Study On The Correlation Between The Development Of Cochlear Nerve And The Effect Of Cochlear Implant In Patients With Sensorineural Hearing Loss

Objective:Comparing the differences in the development of the cochlear nerve and internal auditory canal between patients with sensorineural hearing loss and those with normal hearing,we analyze the correlation between the cross-sectional area of the cochlear nerve and the hearing and speech rehabilitation effect after cochlear implantation and we explore the feasibility of using cochlear nerve cross-sectional area as a predictor of auditory and speech rehabilitation after CI.Methods:A total of 221 patients with severe and extremely severe sensorineural deafness and 42 patients with MRI and 48 patients with CT as normal hearing control group were selected to measure the cochlear nerve cross-sectional area,the width of the cochlear nerve tube and the width of the internal auditory canal,in order to compare the differences in the development of the cochlear nerve and the internal auditory canal according to gender and age and to analyze whether the cochlear nerve cross-sectional area,the width of the cochlear nerve tube and the width of the internal auditory canal were different between the patients with sensorineural deafness and those with normal hearing.Furthermore,we selected 164 cases of patients with unilateral cochlear implant surgery and the 5th years of hearing speech rehabilitation effect assessment after CI,used the correlation test determine the correlation between cochlear nerve cross-sectional area and auditory and speech rehabilitation effect after CI.The 164 patients were further grouped according to the mean cross-sectional area of the cochlear nerve.Independent sample T test was used to compare whether there were differences in auditory and speech rehabilitation effects in patients with different cochlear nerve cross-sectional areas after CI.In addition,we selected 136 cases in patients with bilateral cochlear implants,analyzed the dynamic auditory and speech rehabilitation effect in 2 years after CI,Compared its correlation with the cochlear nerve cross-sectional area.Furthermore,the average cross-sectional area of bilateral cochlear nerve was used as grouping basis to compare the difference of auditory and speech rehabilitation effect of patients with different cross-sectional area of bilateral cochlear nerve after CI.Results:1.In 221 patients,there were no statistically significant differences in the cochlear nerve cross-sectional area,cochlear neural tube width and internal auditory canal width among different genders and left and right sides（P>0.05）,and also no correlation with age（P>0.05）.2.There were statistical differences in the cochlear nerve cross-sectional area,cochlear neural tube width and internal auditory canal width between the deaf group and the normal hearing group（P<0.05）,and the deaf group was less than the normal hearing group.3.There was a correlation between cochlear nerve cross-sectional area,cochlear neural tube width and internal auditory canal width of patients with the deaf group（P<0.05）.When the width of the cochlear neural tube was less than 0.71mm or the width of the internal auditory canal was less than 3.31mm,the possibility of cochlear nerve loss was higher.When the width of internal auditory canal is less than 2.98mm,the possibility of atresia of cochlear neural tube is higher.4.In 164 patients with unilateral cochlear implantation,the cross-sectional area of the cochlear nerve was negatively correlated with the hearing threshold after CI,and positively correlated with the scores of CAP,SIR,the recognition accuracy of spondee words and Chinese standardized short sentences in the middle period after CI.There were significant differences in the scores of CAP,SIR,the recognition accuracy of spondee words and Chinese standardized short sentences in patients with cochlear nerve cross area greater than or equal to 1.01mm~2 and those with cochlear nerve cross area less than 1.01mm~2（P<0.05）,and the former scored higher in all categories.5.136 cases of bilateral sensorineural hearing loss showed that there was a correlation between IT-MAIS,MUSS,CAP,SIR and the cross-sectional area of the cochlear nerve in 2 years after CI.The group A（patients with bilateral cochlear nerves larger than 0.87mm~2）had better postoperative speech rehabilitation effect than the group B（patients with one cochlear nerve larger than 0.87mm~2 and one cochlear nerve smaller than 0.87mm~2）,also had better postoperative speech rehabilitation effect than the group C（patients with both cochlear nerves smaller than 0.87mm~2）.Conclusions:1.The cochlear nerve cross-sectional area,cochlear neural tube width and internal auditory canal width were not correlated with gender and age.The cross-sectional area of the cochlear nerve,the width of the cochlear nerve tube and the width of the internal auditory canal in the patients with severe and very severe sensorineural hearing loss were smaller than those in the hearing normal people,and there was a correlation among the three.2.The auditory and speech rehabilitation effect after unilateral CI was positively correlated with the cross-sectional area of the cochlear nerve on the surgical side,and the side with better development of the cochlear nerve should be chosen for the unilateral CI.Patients with cochlear nerve cross-sectional area bigger than or equal to1.01mm~2 had better auditory and speech rehabilitation over 5 years after CI than those with cochlear nerve cross-sectional area less than 1.01mm~2.3.Bilateral cochlear implantation should be recommended for patients with double severe and very severe sensorineural hearing loss with bilateral cross-sectional area of cochlear nerves both bigger than 0.87mm~2 in order to obtain better hearing and speech rehabilitation effect.