A comparison of magnetic and electrical stimulation of spinal nerves.

The utility of the magnetic coil for stimulation of the cervical spinal nerves was compared to electrical stimulation by a monopolar needle cathode placed onto the spinal lamina in six volunteers. No statistical difference in average amplitudes or areas of evoked CMAPs was found although the size of the magnetic coil evoked potentials was less at C7-8 in several subjects. Electrical stimulation resulted in depolarization at a more proximal site. Electrical stimulation was associated with more discomfort, especially at C5-6. We conclude that electrical stimulation using a monopolar needle as the cathode is the superior technique for the clinical electrophysiologic study of the proximal brachial plexus and cervical spinal nerves.