Unconscious state has been investigated in numerous studies so far, but pathophysiology of this state is not fully understood. Recently, combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) has been developed to allow for non-invasive assessment of neurophysiology in the cerebral cortex. We conducted a systematic literature search for TMS-EEG studies on human unconscious state using PubMed with cross-reference and manual searches. The initial search yielded 137 articles, and 19 of them were identified as relevant, including one article found by manual search. This review included 10 studies for unresponsive wakefulness syndrome (UWS), 9 for minimally conscious states (MCS), 5 for medication-induced unconscious states, and 6 for natural non-rapid eye movement states. These studies analyzed TMS-evoked potential to calculate perturbational complexity index (PCI) and OFF-periods. In particular, PCI was found to be a potentially useful marker to differentiate between UWS and MCS. This review demonstrated that TMS-EEG could represent a promising neuroscientific tool to investigate various unconscious states. Further TMS-EEG research may help elucidate the neural basis of unconscious state.

迄今为止，已经在许多研究中对无意识状态进行了研究，但这种状态的病理生理学尚不完全清楚。最近，联合经颅磁刺激 (TMS) 和脑电图 (EEG) 已被开发用于对大脑皮层的神经生理学进行非侵入性评估。我们使用 PubMed 进行了系统的文献检索，对人类无意识状态的 TMS-EEG 研究进行了交叉引用和手动搜索。最初的搜索产生了 137 篇文章，其中 19 篇被确定为相关文章，其中包括一篇通过人工搜索找到的文章。这篇综述包括 10 项针对无反应觉醒综合征 (UWS) 的研究，9 项针对最低意识状态 (MCS) 的研究，5 项针对药物诱发的无意识状态的研究，以及 6 项针对自然非快速眼动状态的研究。这些研究分析了 TMS 诱发的潜力来计算扰动复杂性指数 (PCI) 和 OFF 期。特别是，PCI 被发现是区分 UWS 和 MCS 的潜在有用标记。这项审查表明，TMS-EEG 可以代表一种有前途的神经科学工具来研究各种无意识状态。进一步的 TMS-EEG 研究可能有助于阐明无意识状态的神经基础。