| Objective; To study the value of imaging in sensorineural hearing loss prospectively.Materials and Methods: 157 patients with sensorineural hearing loss performed high-resolution CT ,plain and contrast MR scan. The sequences of MR included: transverse cranial base GRE T1WI, FSE heavy T2WI, oblique coronal slices T2WI and whole brain T2WI.Results: Among 157 patients with sensorineural hearing loss: mild 9, 1 showed abnormal findings (12%); moderate 30, 6 abnormal(20%); moderate to severe 31,10 abnormal(30%); severe 33 and profound 54, 31 abnormal(36%). Among 70 cases who performed ABR, 53 cases showed normal appearance,37 were cochlear lesions(70%),16 postcochlear lesions (30%). Among 157 patients, cochlear lesions 114,14(12%) abnormal; postcochlear lesions 43, 34 (79%) abnormal, 20 were cochlear nerve lesions, 8 brainstem, 6 cerebral cortex. Among 42 congenital cases, 7(16%) showed abnormal, 4 cochlear, 3 postcochlear. 115 acquired cases,41(35%) showed abnormal findings, 24 drug-induced hearing loss, 9 infected, 4 traumatic, 21 senile, 12 metablic, 13 noise, 32 sudden hearing loss.Conclusion: The lesions which can result in hearing loss included: tumoral,congenital, infection, inner-ear hair-cell lesions and imaging can reliably make diagnosis and differentiation of all kinds of lesions( hair-cell lesions excluded). HRCT mainly show the bone structure such as bony labyrinthine, IAC. MR is very important to evaluate the sensorineural hearing loss which mainly show cranial nerve, ICA, membraneous labyrinthine and cerebral lesions. It is very helpful in differentiating postcochlear lseions but limited in detecting hair-cell lesions. With the degree of hearing loss, it is more helpful and can provide more information for clinician.Part II: The morphological* functional study of auditory cortex in prelingual sensorineural hearing lossObjective: To study the time-dependent changes and mechanisms of auditory cortex in prelingual sensorineural hearing loss. To reveal the laterality of brain between hearing and hearing-loss in order to study the semihemisphere asymmetry is congenital or acquired after exposing to language.Materials and Methods: Two groups (10, 20-year-old ) of hearing-loss patients and hearing subjects received thin-slice anatomical TiWI, MR diffusion, MRS examination. The gray, white matter and total volume of HG,STG,TL were measured, The ROI for ADC measurement were placed on the heschl gyrus(HG), and for NAA/Cr, Cho/Cr on the superior temporal gyrus(STG).Results: There is no statistically difference between 10,20-year-old hearing-loss and hearing about gray, white matter and total volume of bilateral HG, STG, TL (p>0.05) There is also no difference between two groups of ratio of gray to white matter about TL, but there is statistically difference of ratio of gray to white matter about HG between 10,20-year-old hearing-loss and hearing and 20-year-old hearing-loss and hearing about STG (p<0.05) .The left volume of HQSTQTL is statistically larger than that of right between 10,20-year-old hearing-loss patients and hearing subjects (p<0.05) .There was significantly difference of ADC value among hearing,10 , 20-year-old hearing-loss (p<0.05) both left and right HG. There were no statistical difference among groups both in the NAA/Cr and Cho/Cr (p>0.05).Conclusion: Compared to the hearing, there is no obvious changes of volume of HG, STG, TL about 10,20-year-old prelingual hearing-loss patients. The ratio of gray to white matter about HG in 10 ,20-year-old hearing-loss is obviously lager than that of hearing patients. The ratio of gray to white matter about STG in 20-year-old hearing-loss is obviously lager than that of hearing patients but there is no changes in 10-year-old groups.The left semihemisphere volume is statistically larger than that of right between 10,20-year-old hearing-loss patients and hearing subjects.Compared to the hearing, the ADC value increased both in 10 and 20-year-old hearing-loss, and the ADC increasing with longer-time of deafness which indicated the white matter atrophy of HG The NAA/Cr and Cho/Cr of STG had no changes among three groups which indicates the gray matter of STG preserved even in congenital hearing loss.Part III: The functional MR study of auditory cortex in unilateral sensorineural hearing lossObjective: To study the difference of tonotopicity and subcortical area between hearing and unilateral hearing loss patients. To reveal the laterality of functional auditory cortex between hearing and hearing-loss patients. Materials and Methods: 30 hearing subjects and 20 unilateral(10 left, 10 right) hearing -loss received anatomical T1WI, GRE-EPI fMRI with a 1.5T whole body MRI scanner and high-resolution 3D GRE T1WI. Experimental tasks include randomly pure-sound of 500Hz,4000Hz stimulating. Following block design, 4 trial blocks and 5 contrast blocks were performed alternatively. Realigning, normalizing and smoothing were performed using AFNI for fMRI data, activation... |
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