Lehembre R, Gosseries O, Lugo Z, Jedidi Z, Chatelle C, Sadzot B, Laureys S, Noirhomme Q
Coma Science Group, Cyclotron Research Centre and Neurolgy Department, University of Liège, Belgium.
Arch Ital Biol. 2012 Jun-Sep;150(2-3):122-39. doi: 10.4449/aib.v150i2.1374.
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.
意识障碍背景下的脑电图活动是一种类似瑞士军刀的工具，它可以评估认知残余功能的不同方面，检测意识，并提供一种不通过肌肉通道与外界交流的方式。神经科的标准记录能初步全面了解患者的电活动成因，发现异常癫痫样活动，从而指导治疗。尽管视觉模式具有预后价值，但它们不足以在植物状态/无反应觉醒综合征（VS/UWS）和最低意识状态（MCS）患者之间做出诊断。定量脑电图（qEEG）对数据进行处理并提取原始记录中不可见的特征，然后进行分类。目前使用qEEG的结果表明，在群体水平上，MCS患者可以与VS/UWS患者区分开来。事件相关电位（ERP）由不同刺激触发，反映从低级外周感受结构到高级联合皮层与刺激相关的信息处理时间进程。因此，可以评估听觉、视觉或情感通路。不同刺激会引发具有不同时间特征的正性或负性成分。在被动范式中观察到这些成分的存在通常是预后良好的迹象，但它无法区分VS/UWS和MCS患者。最近，研究人员开发了主动范式，表明当受试者在刺激呈现期间将注意力集中在任务上时，成分的幅度会受到调制。因此，患者在被动范式与主动范式下ERP的显著差异可以证明其有意识。然后可以测试基于脑电图的脑机接口（BCI），为患者提供一种交流工具。在过去二十年中，BCI有了很大改进。然而，它们不易适用于昏迷患者，因为这些患者可能有视觉或听觉障碍，或者有不同病变影响其脑电图信号。未来的进展将需要不同病因患者的静息态脑电图和ERP实验的大型数据库。这将有助于识别与意识诊断相关的特定模式。还需要标准化的BCI使用程序，以找到最适合每个患者的技术。
