Recording of single unit potentials in human spinal nerve roots: a new diagnostic tool.

Single unit potentials can be recorded directly with wire electrodes during an operation in man. Since averaging is not necessary this recording method is a fast neuromonitoring tool. Using 2 pairs of platinum electrodes it was possible to record extracellular single unit potentials at 2 sites in nerve root filaments 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 making a differentiation between dorsal and ventral root parts possible. An activity increase due to touching the skin could be recorded. Therefore dermatomes of nerve root filaments and root filaments of dermatomes can be identified during the operation.