ABSTRACT
BACKGROUND: Spinal cord stimulation(SCS) evolved as a direct clinical application of the famous gate-control theory, the idea of activating the central collaterals of large afferent fibers contained in the dorsal column. It is well known that the cord dorsum potential(CDP) evoked by stimulation of dorsal roots or peripheral nerves can be recorded from the cord surface in spinal animals. However, there have been no data about the changes in CDP after SCS. METHODS: Using ball-type electrode, CDP was recorded at the dorsal root entry zone of lumbosacral enlargement in anesthetized cats. The dorsal root was stimulated electrically to activate Adelta-fiber(single pulse of 0.2 ms duration and 1 mA intensity) and C-fiber(single pulse of 0.2 ms duration and 10 mA intensity). Potentials were averaged 10 times and measured before(control) and immediately after, and 10, 20, 30, 40, 50, 60 min after SCS for 20 min. RESULTS: CDP elicited by dorsal root stimulation consisted of the characteristic waves of Adelta-fiber and C-fiber with different time latency. CDP showed significant decrease in the amplitude of C-fiber wave immediately after SCS(75.0+/-8.8%), and 20 min(69.0+/-7.9%), 30 min(75.1+/-4.4%), 40 min(75.4+/-4.4%), 50 min(78.3+/-5.9%), but not 10 min and 60 min, after SCS. However there were no statistically significant decrease in the amplitude of Adelta-fiber wave after SCS. CONCLUSIONS: The above results indicates that SCS suppresses the transmission of nociceptive electrical stimuli via C-fiber, while SCS has little influence on the transmission of electrical nociceptive stimuli via Adelta-fiber.