Electroencephalographic activity in the context of disorders of consciousness is a swiss knife like tool that can evaluate different aspects of cognitive residual function, detect consciousness and provide a mean to communicate with the outside world without using muscular channels. Standard recordings in the neurological department offer a first global view of the electrogenesis of a patient and can spot abnormal epileptiform activity and therefore guide treatment. Although visual patterns have a prognosis value, they are not sufficient to provide a diagnosis between vegetative state/unresponsive wakefulness syndrome (VS/UWS) and minimally conscious state (MCS) patients. Quantitative electroencephalography (qEEG) processes the data and retrieves features, not visible on the raw traces, which can then be classified. Current results using qEEG show that MCS can be differentiated from VS/UWS patients at the group level. Event Related Potentials (ERP) are triggered by varying stimuli and reflect the time course of information processing related to the stimuli from low-level peripheral receptive structures to high-order associative cortices. It is hence possible to assess auditory, visual, or emotive pathways. Different stimuli elicit positive or negative components with different time signatures. The presence of these components when observed in passive paradigms is usually a sign of good prognosis but it cannot differentiate VS/UWS and MCS patients. Recently, researchers have developed active paradigms showing that the amplitude of the component is modulated when the subject's attention is focused on a task during stimulus presentation. Hence significant differences between ERPs of a patient in a passive compared to an active paradigm can be a proof of consciousness. An EEG-based brain-computer interface (BCI) can then be tested to provide the patient with a communication tool. BCIs have considerably improved the past two decades. However they are not easily adaptable to comatose patients as they can have visual or auditory impairments or different lesions affecting their EEG signal. Future progress will require large databases of resting state-EEG and ERPs experiment of patients of different etiologies. This will allow the identification of specific patterns related to the diagnostic of consciousness. Standardized procedures in the use of BCIs will also be needed to find the most suited technique for each individual patient.

中文翻译：

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昏迷，无营养和弱视患者脑功能的电生理检查。

在意识障碍的背景下，脑电图活动就像一把瑞士刀一样的工具，可以评估认知残余功能的不同方面，检测意识并提供一种无需使用肌肉通道即可与外界进行交流的手段。神经科的标准记录提供了患者电生成的第一个整体视图，可以发现异常的癫痫样活动，因此可以指导治疗。尽管视觉模式具有预后价值，但它们不足以在营养状态/无反应性清醒综合征（VS / UWS）和最低意识状态（MCS）患者之间提供诊断。定量脑电图（qEEG）处理数据并检索原始迹线上不可见的特征，然后可以对其进行分类。使用qEEG的最新结果表明，可以在组水平上将MCS与VS / UWS患者区分开。事件相关电位（ERP）由变化的刺激触发，反映了与刺激相关的信息处理的时间过程，从低水平的外周接受结构到高阶缔合皮质。因此可以评估听觉，视觉或情感途径。不同的刺激引起具有不同时间特征的正或负分量。在被动范式中观察到这些成分的存在通常是预后良好的标志，但不能区分VS / UWS和MCS患者。最近，研究人员开发出了主动范式，表明当受试者的注意力集中在刺激演示过程中的任务上时，该分量的幅度被调制。因此，与主动模式相比，被动模式下患者的ERP之间的显着差异可以证明意识。然后可以测试基于EEG的脑机接口（BCI），为患者提供通信工具。在过去的二十年中，BCI有了很大的改善。然而，它们不容易适应昏迷的患者，因为他们可能有视觉或听觉障碍或影响其脑电信号的不同病变。未来的进步将需要大型的数据库，以对不同病因的患者进行静息状态的EEG和ERP实验。这将允许识别与意识诊断有关的特定模式。还需要使用BCI的标准化程序来为每个患者找到最合适的技术。