Sethi N K, Sethi P K, Torgovnick J, Arsura E, Schaul N, Labar D
Department of Neurology, NYP-Weill Cornell Medical Center, New York, NY 10021, USA.
Clin Neurol Neurosurg. 2008 Jul;110(7):729-31. doi: 10.1016/j.clineuro.2008.03.020. Epub 2008 May 16.
The Uniform Determination of Death Act (UDDA) defines death as irreversible cessation of the functions of the entire brain including the brainstem. Many individuals meeting the clinical criteria of brain death can be documented to have some residual sub-cortical and brainstem function on careful testing. Determination of brain death still remains a persistently unresolved issue in health law and bioethics. The determination of brain death is clinical and involves testing for the integrity of brainstem functions. Documentation of irreversible cessation of brainstem functions when the cause of coma is established is usually sufficient to make a diagnosis of brain death. Confirmatory tests like four-vessel angiogram and electroencephalogram (EEG) are required in cases where the clinical testing is inconclusive or unreliable. EEG criteria for electrocerebral silence (ECS) is absence of any detectable cortical activity above 2 microV in a study performed as per the guidelines developed by the American Electroencephalographic Society. EEG studies carried out for ECS are at times contaminated by electromyographic (EMG) artifacts reflecting scalp motor unit activity. A secure EEG diagnosis of ECS cannot be made in such cases. What exactly is the relevance of scalp EMG activity in these clinically brain dead patients? What is the mechanism of generation of this spontaneous scalp EMG activity and how can the diagnosis of brain death be secured in these patients? These issues are explored in this article by highlighting a case.
《统一死亡判定法案》(UDDA)将死亡定义为包括脑干在内的全脑功能不可逆地停止。许多符合脑死亡临床标准的个体在经过仔细检测后,可被证明仍有一些残留的皮质下和脑干功能。脑死亡的判定在卫生法和生物伦理学中仍然是一个悬而未决的问题。脑死亡的判定是临床性的,涉及对脑干功能完整性的检测。当昏迷原因明确时,记录脑干功能的不可逆停止通常足以做出脑死亡的诊断。在临床检测结果不确定或不可靠的情况下,需要进行四血管血管造影和脑电图(EEG)等确认性检查。根据美国脑电图学会制定的指南进行的研究中,脑电图判定脑电静息(ECS)的标准是不存在任何高于2微伏的可检测到的皮质活动。为ECS进行的脑电图研究有时会受到反映头皮运动单位活动的肌电图(EMG)伪迹的干扰。在这种情况下,无法做出可靠的ECS脑电图诊断。在这些临床脑死亡患者中,头皮EMG活动究竟有何关联?这种自发性头皮EMG活动的产生机制是什么,以及如何在这些患者中确保脑死亡的诊断?本文通过突出一个病例来探讨这些问题。