Rayi Appaji, Bonda Kalyan C., Asuncion Ria Monica D.
Charleston Area Medical Center
University of Louisville School of Medicine
Alterations in attention, cognition, or consciousness are clinically characteristic of encephalopathy. This diffuse cerebral dysfunction can vary in severity due to numerous etiologies, including toxic, metabolic, infectious, and degenerative derangements. Acute encephalopathy may range from mild confusion and delirium to coma, typically presenting with a fluctuating course that involves altered mental status, confusion, and changes in motor activity. Symptoms often include lethargy, cognitive impairment, altered memory and information processing, and disturbed sleep-wake cycles. In more chronic, slowly progressive, or static encephalopathies, initial attentional retention may be followed by a loss of cognitive capacity. Encephalopathy is typically observed in older adults and is commonly seen in intensive care units and in postoperative individuals. Despite the new developments in intensive medical care, acute encephalopathy is still a significant cause of morbidity and mortality in hospitalized patients. In this regard, electroencephalography (EEG) enables rapid bedside electrophysiological monitoring, providing dynamic real-time information on neocortical brain activity and dysfunction. EEG is useful for evaluating patients with acute and chronic encephalopathies. The primary role of EEG in this setting is to rule out seizures as a cause of altered mental status. Various patterns can be observed in patients with encephalopathy; abnormal patterns, especially those with an acute-to-subacute onset, are sensitive for encephalopathy but not specific for diagnosing its causes. Most encephalopathies are associated with the slowing of dominant rhythms and background activity. This is most likely due to the involvement of both the cortical neurons and the subcortical white matter dysfunction. Overall, EEG is useful for assessing the extent of cerebral dysfunction in encephalopathy and for monitoring changes in association with clinical progression. A review of EEG emphasized that it is not pathognomonic of encephalopathy or encephalitis. However, when interpreted correctly and within the clinical context, some phenotypes may reflect specific pathophysiology, such as lateralized periodic discharges in herpes simplex virus-1 infection, generalized periodic discharges in sporadic Creutzfeldt-Jakob disease, and extreme delta brushes in anti-N-methyl-D-aspartate receptor autoimmune encephalitis. Specialist guidelines include EEG for disease assessment, monitoring, and prognostication in hepatic, cancer immunotherapy, viral, prion, autoimmune encephalitis, and hypoxic-ischemic encephalopathy. EEG also plays a crucial role in confirming or excluding nonconvulsive seizures or status epilepticus, especially among those who are critically ill, and in understanding recent concepts like epileptic encephalopathy and the ictal-interictal continuum.
脑病在临床上被描述为广泛的注意力、认知或意识改变。由于多种病因，包括中毒、代谢、感染和退行性紊乱，这种弥漫性脑功能障碍的严重程度可能有所不同。急性脑病的范围可能从轻度意识模糊和谵妄到昏迷，通常表现为病程波动，包括精神状态改变、意识模糊和运动活动变化。症状通常包括嗜睡、认知障碍、记忆和信息处理改变以及睡眠 - 觉醒周期紊乱。在更慢性、缓慢进展或静止性的脑病情况下，最初可能存在注意力保留，随后会出现认知能力丧失。脑病通常在老年人群中观察到，在重症监护病房和术后患者中也很常见。尽管重症医学有了新进展，但急性脑病仍然是住院患者发病和死亡的重要原因。在这方面，脑电图（EEG）能够在床边进行快速电生理监测，提供关于新皮质脑活动和功能障碍的动态实时信息。EEG 对评估急性和慢性脑病患者很有用。EEG 在这种情况下的主要作用是排除癫痫发作作为精神状态改变的原因。脑病患者可出现各种脑电图模式；异常模式，尤其是急性至亚急性起病时的模式，对脑病敏感，但对病因诊断不具有特异性。大多数脑病与优势节律和背景活动减慢有关。这很可能是由于皮质神经元和皮质下白质功能障碍均受累。总体而言，EEG 有助于评估脑病中的脑功能障碍程度，并随着临床进展监测变化。一篇关于 EEG 的综述强调，它在脑病或脑炎中很少具有诊断特异性。然而，在正确解读并结合临床背景时，一些脑电图表型可能呈现特定的病理生理学特征，如单纯疱疹病毒 -1 感染时的侧化周期性放电、散发性克雅氏病时的广泛性周期性放电以及抗 N - 甲基 -D - 天冬氨酸受体自身免疫性脑炎时的极端δ刷状波。专业指南将 EEG 纳入肝性脑病、癌症免疫治疗相关脑病、病毒性脑病、朊蛋白病、自身免疫性脑炎和缺氧缺血性脑病的疾病评估、监测和预后判断中。EEG 在确认或排除非惊厥性癫痫发作或癫痫持续状态方面也起着关键作用，尤其是在重症患者中，并且有助于理解癫痫性脑病和发作 - 发作间期连续体等最新概念。
