Khoo Hui Ming, Hao Yongfu, von Ellenrieder Nicolás, Zazubovits Natalja, Hall Jeffery, Olivier André, Dubeau François, Gotman Jean
Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Japan.
Epilepsia. 2017 May;58(5):811-823. doi: 10.1111/epi.13717. Epub 2017 Mar 15.
Intracranial electroencephalography (EEG), performed presurgically in patients with drug-resistant and difficult-to-localize focal epilepsy, samples only a small fraction of brain tissue and thus requires strong hypotheses regarding the possible localization of the epileptogenic zone. EEG/fMRI (functional magnetic resonance imaging), a noninvasive tool resulting in hemodynamic responses, could contribute to the generation of these hypotheses. This study assessed how these responses, despite their interictal origin, predict the seizure-onset zone (SOZ).
We retrospectively studied 37 consecutive patients who underwent stereo-EEG (SEEG) and EEG/fMRI that resulted in significant hemodynamic responses. Hemodynamic response maps were co-registered to postimplantation anatomic imaging, allowing inspection of these responses in relation to SEEG electrode's location. The area containing the most significant t-value (primary cluster) explored with an electrode was assessed for concordance with SEEG-defined SOZ. Discriminant analysis was performed to distinguish the primary clusters having a high probability of localizing the SOZ.
Thirty-one patients had at least one study with primary cluster explored with an electrode, and 24 (77%) had at least one study with primary cluster concordant with the SOZ. Each patient could have multiple types of interictal discharge and therefore multiple studies. Among 59 studies from the 37 patients, 44 had a primary cluster explored with an electrode and 30 (68%) were concordant with the SOZ. Discriminant analysis showed that the SOZ is predictable with high confidence (>90%) if the primary cluster is highly significant and if the next significant cluster is much less significant or absent.
The most significant hemodynamic response to interictal discharges delineates the subset of the irritative zone that generates seizures in a high proportion of patients with difficult-to-localize focal epilepsy. EEG/fMRI generates responses that are valuable targets for electrode implantation and may reduce the need for implantation in patients in whom the most significant response satisfies the condition of our discriminant analysis.
对于药物难治性且难以定位的局灶性癫痫患者，术前进行的颅内脑电图（EEG）仅能采集一小部分脑组织样本，因此需要对致痫区的可能定位提出强有力的假设。EEG/功能磁共振成像（fMRI）是一种可产生血流动力学反应的非侵入性工具，可能有助于提出这些假设。本研究评估了这些尽管起源于发作间期的反应如何预测癫痫发作起始区（SOZ）。
我们回顾性研究了37例连续接受立体脑电图（SEEG）和EEG/fMRI检查且产生显著血流动力学反应的患者。将血流动力学反应图谱与植入后解剖成像进行配准，以便检查这些反应与SEEG电极位置的关系。评估用一个电极探索的包含最高显著t值的区域（主要簇）与SEEG定义的SOZ的一致性。进行判别分析以区分具有高概率定位SOZ的主要簇。
31例患者至少有一项研究用一个电极探索了主要簇，24例（77%）至少有一项研究的主要簇与SOZ一致。每位患者可能有多种发作间期放电类型，因此有多项研究。在这37例患者的59项研究中，44项用一个电极探索了主要簇，30项（68%）与SOZ一致。判别分析表明，如果主要簇高度显著且下一个显著簇显著程度低得多或不存在，则可高度自信地（>90%）预测SOZ。
发作间期放电最显著的血流动力学反应描绘了在很大一部分难以定位的局灶性癫痫患者中产生癫痫发作的刺激区子集。EEG/fMRI产生的反应是电极植入的有价值靶点，对于最显著反应满足我们判别分析条件的患者，可能减少植入需求。
