Three-dimensional neuromagnetic recording in the spinal cord

Recently it has been thought that neuromagnetic recording is expected to be a helpful alternative examination, since it can detect neural conduction by non-invasive skin surface recording. In this study, we recorded three-dimensional spinal cord evoked magnetic fields (SCEFs) in the cervical spinal cord of rabbits, and evaluated their usefulness in the examination of spinal cord function. The rabbits were anesthetized and put on a respirator. Electrical stimuli (10 Hz square wave pulses, 0.03 ms in duration, 8-10 mA in intensity) were applied to the lower thoracic spinal cord with an epidural electrode. SCEFs were recorded at 64-96 measurement points on the skin surface over the cervical spine. In addition, spinal cord evoked potentials (SCEPs) were recorded at the skin surface. The recordings were done before and after the disconnection of the cervical spinal cord. Three-dimensional SCEFs were recorded in all animals and the conducting neuronal activity was visualized by magnetic contour map. The three components of the SCEFs showed characteristic patterns, respectively. The positions of action currents were estimated by dipole localization. Although further studies are necessary, three-dimensional recording of SCEFs could be a helpful method to evaluate the function of the spinal cord. (c) 2004 Elsevier B.V. All rights reserved.