Jalinous R
Department of Engineering, Magstim Company, Limited, Spring Gardens, Whitland, Wales, United Kingdom.
J Clin Neurophysiol. 1991 Jan;8(1):10-25. doi: 10.1097/00004691-199101000-00004.
Magnetic stimulators consist of a high-voltage (400 V to more than 3 kV), high-current (4 kA to more than 20 kA) discharge system producing a brief pulse of magnetic field (1-10 T lasting up to a few milliseconds). In order to ensure safety and reliability, care has to be taken in the construction of magnetic stimulators and especially their stimulating coils, which may come into contact with the patient, by the use of adequate mechanical and electrical insulation and the incorporation of sensors to monitor temperature, voltage, etc. Where possible, equipment should be manufactured to comply with safety standards such as UL504 and IEC601. The effectiveness of a magnetic stimulator depends on many parameters such as the maximization of the peak coil energy, fast magnetic field rise times, and good coil design. It is also important to choose a coil based on its intended clinical application and not simply on account of its high magnetic field strength. A small coil, producing a high surface magnetic field, is suitable in the stimulation of superficial nerves, whereas a larger coil, with a low magnetic field intensity, may well be more suitable for the stimulation of deep nerves. Double, figure-eight, or butterfly coils produce more localised induced currents allowing for more selective stimulation. The exposure of the brain to high magnetic field strengths can also be reduced by using larger coils.
磁刺激器由一个高压（400伏至超过3千伏）、大电流（4千安至超过20千安）的放电系统组成，该系统产生一个短暂的磁场脉冲（1 - 10特斯拉，持续时间可达几毫秒）。为确保安全性和可靠性，在磁刺激器的构造，尤其是其刺激线圈（可能会与患者接触）的构造过程中，必须注意采用适当的机械和电气绝缘措施，并加入传感器来监测温度、电压等。只要有可能，设备应按照诸如UL504和IEC601等安全标准制造。磁刺激器的有效性取决于许多参数，如线圈峰值能量的最大化、快速的磁场上升时间以及良好的线圈设计。根据预期的临床应用来选择线圈也很重要，而不仅仅是基于其高磁场强度。一个产生高表面磁场的小线圈适用于刺激浅表神经，而一个具有低磁场强度的较大线圈可能更适合刺激深部神经。双线圈、8字形线圈或蝶形线圈会产生更局部化的感应电流，从而实现更具选择性的刺激。使用较大的线圈也可以减少大脑暴露于高磁场强度的情况。
