Magnetic augmented translumbosacral stimulation coil stimulation method for accurate evaluation of corticospinal tract function in peripheral neuropathy

摘要

Sir, The limitation of magnetic stimulation is that the prolongation of the central motor conduction time (CMCT) does not exactly indicate the involvement of the corticospinal tract when the spinal nerves are involved, because magnetic stimulation over the spinal enlargements activates the spinal nerves at the neuro-foramina level. Especially for leg muscles, the conduction delay of long spinal nerves (i.e., cauda equina) readily contributes to CMCT prolongation. Recently, we have developed a novel method to activate the most proximal cauda equina around the conus medullaris using a magnetic augmented translumbosacral stimulation (MATS) coil [Figure 1]. We have also reported that the conduction time from the motor cortex to the conus medullaris (cortico-conus motor conduction time, CCCT) can be assessed using the MATS coil in healthy subjects. Here, we demonstrate that the CCCT is hardly affected even when the nerve conduction of peripheral nerves is severely delayed.