Pistoia Francesca, Sacco Simona, Stewart Janet, Sarà Marco, Carolei Antonio
Neurological Institute, Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila 67100, Italy.
Psychology Division, School of Natural Sciences, University of Stirling, Scotland FK8, UK.
Brain Sci. 2016 Oct 8;6(4):47. doi: 10.3390/brainsci6040047.
The experience of pain in disorders of consciousness is still debated. Neuroimaging studies, using functional Magnetic Resonance Imaging (fMRI), Positron Emission Tomography (PET), multichannel electroencephalography (EEG) and laser-evoked potentials, suggest that the perception of pain increases with the level of consciousness. Brain activation in response to noxious stimuli has been observed in patients with unresponsive wakefulness syndrome (UWS), which is also referred to as a vegetative state (VS), as well as those in a minimally conscious state (MCS). However, all of these techniques suggest that pain-related brain activation patterns of patients in MCS more closely resemble those of healthy subjects. This is further supported by fMRI findings showing a much greater functional connectivity within the structures of the so-called pain matrix in MCS as compared to UWS/VS patients. Nonetheless, when interpreting the results, a distinction is necessary between autonomic responses to potentially harmful stimuli and conscious experience of the unpleasantness of pain. Even more so if we consider that the degree of residual functioning and cortical connectivity necessary for the somatosensory, affective and cognitive-evaluative components of pain processing are not yet clear. Although procedurally challenging, the particular value of the aforementioned techniques in the assessment of pain in disorders of consciousness has been clearly demonstrated. The study of pain-related brain activation and functioning can contribute to a better understanding of the networks underlying pain perception while addressing clinical and ethical questions concerning patient care. Further development of technology and methods should aim to increase the availability of neuroimaging, objective assessment of functional connectivity and analysis at the level of individual cases as well as group comparisons. This will enable neuroimaging to truly become a clinical tool to reliably investigate pain in severely brain-injured patients as well as an asset for research.
意识障碍中疼痛的体验仍存在争议。神经影像学研究，如使用功能磁共振成像（fMRI）、正电子发射断层扫描（PET）、多通道脑电图（EEG）和激光诱发电位，表明疼痛感知随意识水平的提高而增加。在无反应觉醒综合征（UWS，也称为植物状态[VS]）患者以及最低意识状态（MCS）患者中，均观察到了对有害刺激的脑激活。然而，所有这些技术都表明，MCS患者与疼痛相关的脑激活模式更类似于健康受试者。功能磁共振成像的研究结果进一步支持了这一点，该结果显示，与UWS/VS患者相比，MCS患者在所谓的疼痛矩阵结构内具有更强的功能连接。尽管如此，在解释结果时，有必要区分对潜在有害刺激的自主反应和对疼痛不适感的意识体验。如果我们考虑到疼痛处理的体感、情感和认知评估成分所需的残余功能和皮质连接程度尚不清楚，情况更是如此。尽管在操作上具有挑战性，但上述技术在意识障碍疼痛评估中的特殊价值已得到明确证明。对与疼痛相关的脑激活和功能的研究有助于更好地理解疼痛感知背后的网络，同时解决有关患者护理的临床和伦理问题。技术和方法的进一步发展应旨在提高神经影像学的可用性、功能连接的客观评估以及个体病例水平的分析以及组间比较。这将使神经影像学真正成为一种临床工具，用于可靠地研究重度脑损伤患者的疼痛，以及一项研究资产。
