Zaveri H P, Duckrow R B, de Lanerolle N C, Spencer S S
Department of Neurology, Yale University School of Medicine, New Haven, CT 06520-8018, U.S.A.
Epilepsia. 2001 Jun;42(6):725-30. doi: 10.1046/j.1528-1157.2001.00500.x.
Two subtypes of temporal lobe epilepsy (TLE) can be defined through clinical observations and analysis of hippocampal tissue resected during surgical procedures for intractable TLE: (a) mesial temporal sclerosis (MTS), which is characterized by extensive changes to the hippocampus and good surgical outcome; and (b) paradoxical temporal lobe epilepsy (PTLE), which is characterized by minimal cell loss and comparatively poorer surgical outcome. Patients in both subtypes have seizures that appear to begin in the medial temporal lobe, but documented differences in substrate and outcome between these subtypes has defined a need to distinguish MTS and PTLE patients before surgery. This report describes a retrospective study to investigate the feasibility of doing so during intracranial monitoring.
Background EEG epochs, 5 min in duration, were recorded from the anterior hippocampus in 14 (10 MTS and four PTLE) patients with consistent localization of seizure onset to medial temporal structures. The power spectral density (PSD) of the EEG epochs was calculated by a Fourier spectral estimator, and the total signal power and power of the delta, theta, alpha, beta, and gamma frequency bands were submitted to group-to-group comparison.
Spectral peaks were observed in the delta band in all PSD estimates and in the theta band in nine of 14 (seven MTS, two PTLE) estimates. The MTS and PTLE subtypes could be distinguished by the total signal power and delta band power. These power measurements were greater in the PTLE subtype.
Both delta and theta spectral components are present in hippocampal background EEGs recorded from patients with TLE. The results indicate that group differences exist in spectral measures of background hippocampal signals recorded from MTS and PTLE subtypes. This suggests both that substrate differences in cellular composition and connectivity are reflected in hippocampal background EEGs and that spectral measurements of these signals may hold promise for tests to identify the group membership of individual patients.
通过临床观察以及对难治性颞叶癫痫手术过程中切除的海马组织进行分析，可定义颞叶癫痫（TLE）的两种亚型：（a）内侧颞叶硬化（MTS），其特征为海马发生广泛改变且手术效果良好；（b）矛盾性颞叶癫痫（PTLE），其特征为细胞损失极少且手术效果相对较差。这两种亚型的患者发作似乎均起始于内侧颞叶，但这些亚型在发病机制和预后方面已证实存在差异，这表明在手术前区分MTS和PTLE患者很有必要。本报告描述了一项回顾性研究，以探讨在颅内监测期间进行此项区分的可行性。
从14例（10例MTS和4例PTLE）发作起始部位一致定位于内侧颞叶结构的患者的前海马记录持续5分钟的背景脑电图片段。通过傅里叶频谱估计器计算脑电图片段的功率谱密度（PSD），并将总信号功率以及δ、θ、α、β和γ频段的功率进行组间比较。
在所有PSD估计中均观察到δ频段的频谱峰值，在14例中的9例（7例MTS，2例PTLE）估计中观察到θ频段的频谱峰值。MTS和PTLE亚型可通过总信号功率和δ频段功率进行区分。这些功率测量值在PTLE亚型中更大。
TLE患者海马背景脑电图中同时存在δ和θ频谱成分。结果表明，从MTS和PTLE亚型记录的海马背景信号的频谱测量存在组间差异。这表明细胞组成和连接性的发病机制差异反映在海马背景脑电图中，并且这些信号的频谱测量可能有望用于识别个体患者所属组别的检测。
