From the Departments of Neurological Surgery (D.L.P., K.E.W., R.P.N., V.L.M., S.N., D.J.E.), Radiology and Radiological Sciences (V.L.M., D.J.E.), Biostatistics (V.L.M., S.W.R., D.J.E.), and Neurology (H.K.), Vanderbilt University Medical Center; Vanderbilt University Institute of Imaging Science (K.E.W., G.W.J., H.F.J.G., V.L.M., S.N., D.J.E.); Vanderbilt Institute for Surgery and Engineering (K.E.W., G.W.J., H.F.J.G., V.L.M., S.N., D.J.E.); Department of Biomedical Engineering (G.W.J., H.F.J.G., V.L.M., S.W.R., S.N., D.J.E.), Vanderbilt University, Nashville, TN; Departments of Neurosurgery and Biomedical Engineering (J.D.R.), University of Utah, Salt Lake City; and Department of Pediatrics (S.B.R.), Vanderbilt Children's Hospital, Nashville, TN.
Neurology. 2022 May 17;98(20):e2060-e2072. doi: 10.1212/WNL.0000000000200386. Epub 2022 Mar 25.
Functional connectivity (FC) measures can be used to differentiate epileptogenic zones (EZs) from non-EZs in patients with medically refractory epilepsy. Little work has been done to evaluate the stability of stereo-EEG (SEEG) FC measures over time and their relationship with antiseizure medication (ASM) use, a critical confounder in epilepsy FC studies. We aimed to answer the following questions: Are SEEG FC measures stable over time? Are they influenced by ASMs? Are they affected by patient data collection state?
In 32 patients with medically refractory focal epilepsy, we collected a single 2-minute prospective SEEG resting-state (awake, eyes closed) data set and consecutive 2-minute retrospective pseudo-rest (awake, eyes open) data sets for days 1-7 postimplantation. ASM dosages were recorded for days 1-7 postimplantation and drug load score (DLS) per day was calculated to standardize and compare across patients. FC was evaluated using directed and nondirected measures. Standard clinical interpretation of ictal SEEG was used to classify brain regions as EZs and non-EZs.
Over 7 days, presumed EZs consistently had higher FC than non-EZs when using between imaginary coherence (ImCoh) and partial directed coherence (PDC) inward strength, without accounting for DLS. These measures were demonstrated to be stable over a short-term period of 3 consecutive days with the same DLS. Between ImCoh FC differences between EZs and non-EZs were reduced with DLS decreases, whereas other measures were not affected by DLS. FC differences between EZs and non-EZs were seen during both resting-state and pseudo-rest conditions; ImCoh values were strongly correlated between the 2 conditions, whereas PDC values were not.
Inward and nondirected SEEG FC is higher in presumed EZs vs non-EZs and measures are stable over time. However, certain measures may be affected by ASM dose, as between ImCoh differences between EZs and non-EZs are less pronounced with lower doses, and other measures such as PDC are poorly correlated across recording conditions. These findings allow novel insight into how SEEG FC measures may aid surgical localization and how they are influenced by ASMs and other factors.
功能连接（FC）测量可用于区分药物难治性癫痫患者的致痫区（EZ）与非致痫区（EZ）。很少有研究评估立体脑电图（SEEG）FC 测量值随时间的稳定性及其与抗癫痫药物（ASM）使用的关系，ASM 是癫痫 FC 研究中的一个关键混杂因素。我们旨在回答以下问题：SEEG FC 测量值随时间稳定吗？它们是否受 ASM 影响？它们是否受患者数据采集状态影响？
在 32 名药物难治性局灶性癫痫患者中，我们在植入后第 1-7 天收集了单次 2 分钟的前瞻性 SEEG 静息态（清醒，闭眼）数据集和连续 2 分钟的回顾性假性静息（清醒，睁眼）数据集。记录植入后第 1-7 天的 ASM 剂量，并计算每天的药物负荷评分（DLS）以标准化并比较患者间差异。使用定向和非定向测量来评估 FC。使用发作期 SEEG 的标准临床解释将脑区分类为 EZ 和非-EZ。
在 7 天内，使用虚构相干（ImCoh）和部分定向相干（PDC）内向强度时，与非 EZ 相比，假定的 EZ 始终具有更高的 FC，而不考虑 DLS。这些措施在 3 天的短期时间内表现出稳定性，且 DLS 相同。随着 DLS 的降低，EZ 和非 EZ 之间的 ImCoh FC 差异减小，而其他措施不受 DLS 影响。在静息态和假性静息条件下均观察到 EZ 和非 EZ 之间的 FC 差异；2 种条件之间的 ImCoh 值相关性很强，而 PDC 值则不然。
与非 EZ 相比，假定的 EZ 中的内向和非定向 SEEG FC 更高，并且随时间稳定。然而，某些措施可能会受到 ASM 剂量的影响，因为随着剂量的降低，EZ 和非 EZ 之间的 ImCoh 差异不那么明显，而其他措施（如 PDC）在记录条件之间相关性较差。这些发现为我们提供了新的见解，了解 SEEG FC 测量如何有助于手术定位，以及它们如何受到 ASM 和其他因素的影响。
