Background. The minimally conscious state (MCS) is subcategorized into MCS− and MCS+, depending on the absence or presence, respectively, of high-level behavioral responses such as command-following. Objective. We aim to investigate the functional and structural neuroanatomy underlying the presence of these responses in MCS− and MCS+ patients. Methods. In this cross-sectional retrospective study, chronic MCS patients were diagnosed using repeated Coma Recovery Scale–Revised assessments. Fluorodeoxyglucose-positron emission tomography data were acquired on 57 patients (16 MCS−; 41 MCS+) and magnetic resonance imaging with voxel-based morphometry analysis was performed on 66 patients (17 MCS−; 49 MCS+). Brain glucose metabolism and gray matter integrity were compared between patient groups and control groups. A metabolic functional connectivity analysis testing the hypothesis of preserved language network in MCS+ compared with MCS− was also done. Results. Patients in MCS+ presented higher metabolism mainly in the left middle temporal cortex, known to be important for semantic processing, compared with the MCS− group. The left angular gyrus was also functionally disconnected from the left prefrontal cortex in MCS− compared with MCS+ group. No significant differences were found in gray matter volume between patient groups. Conclusions. The clinical subcategorization of MCS is supported by differences in brain metabolism but not in gray matter structure, suggesting that brain function in the language network is the main support for recovery of command-following, intelligible verbalization and/or intentional communication in the MCS. Better characterizing the neural correlates of residual cognitive abilities of MCS patients contributes to reduce their misdiagnosis and to adapt therapeutic approaches.

中文翻译：

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大脑代谢而非灰质体积是最低意识状态 (MCS) 中语言功能存在的基础：MCS+ 与 MCS− 神经影像学差异

背景。最低意识状态 (MCS) 被细分为 MCS- 和 MCS+，分别取决于高级行为反应（例如命令遵循）的缺失或存在。客观的。我们的目标是研究 MCS- 和 MCS+ 患者中存在这些反应的功能和结构神经解剖学。方法。在这项横断面回顾性研究中，慢性 MCS 患者使用重复的昏迷恢复量表 - 修订评估进行诊断。对 57 名患者（16 MCS-；41 MCS+）采集了氟脱氧葡萄糖 - 正电子发射断层扫描数据，并对 66 名患者（17 MCS-；49 MCS+）进行了基于体素形态测量分析的磁共振成像。比较患者组和对照组之间的脑葡萄糖代谢和灰质完整性。还进行了代谢功能连接分析，测试了 MCS+ 与 MCS- 中保留语言网络的假设。结果。与 MCS- 组相比，MCS+ 患者主要在左侧中颞叶皮层表现出更高的代谢，这对语义处理很重要。与 MCS+ 组相比，左角回在 MCS- 中也与左前额叶皮层功能断开。患者组之间的灰质体积没有发现显着差异。结论。MCS 的临床子分类得到大脑代谢差异的支持，但不支持灰质结构的差异，这表明语言网络中的大脑功能是 MCS 中恢复命令遵循、可理解的语言表达和/或有意交流的主要支持。