Department of Physiology, University of Utah School of Medicine, 420 Chipeta Way, Suite 1700, Salt Lake City, UT 84108, United States.
Epilepsy Res. 2011 Dec;97(3):324-31. doi: 10.1016/j.eplepsyres.2011.10.017. Epub 2011 Nov 16.
The concept of a preictal state is based on the belief that it may be possible to predict seizures before they occur. The preictal state is viewed as a time period when a seizure is practically inevitable, or at least a period of greatly increased seizure probability. Changes in seizure frequency may provide insight into how seizure probability increases after brain injury. Here, time-dependent changes in the frequency of spontaneous recurrent seizures after brain injury are summarized from published, nearly continuous, electrographic (EEG) recordings of kainate-treated rats and neonatal rats subjected to hypoxia-ischemia. For these animal models, seizure frequency - and thus seizure probability - was a sigmoid function of time after the brain injury. This observation differs from the traditional view, where the development of epilepsy after brain injury is a step-function of time, and the latent period is the time between a brain injury and the first spontaneous seizure. Based on backward extrapolation of the plots of seizure frequency versus time, these data suggest that seizure probability increases continuously during the latent period. Also, spontaneous recurrent seizures frequently occurred in clusters, suggesting that the intra-cluster seizure intervals are periods of high seizure probability. Thus, seizure probability progressively increases as a function of time after an epileptogenic brain injury, and is particularly high between seizures within a cluster, as compared to the time between clusters. These data suggest that the detectors of the preictal state need to be accurate (and tested) over a very wide range of seizure probabilities, and that studies on the physiological events that occur during seizure clusters may provide insight on the properties of the preictal state.
痫性发作前状态的概念基于这样一种假设，即有可能在痫性发作发生之前对其进行预测。痫性发作前状态被视为一种癫痫发作几乎不可避免的时期，或者至少是癫痫发作概率大大增加的时期。发作频率的变化可以深入了解脑损伤后癫痫发作概率的增加情况。在这里，总结了从发表的、近乎连续的、海人酸处理大鼠和缺氧缺血新生大鼠的脑电图（EEG）记录中获得的脑损伤后自发性复发性癫痫发作频率的时间依赖性变化。对于这些动物模型，发作频率 - 因此癫痫发作概率 - 是脑损伤后时间的 S 形函数。这一观察结果与传统观点不同，传统观点认为脑损伤后癫痫的发展是时间的阶跃函数，潜伏期是脑损伤和第一次自发性癫痫发作之间的时间。基于对发作频率与时间的关系进行反向外推，这些数据表明在潜伏期内癫痫发作概率持续增加。此外，自发性复发性癫痫发作经常呈簇状发生，这表明簇内的发作间隔是癫痫发作概率较高的时期。因此，癫痫发作概率随着脑致痫性损伤后时间的推移呈函数递增，在簇内发作之间与簇之间相比，其概率特别高。这些数据表明，痫性发作前状态的检测器需要在非常广泛的癫痫发作概率范围内进行准确（和测试），并且对发作簇期间发生的生理事件的研究可能为痫性发作前状态的特性提供深入了解。
