Influence Of Dose With Inner Ear To Sensorineural Hearing Loss In Head And Neck Carcinoma

Objective:To analyze the relationship between hearing loss in nasopharyngeal carcinoma and dose to inner ear,and to analyze the influences of hearing loss.Patients and method:Totally 53 patients with nasopharyngeal carcinoma were treated with Intensity-modulated radiotherapy in a hospital from January1 2015 to June1 2015.All patients were diagnosed by pathology.The cochlea was outlined by a same radiologist on the CT planning images.Then calculated the dose of each cochlea by the dose-volume histograms.The maximum dose(Dmax),the minimum dose(Dmin)and the mean dose(D mean)were calculated for each ear.Pure tone audiometry was conducted before radiotherapy,6 months after radiotherapy a nd 12 months after radiotherapy and hearing situation was evaluated.Patients were younger than 70 years of age,the tympanograms were A before radiotherapy.Patients were selected to meet the requirements,according to the diffe rent doses of the inner ear,patients were divided into low dose group(inner ear dose less than 45Gy)and high dose group(inner ear dose higher than 45Gy).The purpose of this study is to compare the relationship between the effects of irradiation dose and the incidence of sensorineural hearing loss after radiotherapy,and to evaluate the effect of time and frequency after radiotherapy on sensorineural hearing loss after radiotherapy.Results: There are 12 people in the low dose group,and the number of high dose group is 18.The dose(Dmin,Dmean,Dmax)of the low dose group was significantly lower than that of the high dose group(P <0.01).The bone conduction thresholds of the natural frequency(0.5K hz,1K hz,2Khz,4K hz)in the 6th and 12 th months after radiotherapy were higher than those before radiotherapy.The mean frequency of bone conduction in the low dose group was lower than that in the high dose group after radiotherapy(P <0.05).The incidence of severe hearing loss in the 12 th month after radiotherapy was lower than that in the high dose group,the difference was statistically significant(P <0.05).The rate of otoacoustic emission was significantly higher in the 12 th month after radiotherapy than that in the high dose group(P <0.05).Conclusion: In nasopharyngeal carcinoma patients with concurrent radiotherapy and chemotherapy,when the cochlea exposure dose is less than 45 Gy,the damage of the hair cells of the cochlea and the degree of hearing loss and the incidence of severe hearing loss can be reduced.