Schmid U D, Walker G, Hess C W, Schmid J
Department of Neurology, University Hospital, Berne, Switzerland.
J Neurol Neurosurg Psychiatry. 1990 Sep;53(9):770-7. doi: 10.1136/jnnp.53.9.770.
Cervical motor roots and the brachial plexus were excited transcutaneously with magnetic (MagStim) and electrical stimulation (ElStim) applied dorsally over the spine and over the supraclavicular fossa (Erb's point). The compound muscle action potentials (CMAPs) from the abductor digiti minimi (ADM) and the biceps muscles (BICEPS) could be evoked with either stimulating technique in all 52 subjects tested. With MagStim over the spinous process C7, greater CMAPs were obtained from ADM (p less than or equal to 0.0001, paired t test) and BICEPS (p less than or equal to 0.005) when the inducing current in the coil as viewed from behind was clockwise for the right arm and vice versa. ElStim with the cathode over C7/T1 and the anode directed cranially provided greater CMAPs from the ADM (p less than or equal to 0.0001) and smaller CMAPs from the BICEPS (p less than or equal to 0.01) than with the inverse polarity. MagStim of the cervical roots provided CMAPs which were smaller from ADM (p less than or equal to 0.0001), and greater from BICEPS (p less than or equal to 0.0001), than ElStim (cathode C7/T1), whereas latencies did not differ significantly (p less than or equal to 0.3). When comparing ElStim and MagStim applied over Erb's point, the former yielded greater CMAPs and 0.5 ms longer latencies from both the ADM and BICEPS (p less than or equal to 0.001). From these data and additional studies in four patients, including direct intraoperative root stimulation in one of them, it is concluded that ElStim and MagStim over the spine excite the motor roots at a similar site, that is, within a few cm outside the intervertebral foramina. The site of stimulation is difficult to predict and depends on the placement of the stimulating devices and the intensities used. In contrast, MagStim of the brachial plexus over Erb's point occurs on average about 3.5 cm distal to the site of ElmStim.
通过在脊柱背侧和锁骨上窝（Erb点）进行磁刺激（MagStim）和电刺激（ElStim），经皮刺激颈运动神经根和臂丛神经。在所有52名受试对象中，两种刺激技术均可诱发出来自小指展肌（ADM）和肱二头肌（BICEPS）的复合肌肉动作电位（CMAP）。当从后方看线圈中的感应电流顺时针时，在C7棘突上进行MagStim刺激时，ADM（配对t检验，p≤0.0001）和BICEPS（p≤0.005）可获得更大的CMAP，右臂情况相反。阴极置于C7/T1且阳极指向上方的ElStim刺激，与极性相反时相比，ADM可获得更大的CMAP（p≤0.0001），BICEPS可获得更小的CMAP（p≤0.01）。与阴极置于C7/T1的ElStim相比，颈神经根的MagStim刺激所产生的CMAP，ADM更小（p≤0.0001），BICEPS更大（p≤0.0001），而潜伏期无显著差异（p≤0.3）。当比较在Erb点进行的ElStim和MagStim时，前者从ADM和BICEPS均可产生更大的CMAP，且潜伏期长0.5 ms（p≤0.001）。根据这些数据以及对4例患者的额外研究（其中1例患者术中进行了直接神经根刺激），得出结论：脊柱上的ElStim和MagStim在相似部位刺激运动神经根，即椎间孔外几厘米处。刺激部位难以预测，取决于刺激装置的放置和使用强度。相比之下，在Erb点对臂丛神经进行的MagStim刺激平均发生在ElStim刺激部位远端约3.5 cm处。
