Seizures result from a variety of pathologies and exhibit great diversity in their dynamics. Although many studies have examined the dynamics of seizure initiation, few have investigated the mechanisms leading to seizure termination. We examined intracranial recordings from patients with intractable focal epilepsy to differentiate seizure termination patterns and investigate whether these termination patterns are indicative of different underlying mechanisms. Seizures (n=710) were recorded intracranially from 104 patients and visually classified as focal or secondarily generalized. Only two patterns emerged from this analysis: (a) those that end simultaneously across the brain (synchronous termination), and (b) those whose ictal activity terminates in some regions but continues in others (asynchronous termination). Finally, seizures ended with either an intermittent bursting pattern (burst suppression pattern), or continuous activity (continuous bursting). These findings allowed for a classification and quantification of the burst suppression ratio, absolute energy and network connectivity of all seizures and comparison across different seizure termination patterns. We found that different termination patterns can manifest within a single patient, even in seizures originating from the same onset locations. Most seizures terminate with patterns of burst suppression regardless of generalization but that seizure that secondarily generalize show burst suppression patterns in 90% of cases, while only 60% of focal seizures exhibit burst suppression. Interestingly, we found similar absolute energy and burst suppression ratios in seizures with synchronous and asynchronous termination, while seizures with continuous bursting were found to be different from seizures with burst suppression, showing lower energy during seizure and lower burst suppression ratio at the start and end of seizure. Finally, network density was observed to increase with seizure progression, with significantly lower densities in seizures with continuous bursting compared to seizures with burst suppression. Our study demonstrates that there are a limited number of seizure termination patterns, suggesting that, unlike seizure initiation, the number of mechanisms underlying seizure termination is constrained. The study of termination patterns may provide useful clues about how these seizures may be managed, which in turn may lead to more targeted modes of therapy for seizure control.

中文翻译：

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癫痫发作终止模式的量化揭示了癫痫发作终止的途径有限

癫痫发作的病因多种多样，其动力学表现出极大的多样性。尽管许多研究检查了癫痫发作的动力学，但很少研究导致癫痫发作终止的机制。我们检查了顽固性局灶性癫痫患者的颅内记录，以区分癫痫发作的终止方式，并调查这些终止方式是否表明了不同的潜在机制。记录了104例患者的颅内癫痫发作（n = 710），并在视觉上分类为局灶性或继发性。该分析仅得出两种模式：（a）同时在大脑中终止的模式（同步终止），和（b）短暂活动在某些区域终止但在其他区域继续的模式（异步终止）。最后，癫痫发作以间歇性爆发模式（爆发抑制模式）或连续活动（连续爆发）结束。这些发现可以对所有癫痫发作的猝发抑制率，绝对能量和网络连通性进行分类和量化，并可以对不同癫痫发作终止模式进行比较。我们发现，即使在源自相同发作部位的癫痫发作中，不同的终止模式也可能在单个患者中出现。大多数癫痫发作均以猝发抑制模式结束，而与泛化无关，但在90％的病例中，次泛化的癫痫发作表现出猝发抑制模式，而仅60％的局灶性发作表现出猝发抑制。有趣的是，我们发现在同步和异步终止的癫痫发作中，绝对能量和猝发抑制比相似，而连续猝发的癫痫发作与猝发抑制的癫痫发作有所不同，表现出发作期间的能量较低，发作的开始和结束时发作抑制率较低。 。最后，观察到网络密度随着癫痫发作的进行而增加，与具有爆发抑制的癫痫发作相比，连续爆发的癫痫发作的密度显着降低。我们的研究表明，癫痫发作终止模式的数量有限，这表明与癫痫发作不同，癫痫发作终止的机制数量受到限制。对终止模式的研究可能会为如何管理这些癫痫发作提供有用的线索，