Laurent B, Peyron R, Garcia Larrea L, Mauguière F
Service de Neurologie de Saint-Etienne et Centre stéphanois de la douleur, Lyon, France.
Rev Neurol (Paris). 2000 Apr;156(4):341-51.
The study of pain integration, in vivo, within the human brain has been largely improved by the functional neuro-imaging techniques available for about 10 years. Positron Emission Tomography (PET), complemented by laser evoked potentials (LEP) and functional Magnetic Resonance Imaging (fMRI) can nowadays generate maps of physiological or neuropathic pain-related brain activity. LEP and fMRI complement PET by their better temporal resolution and the possibility of individual subject analyze. Recent advances in our knowledge of pain mechanisms concern physiological acute pain, neuropathic pain and investigation of analgesic mechanisms. The sixteen studies using PET have demonstrated pain-related activations in thalamus, insula/SII, anterior cingulate and posterior parietal cortices Activity in right pre-frontal and posterior parietal cortices, anterior cingulate and thalami can be modulated by attention (hypnosis, chronic pain, diversion, selective attention to pain) and probably subserve attentional processes rather than pain analysis. Responses in insula/SII cortex presumably subserve discriminative aspects of pain perception while SI cortex is particularly involved in particular aspects of pain discrimination (movement, contact.) In patients, neuropathic pain, angina and atypical facial pain result in PET abnormalities whose significance remain obscure but which are localized in thalamus and anterior cingulate cortices suggesting their distribution is not random while discriminative responses remain detectable in insula/SII. Drug or stimulation induced analgesia are associated with normalization of basal thalamic abnormalities associated with many chronic pains. The need to investigate the significance of these responses, their neuro-chemical correlates (PET), their time course, the individual strategies by which they have been generated by correlating PET data with LEP and fMRI results, are the challenges that remain to be addressed in the next few years by physicians and researchers. To advance our knowledge of the mechanisms generating both abnormal pain and analgesia (drugs and surgical techniques) in patients is the main motivation of such anexciting challenge.
大约10年来可用的功能神经成像技术极大地推动了对人脑中疼痛整合的活体研究。正电子发射断层扫描（PET），辅以激光诱发电位（LEP）和功能磁共振成像（fMRI），如今能够生成与生理性或神经性疼痛相关的脑活动图谱。LEP和fMRI通过更好的时间分辨率以及对个体受试者进行分析的可能性对PET起到补充作用。我们在疼痛机制方面的最新进展涉及生理性急性疼痛、神经性疼痛以及镇痛机制的研究。16项使用PET的研究已证明，在丘脑、脑岛/第二躯体感觉区、前扣带回和顶叶后皮质存在与疼痛相关的激活。右前额叶和顶叶后皮质、前扣带回和丘脑的活动可通过注意力（催眠、慢性疼痛、转移注意力、对疼痛的选择性关注）进行调节，可能服务于注意力过程而非疼痛分析。脑岛/第二躯体感觉区皮质的反应大概服务于痛觉感知的辨别方面，而第一躯体感觉区皮质特别参与疼痛辨别的特定方面（运动、接触）。在患者中，神经性疼痛、心绞痛和非典型面部疼痛会导致PET异常，其意义仍不明确，但这些异常位于丘脑和前扣带回皮质，表明其分布并非随机，而在脑岛/第二躯体感觉区仍可检测到辨别性反应。药物或刺激诱导的镇痛与许多慢性疼痛相关的丘脑基础异常的正常化有关。研究这些反应的意义、其神经化学相关性（PET）、时间进程，以及通过将PET数据与LEP和fMRI结果相关联来探究它们产生的个体策略，是医生和研究人员在未来几年仍需应对的挑战。推动我们对患者中产生异常疼痛和镇痛（药物和手术技术）机制的认识是这一激动人心挑战的主要动力。
