High-frequency oscillations and seizure generation in neocortical epilepsy
High-frequency oscillations and seizure generation in neocortical epilepsy
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DOI：
10.1093/brain/awh149
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发表时间：
2004-07-01
期刊：
影响因子：
14.5
通讯作者：
Litt, B
中科院分区：
文献类型：
--
作者：
Worrell, GA;Parish, L;Litt, B
新皮质癫痫发作在发病时往往定位不良、爆炸性和广泛性，因此在没有相关局灶性脑病变的情况下，不适合进行癫痫手术。我们首次在一组未经选择的新皮质癫痫患者中发现，高频（60- 100hz）癫痫样振荡高度局限于癫痫发作区，在癫痫发作之前和暂时从癫痫发作中消失。在研究期间，在23例连续植入颅内电极进行术前评估的患者中，所有6例新皮质癫痫患者都观察到了这些结果。这些患者中的大多数癫痫发作（62%）在新皮层癫痫发作前20分钟高频活动增加。与在正常大脑中观察到的相反，高频活动受到行为状态的强烈调节，并且在慢波睡眠期间达到最大，这可能解释了在睡眠期间新皮层发作癫痫的倾向。这些发现指出，神经调节回路（可能涉及丘脑）在新皮质癫痫发作产生的机制中起着重要作用。这些发现表明，高频癫痫样振荡可能在临床上有助于定位新皮质癫痫的癫痫发作区，识别癫痫发作可能性增加的时期，并阐明新皮质ictogenesis的机制。证实长时间的高频活动爆发可以预测局灶性新皮层癫痫发作，需要对大量患者进行连续、长时间的记录进行前瞻性验证。重要的是，结果表明，目前临床实践中用于定位癫痫性脑的动态范围在很大程度上忽略了作为癫痫性脑特征的基本振荡。这可能证明许多目前可用的临床脑电图系统和脑电图分析方法利用的动态范围丢弃了临床重要信息。
Neocortical seizures are often poorly localized, explosive and widespread at onset, making them poorly amenable to epilepsy surgery in the absence of associated focal brain lesions. We describe, for the first time in an unselected group of patients with neocortical epilepsy, the finding that high-frequency (60-100 Hz) epileptiform oscillations are highly localized in the seizure onset zone, both before and temporally removed from seizure onset. These findings were observed in all six patients with neocortical epilepsy out of 23 consecutive patients implanted with intracranial electrodes for pre-surgical evaluation during the study period. The majority of seizures (62%) in these patients were anticipated by an increase in high-frequency activity in the 20 min prior to neocortical seizure onset. Contrary to observations in normal brain, high-frequency activity was strongly modulated by behavioural state, and was maximal during slow-wave sleep, which may explain the propensity for neocortical onset seizures to begin during sleep. These findings point to an important role for neuromodulatory circuits, probably involving the thalamus, in mechanisms underlying seizure generation in neocortical epilepsy. These findings demonstrate that high-frequency epileptiform oscillations may prove clinically useful in localizing the seizure onset zone in neocortical epilepsy, for identifying periods of increased probability of seizure onset, and in elucidating mechanisms underlying neocortical ictogenesis. Confirmation that prolonged bursts of high-frequency activity may predict focal onset neocortical seizures will require prospective validation on continuous, prolonged recordings in a larger number of patients. Importantly, the results show that the dynamic range utilized in current clinical practice for localization of epileptogenic brain largely ignores fundamental oscillations that are signatures of an epileptogenic brain. It may prove that many currently available clinical EEG systems and EEG analysis methods utilize a dynamic range that discards clinically important information.