Experiences with the Intraoperative Single Unit Potential Recording of Spinal Cord and Cauda Equina Disorders

We applied the method of recording single unit potentials with wire electrodes to humans. Using two pairs of platinum electrodes it was possible to record extracellular single unit potentials at two different places in nerve root filaments smaller than 1 mm in diameter in the spinal canal and to determine conduction velocities. Afferent and efferent single unit potentials could be distinguished from each other by a reversed conduction time and a reversed potential change. It was also possible to record an activity increase due to skin receptor stimulation (Fig.1); therefore the method can be used as a diagnostic tool during surgery (1).