Protective Effects Of Radix Salvia Miltiorrhiza On Radioactive Damages Of The Cochlea By Laser System

Objective Experiments in guinea pigs were performed to study the effect of superpulsed CO₂ laser irradiation in different power on the inner ear, and whether Radix Salvia Miltiorrhiza had protective effects on damages caused by laser'irradiation.Methods The experiments comprised two parts, finished in two stage. In the first stage, low peak power(P_peak=125w, P_average≤4w) of superpulsed CO₂ laser was adopted, 24 guinea pigs were divided into Control group,Laser 2w group and Laser 4w group, with 8 in each group.The latter two groups were performed fenestration on the basal turn of cochlea using laser irradiation with power 2w and 4w respectively, the Control group only exposed basal turn of cochlea only. In the second stage high peak power(P_peak=300w, P_average≥5w) of laser was adopted, 16 guinea pigs are divided into Laser 5w group and Salvia group, both were made perforation on the basal turn by laser irradiation with 5w, and the Salvia group was given Radix Salvia Miltiorrhiza by intraperitoneal injection. Auditory brainstem response(ABR) was conducted 1 day before operative and on post operative 1d, 7d, and 21d respectively. Light and scanning electron microscope were performed to observe the changes of cochlear morphology.Results The threshold of ABR shifted in Laser 2w group and Laser 4w group on the 1st day after operation, raising 10～15dB and 10～20dB respectively, but both nearly recoverd the level of pre-operation after 21 days, the Control group changed slightly in experiment stage. The morphology of Laser 2w group changed slightly,and Laser 4w group showed hair cell stereocilia scattered mainly and missing less, compared with the control group which was usually normal. In the second stage, the ABR threshold at Laser 5w group and Salvia group shifted significantly(p<0.05), there was no appreciable difference between two groups(p>0.05). After 21 days, two groups improved to some extent,exhibiting threshold shifts of 17dB and 13dB respectively compared with pre-operation(p<0.05), but no significant difference was noted between two groups(p>0.05). In the terms of morphology alterations, outer hair cell stereocilia in Laser 5w group were scattered and missing obviously, inner hair cell stereociliaare scattered and disarranged mainly, missing partly, while the Salvia group was damaged lessly relatively.Conclusion The experimental results presented indicated that low peak power superpulsed CO₂ laser can ablate the bone tissue of cochlea, and had a high application safety for laser fenestration. Although the high peak power had more ablation efficiency, the morphology and function of cochlea were affected seriously. Fortunately, Radix Salvia Miltiorrhiza had protective effects on damages of cochlea caused by superpulsed CO₂ laser。...