OBJECTIVE Due to the problems with behavioral diagnosis of patients with prolonged DOC (disorders of consciousness), complementary approaches based on objective measurement of neural function are necessary. In this pilot study, we assessed the sensitivity of auditory chirp-evoked responses to the state of patients with severe brain injury as measured with CRS-R (Coma Recovery Scale - Revised). METHODS A convenience sample of fifteen DOC patients was included in the study. Auditory stimuli, chirp-modulated at 1-120 Hz were used to evoke auditory steady-state response (ASSR). Phase-locking index (PLI) estimates within low gamma and high gamma windows were evaluated. RESULTS The PLI estimates within a narrow low gamma 38-42 Hz window positively correlated with the CRS-R total score and with the scores of the Auditory and Visual Function subscales. In the same low gamma window, significant difference in the PLIs was found between minimally conscious (MCS) and vegetative state (VS) patients. We did not observe any between-group differences nor any significant correlations with CRS-R scores in the high gamma window (80-110 Hz). CONCLUSIONS Our results support the notion that the activity around 40 Hz may serve as a possible marker of the integrity of thalamocortical networks in prolonged DOC patients. SIGNIFICANCE Auditory steady-state responses at gamma-band frequencies highlight the role of upper parts of auditory system in evaluation of the level of consciousness in DOC patients.

中文翻译：

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听觉稳态对chi调制音的反应：对意识障碍患者的一项初步研究。

目的由于长期DOC（意识障碍）患者的行为诊断存在问题，因此需要基于客观神经功能测量的补充方法。在这项前瞻性研究中，我们评估了听觉responses诱发的反应对严重脑损伤患者的状态的敏感性，以CRS-R（科马恢复量表-修订版）进行了测量。方法本研究纳入了15名DOC患者的便利样本。使用在1-120 Hz处Hz调制的听觉刺激来诱发听觉稳态反应（ASSR）。评估了低伽玛窗和高伽玛窗内的锁相指数（PLI）估计值。结果在一个狭窄的低伽玛38-42 Hz窗口内，PLI估计值与CRS-R总评分以及听觉和视觉功能子量表的评分呈正相关。在相同的低伽玛窗口中，最低意识（MCS）患者和植物人（VS）患者之间的PLI差异显着。在高伽玛窗口（80-110 Hz）中，我们没有观察到任何组间差异或与CRS-R得分的显着相关性。结论我们的研究结果支持以下观点：在40赫兹左右的活动可能是长期DOC患者丘脑皮质网络完整性的可能标志。意义γ频段频率的听觉稳态反应突显了听觉系统上部在DOC患者意识水平评估中的作用。在高伽玛窗口（80-110 Hz）中，我们没有观察到任何组间差异或与CRS-R得分的显着相关性。结论我们的研究结果支持以下观点：在40赫兹左右的活动可能是长期DOC患者丘脑皮质网络完整性的可能标志。意义γ频段的听觉稳态反应突出了听觉系统上部在DOC患者意识水平评估中的作用。在高伽玛窗口（80-110 Hz）中，我们没有观察到任何组间差异或与CRS-R得分的显着相关性。结论我们的结果支持以下观点，即40 Hz附近的活动可能是长时间DOC患者丘脑皮质网络完整性的可能标志。意义γ频段的听觉稳态反应突出了听觉系统上部在DOC患者意识水平评估中的作用。