Jirsch J D, Urrestarazu E, LeVan P, Olivier A, Dubeau F, Gotman J
Montreal Neurological Institute and Hospital, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada.
Brain. 2006 Jun;129(Pt 6):1593-608. doi: 10.1093/brain/awl085. Epub 2006 Apr 21.
Discrete high-frequency oscillations (HFOs) in the range of 100-500 Hz have previously been recorded in human epileptic brains using depth microelectrodes. We describe for the first time similar oscillations in a cohort of unselected focal epileptic patients implanted with EEG macroelectrodes. Spectral analysis and visual inspection techniques were used to study seizures from 10 consecutive patients undergoing pre-surgical evaluation for medically refractory focal epilepsy. Four of these patients had focal seizure onset in the mesial temporal lobe, and in all 12 of their seizures, well-localized, segmental, very high frequency band (VHF: 250-500 Hz) oscillations were visually identified near the time of seizure onset from contacts in this zone. Increased high-frequency band (HF: 100-200 Hz) activity compared with the background was distinguished both visually and with spectral analysis later in the seizures of 3/4 mesial temporal patients, involving contacts in the generator region and, in one patient, areas of contralateral peri-hippocampal propagation. Three patients with well-defined neocortical seizure-onset areas also demonstrated focal HF or VHF oscillations confined to the seizure-onset channels during their eight seizures. No discrete HF or VHF activity was present in the poorly localized seizures from the remaining three patients. These results show that discrete HFOs can be recorded from human focal epileptic brain using depth macroelectrodes, and that they occur mostly in regions of primary epileptogenesis and rarely in regions of secondary spread. Absent high-frequency activity seems to indicate poor localization, whereas the presence of focal HFOs near the time of seizure onset may signify proximity to the epileptogenic focus in mesial temporal lobe and neocortical seizures. We postulate that focal HFOs recorded with depth macroelectrodes reflect the partial synchronization of very local oscillations such as those previously studied using microelectrodes, and result from interconnected small neuronal ensembles. Our finding that localized HFOs occur in varying anatomical structures and pathological conditions perhaps indicates commonality to diverse epileptogenic aetiologies.
此前已使用深度微电极在人类癫痫大脑中记录到100 - 500赫兹范围内的离散高频振荡（HFOs）。我们首次描述了在一组植入脑电图（EEG）宏观电极的未经挑选的局灶性癫痫患者中出现的类似振荡。使用频谱分析和视觉检查技术研究了10例连续接受药物难治性局灶性癫痫术前评估患者的癫痫发作情况。其中4例患者的局灶性癫痫发作起始于内侧颞叶，在他们所有12次癫痫发作中，在发作起始时刻附近，从该区域的电极触点处肉眼可识别出定位良好、节段性的甚高频波段（VHF：250 - 500赫兹）振荡。在3/4内侧颞叶患者癫痫发作后期，通过视觉和频谱分析均发现与背景相比高频波段（HF：100 - 200赫兹）活动增加，涉及起源区域的电极触点，在1例患者中还涉及对侧海马旁传播区域。3例具有明确新皮质癫痫发作起始区域的患者在其8次癫痫发作期间也表现出局限于癫痫发作起始通道的局灶性HF或VHF振荡。其余3例患者定位不佳的癫痫发作中未出现离散的HF或VHF活动。这些结果表明，使用深度宏观电极可从人类局灶性癫痫大脑中记录到离散的HFOs，且它们大多发生在原发性癫痫发生区域，很少出现在继发性扩散区域。高频活动缺失似乎表明定位不佳，而在癫痫发作起始时刻附近出现局灶性HFOs可能意味着在内侧颞叶和新皮质癫痫中接近癫痫病灶。我们推测，用深度宏观电极记录到的局灶性HFOs反映了非常局部振荡的部分同步，如先前使用微电极研究的那些振荡，并且是由相互连接的小神经元群产生的。我们发现局部HFOs出现在不同的解剖结构和病理状况中，这或许表明其在多种癫痫病因中具有共性。
