Effects of laser irradiation on the spinal cord for the regeneration of crushed peripheral nerve in rats

BACKGROUND AND OBJECTIVE: The purpose of the present study was to examine the recovery of the crushed sciatic nerve of rats after low-power laser irradiation applied to the corresponding segments of the spinal cord. STUDY DESIGN/MATERIALS AND METHODS: After a crush injury to the sciatic nerve in rats, low-power laser irradiation was applied transcutaneously to corresponding segments of the spinal cord immediately after closing the wound by using 16 mW, 632 nm He-Ne laser. The laser treatment was repeated 30 minutes daily for 21 consecutive days. RESULTS: The electrophysiologic activity of the injured nerves (compound muscle action potentials--CMAPs) was found to be approximately 90% of the normal precrush value and remained so for up to a long period of time. In the control nonirradiated group, electrophysiologic activity dropped to 20% of the normal precrush value at day 21 and showed the first signs of slow recovery 30 days after surgery. The two groups were found to be significantly different during follow-up period (P < 0.001). CONCLUSION: This study suggests that low-power laser irradiation applied directly to the spinal cord can improve recovery of the corresponding insured peripheral nerve.