Hollerbach S, Kamath M V, Lock G, Schölmerich J, Upton A R, Tougas G
Klinik und Poliklinik für Innere Medizin I, Universität Regensburg, Germany.
Z Gastroenterol. 1998 Apr;36(4):313-24.
Increasing awareness is attributed to altered sensory perception in the pathogenesis of gastrointestinal disorders. Evoked potentials (EP), which represent the brain's electrical response to peripheral stimulation, have recently been used to investigate where and how (GI) afferent information is processed along the brain-gut axis. EP can be obtained with electrical stimulation or balloon distention in the esophagus in humans. Stimulation of afferent neural pathways in the esophagus produces cerebral evoked responses allowing assessment of the peripheral afferent neural pathways involved, and of the function of integrative neural centers within the brain. Recent studies using esophageal EP indicate that the cerebral response to either mode of stimulation depends on the perception of the stimuli. Using electrical stimulation, a clear dose-response relationship is found. The EP response obtained with electrical stimulation is in keeping with those recorded using direct cervical stimulation of the vagus nerve, supporting evidence that esophageal EP are produced by activation of afferent vagal pathways. From the conduction velocity of the autonomic (vagal) nerves conveying information from esophagus to brain, it was concluded that non-painful electrical stimuli predominantly activate fast conducting myelinated afferent sensory fibers (A-fibers), while EP to balloon distention are largely due to activation of unmyelinated C-fibers. Techniques, however, vary widely amongst different investigators, and some electrophysiological parameters remain controversial, as there is no standard approach. Using balloon distention, EP waveforms vary widely between laboratories, suggesting that EP are substantially influenced by the stimulator devices (pump, respirator). EP to balloon distention are hampered by a relatively low signal-to-noise ratio (SNR), which is probably due to long inflation-deflation time (> 200 ms). With electrical stimulation, there is much less variability between different groups, and SNR is distinctly higher. This method appears to be most attractive for studies of afferent esophageal function. Standardization of the techniques is important, before esophageal EP can be regarded as a useful diagnostic approach in patient groups.
胃肠道疾病发病机制中，意识增强归因于感觉知觉的改变。诱发电位（EP）代表大脑对外周刺激的电反应，最近已被用于研究胃肠道（GI）传入信息在脑-肠轴上的处理位置和方式。在人类中，可通过食管的电刺激或球囊扩张来获得EP。刺激食管中的传入神经通路会产生大脑诱发反应，从而可以评估所涉及的外周传入神经通路以及大脑中整合神经中枢的功能。最近使用食管EP的研究表明，大脑对任何一种刺激模式的反应都取决于对刺激的感知。使用电刺激时，会发现明显的剂量反应关系。电刺激获得的EP反应与直接颈段刺激迷走神经所记录的反应一致，支持了食管EP是由迷走传入通路激活产生的证据。根据从食管向大脑传递信息的自主（迷走）神经的传导速度，得出的结论是，无痛电刺激主要激活快速传导的有髓传入感觉纤维（A纤维），而球囊扩张引起的EP很大程度上是由于无髓C纤维的激活。然而，不同研究者使用的技术差异很大，并且一些电生理参数仍存在争议，因为没有标准方法。使用球囊扩张时，不同实验室之间的EP波形差异很大，这表明EP受到刺激设备（泵、呼吸机）的显著影响。球囊扩张引起的EP受到相对较低的信噪比（SNR）的阻碍，这可能是由于较长的充气-放气时间（>200毫秒）。使用电刺激时，不同组之间的变异性要小得多，并且SNR明显更高。这种方法似乎对传入食管功能的研究最具吸引力。在食管EP可被视为患者群体中一种有用的诊断方法之前，技术标准化很重要。
