Carrière Manon, Cassol Helena, Aubinet Charlène, Panda Rajanikant, Thibaut Aurore, Larroque Stephen K, Simon Jessica, Martial Charlotte, Bahri Mohamed A, Chatelle Camille, Martens Géraldine, Chennu Srivas, Laureys Steven, Gosseries Olivia
Coma Science Group, GIGA-Consciousness, University of Liège, 4000 Liège, Belgium.
Centre du Cerveau2, University Hospital of Liège, 4000 Liège, Belgium.
Brain Commun. 2020 Dec 12;2(2):fcaa195. doi: 10.1093/braincomms/fcaa195. eCollection 2020.
Auditory localization (i.e. turning the head and/or the eyes towards an auditory stimulus) is often part of the clinical evaluation of patients recovering from coma. The objective of this study is to determine whether auditory localization could be considered as a new sign of minimally conscious state, using a multimodal approach. The presence of auditory localization and the clinical outcome at 2 years of follow-up were evaluated in 186 patients with severe brain injury, including 64 with unresponsive wakefulness syndrome, 28 in minimally conscious state minus, 71 in minimally conscious state plus and 23 who emerged from the minimally conscious state. Brain metabolism, functional connectivity and graph theory measures were investigated by means of F-fluorodeoxyglucose positron emission tomography, functional MRI and high-density electroencephalography in two subgroups of unresponsive patients, with and without auditory localization. These two subgroups were also compared to a subgroup of patients in minimally conscious state minus. Auditory localization was observed in 13% of unresponsive patients, 46% of patients in minimally conscious state minus, 62% of patients in minimally conscious state plus and 78% of patients who emerged from the minimally conscious state. The probability to observe an auditory localization increased along with the level of consciousness, and the presence of auditory localization could predict the level of consciousness. Patients with auditory localization had higher survival rates (at 2-year follow-up) than those without localization. Differences in brain function were found between unresponsive patients with and without auditory localization. Higher connectivity in unresponsive patients with auditory localization was measured between the fronto-parietal network and secondary visual areas, and in the alpha band electroencephalography network. Moreover, patients in minimally conscious state minus significantly differed from unresponsive patients without auditory localization in terms of brain metabolism and alpha network centrality, whereas no difference was found with unresponsive patients who presented auditory localization. Our multimodal findings suggest differences in brain function between unresponsive patients with and without auditory localization, which support our hypothesis that auditory localization should be considered as a new sign of minimally conscious state. Unresponsive patients showing auditory localization should therefore no longer be considered unresponsive but minimally conscious. This would have crucial consequences on these patients' lives as it would directly impact the therapeutic orientation or end-of-life decisions usually taken based on the diagnosis.
听觉定位（即将头部和/或眼睛转向听觉刺激源）通常是昏迷康复患者临床评估的一部分。本研究的目的是采用多模态方法确定听觉定位是否可被视为最低意识状态的一个新体征。对186例重型脑损伤患者进行了听觉定位情况及2年随访时临床转归的评估，其中包括64例无反应觉醒综合征患者、28例低意识状态患者、71例高意识状态患者和23例从低意识状态中清醒过来的患者。通过18F-氟脱氧葡萄糖正电子发射断层扫描、功能磁共振成像和高密度脑电图，对有无听觉定位的两个无反应患者亚组的脑代谢、功能连接和图论指标进行了研究。这两个亚组还与低意识状态患者亚组进行了比较。在无反应患者中，13%观察到听觉定位；在低意识状态患者中，46%观察到听觉定位；在高意识状态患者中，62%观察到听觉定位；在从低意识状态中清醒过来的患者中，78%观察到听觉定位。观察到听觉定位的概率随着意识水平的提高而增加，并且听觉定位的存在可以预测意识水平。有听觉定位的患者（2年随访时）生存率高于无听觉定位的患者。有无听觉定位的无反应患者之间存在脑功能差异。在有听觉定位的无反应患者中，额顶叶网络与二级视觉区域之间以及α波段脑电图网络中的连接性更高。此外，低意识状态患者在脑代谢和α网络中心性方面与无听觉定位的无反应患者有显著差异，而与有听觉定位的无反应患者没有差异。我们的多模态研究结果表明，有无听觉定位的无反应患者之间存在脑功能差异，这支持了我们的假设，即听觉定位应被视为最低意识状态的一个新体征。因此，表现出听觉定位的无反应患者不应再被视为无反应，而应被视为最低意识状态。这将对这些患者的生活产生至关重要的影响，因为它将直接影响通常基于诊断做出的治疗方向或临终决策。
