Neurological examination of non-communicating patients relies on a few decisive items that enable the crucial distinction between vegetative state (VS)—also coined unresponsive wakefulness syndrome (UWS)—and minimally conscious state. Over the past 10 years, this distinction has proven its diagnostic value as well as its important prognostic value on consciousness recovery. However, clinicians are currently limited by three factors: (i) the current behavioural repertoire of minimally conscious state items is limited and restricted to a few cognitive domains in the goldstandard revised version of the Coma Recovery Scale; (ii) a proportion of ∼15–20% clinically VS/UWS patients are actually in a richer state than VS/UWS as evidenced by functional brain imaging; and (iii) the neurophysiological and cognitive interpretation of each minimally conscious state item is still unclear and debated. In the current study we demonstrate that habituation of the auditory startle reflex (hASR) tested at bedside constitutes a novel, simple and powerful behavioural sign that can accurately distinguish minimally conscious state from VS/UWS. In addition to enlarging the minimally conscious state items repertoire, and therefore decreasing the low sensitivity of current behavioural measures, we also provide an original and rigorous description of the neurophysiological basis of hASR through a combination of functional (high density EEG and ¹⁸F-fluorodeoxyglucose PET imaging) and structural (diffusion tensor imaging MRI) measures. We show that preservation of hASR is associated with the functional and structural integrity of a brain-scale fronto-parietal network, including prefrontal regions related to control of action and inhibition, and meso-parietal areas associated with minimally conscious and conscious states. Lastly, we show that hASR predicts 6-month improvement of consciousness. Taken together, our results show that hASR is a cortically-mediated behaviour, and suggest that it could be a new clinical item to clearly and accurately identify non-communicating patients who are in the minimally conscious state.

中文翻译：

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听觉惊吓反射的习惯化是最低意识状态的新标志。

非沟通性患者的神经学检查依赖于一些决定性的项目，这些项目能够区分植物状态（VS）（也称为无反应觉醒综合征（UWS））和最低意识状态。在过去的10年里，这种区别已经证明了其诊断价值以及对意识恢复的重要预后价值。然而，临床医生目前受到三个因素的限制：（i）目前的最低意识状态项目的行为范围有限，仅限于昏迷恢复量表黄金标准修订版中的几个认知领域；(ii) 约 15-20% 的临床 VS/UWS 患者实际上处于比 VS/UWS 更丰富的状态，如功能性脑成像所证明；(iii) 每个最低意识状态项目的神经生理学和认知解释仍然不清楚并存在争议。在当前的研究中，我们证明在床边测试的听觉惊吓反射（hASR）的习惯化构成了一种新颖、简单且强大的行为标志，可以准确地区分最低意识状态与 VS/UWS。除了扩大最低意识状态项目库，从而降低当前行为测量的低敏感性之外，我们还通过功能性（高密度脑电图和 18 F-氟脱氧葡萄糖）的组合，对 hASR 的神经生理学基础进行了原始且严格的^描述。 PET 成像）和结构（扩散张量成像 MRI）测量。我们表明，hASR 的保存与大脑规模的额顶叶网络的功能和结构完整性相关，包括与行为和抑制控制相关的前额叶区域，以及与最低意识和意识状态相关的中顶叶区域。最后，我们表明 hASR 可以预测 6 个月的意识改善。总而言之，我们的结果表明 hASR 是一种皮质介导的行为，并表明它可能是一个新的临床项目，可以清楚、准确地识别处于最低意识状态的非沟通患者。