants included involvement of eloquent cortex, multiple seizure foci, or regional neocortical epilepsy. Furthermore, as RNS leads are placed at the hypothesized SOZ, their locations serve as a proxy for the suspected SOZ. Demographics of the healthy controls were age and gender matched to the epilepsy cohort (Supplementary Table 2).
表 1 显示了所有参与者的人口统计学特征、癫痫发作特征和 RNS 导联配置( ,女性),并按应答者状态进行了分层。应答者和非应答者的平均年龄、癫痫持续时间、病因、启用 RNS 刺激的持续时间和基线发作频率没有显著差异。其他特征,包括癫痫发作分类、脑叶定位、RNS 导联偏侧、RNS 植入时是否已进行切除术等,均无统计学差异。此外,在使用的 ASM 数量或作用机制方面,各组间也无统计学差异(补充图 2,补充表 1)。一名参与者患有双侧颞叶中叶癫痫。其他参试者的 RNS 指征包括受累的强皮质、多个癫痫发作灶或区域性新皮质癫痫。 此外,由于 RNS 导联被放置在假定的 SOZ 上,因此其位置可作为疑似 SOZ 的代表。健康对照组的人口统计学特征 年龄和性别与癫痫队列相匹配(补充表 2)。

Spatial functional connectivity maps for responders and non-responders
应答者和非应答者的空间功能连接图

To quantify intrinsic network connectivity, spatial FC maps were computed for each participant using pre-implant MEG. Fig. 1A-C compare spatial maps of a representative responder and non-responder to spatial FC maps averaged across healthy controls. Relative to controls, elevated FC is observed in the alpha band of the example responder, whereas reduced FC is observed in alpha and beta bands of the example non-responder. Region-to-region FCs of participants were normalized to those of healthy controls to facilitate comparison across participants with diverse epileptogenic networks. Normalized region-to-region FC maps demonstrate elevated connectivity in the alpha band of the responder and reduced connectivity in the alpha and beta bands of the non-responder (Fig. 1D and E). Summary statistics of the distribution of normalized region-to-region FCs in alpha and beta bands demonstrate an increased mean and dispersion (standard deviation, SD) in the responder, as compared with the non-responder (Fig. 1D and E, inset).
为了量化内在网络连通性,我们使用植入前 MEG 计算了每位受试者的空间 FC 图。图 1A-C 将具有代表性的反应者和非反应者的空间图与健康对照组的平均空间 FC 图进行了比较。与对照组相比,在反应者的 alpha 波段观察到 FC 升高,而在非反应者的 alpha 和 beta 波段观察到 FC 降低。参与者的区域间 FC 与健康对照组的 FC 进行了归一化处理,以便于对具有不同致痫网络的参与者进行比较。归一化的区域到区域 FC 图显示,反应者 alpha 波段的连通性升高,而非反应者 alpha 和 beta 波段的连通性降低(图 1D 和 E)。α和β波段归一化区域到区域FC分布的汇总统计显示,与非反应者相比,反应者的平均值和离散度(标准偏差,SD)都有所增加(图1D和E,插图)。

Functional connectivity as a predictor of responder and non-responders
预测应答者和非应答者的功能连通性

