Motor evoked potentials from the bladder on magnetic stimulation of the cauda equina: a new technique for investigation of autonomic bladder innervation

Although neurophysiological techniques have become widely accepted in the diagnostic evaluation of urogenital tract dysfunction, arguments have been forwarded to question their validity. Current techniques merely deal with somatosensory nerves, whereas micturition and sexual functions depend on autonomic motor nerve function as well. This study presents a new technique of motor evoked potentials obtained after magnetic stimulation of the cauda equina. Bladder and pelvic floor motor evoked potentials could be measured with concentric needle electrodes. Mean latency was 35.6 msec. for bladder motor evoked potentials and 10.6 msec. for pelvic floor motor evoked potentials. The technique was easy to perform, and provided consistent and objective data. No harmful side effects were noted