Abstract
A non-invasive method of magnetic stimulation of the spinal roots was designed. The basic idea is to concentrate induced eddy currents in a target by a pair of opposing pulsed magnetic fields. A figure-eight coil was positioned a little laterally from the median line of the back so that time-varying magnetic fields could pass through the body in the opposite directions around the target. Magnetic stimulation of the spinal roots was carried out in the human and rabbit. Each spine level was stimulated selectively with electromyographic (EMG) waves related to both the H-reflex and M-wave. Our results indicate that the M-wave can be produced by currents flowing either in the rostral or caudal direction, whereas the H-reflex is only generated by curents flowing in the caudal direction. The H-reflex elicited by magnetic stimulation of the nerve in the vicinity of the spine could provide a new tool in diagnosis of intra-and infraspinal neuro-muscular diseases.
