Cord dorsum potentials suppressed by low power laser irradiation on a peripheral nerve in the cat.

The effects of low-power helium-neon laser irradiation on the cord dorsum potentials (CDP) evoked by electrical nerve stimulation of a distal portion of exposed sural nerve were observed in unanesthetized decerebrate cats. These evoked CDP were significantly suppressed (25.6 +/- 2.5%, p less than 0.01) during low-power laser irradiation. It is suggested that the analgesic effects of low power laser irradiation is based on the decrease of ascending signals from the spinal cord to the higher central nervous system. The suppressive effect of low power laser irradiation upon the impulse transmission of nerve fibers is discussed.