Experimental Research On Inhibition Of Secondary Injury By Low Power Laser Irradiation Therapy Following Spinal Cord Injury

In most countries, the annual incidence rate of spinal cord injury(SCI) is 20-40 person in ever million. Although the protective measures have been switched on, there is no indication that the rate will be diminished. The primary cause of SCI is road accident(45.4%),and other causes include falling from high locality and athletic injury whereas the SCI caused by colliery accident is striking in China. SCI often leads to lifelong disability of the patient, resulting in enormous suffering and burden of the family and society. During the period of postinjury of SCI, there is a secondary lesion caused by the primary injury, which leads to a even greater injury several times more than the original injury. Therefore, how to relieve the secondary injury is the hot topic studied internationally for the past many years. However, up to now, there isn't acknowledged method to relieve the secondary injury except for the large doses of Methylprednisolone, that has some effect. Therefore, Management in the early stage an prevent or reverse those secondary pathological damages,reduce apoptosis neural cells,and greatly improve the neural functional recovey of the injured spinal cord. Low power laser irradiation has been used widely in the clinical work , with its facility of no side effect, acceptable by patients. Low power laser has biologic stimulating effect which activate many enzyme and modulate permeability of cell membrane. For this reason, we selected to hemisection SCI model by low power laser irradiation, observed the effect which the laser decrease secondary injury and restore spinal cord, and discuss the mechanisms.This thesis comprises two parts. In part one, we used HE staining to study effect of low power laser and to find out optimization wave length and power. In order to search more convenience and reliable method, we considered using three different power (100nW, 150nW, 200nW) and four different time point (1d,7d, 14d, 21d).we examined area of the injury region. The reault showed that:1. After 1d SCI , the irradiation group is not higher than in control group with statistically significant difference. However, else time point, the irradiation group is higher than in control group with statistically significant difference (P < 0. 05). These results mainly attributed to laser accumulative effect.2. The area of injury region of 150nW group is smallest than other group. So ,we can demonstrate that 810nm, 150nW is optimization and penetrate deep into the body and promote neuronal regeneration and functional recovery.In part two, SD rats were divided randomly into two groups, control group and irradiation group. All SD rats were selected to hemisection SCI model,low laser transmission from surface of the skin to the depth of the spinal cord by 810nm, 150nW. By the method of Immunohistochemistry and HE staining , we observed spinal cord hollow, glial scar change and the expression of CS56 in 1, 3, 7, 14d after injury. The reault showed that:1. The spinal cord hollow of the irradiation group become smaller than control group with statistically significant difference (P < 0. 05), and the expression of NF in irradiation group increased nearby injury area. The expression of CS56 in irradiation group decreased after spinal cord injury than in control group with statistically significant difference (P < 0. 05).In conclusion, by low power laser irradiation therapy, glial scar of the injury area and the expression of CS56 decreased. Therefore, low power laser irradiation therapy can relieve the secondary spinal cord injury and promote nerve recovery.