The different peaks of somatosensory-evoked potentials (SEP) originate from a variety of anatomical sites in the central nervous system. The origin of the median nerve subcortical N18 SEP has been studied under various conditions, but the exact site of its generation is still unclear. While it has been claimed to be located in the thalamic region, other studies indicated its possible origin below the pontomedullary junction. Here, we scrutinized and compared SEP recordings from median nerve stimulation through deep brain stimulation (DBS) electrodes implanted in various subcortical targets. We studied 24 patients with dystonia, Parkinson’s disease, and chronic pain who underwent quadripolar electrode implantation for chronic DBS and recorded median nerve SEPs from globus pallidus internus (GPi), subthalamic nucleus (STN), thalamic ventral intermediate nucleus (Vim), and ventral posterolateral nucleus (VPL) and the centromedian–parafascicular complex (CM-Pf). The largest amplitude of the triphasic potential of the N18 complex was recorded in Vim. Bipolar recordings confirmed the origin to be close to Vim electrodes (and VPL/CM-Pf) and less close to STN electrodes. GPi recorded only far-field potentials in unipolar derivation. Recordings from DBS electrodes located in different subcortical areas allow determining the origin of certain subcortical SEP waves more precisely. The subcortical N18 of the median nerve SEP—to its largest extent—is generated ventral to the Vim in the region of the prelemniscal radiation/ zona incerta.

体感诱发电位 (SEP) 的不同峰值源自中枢神经系统的多个解剖部位。正中神经皮层下N18 SEP的起源已在各种条件下进行了研究，但其产生的确切部位仍不清楚。虽然据称它位于丘脑区域，但其他研究表明它可能起源于脑桥延髓交界处以下。在这里，我们仔细检查并比较了通过植入各种皮层下目标的深部脑刺激 (DBS) 电极进行正中神经刺激的 SEP 记录。我们研究了 24 名患有肌张力障碍、帕金森病和慢性疼痛的患者，他们接受了四极电极植入以进行慢性 DBS，并记录了来自苍白球内部 (GPi)、丘脑底核 (STN)、丘脑腹侧中间核 (Vim) 和腹侧的正中神经 SEP。后外侧核（VPL）和中心正中束旁复合体（CM-Pf）。在 Vim 中记录 N18 复合体三相电位的最大幅度。双极记录证实起源靠近 Vim 电极（和 VPL/CM-Pf），而不那么靠近 STN 电极。GPi 在单极推导中仅记录远场电位。位于不同皮层下区域的 DBS 电极的记录可以更精确地确定某些皮层下 SEP 波的起源。正中神经 SEP 的皮层下 N18 在其最大范围内产生于 Vim 腹侧的丘系前辐射/未定带区域。