Group-averaged spatial maps of normalized FCs demonstrated global network changes with responders exhibiting higher FC in alpha and beta bands as compared to nonresponders (Fig. 2A and B). Averaging the FCs across the global spatial maps, responders were found to have higher mean FC in the alpha, beta, and gamma bands, as compared with non-responders (Fig. 2C, alpha, p p ; beta, 0.001; gamma, . Responders had positive mean normalized FC in the alpha band, implying an increase in mean connectivity relative to healthy controls. In contrast, non-responders had negative mean normalized FCs in the alpha frequencies, suggesting an overall reduction in connectivity as compared to the healthy controls. Both responders and non-responders had negative mean normalized FC in the beta and gamma frequencies, but non-responders exhibited higher magnitudes, implying more severely disrupted connectivity.
归一化 FC 的组均值空间图显示了全球网络的变化,与非应答者相比,应答者在α和β波段表现出更高的 FC(图 2A 和 B)。将全局空间图中的 FC 平均化后发现,与非应答者相比,应答者在α、β 和γ 波段的平均 FC 更高(图 2C,α,p p ;β, 0.001;γ, 。应答者在α波段的平均归一化 FC 值为正,这意味着相对于健康对照组,应答者的平均连通性有所增加。与此相反,非应答者阿尔法频率的平均归一化 FC 值为负值,表明与健康对照组相比,其连接性总体上有所降低。应答者和非应答者在β和γ频率上的平均归一化FC均为负值,但非应答者的幅度更大,这意味着连接性受到了更严重的破坏。
Regional FC demonstrated less robust frequency-specific differentiation between responders and non-responders than global FC. Hemispheric FC did not yield statistical differences between responders and non-responders in the gamma band but continued to demonstrate a statistically significant increase in the alpha and beta bands in responders as compared with non-responders (alpha,
与全局 FC 相比,区域 FC 对有反应者和无反应者的频率特异性区分较弱。半球 FC 在伽马波段 上没有显示出应答者和非应答者之间的统计学差异,但在阿尔法和贝塔波段上,应答者与非应答者相比继续显示出显著的统计学差异(阿尔法波段:α;贝塔波段:β;阿尔法波段:α;贝塔波段:β)、
Table I Participant characteristics, stratified by responder (R) and non-responder (NR) status
表 I 按应答者(R)和非应答者(NR)状态分列的参与者特征
All participants
所有与会者
-values
Age, 0.349
Gender, F (%) 性别,女性(%) 0.704
Duration of epilepsy,
癫痫持续时间、
0.198
Duration stimulation enabled, mos
启用刺激的持续时间(月
0.948
Number of ASMs, no.
ASM 数量,编号
0.671
Etiology, no. (%) 病因,人数(%) 0.508
Cryptogenic II (50) -
Encephalitis I (4.5) I (II.I) -
AVM I (4.5) I (II.I) -
PVNH I (II.I) -
Genetic/developmental 遗传/发育 -
FCD -
Stroke I (3.2) I (II.I) -
Seizure type , no. (%)
癫痫发作类型 ,人数 (%)
0.079
FAS I (II.I) -
FIAS -
FBTC -
Baseline seizure frequency, per wk
基线发作频率,每周
0.070
RNS lead locations', no. (%)
RNS 牵头地点",人数(%)
0.233
Frontal -
Neocortical temporal 新皮层颞叶 -
Mesial temporal 颞中部 I (II.I) -
Insular -
Parietal II (35.5) -
Occipital -
Other I (3.2) I (4.5) -
Prior resection, Y (%)
切除术前,Y(%)
I (II.I) 0.379
Concurrent resection, Y (%)
同期切除术,Y(%)
0.677
RNS lead types, no. (%)
RNS 导联类型,数量(%)
0.569
Strips only -
Depths only I (3.2) I (4.5) -
Neocortical + Depth 新皮层 + 深度 I (II.I) -
RNS lead lateralization, no. (%)
RNS 导联侧向,人数(%)
0.459
Right -
Left -
Both I (II.I) -
Values for age, duration of epilepsy, duration stimulation enabled, and baseline seizure frequency are given in medians with interquartile ranges in parentheses. Values for number of ASMs are given in means with standard deviations in parentheses.
年龄、癫痫持续时间、启用刺激的持续时间和基线发作频率的数值以中位数表示,括号内为四分位数范围。ASM 次数的数值以均值表示,括号内为标准差。
Differences between ( seizure reduction) and NR ( seizure reduction). Statistical testing performed by the Wilcoxon-Mann-Whitney test for two-sample comparisons. Fisher's exact testing was performed for categorical testing; post hoc P-values from multiple comparison testing is provided if Fisher's exact testing met significance, . May include more than one type for individual participants.
( 癫痫发作减少)与 NR ( 癫痫发作减少)之间的差异。统计检验采用 Wilcoxon-Mann-Whitney 检验进行双样本比较。费舍尔精确检验用于分类检验;如果费舍尔精确检验具有显著性,则提供多重比较检验的事后 P 值, 。 单个参与者可能包含多个类型。
'Counts include each lead per participant.
计数包括每位参与者的每条线索。
antiseizure medications; arteriovenous malformation; periventricular nodular heterotopia; focal cortical dysplasia; FAS = focal aware seizure; focal impaired awareness seizure; focal to bilateral tonic-clonic seizure.
抗癫痫药物; 动静脉畸形; 室周结节性异位; 局灶性皮质发育不良;FAS = 局灶性意识发作; 局灶性意识障碍发作; 局灶性至双侧强直阵挛发作。
beta, . Although revealing similar trends, the lobar FC did not yield significant findings in any frequency band.
beta, 。虽然揭示了类似的趋势,但叶 FC 在任何频段都没有得出显著的结果。