Vibra-tactile FMRI And Functional Connectivity For Auditory And Language-related Cortex In Infants With Congenital Sensorineural Hearing Loss

Objective:To investigate feasibility of vibra-tactile fMRI for auditory and language-related cortex in infants with profoundly congenital sensorineural hearing loss. To investigate changes of functional connectivity between auditory and language-related cortex in infants of different age younger than 4 years old with profoundly congenital sensorineural hearing loss in sleep state using MRI.Materials and Methods:38 infants with bilateral profoundly congenital sensorineural hearing loss were included in our study. The age was from 6-48 months. The result of ABR was more than 91dBnHL.15 infants with bilateral profoundly congenital sensorineural hearing loss had cochlear implantation,12 of them had been followed up,5 aged from 24-48 months. They were divided into 3 groups according to cerebral hyperplasia. GroupⅠaged from 0 to 12 months(12months included), including 10 subjects. GroupⅡaged from 12 to 24 months(24months included), including 14 subjects. GroupⅢaged from 24 to 48 months, including 14 subjects.3 subjects with normal hearing and 2 subjects with wild hearing loss, the result of ABR was 50dBnHL aged from 7-48months. None of subjects had mental disease and dysplasia of the central nervous system. All subjects were performed anatomical T1WI, EPI and high-resolution 3D GRE T1WI by Marconi Eclipse 1.5T MRI scanner. Parameters of EPI sequence were slice thickness 5 mm, Slice interspace 0mm, slice number 20, FOV 24cm×24cm, Flip angle 90°, TR 2000 ms, TE 40 ms.70 frames and 1400 images were scaned. Total scan time was 140 seconds. All subjects were given the vibra-tactile stimulation of block mode on the right ankle. AFNI software was used to process fMRI data. Activated frequency of primary and secondary auditory cortex were compared by chi square test. Activated voxels size of auditory and language-related cortex between deaf and control group were compared by SPSS13.0 software. Choose deaf infants profoundly congenital sensorineural hearing loss who belong to partⅠ. All subjects were performed anatomical T1WI, EPI sequence and high-resolution 3D GRE T1WI by Marconi Eclipse 1.5T MRI scanner. Parameters of EPI sequence: Slice thickness 5 mm, Slice interspace 0.5mm, slice number 20, FOV 240 mm×240 mm, Flip angle 90°,TR 2000 ms, TE 40 ms,180 frames 3600 images were scaned, total scan time was 360 seconds. Coefficient R of functional connectivity between auditory and language-related cortex were calculated by SPM5 and REST software.Coefficient R among three groups were compared by SPSS13.0 software. There were significant difference in coefficient R of functional connectivity among three deaf groups between right secondary auditory cortex and right middle frontal gyrus, between right secondary auditory cortex and left inferior frontal gyrus(P<0.05). Coefficient R of functional connectivity of groupⅢaged from 24 to 48 months were lower than groupⅠandⅡaged from 0 to 24 months(24months included). There was no significant difference in coefficient R of functional connectivity between left auditory cortex and bilateral language-related cortex, between right primary auditory cortex and bilateral language-related cortex among three groups (P>0.05).Results:Auditory and language-related cortex were activated in vibra-tactile fMRI. Auditory cortex included primary (BA41), secondary auditory cortex (BA42,22). There was no significant difference in activated frequency of primary and secondary auditory cortex between deaf groups and control group. There was significant difference between deaf groups and control group in activated voxels of auditory cortex, in which deaf groups were more than control group(P<0.05). There was significant difference among three deaf groups in activated voxels of auditory cortex(P<0.05), in which GroupⅠandⅡwere less than groupⅢand no significant difference between groupⅠandⅡ(P>0.05). The size of Activated voxels in primary (BA41), secondary auditory cortex (BA42,22) were compared among three deaf groups. There was no significant difference among three groups in size of activated voxels of BA41 and BA42(P>0.05), however there was significant difference in size of activated voxels of BA22 among three deaf groups, in which GroupⅠandⅡwas less than groupⅢ(P<0.05). In vibra-tactile fMRI study, language-related cortex were activated. Language-related cortex included angular gyrus, middle frontal gyrus, inferior frontal gyrus, superior temporal gyrus, middle temporal gyrus. There was significant difference in the size of activated voxels of language-related cortex between deaf groups and control group, in which GroupⅠ,ⅡandⅣwere less than groupⅢ(P<0.05). There was no significant difference in the size of activated voxels of language-related cortex among groupⅠ,ⅡandⅣ(P>0.05).12 patients who had received cochlear implantation were followed up half a years later. The life ability recovered to normal level in infants aged younger than 2 years old(24months included), but the life ability recovered to edge level in the ones aged older than 2 years old. These results were accordance with critical period of cerebrum's development and results of follow-up.Conclusion:Vibra-tactile fMRI can be used for auditory and language-related cortex in infants of different ages younger than 4 years old with profoundly congenital sensorineural hearing loss. Functional connectivity were decreased in groupⅢaged older than 2 years old between the left and right secondary auditory cortex, between right secondary auditory cortex and right middle frontal gyrus, between right secondary auditory cortex and left inferior frontal gyrus in in the ones aged older than 2 years old with profoundly congenital sensorineural hearing loss, which may result from function reorganization of auditory and language-related cortex in infants aged older than 2 years old.