PERCEPTION THRESHOLD AND ELECTRODE POSITION FOR SPINAL-CORD STIMULATION

The perception threshold for epidural spinal cord stimulation in chron ic pain management was analyzed on 3993 testing data obtained from 136 implanted patients. The initial areas of paresthesiae due to stimulat ion were recorded and reported as the stimulation map according to the location of electrodes. Measurement of dorsal thickness of the cerebr ospinal fluid (CSF) layer was obtained from 26 subjects using magnetic resonance imaging (MRI). The results indicate that the perception thr eshold is a function of the spinal level of the implanted electrodes, of the mediolateral position in the spinal canal and the contact separ ation of electrode. Differences in perception threshold at various ver tebral levels are mainly due to varying depths of the dorsal CSF layer . The medially placed electrodes caudal to the mid-cervical levels hav e a higher perception threshold than more laterally placed ones. The e lectrodes at high and mid-cervical levels, however, have a smaller per ception threshold if placed medially. The information obtained from th is investigation has important implications for the design of a new-ge neration stimulation system and clinical application to maximize the l ongevity of the power source.