Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan, Taiwan; Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan; Department of Diagnostic Radiology, Chang Gung Memorial Hospital, Keelung, Taiwan; Medical Imaging Research Center, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan.
Department of Foreign Languages and Literature, National Tsing Hua University, Hsinchu, Taiwan.
Am J Obstet Gynecol. 2023 May;228(5S):S1241-S1245. doi: 10.1016/j.ajog.2023.02.012. Epub 2023 Mar 21.
Characterizing a labor pain-related neural signature is a key prerequisite for devising optimized pharmacologic and nonpharmacologic labor pain relief methods. The aim of this study was to describe the neural basis of labor pain and to provide a brief summary of how epidural anesthesia may affect pain-related neuronal activity during labor. Possible future directions are also highlighted. By taking advantage of functional magnetic resonance imaging, brain activation maps and functional neural networks of women during labor that have been recently characterized were compared between pregnant women who received epidural anesthesia and those who did not. In the subgroup of women who did not receive epidural anesthesia, labor-related pain elicited activations in a distributed brain network that included regions within the primary somatosensory cortex (postcentral gyrus and left parietal operculum cortex) and within the traditional pain network (lentiform nucleus, insula, and anterior cingulate gyrus). The activation maps of women who had been administered epidural anesthesia were found to be different-especially with respect to the postcentral gyrus, the insula, and the anterior cingulate gyrus. Parturients who received epidural anesthesia were also compared with those who did not in terms of functional connectivity from selected sensory and affective regions. When analyzing women who did not receive epidural anesthesia, marked bilateral connections from the postcentral gyrus to the superior parietal lobule, supplementary motor area, precentral gyrus, and the right anterior supramarginal gyrus were observed. In contrast, women who received epidural anesthesia showed fewer connections from the postcentral gyrus-being limited to the superior parietal lobule and supplementary motor area. Importantly, one of the most noticeable effects of epidural anesthesia was observed in the anterior cingulate cortex-a primary region that modulates pain perception. The increased outgoing connectivity from the anterior cingulate cortex in women who received epidural anesthesia indicates that the cognitive control exerted by this area might play a major role in the relief from labor pain. These findings not only affirmed the existence of a brain signature for pain experienced during labor, but they also showed that this signature can be altered by the administration of epidural anesthesia. This finding raises a question about the extent to which the cingulo-frontal cortex may exert top-down influences to gate women's experiences of labor-related pain. Because the anterior cingulate cortex is also involved in the processing and modulation of emotional content, such as fear and anxiety, a related question is about the extent to which the use of epidural anesthesia can affect different components of pain perception. Finally, inhibition of anterior cingulate cortex neurons may represent a potential new therapeutic target for alleviating labor-associated pain.
描述分娩疼痛相关的神经特征是设计优化的药物和非药物分娩镇痛方法的关键前提。本研究旨在描述分娩疼痛的神经基础，并简要总结硬膜外麻醉如何影响分娩过程中的疼痛相关神经元活动。还强调了可能的未来方向。利用功能磁共振成像，比较了最近描述的接受和未接受硬膜外麻醉的孕妇在分娩时的大脑激活图谱和功能神经网络。在未接受硬膜外麻醉的孕妇亚组中，分娩相关疼痛引起了分布在初级体感皮层（中央后回和左顶叶脑岛皮层）和传统疼痛网络（豆状核、脑岛和前扣带回）内的脑网络的激活。接受硬膜外麻醉的女性的激活图谱被发现有所不同 - 特别是中央后回、脑岛和前扣带回。还比较了接受硬膜外麻醉的产妇和未接受硬膜外麻醉的产妇在选定的感觉和情感区域的功能连接。当分析未接受硬膜外麻醉的女性时，观察到从中央后回到顶叶上回、辅助运动区、中央前回和右侧额上前缘回的双侧连接明显增加。相比之下，接受硬膜外麻醉的女性从中枢后回的连接较少，仅限于顶叶上回和辅助运动区。重要的是，硬膜外麻醉最明显的影响之一发生在前扣带皮层 - 这是调节疼痛感知的主要区域。接受硬膜外麻醉的女性前扣带皮层传出连接增加表明，该区域的认知控制可能在分娩疼痛缓解中发挥主要作用。这些发现不仅证实了分娩疼痛存在大脑特征，而且表明硬膜外麻醉可以改变这种特征。这一发现提出了一个问题，即扣带前皮质可能在多大程度上发挥自上而下的影响来控制女性分娩相关疼痛的体验。由于前扣带皮层还参与处理和调节情绪内容，如恐惧和焦虑，因此还有一个相关的问题是，硬膜外麻醉的使用在多大程度上会影响疼痛感知的不同成分。最后，抑制前扣带皮层神经元可能代表缓解与分娩相关疼痛的潜在新治疗靶点。
