Coleman Martin R, Rodd Jennifer M, Davis Matthew H, Johnsrude Ingrid S, Menon David K, Pickard John D, Owen Adrian M
Impaired Consciousness Study Group, Wolfson Brain Imaging Centre, University of Cambridge, UK.
Brain. 2007 Oct;130(Pt 10):2494-507. doi: 10.1093/brain/awm170. Epub 2007 Sep 7.
A diagnosis of vegetative state is made if a patient demonstrates no evidence of awareness of self or environment, no evidence of sustained, reproducible, purposeful or voluntary behavioural response to sensory stimuli and critically no evidence of language comprehension. For those patients who retain peripheral motor function, rigorous behavioural assessment is usually able to determine retained function. However, some patients do not retain the ability to respond overtly to command and it is becoming increasingly accepted that assessment of these patients should include techniques, which do not rely on any 'motor action' on the part of the patient. Here, we apply a hierarchical functional magnetic resonance imaging (fMRI) auditory processing paradigm to determine the extent of retained language processing in a group of 14 aetiologically heterogeneous patients who met the diagnostic criteria for either the vegetative state (n = 7), the minimally conscious state (n = 5), or who were in a severely disabled condition having emerged from a minimally conscious state (n = 2). Three different levels of speech processing were assessed: (i) Low-level auditory responses were measured using a contrast between a set of auditory stimuli and a silence baseline; (ii) mid-level speech perception processing abilities were assessed by comparing intelligible speech to unintelligible noise stimuli and (iii) high-level semantic aspects of speech processing were assessed by comparing sentences that were made difficult to understand by the presence of words that were semantically ambiguous compared to matched low-ambiguity sentences. As expected the two severely disabled, but conscious patients showed preserved speech processing at all three levels. However, contrary to the diagnostic criteria defining the vegetative state, three patients (1 traumatic, 2 non-traumatic aetiology) demonstrated some evidence of preserved speech processing. The remaining four patients (1 traumatic, 3 non-traumatic aetiology) with a diagnosis of vegetative state showed no significant activation in response to sound compared with silence. These results provide further evidence that a subset of patients fulfilling the behavioural criteria for the vegetative state retain islands of preserved cognitive function.
如果患者没有自我或环境意识的证据，没有对感觉刺激做出持续、可重复、有目的或自愿行为反应的证据，且至关重要的是没有语言理解能力的证据，则可诊断为植物状态。对于那些保留外周运动功能的患者，严格的行为评估通常能够确定其保留的功能。然而，一些患者不具备对指令做出明显反应的能力，并且越来越多的人接受对这些患者的评估应包括不依赖患者任何“运动动作”的技术。在此，我们应用一种分层功能磁共振成像（fMRI）听觉处理范式，以确定一组14名病因各异的患者中保留的语言处理程度，这些患者符合植物状态（n = 7）、最低意识状态（n = 5）的诊断标准，或处于从最低意识状态恢复后严重残疾的状态（n = 2）。评估了三种不同水平的言语处理：（i）使用一组听觉刺激与安静基线之间的对比来测量低水平听觉反应；（ii）通过将可理解的言语与不可理解的噪声刺激进行比较来评估中级言语感知处理能力；（iii）通过将存在语义模糊词的句子与匹配的低模糊度句子进行比较，来评估言语处理的高级语义方面。正如预期的那样，两名严重残疾但有意识的患者在所有三个水平上都表现出保留的言语处理能力。然而，与定义植物状态的诊断标准相反，三名患者（一名创伤性病因，两名非创伤性病因）表现出一些保留言语处理的证据。其余四名诊断为植物状态的患者（一名创伤性病因，三名非创伤性病因）与安静相比，对声音没有明显的激活反应。这些结果进一步证明，一部分符合植物状态行为标准的患者保留了认知功能岛。
