An FMRI Study Of Cerebral Functional Cortex In Infants Congenital Hearing Loss

Objective:To observe activation of the auditory cortex and the Broca's cortex with functional magnetic resonance imaging(fMRI) after given vibrotactile stimulation,to identify the function of the auditory cortex in infants with profoundly congenital sensorineural hearing loss.To investigate initially the role of fMRI in pediatric cochlear implantation candidates who were under sedation for evaluation of auditory function.To demonstrate whether the fMRI could be considered a means of assessing residual function in the auditory cortex in infants with profoundly congenital sensorineural hearing loss,and whether fMRI could be translated into a prognostic indicator for outcome after cochlear implantation in prelingual hearing loss infants and toddlers with residual hearing.According to the activation of the cortex to judge the reorganization of cortex in infants after hearing loss.Materials and Methods:19 profoundly congenital hearing loss infants,of whom 10 were male,9 were female,the patients were aged from 12～38 months with the average age was 20.7 months.All infants were bilateral congenital sensorineural hearing loss,the result of the ABR was more than 91 dB.None of the subjects had mental disease and dysplasia of the central nervous system.3 hearing subjects were aged from 7～24 months with the average age was 16.3 months,of whom 2 were male and 1 was female.In this group,the hearing of 2 subjects was normal,and about the hearing of the third subject,the right ear was normal,the ABR result of the left ear was 25dB.All the subjects performed anatomical T1WI,GRE-EPI fMRI with a 1.5T whole body MRI scanner and high-resolution 3D GRE T1WI.All the subjects were given the vibrotactile stimulation on the right leg adjoin with the ankle.In fMRI, block-design paradigm was used.fMRI image analysis was performed using statistical parameter mapping 5(SPM5),activation foci were superposed on high-resolution T1WI.Group and inter-group analysis were performed using the second level analysis of SPM5.Results:After given the vibrotactile stimulation,the brain areas activated in profoundly congenital hearing loss infants were:bilateral transverse temporal gyri, superior temporal gyrus,middle temporal gyrus,inferior temporal gyrus,bilateral precentral gyrus,postcentral gyrus,bilateral paracentral lobule,bilateral middle frontal gyrus,inferior frontal gyrus,bilateral inferior parietal lobule,bilateral occipital lobe,bilateral insular lobe,and bilateral fusiform gyrus and so on.the brain areas activated in control group were:right transverse temporal gyri, superior temporal gyrus,middle temporal gyrus,left middle occipital gyrus,inferior occipital gyrus,lingual gyrus,left thalamus,bilateral middle frontal gyrus and bilateral cuneus.One-sample t test was used in profoundly congenital hearing loss infants and control group,the activated brain areas were:bilateral transverse temporal gyri, superior temporal gyrus,middle temporal gyrus,bilateral insular lobe,bilateral precentral gyrus,postcentral gyrus,bilateral cingulate gyrus,bilateral inferior parietal lobule,bilateral superior parietal lobule,bilateral superior frontal gyrus.The results indicated that the profoundly congenital hearing loss infants had used more brain areas after given vibrotactile stimulation and the intensity was increased.Conclusions:The bilateral primary and secondary auditory cortex were activated in profoundly congenital hearing loss infants,which meant the bilateral auditory cortex also had function;The bilateral tempral lobe had been activated after given vibrotactile stimulation hearing loss infants meant it had integration of touch and sound in auditory cortex and the related brain areas;To compare with the control group,the profoundly congenital hearing loss infants activated more brain areas and bigger intensity,indicated the cortex of the hearing loss infants became more sensitivity.