Department of Neurophysiology Houston Methodist Health System, Houston, Texas.
Department of Neurosurgery Lenox Hill Hospital/Donald and Barbara Zucker School of Medicine at Hofstra, New York, New York.
Neurodiagn J. 2022 Sep;62(3):164-177. doi: 10.1080/21646821.2022.2107862.
Current intraoperative somatosensory evoked potential (SSEP) guidelines recommend bipolar stimulation with the anode at or near the crease of the wrist and the cathode 2-4 cm proximal to the anode for median nerve SSEPs. The rationale for this cathode proximal bipolar configuration appears to be the avoidance of anodal blocking; however, there is a paucity of experimental support for the existence of anodal blocking. Evidence that bipolar stimulation preferentially drives stimulation from the cathode better than monopolar cathodal or monopolar anodal in peripheral nerves in human neurophysiology is also lacking. This study compared anode proximal to anode distal bipolar stimulation of median nerve SSEPs and the efficacy of monopolar cathode to monopolar anode stimulation in generating median, ulnar, and tibial nerve SSEPs. No difference in median nerve cortical SSEP amplitude was observed between anode proximal and anode distal bipolar stimulation at supramaximal stimulation suggesting cathode proximal bipolar is equal to anode proximal bipolar stimulation at supramaximal intensity. This data suggests that anodal blocking does not occur in intraoperative SSEPs. Furthermore, no differences were observed in ulnar, median, and tibial nerve SSEP cortical or subcortical amplitudes and latencies between monopolar cathodal or monopolar anodal stimulation suggesting monopolar cathode and anode stimulation are equally effective at evincing intraoperative SSEPs at supramaximal intensity.
目前术中体感诱发电位 (SSEP) 指南建议使用阳极在腕部皱褶处或附近，阴极在阳极近端 2-4cm 处进行双极刺激，用于正中神经 SSEP。这种阴极近端双极配置的原理似乎是避免阳极阻断；然而，阳极阻断的存在缺乏实验支持。在人体神经生理学中，也缺乏双极刺激优先从阴极驱动刺激而不是单极阴极或单极阳极的证据。本研究比较了正中神经 SSEP 的阳极近端至阳极远端双极刺激以及单极阴极与单极阳极刺激在产生正中、尺和胫神经 SSEP 方面的效果。在最大刺激下，阳极近端和阳极远端双极刺激对正中神经皮质 SSEP 幅度没有差异，这表明在最大强度下，阴极近端双极与阳极近端双极刺激相同。这一数据表明，术中 SSEP 中不会发生阳极阻断。此外，在单极阴极或单极阳极刺激下，尺神经、正中神经和胫神经 SSEP 皮质或皮质下幅度和潜伏期均无差异，这表明在最大强度下，单极阴极和阳极刺激在产生术中 SSEP 方面同样有效。
