The Effect of Four Weeks Low-Power Laser Irradiation(660 nm) on Thermal Hyperalgesia in the Model of Spinal Cord Injury Induced in Adult Male Rats

‌Introduction: Spinal cord injury is one of the important unresolved problems in the medical society leading to adverse consequences, such as motionlessness and neuropathic pain. Neuropathic pain is seen in both forms of hyperalgesia and allodynia. In this study, the effects of low-level laser radiation on hyperalgesia pain have been investigated.   Material & Methods: In this experimental study, animals (N=16) were divided into two groups(i.e., spinal cord injury and laser treatment). Aneurysm clip was used to induce spinal cord injury. Half an hour after the induction of spinal cord injury, animals were exposed to laser for 45 seconds every day up to four weeks. At the end of each week, the animals underwent a heat-hyperalgesia test. The results were analyzed in Prism software,version 6 .The value of  P <0.05 was considered significant.   Findings: Surgery of the induced spinal cord injury reduced threshold of hyperalgesia pain, compared to the control group (P<0.001). Low-level laser radiation for four weeks increased the pain threshold so that the pain proved equal to the control group and there was a significant difference between treated and spinal cord injured animals (P<0.001).   Discussion & Conclusions: Using a low-level laser as an anti-inflammatory agent in the first line treatment can be useful in controlling injury side effects shortly after a spinal cord injury; moreover,it can reduce the pain and inflammation caused by spinal cord injury.