Sensory nerve conduction in the human spinal cord: epidural recordings made during scoliosis surgery.

This report describes the waveform and properties of somatosensory evoked potentials recorded from various levels of the human spinal cord, with electrodes inserted into the epidural space and the stimulus delivered to the posterior tibial nerve at the knee. The object was to provide a means of monitoring spinal cord function during surgery for the correction of spinal deformities. The responses could be resolved into at least three components with different activation thresholds and different conduction velocities within the spinal cord (45-80 m/s approximately). The findings are in accord with recent studies, suggesting that the fast activity may be conducted in the dorsal spinocerebellar tract and the slower waves in the posterior columns.