Spinal nerve roots were stimulated by magnetic stimulation over the spine percutaneously. Peripheral motor conduction time (PMCT) was calculated by the latencies of the M-wave and F-wave. The difference between the PMCT and the latency of CMAP elicited by magnetic stimulation over the spine showed the cauda equina conduction time (CELT). The target muscle was abductor hallucis. In 58 healthy volunteers, CECT was 3.5±1.0ms. CECT showed within the normal range in 12 cases of lumber disc herniation and 13 cases of lumbar spinal canal stenosis with L5 or S1 radiculopathy. CECT was 5.3±2.0ms in 15 cases of lumber spinal canal stenosis with cauda equina lesions. In conclusion, the cauda equina conduction time was delaied in lumber spinal canal stenosis with cauda equina lesion.
