Chinzei M, Chinzei T, Yonezawa T, Lee C S, Tagami M, Hanaoka K, Imachi K
Surgical Center, University of Tokyo Faculty of Medicine.
Masui. 1999 Jan;48(1):9-17.
We aimed to develop a method of accurately identifying the dorsal root for the corresponding peripheral afferent nerve under endoscopic observation. We developed an endoscope with an external diameter of 1.8 mm. After small laminectomy on the lower thoracic vertebrae, we inserted this endoscope carefully into the epidural and then subarachnoid spaces. We observed structures in these spaces with the endoscope. We tried to determine the spatial relationship between these electrodes and dorsal root. After identifying each space, we inserted two electrodes into the visualized space to record evoked potentials; a bipolar electrode (protocol 1) and a catheter-type eight polar electrode (protocol 2). Each pole could be distinguished by marks. To stimulate peripheral nerves, we inserted needle-type electrodes into Th 10, 11 and 12 intercostal nerves. We attempted to record potentials from dorsal surface of the cord generated by intercostal nerve stimulus. Protocol 1: We moved the position of the bipolar recording electrodes between Th 9 and L 1 by 1 cm increment, and obtained evoked potentials correspondingly. Protocol 2: We chose the neighboring pairs of poles sequentially from the tip of the catheter for bipolar recording. At the end of each experiment, we dissected the animal and checked the intercostal nerve originating from the root. With the endoscope, we could clearly observe structures in the epidural and subarachnoid spaces. We could record evoked potentials from the dorsal spinal cord with the electrodes located either in epidural or in subarachnoid spaces. Shapes of evoked potentials changed characteristically according to the relative position between the root and the electrode. The largest potentials were obtained when the electrode was nearest to the dorsal root, of which the peripheral nerve was being stimulated. By combining endoscopy with the electrophysiological technique, we could accurately identify the dorsal roots for the corresponding peripheral afferent nerves. This method may be used for the selective dorsal root blockade under the visual field.
我们旨在开发一种在内镜观察下准确识别相应外周传入神经背根的方法。我们研制了一种外径为1.8毫米的内窥镜。在对下胸椎进行小范围椎板切除术后，我们小心地将该内窥镜插入硬膜外腔，然后进入蛛网膜下腔。我们用内窥镜观察这些腔隙内的结构。我们试图确定这些电极与背根之间的空间关系。在识别出每个腔隙后，我们将两个电极插入可视化腔隙以记录诱发电位；一个双极电极（方案1）和一个导管型八极电极（方案2）。每个电极极可通过标记区分。为了刺激外周神经，我们将针型电极插入第10、11和12肋间神经。我们试图记录肋间神经刺激在脊髓背表面产生的电位。方案1：我们将双极记录电极在第9胸椎和第1腰椎之间以1厘米的增量移动位置，并相应地获得诱发电位。方案2：我们从导管尖端依次选择相邻的电极对进行双极记录。在每个实验结束时，我们解剖动物并检查源自该神经根的肋间神经。通过内窥镜，我们可以清楚地观察硬膜外腔和蛛网膜下腔内的结构。我们可以用位于硬膜外腔或蛛网膜下腔内的电极记录脊髓背侧的诱发电位。诱发电位的形状根据神经根与电极之间的相对位置而有特征性变化。当电极最靠近正在被刺激的外周神经的背根时，可获得最大电位。通过将内窥镜检查与电生理技术相结合，我们可以准确识别相应外周传入神经的背根。该方法可用于视野下的选择性背根阻滞。
