Ruohonen J, Ravazzani P, Nilsson J, Panizza M, Grandori F, Tognola G
Helsinki University Central Hospital, Medical Engineering Center, Finland.
IEEE Trans Biomed Eng. 1996 Jul;43(7):669-78. doi: 10.1109/10.503174.
Magnetic stimulation is a method to study several nervous disorders as well as the intact nervous system in humans. Interest in magnetic stimulation of peripheral nerves has grown rapidly, but difficulties in locating the site of excitation have prevented it from becoming a routine clinical tool. It has been reasoned that the activating function of long and straight nerves is the first spatial derivative of the electric field component parallel to the nerves. Therefore, to predict the site of activation, one has to compute this field feature. We describe here an analytical mathematical model and investigate the influence of volume-conductor shape on the induced field. Predictions of the site of activation are given for typical stimulation coil arrangements and these results are compared with experimental and literature data. Comparisons suggest that the activating function is not simply the spatial gradient of the induced electric field, but that other mechanisms are also involved. The model can be easily utilized in the search for more efficient coil constructions and improved placements with respect to the target nerves.
磁刺激是一种研究人类多种神经疾病以及完整神经系统的方法。对外周神经进行磁刺激的研究兴趣迅速增长，但难以确定兴奋部位阻碍了它成为一种常规临床工具。据推断，长直神经的激活功能是平行于神经的电场分量的一阶空间导数。因此，为了预测激活部位，必须计算该场特征。我们在此描述一种解析数学模型，并研究体积导体形状对感应场的影响。针对典型的刺激线圈布置给出了激活部位的预测结果，并将这些结果与实验数据和文献数据进行了比较。比较结果表明，激活功能并非简单地是感应电场的空间梯度，还涉及其他机制。该模型可轻松用于寻找更高效的线圈结构以及相对于目标神经的更佳放置方式。
