Infantile spasms (IS) and seizures with focal onset have different clinical expressions, even when electroencephalography (EEG) associated with IS has some degree of focality. Oddly, identical pathology (with, however, age-dependent expression) can lead to IS in one patient vs. focal seizures in another or even in the same, albeit older, patient. We therefore investigated whether the cellular mechanisms underlying seizure initiation are similar in the two instances: spasms vs. focal. We noted that in-common EEG features can include (i) a background of waves at alpha to delta frequencies; (ii) a period of flattening, lasting about a second or more – the electrodecrement (ED); and (iii) often an interval of very fast oscillations (VFO; ~70 Hz or faster) preceding, or at the beginning of, the ED. With IS, VFO temporally coincides with the motor spasm. What is different between the two conditions is this: with IS, the ED reverts to recurring slow waves, as occurring before the ED, whereas with focal seizures the ED instead evolves into an electrographic seizure, containing high-amplitude synchronized bursts, having superimposed VFO. We used in vitro data to help understand these patterns, as such data suggest cellular mechanisms for delta waves, for VFO, for seizure-related burst complexes containing VFO, and, more recently, for the ED. We propose a unifying mechanistic hypothesis – emphasizing the importance of brain pH – to explain the commonalities and differences of EEG signals in IS versus focal seizures.

中文翻译：

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婴儿痉挛症与癫痫发作的区别局灶性癫痫发作：提出的常见细胞机制


婴儿痉挛症 (IS) 和局灶性癫痫发作具有不同的临床表现，即使与 IS 相关的脑电图 (EEG) 具有一定程度的局灶性。奇怪的是，相同的病理学（然而，具有年龄依赖性表达）可能导致一名患者出现 IS，而另一名患者甚至同一名患者（尽管年龄较大）出现局灶性癫痫发作。因此，我们研究了这两种情况下癫痫发作引发的细胞机制是否相似：痉挛与局灶性。我们注意到常见的脑电图特征可以包括（i）α到δ频率的波背景； (ii) 一段持续约一秒或更长时间的平坦期——电极衰减（ED）； (iii) 通常在 ED 之前或开始时有一段非常快的振荡（VFO；约 70 Hz 或更快）。对于 IS，VFO 在时间上与运动痉挛同时发生。这两种情况之间的不同之处在于：对于 IS，ED 恢复为重复出现的慢波，如在 ED 之前发生的那样，而对于局灶性癫痫发作，ED 相反演变成电图癫痫发作，包含高振幅同步突发，具有叠加的 VFO 。我们用过体外数据来帮助理解这些模式，因为这些数据表明了 δ 波、VFO、包含 VFO 的癫痫相关突发复合体以及最近的 ED 的细胞机制。我们提出了一个统一的机制假说——强调大脑 pH 值的重要性——来解释 IS 与局灶性癫痫发作中脑电图信号的共性和差异。