Amplitude Of Low-frequency Fluctuation And Functional Connectivity For Auditory And Language-related Cortex In Infants With Congenital Sensorineural Hearing Loss

Part I The study of amplitude of low-frequency fluctuation for auditory and language-related cortex in infants with congenital sensorineural hearing loss Objective:To investigate the change of ALFF value for auditory and language-related cortex in infants aging6-48months with profoundly congenital sensorineural hearing loss.Materials and Methods:Totally34infants with bilateral profoundly congenital sensorineural hearing loss and20age-matched contrast with normal hearing were recruited in our study. They were divided into4groups according to the sensitive period of brain development. Group Ⅰ:17subjects aging6-24months with hearing loss, Group II:8subjects aging24-48months with normal hearing, GroupⅢ:17subjects aging24-48months with hearing loss, GroupⅣ:12subjects aging24-48months with normal hearing. All subjects were performed FSE T1WI, T2WI, GRE-EPI and high-resolution3D MP-RAGE TIWI by Simens3.0T MRI scanner. Parameters of GRE-EPI sequence were TR/TE3000ms,30ms, slice thickness5mm, slice interspace0mm, slice number38, FOV220x220mm, flip angle90°, matrix64X64,230frames and8740images were scaned, total scan time11mins. Parameters of MP-RAGE sequence were TR/TE1900/2.53ms, FOV250X250mm, flip angle9°, matrix256×256, slice thickness lmm, slice interspace0mm, slice number160, total scan time4mins. SPM8software was used to preprocess fMRI data, ALFF values were calculated by REST software and two-sample t test was performed between Group I and III, Group II and IV, Group I and II, Group Ⅲ and Ⅳ, the inter-group discrepancy is significant when P value is less than0.01(uncorrected), cluster size more than10voxels.Results:Compared with Group Ⅲ, ALFF value of right BA22area, bilateral middle frontal gyrus and superior temporal gyrus, right middle temporal gyrus show decreased, and ALFF value of right middle frontal gyrus and middle occipital gyrus, bilateral superior parietal gyrus show increased in group Ⅰ. Compared with Group IV, ALFF value of right BA22area, bilateral middle frontal gyrus, right superior temporal gyrus, left angular gyrus show decreased, and ALFF value of left inferior occipital gyrus, show increased in group Ⅱ. Compared with Group Ⅱ, ALFF value of left BA41, BA22area, middle frontal gyrus, inferior frontal gyrus, superior temporal gyrus,1show decreased, and ALFF value of bilateral superior parietal gyrus, show increased in group I. Compared with Group IV, ALFF value of bilateral middle frontal gyrus, left inferior frontal gyrus, bilateral superior temporal gyrus, left middle temporal gyrus show decreased in groupIV.Conclusion:ALFF value of right BA22area and part language-related cortex showed decreased, and with the extent of of hearing loss duration, ALFF value of left auditory cortex and language-related cortex gradually increased, which indicated the hearing rehabilitation after cochlear implantation in infants with profoundly congenital sensorineural hearing loss, older than24months was not so satisfied due to the functional reorganization of auditory cortex and language-related cortex. Moreover, ALFF value of the language-related cortex in the control group with normal hearing showed gradually increasing with age extending, which consistent with the language development process.Part Ⅱ Functional connectivity between auditory, language-related cortex and whole brain in infants with congenital sensorineural hearing loss Objective:To investigate changes of functional connectivity between auditory, language-related cortex and whole brain in infants between6-48months of different age stage with profoundly congenital sensorineural hearing loss under sedation.Materials and Methods:The experimental objects and acquisition sequences were same as Part Ⅰ. SPM8software was used to preprocess fMRI data, then extract the time sequence of90brain regions in every infants, build matrix of90*90, every element in the matrix was just coefficient r, next Fisher change, z=0.5×log[(1+r)/(1-r)], collect4005(90*89/2) pieces of connectivity. Two-sample t test was performed between Group I and III, Group II and IV, Group I and II, GroupⅢand IV, the inter-group discrepancy is significant when P value is less than0.01(FDR corrected).Results:compared with the normal control, infants with profoundly congenital sensorineural hearing loss under sedation, the functional connectivity between auditory/language-related cortex and somatic sensation, visual cortex, basal ganglia and part of default mode network changed, and showed decreasing with the extent of the duration of hearing loss.Conclusion:Hearing deprivation influence the functional connectivity between auditory/language-related cortex and sensation, visual functional cortex, and the connectivity decreased with the extent of the duration of hearing loss.